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Type 3c diabetes mellitus (T3cDM), also known as pancreatogenic diabetes, refers to diabetes caused by disease of the exocrine pancreas. T3cDM is not commonly recognised by clinicians and frequently it is misclassified as T1DM, or more commonly, T2DM. T3cDM can be difficult to distinguish from T1DM and T2DM, and it often co-exists with the latter. The aim of this review is to describe T3cDM, along with its complications, diagnosis and management. We focus on the nutritional implications of T3cDM for those with chronic pancreatitis, and provide a practical guide to the nutritional management of this condition., Author(s): S N Duggan [sup.1] , N Ewald [sup.2] , L Kelleher [sup.3] , O Griffin [sup.1] , J Gibney [sup.4] , K C Conlon [sup.1] Author Affiliations: (1) Department [...]

Wastewater treatment plants (WWTPs) have been described as key contributors of microplastics (MPs) to aquatic systems, yet temporal fluctuations in MP concentrations and loads downstream are underexplored. This study investigated how different sampling frequencies (hourly, weekly, and monthly) affect MP estimates in a stream linked to a single WWTP. Utilizing fluorescence microscopy and Raman spectroscopy, considerable hourly variations in MP concentrations were discovered, while the polymer composition remained consistent. This temporal variability in MP loads was influenced by MP concentration, discharge rates, or a mix of both. These results show a high uncertainty, as relying on sparse snapshot samples combined with annual discharge data led to significant uncertainties in MP load estimates (over- and/or underestimation of emissions by 3.8 billion MPs annually at this site). Our findings stress the necessity of higher-frequency sampling for better comprehending the hydrodynamic factors influencing MP transport. This improved understanding enables a more accurate quantification of MP dynamics, crucial for downstream impact assessments. Therefore, preliminary reconnaissance campaigns are essential for designing extended, representative site-monitoring programs and ensuring more precise trend predictions on a larger scale., Competing Interests: The authors declare no competing financial interest., (© 2024 The Authors. Published by American Chemical Society.)

Objectives: Rapid Access Chest Pain Clinics (RACPCs) provide safe and efficient follow-up for outpatients presenting with new-onset chest pain. RACPC delivery by telehealth has not been reported. We sought to evaluate a telehealth RACPC established during the coronavirus disease 2019 (COVID-19) pandemic. There was a need to reduce the frequency of additional testing arranged by the RACPC during this time, and the safety of this approach was also explored. Methods: This was a prospective evaluation of a cohort of RACPC patients reviewed by telehealth during the COVID-19 pandemic compared with a historical control group of face-to-face consultations. The main outcomes included emergency department re-presentation at 30 days and 12 months, major adverse cardiovascular events at 12 months, and patient satisfaction scores. Results: One hundred forty patients seen in the telehealth clinic were compared with 1,479 in-person RACPC controls. Baseline demographics were similar; however, telehealth patients were less likely to have a normal prereferral electrocardiogram than RACPC controls (81.4% vs. 88.1%, p  = 0.03). Additional testing was ordered less often for telehealth patients (35.0% vs. 80.7%, p < 0.001). Rates of adverse cardiovascular events were low in both groups. One hundred twenty (85.7%) patients reported being satisfied or highly satisfied with the telehealth clinic service. Conclusions: In the setting of COVID-19, a telehealth RACPC model with reduced use of additional testing facilitated social distancing and achieved clinical outcomes equivalent to a face-to-face RACPC control. Telehealth may have an ongoing role beyond the pandemic, supporting specialist chest pain assessment for rural and remote communities. Pending further study, it may be safe to reduce the frequency of additional testing following RACPC review.

While microplastic inputs into rivers are assumed to be correlated with anthropogenic activities and to accumulate towards the sea, the impacts of water management on downstream microplastic transport are largely unexplored. A comparative study of microplastic abundance in Boulder Creek (BC), and its less urbanized tributary South Boulder Creek (SBC), (Colorado USA), characterized the downstream evolution of microplastics in surface water and sediments, evaluating the effects of urbanization and flow diversions on the up-to-downstream profiles of microplastic concentrations and loads. Water and sediment samples were collected from 21 locations along both rivers and microplastic properties determined by fluorescence microscopy and Raman spectroscopy. The degree of catchment urbanization affected microplastic patterns, as evidenced by greater water and sediment concentrations and loads in BC than the less densely populated SBC, which is consistent with the differences in the degree of urbanization between both catchments. Microplastic removal through flow diversions was quantified, showing that water diversions removed over 500 microplastic particles per second from the river, and caused stepwise reductions of downstream loads at diversion points. This redistribution of microplastics back into the catchment should be considered in large scale models quantifying plastic fate and transport to the oceans., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

While microplastics (MP) have been found in aquatic ecosystems around the world, the understanding of drivers and controls of their occurrence and distribution have yet to be determined. In particular, their fate and transport in river catchments and networks are still poorly understood. We identified MP concentrations in water and streambed sediment at fifteen locations across the Neuse River Basin in North Carolina, USA. Water samples were collected with two different mesh sizes, a trawl net (>335 μm) and a 64 μm sieve used to filter bailing water samples. MPs >335 μm were found in all the water samples with concentrations ranging from 0.02 to 221 particles per m 3 (p m -3 ) with a median of 0.44 p m -3 . The highest concentrations were observed in urban streams and there was a significant correlation between streamflow and MP concentration in the most urbanized locations. Fourier Transform Infrared (FTIR) analysis indicated that for MPs >335 μm the three most common polymer types were polyethylene, polypropylene, and polystyrene. There were substantially more MP particles observed when samples were analyzed using a smaller mesh size (>64 μm), with concentrations ranging from 20 to 130 p m -3 and the most common polymer type being polyethylene terephthalate as identified by Raman spectroscopy. The ratio of MP concentrations (64 μm to 335 μm) ranged from 35 to 375, indicating the 335 μm mesh substantially underestimates MPs relative to the 64 μm mesh. MPs were detected in 14/15 sediment samples. Sediment and water column concentrations were not correlated. We estimate MP (>64 μm) loading from the Neuse River watershed to be 230 billion particles per year. The findings of this study help to better understand how MPs are spatially distributed and transported through a river basin and how MP concentrations are impacted by land cover, hydrology, and sampling method., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Authors. Published by Elsevier B.V. All rights reserved.)

The Okavango Panhandle is the main influent watercourse of the Okavango Delta, an inland sink of the entire sediment load of the Cubango-Okavango River Basin (CORB). The sources of pollution in the CORB, and other endorheic basins, are largely understudied when compared to exorheic systems and the world's oceans. We present the first study of the distribution of microplastic (MP) pollution in surface sediments of the Okavango Panhandle in Northern Botswana. MP concentrations (64 μm-5 mm size range) in sediment samples from the Panhandle range between 56.7 and 399.5 particles kg -1 (dry weight) when analysed with fluorescence microscopy. The concentrations of MP in the 20 μm to 5 mm grain size range (analysed with Raman spectroscopy) range between 1075.7 and 1756.3 particles kg -1 . One shallow core (15 cm long) from an oxbow lake suggests that MP size decreases with depth while MP concentration increases downcore. Raman Spectroscopy revealed that the compositions of the MP are dominated by polyethene terephthalate (PET), polypropylene (PP), polyethene (PE), polystyrene (PS), and polyvinyl chloride (PVC). From this novel data set it was possible to estimate that 10.9-336.2 billion particles could be transported into the Okavango Delta annually, indicating that the region represents a significant sink for MP, raising concerns for the unique wetland ecosystem., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Fulvio Franchi reports financial support was provided by Permanent Okavango River Basin Water Commission. Stefan Krause reports financial support was provided by Leverhulme Trust. Uwe Schneidewind reports financial support was provided by German Research Foundation., (Copyright © 2023 The Authors. Published by Elsevier B.V. All rights reserved.)

We present here a technique for setting up detection limits on any fluorescent microscope in conjunction with the fluorophore Nile Red for microplastic identification. Our method also describes a rigorous morphology-specific identification key for microplastics to reduce subjectivity between researchers. The detection limits were established for nine common polymer types and five natural substrates which could result in false-positive signals when using Nile Red for microplastic identification. This method was then applied to real freshwater samples and identified particles were validated with micro-FTIR or Raman spectroscopy. This approach may reduce subjectivity in microplastic identification and counting and enhances transparency, repeatability and harmonization within microplastic research community.•Instructions for calibration of detection limits for microplastics on fluorescence microscope systems described•Microplastic identification key developed and tested to reduce false positive detection•Lower subjectivity for microplastic identification obtained using the detection limits & identification key., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2023 The Author(s).)

The study of ocular manifestations of neurodegenerative disorders, Oculomics, is a growing field of investigation for early diagnostics, enabling structural and chemical biomarkers to be monitored overtime to predict prognosis. Traumatic brain injury (TBI) triggers a cascade of events harmful to the brain, which can lead to neurodegeneration. TBI, termed the "silent epidemic" is becoming a leading cause of death and disability worldwide. There is currently no effective diagnostic tool for TBI, and yet, early-intervention is known to considerably shorten hospital stays, improve outcomes, fasten neurological recovery and lower mortality rates, highlighting the unmet need for techniques capable of rapid and accurate point-of-care diagnostics, implemented in the earliest stages. This review focuses on the latest advances in the main neuropathophysiological responses and the achievements and shortfalls of TBI diagnostic methods. Validated and emerging TBI-indicative biomarkers are outlined and linked to ocular neuro-disorders. Methods detecting structural and chemical ocular responses to TBI are categorised along with prospective chemical and physical sensing techniques. Particular attention is drawn to the potential of Raman spectroscopy as a non-invasive sensing of neurological molecular signatures in the ocular projections of the brain, laying the platform for the first tangible path towards alternative point-of-care diagnostic technologies for TBI.

Saliva analysis has been gaining interest as a potential non-invasive source of disease indicative biomarkers due to being a complex biofluid correlating with blood-based constituents on a molecular level. For saliva to cement its usage for analytical applications, it is paramount to gain underpinning molecular knowledge and establish a 'baseline' of the salivary composition in healthy individuals as well as characterize how these factors are impacting its performance as potential analytical biofluid. Here, we have systematically studied the molecular spectral fingerprint of saliva, including the changes associated with gender, age, and time. Via hybrid artificial neural network algorithms and Raman spectroscopy, we have developed a non-destructive molecular profiling approach enabling the assessment of salivary spectral changes yielding the determination of gender and age of the biofluid source. Our classification algorithm successfully identified the gender and age from saliva with high classification accuracy. Discernible spectral molecular 'barcodes' were subsequently constructed for each class and found to primarily stem from amino acid, protein, and lipid changes in saliva. This unique combination of Raman spectroscopy and advanced machine learning techniques lays the platform for a variety of applications in forensics and biosensing., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Crown Copyright © 2021. Published by Elsevier B.V. All rights reserved.)

Background: A progressive reduction in the secretion of pancreatic enzymes in patients with chronic pancreatitis (CP) results in malabsorption and ultimate malnutrition. However, the pathogenesis of malnutrition is multifactorial and other factors such as chronic inflammation, alcohol excess and poor dietary intake all contribute. Patients may restrict their dietary intake due to poor appetite or to avoid gastrointestinal symptoms and abdominal pain. Whilst up to half of patients with chronic pancreatitis are reportedly malnourished, the dietary intake of patients with CP is relatively understudied and has not been systematically reviewed to date., Aim: To perform a systematic review and meta-analysis of the dietary intakes of patients with CP compared to healthy controls, and to compare the dietary intake of patients with alcohol-related CP and non-alcohol-related CP., Methods: A systematic literature search was performed using EMBASE, MEDLINE, and Cochrane review on studies published between 1946 and August 30 th , 2019. Adult subjects with a diagnosis of CP who had undergone dietary assessment were included in the systematic review (qualitative analysis). Studies on patients with other pancreatic diseases or who had undergone pancreatic surgery were not included. Studies comparing the dietary intake of patients with CP to that of healthy controls were included in the meta-analysis (quantitative analysis). Meta-analysis was performed using Review Manager 5.3. Newcastle Ottawa Scale (NOS) was used to assess quality of studies., Results: Of 6715 studies retrieved in the search, 23 were eligible for qualitative analysis while 12 were eligible for quantitative analysis. In the meta-analysis, the total energy (calorie) intake of patients with CP was similar to that of healthy controls [mean difference (MD): 171.3; 95% confidence interval (CI): -226.01, 568.5; P = 0.4], however patients with CP consumed significantly fewer non-alcohol calories than controls [MD: -694.1; 95%CI: -1256.1, (-132.1); P = 0.02]. CP patients consumed more protein, but carbohydrate and fat intakes did not differ significantly. Those with alcohol-related CP consumed more mean (standard deviation) calories than CP patients with a non-alcohol aetiology [2642 (1090) kcal and 1372 (394) kcal, respectively, P = 0.046], as well as more protein, fat, but not carbohydrate., Conclusion: Although patients with CP had similar calorie intake to controls, studies that analysed the contribution of alcohol to energy intake showed that patients with CP consumed fewer non-alcohol calories than healthy controls. A high calorie intake, made up to a large degree by alcohol, may in part contribute to poor nutritional status in CP., Competing Interests: Conflict-of-interest statement: The authors declare no conflicts of interest., (©The Author(s) 2021. Published by Baishideng Publishing Group Inc. All rights reserved.)

Beyond simple identification of either the presence or absence of microplastic particles in the environment, quantitative accuracy has been criticised as being neither comparable nor reproducible. This is, in part, due to difficulties in the identification of synthetic particles amidst naturally occurring organic and inorganic components. The fluorescent stain Nile red has been proposed as a tool to overcome this issue, but to date, has been used without consideration of polymer specific fluorescent variability. The aim of this study was to evaluate the efficacy of Nile red for microplastic detection by systematically investigating what drives variations in particle pixel brightness (PPB). The results showed that PPB varied between polymer type, shape, size, colour and by staining procedure. Sand, an inorganic component of the sample matrix does not fluoresce when stained with Nile red. In contrast the organic components, wood and chitin, fluoresce between 1.40 and 12 arbitrary units (a.u.) and 32 and 74 a.u. after Nile red staining, respectively. These data informed the use of a PPB threshold limit of 100 a.u., which improved the detection of EPS, HDPE, PP and PA-6 from the 6 polymers tested and reduced analysis time by 30-58% compared to unstained samples. Conversely, as with traditional illumination, PET and PVC were not accurately estimated using this approach. This study shows that picking a threshold limit is not arbitrary but rather must be informed by polymer specific fluorescent variability and matrix considerations. This is an essential step needed to facilitate comparability and reproducibility between individual studies., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Some trips are better than others, and more and more studies find that active travel (walking and cycling) is more satisfying than motorized forms of travel (using the car or public transport). Why is this the case? Using data on travel satisfaction from 4134 commutes to a large University campus in Dublin, Ireland, this paper replicates the differences in travel satisfaction between active and motorized travel. We attribute these differences in large part to the duration of the trip. Subjective trip characteristics, such as safety and convenience, also play important roles. The trip duration explains rush-hour effects as well as why people starting from less affluent and more difficult-to-reach places are less satisfied with their trips. Longer-term policy options suggested by these results include infrastructure developments and spatial development strategies. A shorter-term initiative would be to delay university schedules in the morning to avoid low travel satisfaction during the slow rush-hour period and simultaneously ease pressure on the transport network at peak times., (© 2020 Elsevier Ltd. All rights reserved.)

Background: Gait analysis is the study of human locomotion. In massage therapy, this observation is part of an assessment process that informs treatment planning. Massage therapy students must apply the theory of gait assessment to simulated patients. At Humber College, the gait assessment module traditionally consists of a textbook reading and a three-hour, in-class session in which students perform gait assessment on each other. In 2015, Humber College acquired a three-dimensional motion capture system., Purpose: The purpose was to evaluate the use of 3D motion capture in a gait assessment module compared to the traditional gait assessment module., Participants: Semester 2 massage therapy students who were enrolled in Massage Theory 2 (n = 38)., Research Design: Quasi-experimental, wait-list comparison study., Intervention: The intervention group participated in an in-class session with a Qualisys motion capture system., Main Outcome Measures: The outcomes included knowledge and application of gait assessment theory as measured by quizzes, and students' satisfaction as measured through a questionnaire., Results: There were no statistically significant differences in baseline and post-module knowledge between both groups (pre-module: p = .46; post-module: p = .63). There was also no difference between groups on the final application question ( p = .13). The intervention group enjoyed the in-class session because they could visualize the content, whereas the comparison group enjoyed the interactivity of the session. The intervention group recommended adding the assessment of gait on their classmates to their experience. Both groups noted more time was needed for the gait assessment module., Conclusions: Based on the results of this study, it is recommended that the gait assessment module combine both the traditional in-class session and the 3D motion capture system., Competing Interests: CONFLICT OF INTEREST NOTIFICATION The authors declare there are no conflicts of interest.

ZnO nanorods are used in devices including field effects transistors, piezoelectric transducers, optoelectronics and gas sensors. However, for efficient and reproducible device operation and contact behaviour, surface contaminants must be removed or controlled. Here we use low doses of argon bombardment to remove surface contamination and make reproducible lower resistance contacts. Higher doses strip the surface of the nanorods allowing intrinsic surface measurements through a cross section of the material. Photoluminescence finds that the defect distribution is higher at the near-surface, falling away in to the bulk. Contacts to the n-type defect-rich surface are near-Ohmic, whereas stripping away the surface layers allows more rectifying Schottky contacts to be formed. The ability to select the contact type to ZnO nanorods offers a new way to customize device behaviour.

A wide range of statutory and non-statutory child protection and family support services exist to prevent the occurrence or re-occurrence of maltreatment. They may be oriented towards primary, secondary or tertiary levels of prevention, employ various types of professional and/or paraprofessional workers, and target a diverse range of groups. The purpose of this study was to examine the experiences of parents who were directed by child protection authorities to attend a tertiary level child protection and family enhancement program. In depth unstructured interviews were used to gather data about these parents' experience. Thematic content analysis of these transcripts identified four major themes as follows: 1) It's a good place to be: Participation as an affordable social outlet; 2) Learning about kids: Participation as a source of learning; 3) They are there for me: Participation as a source of practical help and support; and, 4) I am a good mother: Participation as a source of tension and conflict. Participants' perceptions of friendship with workers emerged as the most significant and valued aspect of their experience. These feelings of friendship were tested when staff undertook their mandatory reporting role. Feelings of betrayal arose that challenged the women's previous unconditional feelings of trust, and jeopardized the therapeutic relationships that had been established.

A descriptive comparative design was used to evaluate the Cottage Community Care Pilot Project, a family support/child protection initiative linking trained volunteers with "vulnerable" first-time parents. Fifty-eight eligible and consenting families enrolled in the program and formed the intervention group. A further 35 eligible families consented to participate in the evaluation and received assessments only and formed the comparison group. No differences were evident between the intervention and comparison groups on parenting readiness. For the intervention group (n = 25), improvements occurred in seven aspects of family functioning (items on the Scale of Family Functioning) when contrasted to the comparison group (n = 24). Two areas of family functioning were found to be statistically significant: access to social support (p = 0.02) and age appropriate expectations of infants (p < 0.001). Participants reported satisfaction with the program, and the study emphasized the need to include all families, not just those at risk. This evaluation supports the continued development of volunteer-support programs and the active role that public health nurses play in the growth and development of children in our communities.

A brief overview regarding the quality control testing of the Sabin oral polio vaccine is provided. Product testing procedures and specifications are established through product license agreements between the vaccine manufacturer and the FDA Center for Biologics Evaluation and Research. The manufacture and testing of ORIMUNE is a multi-stage process that is closely monitored by the FDA following explicit protocols and requires extensive quality control testing at various stages.

Objectives: To determine the associations between the suppression of HIV-1 long terminal repeat (LTR)-mediated gene expression by CD8+ T-cell supernatants and clinical correlates of well-being, including CD4+ and CD8+ T-cell counts, beta-chemokine production and clinical stage of disease., Methods: Culture supernatants of activated CD8+ T cells derived from a panel of HIV-1-infected subjects were assessed for their ability to suppress HIV-1 LTR-mediated chloramphenicol acetyl transferase (CAT) expression. The percentage suppression of gene expression was correlated with CD4+ and CD8+ T-cell counts and clinical stage of infection. Some individuals within this group were followed at 2-3 month intervals over time to assess the consistency of the suppression. Selected CD8+ T-cell culture supernatants of diverse suppressive ability were screened for the levels of the beta-chemokines macrophage inflammatory protein (MIP)-1 alpha, MIP-1 beta and RANTES., Results: The ability of CD8+ T cells of HIV-1 infected subjects to suppress HIV-1 LTR-mediated gene expression did not show a dependence upon high CD4+ T-cell counts or on the clinical stage or duration of infection. The ability to suppress gene expression did show a relationship with higher CD8+ T-cell counts and correlated with the levels of beta-chemokines in the culture supernatants. In contrast, strong suppression was mediated by CD8+ T-cell supernatants from some subjects with very low CD8+ T-cell counts and relatively low chemokine levels., Conclusions: Although the suppression of gene expression by CD8+ T-cell culture supernatants showed statistical correlation with beta-chemokine levels and with higher CD8+ T-cell count, no correlation could be found with correlates of clinical well-being.

Information was sought on the relative extent to which transport-defective, methotrexate-resistant phenotypes emerge among the total subpopulation of resistant phenotypes during therapeutic challenge of leukemic cells in vivo. A number of monoclonal methotrexate-resistant sublines of the L1210 leukemia were derived during methotrexate therapy of leukemic mice and biochemically characterized. Of the total number of 14 sublines derived, five exhibited altered [3H]methotrexate transport alone, five exhibited increased dihydrofolate reductase content alone (2- to 18-fold), and four showed alterations in both of these properties. Methotrexate binding and substrate turnover rate for dihydrofolate reductase appeared to be unchanged in any of the resistant sublines. The relative resistance of each subline was accounted for by the biochemical alterations observed. Among the transport-defective sublines, one subcategory showed a 3- to 4-fold reduction in apparent influx Vmax for [3H]methotrexate, a second category showed both a 5-fold reduction in influx Vmax and a 3-fold increase in the apparent influx Km, and one subline showed only a 2-fold increase in Km. Otherwise, Michaelis-Menten saturation kinetics for influx was observed in each case and in the case of the parental line and the other resistant sublines. None of the resistant sublines exhibited altered efflux of [3H]methotrexate. Steady-state levels measured for intracellular exchangeable (osmotically active) fractions of drug accurately reflected the values for specific kinetic parameters determined for each sensitive and resistant cell line. These studies show that transport-defective phenotypes represent a major category of methotrexate-resistant cell types which emerge initially from leukemic cell populations under therapy in mice. Based on considerations discussed here, it is reasonable to assume that a similar relative occurrence of this phenotype would result during methotrexate therapy of leukemia patients.

The M5076 murine "ovarian" tumor which is naturally refractive to methotrexate was found to be highly responsive to the lipophilic antifolate, metoprine. M5076 cells were markedly deficient in mediated entry of methotrexate. This was in contrast to the L1210 leukemia, a tumor highly responsive to methotrexate but poorly responsive to metoprine. Two L1210 leukemia sublines, with acquired resistance to methotrexate by virtue of a deficiency in mediated entry of drug similar to that seen for M5076 cells, were found to be collaterally sensitive to metoprine. The insensitivity to methotrexate of the M5076 tumor and the two L1210 sublines is associated with low saturability (high Km) and reduced capacity (low Vmax) for mediated influx of drug. 5-Methyltetrahydrofolate, the major circulating folate in blood but not metoprine, shares this mediated route for entry. Therefore, a relatively low level of accumulation of this natural folate in these methotrexate-resistant tumors, in the face of a metoprine-induced blockade at the level of dihydrofolate reductase, probably accounts for the high sensitivity of these tumors to this lipophilic agent. Evidence for this notion was derived during transport and growth experiments in vitro using 5-formyltetrahydrofolate as a model folate coenzyme. The value for influx Vmax of this folate compound in a transport-deficient methotrexate-resistant subline compared to the parental L1210 was reduced to the same extent as that shown for methotrexate. Growth of this resistant L1210 subline showed a greater requirement for this model compound than did the parental line. Also, the concentration necessary for 50% inhibition by metoprine in the presence of this reduced folate was lower in the resistant subline. Inhibition of each cell line by metoprine, on the other hand, was the same when folic acid was used as the folate source. The implications of these findings for the use of lipophilic antifolates as alternative therapy for some methotrexate-resistant tumors are discussed.