Gynecological sarcomas, surgical management: primary, metastatic, and recurrent disease.

Adult-type gynecological soft tissue and visceral sarcomas are rare tumors, with an estimated incidence of 13% of all sarcomas and 4% of all gynecological malignancies. They most often develop in the uterus (83%), followed by the ovaries (8%), vulva and vagina (5%), and other gynecological organs (2%). The objective of this review is to provide an overview of the current management of gynecological sarcomas, according to international guidelines. The management of gynecological sarcomas should follow the recommendations for the management of soft tissue and visceral sarcomas. Centralizing cases in expert centers improves patient survival, both for the diagnostic phase and for multidisciplinary therapeutic management. In the case of pelvic soft tissue sarcomas, a radiological biopsy is essential before any surgical decision is taken. In the case of a myometrial tumour which may correspond to a sarcoma, if conservative surgery such as myomectomy or morcellation is planned, an ultrasound-guided biopsy with pathological analysis including comparative genomic hybridization analysis must be carried out. In all cases, en bloc surgery, without rupture, is mandatory. Many rare histological subtypes require specific surgical management.

Intraepithelial tumor-infiltrating lymphocytes shape loco-regional PET/CT spread of locally advanced cervical cancer.

BACKGROUND: Data suggest an association between positron emission tomography/CT (PET/CT) metabolic metrics and tumor microenvironment in several malignancies, and a potential role of PET/CT to monitor response to immunotherapy. OBJECTIVE: To evaluate the correlation between tumor loco-regional extension and tumor-infiltrating lymphocyte infiltration in locally advanced cervical cancer prior to concurrent chemo-radiotherapy.The secondary objective was to assess the association between tumor-infiltrating lymphocytes and PET/CT metabolic metrics. METHODS: Patients with locally advanced cervical cancer and negative para-aortic extensions on PET/CT were included. Two senior nuclear medicine physicians specializing in gynecologic oncology reviewed all PET/CT exams, and extracted tumor maximum standardized uptake value, metabolic tumor volume, and total lesion glycolysis, as well as pelvic lymph node involvement. One senior gynecologic oncology pathologist assessed intraepithelial tumor-infiltrating lymphocytes and stromal tumor-infiltrating lymphocytes. Intraepithelial tumor-infiltrating lymphocytes were categorized following previous studies as <1% and >1%. The cut-off for stromal tumor-infiltrating lymphocytes was chosen empirically: intermediate <60% and high >60%. RESULTS: 86 patients were included. Intraepithelial tumor-infiltrating lymphocytes were not significantly associated with tumor metabolic metrics. Intraepithelial tumor-infiltrating lymphocytes were not significantly associated with maximum standard uptake value (p=0.16), or metabolic tumor volume (p=0.19). Tumors with <1% intraepithelial tumor-infiltrating lymphocytes score were associated with a higher MRI tumor size (≥ median) (63.3% vs 39.3%, p=0.04). Patients with pelvic lymph node uptake were significantly more frequent in patients with high stromal tumor-infiltrating lymphocytes score (≥60%) (61.5% vs 31.7%, p=0.009). CONCLUSIONS: Poor or absent intraepithelial tumor-infiltrating lymphocytes were associated with more advanced disease at diagnosis and larger tumor size. Tumor-infiltrating lymphocytes were not associated with tumor metabolic activity. Intraepithelial and stroma tumor-infiltrating lymphocytes are not redundant and should be assessed separately. Further work is needed to evaluate the association between tumor metabolic profile and immune populations, including different T-cell subtypes for patient selection for immunotherapy strategies.

Eyebrow trichoscopy in leprosy.

BACKGROUND: Trichoscopy is a noninvasive technique based on the analysis of hair structures and the scalp, which allows for early diagnosis of different forms of alopecia. METHODS: We conducted a descriptive cross-sectional study in the Dermatology Department of Hospital Universitario "Dr. José Eleuterio González" in Monterrey, Northeastern Mexico. We included 25 patients with a confirmed diagnosis of leprosy. Ten dermoscopic characteristics were assessed in the eyebrows of these patients. Images of the medial and distal portions of the eyebrows were included. Cohen's kappa coefficient was used for the analysis of coherence between the findings of two dermatologists. RESULTS: Of the 25 patients, 14 were male (56%) and 11 were female (44%), with a median age of 60.28 years (IQR: 40-87). The most common findings in the medial eyebrow included vellus hair (96%) and white-yellowish structureless areas (84%). Furthermore, the most common features of the distal eyebrow included vellus hair (96%), white yellowish structureless areas (92%), and pinpoint white dots (92%). CONCLUSIONS: To the best of our knowledge, this study is the first of its kind to describe trichoscopy findings in different leprosy subtypes and classify them into medial and distal eyebrow findings, which seem to be the most affected areas. Identification of these changes is easier in the distal portion of the eyebrows in every subtype of leprosy. We also discovered new trichoscopic findings in the eyebrows: perifollicular hyperpigmentation and yellow dots.

Is minimally invasive surgical approach a reasonable option in apparent early stage epithelial ovarian cancer restaging? Results from a multicentric retrospective study.

INTRODUCTION: To perform surgical staging of early stage ovarian cancer (EOC), conventional laparoscopy (LS) and robot-assisted laparoscopy (RLS) appear to be reliable procedures compared to open surgery. But oncologicals results with long-term follow up are limited in the literature. The objective of this study is to evaluate the surgical and long-term survival for patients managed by minimally invasive surgery (MIS). MATERIALS AND METHODS: We conducted a multicentric retrospective study in 6 institutions. All patients referred for epithelial EOC (apparent stage I-IIa) managed with LS and RLS were involved. RESULTS: From December 2008 to December 2017, 140 patients were included (109 in LS group and 31 in RLS group). A total of 27 (19.2 %) patients were upstaged to an advanced ovarian cancer (FIGO stage > IIA), and 73 % of patients received chemotherapy. Mean operative time was 265,8 ± 88,4 min and significantly longer in RLS group (LS = 254,5 ± 86,8; RLS = 305,6 ± 85,5; p = 0,008). Rate of severe post-operative complications (grade 3) was 5,7 %. Thirteen conversion to laparotomy occurred, including one per-operative hemorrhaege. After a mean follow-up of 60,7 months, 29 (20.7 %) patients recurred, with a time to recurrence was >24 months in 51,7 % of cases. Overall survival (OS) was 88.6 % and disease-free survival (DFS) was 79.3 %. Oncologic outcomes were similar between LS and RLS group (OS: p = 0,504 and DFS: p = 0,213). CONCLUSION: Surgical staging of EOC by LS or RLS approach has long-term equivalent surgical and oncological approach. These results seem to be equivalent to open surgery according to literature review.

Risk factors associated with intraventricular hemorrhage in very-low-birth-weight premature infants.

PURPOSE: To analyze the association between risk factors and severe intraventricular hemorrhage (grade II-IV) in PNB under 1500 g. METHODS: Multicenter, retrospective, analytical, case-control study in PNB under 34 weeks and under 1500 g admitted to the NICU. CASE: PNB with severe intraventricular hemorrhage (grade II-IV). Logistic regression analysis was used to adjust for IVH-associated variables and odds ratios (OR). RESULTS: A total of 90 PNB files were analyzed, 45 cases and 45 controls. The highest risk factors for severe IVH were lower gestational age (OR 1.3, p < 0.001), perinatal asphyxia (OR 12, p < 0.001), Apgar < 6 at minute 1 and 5 (OR 6.3, p < 0.001). CONCLUSION: Lower gestational age, birth asphyxia, Apgar score lower of 6, and respiratory-type factors are associated with increased risk for severe IVH.

Clinical impact of gender and age at onset on disease trajectory in primary progressive multiple sclerosis patients.

BACKGROUND AND OBJECTIVES: Primary-progressive multiple sclerosis (PPMS) is characterized by gradual neurological deterioration without relapses. This study aimed to investigate the clinical impact of gender and age at disease onset on disease progression and disability accumulation in patients with this disease phenotype. METHODS: Secondary data from the RelevarEM registry, a longitudinal database in Argentina, were analyzed. The cohort comprised patients with PPMS who met inclusion criteria. Statistical analysis with multilevel Bayesian robust regression modeling was conducted to assess the associations between gender, age at onset, and Expanded Disability Status Scale (EDSS) score trajectories. RESULTS: We identified 125 patients with a confirmed diagnosis of PPMS encompassing a total of 464 observations. We found no significant differences in EDSS scores after 10 years of disease progression between genders (-0.08; credible interval (CI): -0.60, 0.42). A 20-year difference in age at onset did not show significant differences in EDSS score after 10 years of disease progression (0.281; CI: -0.251, 0.814). Finally, we also did not find any clinically relevant difference between gender EDSS score with a difference of 20 years in age at onset (-0.021; CI: -0.371, 0.319). CONCLUSION: Biological plausibility of gender and age effects does not correlate with clinical impact measured by EDSS score.

Temporal relationship between levetiracetam nonadherence and breakthrough seizures in a preclinical model of temporal lobe epilepsy.

OBJECTIVE: Poor medication adherence remains a concern for individuals managing their epilepsy with antiseizure medicines (ASMs); however, ethical concerns around withholding medication make it impossible to study the causal relationship between missed doses and seizures in patients. Previous preclinical studies from our group suggest that mechanistically distinct ASMs have varying degrees of forgiveness when a dose is missed. However, with only a few ASMs studied in the context of nonadherence, we sought to expand on previous work to understand the relationship between levetiracetam (LEV) nonadherence and breakthrough seizures. METHODS: Chronic oral dosing was initiated in rats with established epilepsy via our automated medication-in-food delivery system coupled to 24/7 video-electroencephalographic recording. Baseline seizure burden was established for 4 weeks before enrolling subjects into a 4-week treatment period with LEV in a 100% fully adherent (75 mg/kg four times daily) or 50% variably adherent paradigm. The temporal relationship between missed doses and breakthrough seizures was correlated with LEV plasma and brain concentrations in separate cohorts of animals. RESULTS: Full adherence to LEV significantly improved seizure control by 50% in half of the animals. Poor adherence worsened seizure frequency by 85%, with most rats having more severe seizures that formed in clusters following missed doses. LEV concentrations remained below therapeutic levels (<10 µg/mL) in nonadherent animals, with brain and plasma levels directly correlating with the degree of adherence in a 24-h period. Missed doses of LEV immediately increased the risk of breakthrough seizures; however, this risk was significantly reduced with improved adherence in a 24-h period. SIGNIFICANCE: These findings enhance our understanding of ASM nonadherence in preclinical models, highlighting that the timing of missed doses and their impact on seizures may vary between different ASMs. Notably, LEV demonstrates a robust pharmacokinetic reliance on missed doses leading to breakthrough seizures.

Assessing the dynamics of CO adsorption on Cu(110) using the vdW-DF2 functional and artificial neural networks.

In this work, we revisit the dynamics of carbon monoxide molecular chemisorption on Cu(110) by using quasi-classical trajectory calculations. The molecule-surface interaction is described through an atomistic neural network approach based on Density Functional Theory calculations using a nonlocal exchange-correlation (XC) functional that includes the effect of long-range dispersion forces: vdW-DF2 [Lee et al. Phys. Rev. B, 82, 081101 (2010)]. With this approach, we significantly improve the agreement with experiments with respect to a similar previous study based on a semi-local XC functional. In particular, we obtain excellent agreement with molecular beam experimental data concerning the dependence of the initial sticking probability on surface temperature and impact energy at normal incidence. For off-normal incidence, our results also reproduce two trends observed experimentally: (i) the preferential sticking for molecules impinging parallel to the [1̄10] direction compared to [001] and (ii) the change from positive to negative scaling as the impact energy increases. Nevertheless, understanding the origin of some remaining quantitative discrepancies with experiments requires further investigations.

Minimally Invasive Surgery for Managing Grade IV and V Spondylolisthesis.

Surgical treatment of high-grade spondylolisthesis is controversial and aims at restoring the spinopelvic sagittal balance through complete or partial reduction of the listhesis. Nerve decompression and interbody fusion are necessary for patients presenting with neurological deficit, severe pain, lower limb asymmetry, or deformities. We present the case and the results of a patient with high-grade spondylolisthesis, in whom minimally invasive management was performed. A narrative review in this topic is also provided. We performed a literature review of high-grade spondylolisthesis to compare our technique to current surgical alternatives. We included articles from PubMed, Embase, Scopus, Ovid, and Science Direct published between 1963 and 2022 that were written in English, German, and Spanish. The terms used were the following: "high grade spondylolisthesis," "spondyloptosis," "surgical management," "interbody fusion," and "arthrodesis." In all, 485 articles were displayed, from which we filtered 112 by title and abstract. At the end, 75 references were selected for the review. Different interbody fusion techniques can be used to correct the lumbosacral kyphosis and restore the spinopelvic parameters. A complete reduction of the listhesis is not always required. The surgical procedure carried out in our patient corresponds to the first known case of minimally invasive circumferential arthrodesis with iliac screws and sacral fixation in a high-grade dysplastic spondylolisthesis. This approach guarantees the correction of the lumbosacral kyphosis and a complete reduction of the listhesis. Further studies are required to determine whether the results of this case can be extrapolated to other patients with high-grade spondylolisthesis.

Expression of HIF-1α in pediatric asthmatic patients.

Background: Several studies have suggested that HIF-1α regulates eosinophil activity and induces epithelial inflammation via NF-κB activation in the pathophysiology of asthma. The purpose of this study was to examine the expression of the transcription factors HIF-1α and nuclear HIF in mononuclear cells obtained from peripheral blood samples of healthy pediatric patients, asthmatic patients, and asthmatic exacerbations, regardless of disease severity. Methods: HIF-1 levels were measured using immunocytochemistry in 133 patients aged 6 to 17 years in this crosssectional and comparative study. A microscope was used to examine glass slides, and positive cells were counted in four fields per slide using an image analyzer. Results: HIF-1α and nuclear HIF levels were significantly higher in asthma patients and even higher in patients experiencing asthma attacks (p<0.0001, 95% CI). There was no significant difference in the percentage of HIF-1α expression between groups with intermittent asthma and those with mild persistent asthma, nor between patients with asthma and those experiencing asthma exacerbations. Conclusions: When compared to healthy individuals, the expression of nuclear HIF and HIF-1α is increased in peripheral mononuclear cells in asthma patients and even more so in asthma exacerbations. This suggests that HIF-1α is important in the pathogenesis of this disease.

The Structure-Function Relationship of Branched Polyethylenimine Impregnated over Mesoporous Carbon Aerogels: An In-Depth Thermogravimetric Insight.

We present a comprehensive thermogravimetric analysis (TGA) of polyethylenimine (PEI)-impregnated resorcinol-formaldehyde (RF) aerogels. While numerous studies focus on PEI-impregnated SBA, RF materials have been less examined, despite their interest and specificities. As most articles on PEI-impregnated porous materials follow typical experimental methods defined for SBA, particularities of RF-PEI materials could remain unheeded. The design of nonisothermal TGA protocols, completed with nitrogen isotherms, based on the systematic filling of the matrix delivers a fundamental understanding of the relationship between the structure and function. This study demonstrates (i) the competition between the matrix and PEI for CO2-physisorption (φ) and CO2-chemisorption (χ), (ii) the hysteresis ([Formula: see text]) of CO2 capture at low temperature attributed to the kinetic (K) hindrance of CO2 diffusion (D) through PEI film/plugs limiting the chemisorption, and (iii) the thermodynamic (θ) equilibrium limiting the capture at high temperature. At variance with SBA-PEI materials, the first layers of PEI in RF are readily available for CO2 capture given that this matrix does not covalently bind PEI as SBA. A facile method allows the discrimination between physi- and chemisorption, exhibiting how the former decreases with PEI coverage. The CO2 capture hysteresis, while seldom introduced or discussed, underlines that the commonly accepted operating temperature of the "maximum capture" is based on an incomplete experiment. Through isotherm adsorption analysis, we correlate the evolution of this maximum to the morphological distribution of PEI. This contribution highlights the specificities of RF-PEI and the advantages of our TGA protocol in understanding the structure/function relationship of this kind of material by avoiding the typical direct applications of SBA-specific protocols. The method is straightforward, does not need large-scale facilities, and is applicable to other materials. Its easiness and rapidness are suited to high-volume studies, befitting for the comprehensive evaluation of interacting factors such as the matrix's nature, pore size, and PEI weight.

Unraveling Resistance to Immunotherapy in MSI-High Colorectal Cancer.

Colorectal cancer (CRC) is the third most common cancer and the second leading cause of cancer-related deaths. Incidences of early CRC cases are increasing annually in high-income countries, necessitating effective treatment strategies. Immune checkpoint inhibitors (ICIs) have shown significant clinical efficacy in various cancers, including CRC. However, their effectiveness in CRC is limited to patients with mismatch-repair-deficient (dMMR)/microsatellite instability high (MSI-H) disease, which accounts for about 15% of all localized CRC cases and only 3% to 5% of metastatic CRC cases. However, the varied response among patients, with some showing resistance or primary tumor progression, highlights the need for a deeper understanding of the underlying mechanisms. Elements involved in shaping the response to ICIs, such as tumor microenvironment, immune cells, genetic changes, and the influence of gut microbiota, are not fully understood thus far. This review aims to explore potential resistance or immune-evasion mechanisms to ICIs in dMMR/MSI-H CRC and the cell types involved, as well as possible pitfalls in the diagnosis of this particular subtype.

The Potential of Essential Oils from Active Packaging to Reduce Ethylene Biosynthesis in Plant Products. Part 1: Vegetables (Broccoli and Tomato).

Essential oils (EOs) extracted from plants have a high potential to reduce ethylene biosynthesis, although their effects have not been deeply studied yet on the key components of the ethylene biosynthesis pathway: l-aminocyclopropane-1-carboxylic (ACC) oxidase activity, ACC synthase activity, and ACC content. Hence, the present study aimed to elucidate the effects of released EOs from active packaging (with different EO doses ranging from 100 to 1000 mg m-2) on the ethylene biosynthesis key components of broccoli and tomato under different storage temperature scenarios. The largest ethylene inhibitory effects on broccoli and tomatoes were demonstrated by grapefruit EO and thyme essential EO (up to 63%), respectively, which were more pronounced at higher temperatures. Regarding EO doses, active packaging with a thyme EO dose of 1000 mg m-2 resulted in the strongest reduction (33-38%) of ethylene production in tomatoes. For broccoli, identical results were shown with a lower grapefruit EO dose of 500 mg m-2. The studied EO-active packaging decreased ACC synthase and ACC oxidase activities by 40-50% at 22 °C. Therefore, this EO-active packaging is a natural and effective technology to reduce ethylene biosynthesis in broccoli and tomatoes when they are stored, even in unsuitable scenarios at high temperatures.

The Potential of Essential Oils from Active Packaging to Reduce Ethylene Biosynthesis in Plant Products. Part 2: Fruits (Blueberries and Blackberries).

Plant essential oils (EOs) have an important ability to inhibit ethylene biosynthesis. Nevertheless, the effects of EOs on the key components of ethylene biosynthesis (l-aminocyclopropane-1-carboxylic (ACC) oxidase activity, ACC synthase activity, and ACC content) have not yet been thoroughly studied. Accordingly, this study focused on the effects of emitted EOs from active packaging (EO doses from 100 to 1000 mg m-2) on the key components of ethylene biosynthesis of blueberries and blackberries under several storage temperatures. Anise EO and lemon EO active packaging induced the greatest inhibitory effects (60-76%) on the ethylene production of blueberries and blackberries, respectively, even at high storage temperatures (22 °C). In terms of EO doses, active packaging with 1000 mg m-2 of anise EO or lemon EO led to the highest reduction of ethylene production, respectively. At 22 °C, the investigated EO active packing reduced the activities of ACC synthase and ACC oxidase up to 50%. In order to minimise ethylene biosynthesis in blueberries and blackberries when they are stored even under improper temperature scenarios at high temperatures, this EO active packaging is a natural and efficient technological solution.

ThyroidPrint®: clinical utility for indeterminate thyroid cytology.

Molecular testing contributes to improving the diagnosis of indeterminate thyroid nodules (ITNs). ThyroidPrint® is a ten-gene classifier aimed to rule out malignancy in ITN. Post-validation studies are necessary to determine the real-world clinical benefit of ThyroidPrint® in patients with ITN. A single-center, prospective, noninterventional clinical utility study was performed, analyzing the impact of ThyroidPrint® in the physicians' clinical decisions for ITN. Demographics, nodule characteristics, benign call rates (BCRs), and surgical outcomes were measured. Histopathological data were collected from surgical biopsies of resected nodules. Of 1272 fine-needle aspirations, 109 (8.6%) were Bethesda III and 135 (10.6%) were Bethesda IV. Molecular testing was performed in 155 of 244 ITN (63.5%), of which 104 were classified as benign (BCR of 67.1%). After a median follow-up of 15 months, 103 of 104 (99.0%) patients with a benign ThyroidPrint® remained under surveillance and one patient underwent surgery which was a follicular adenoma. Surgery was performed in all 51 patients with a suspicious for malignancy as per ThyroidPrint® result and in 56 patients who did not undergo testing, with a rate of malignancy of 70.6% and 32.1%, respectively. A higher BCR was observed in follicular lesion of undetermined significance (87%) compared to atypia of undetermined significance (58%) (P < 0.05). False-positive cases included four benign follicular nodules and six follicular and four oncocytic adenomas. Our results show that, physicians chose active surveillance instead of diagnostic surgery in all patients with a benign ThyroidPrint® result, reducing the need for diagnostic surgery in 67% of patients with preoperative diagnosis of ITN.

"Border closure only increased precariousness": a qualitative analysis of the effects of restrictive measures during the COVID-19 pandemic on Venezuelan's health and human rights in South America.

BACKGROUND: In 2010, a political and social crisis pushed thousands of Venezuelans out of their country; today, seven million Venezuelans live abroad. In addition, during the COVID-19 pandemic, border closure increased and affected specific vulnerable migration flows, such as Venezuelans trying to migrate to Chile through the Northern borders. In this context, there is little evidence of migrants' health status and needs, their access to health services, and other basic needs (e.g., housing) from a human rights perspective. Therefore, we qualitatively explored the effects of border closure due to the COVID-19 pandemic on Venezuelan migrants' health and human rights, focusing on access to healthcare in the Northern Chilean border that adjoins Peru and Bolivia. METHODS: Following a case-study qualitative design, we conducted an ethnography that included participatory observation of relevant sites (e.g., hospitals, main squares, migrant shelters) in Antofagasta, Iquique, and Arica and 30 in-depth interviews with actors in the health sector (n = 7), experts from the non-governmental sector (n = 16), and governmental actors (n = 7) in three large cities close to the Northern border. RESULTS: We found four main dimensions: (i) border and migration processes, (ii) specific groups and intersectionality, (iii) barriers to healthcare services, and (iv) regional and local responses to the crisis during the COVID-19 pandemic. Programs characterized by the presence of healthcare providers in the field were essential to attend to migrants' health needs at borders. CONCLUSIONS: Coordination between actors is crucial to implement regional protocols that respond to current migration phenomena and migrants' health needs. Health policies using a human rights approach are urgently required to respond to migrants' healthcare needs at borders in South America.

Promotores' perspectives on the virtual adaptation of a hereditary breast cancer education program.

Breast cancer is the most common cancer in women in the United States (U.S.) and the leading cause of cancer related death among U.S. Hispanics/Latinas (H/Ls). H/Ls have lower rates of screening and longer time to follow up after an abnormal mammogram. We developed a comprehensive community health educator (promotores)-led education and risk identification program for Spanish-speaking H/Ls in California to increase mammography screening, genetic testing, and the understanding of the impact of family history on cancer risk. Due to COVID-19, we adapted the program to a virtual platform. The experience of transforming the program to a virtual platform provided unique opportunities for collaboration between researchers, community partners, and participants. Promotores are major partners in community based participatory research and in the provision of health care services, but their voices are often excluded from scientific reports. This commentary is an effort to provide a platform for promotores to share their experiences and for the readers to understand their approach in bridging the gap between health care services and communities.

Murine erythroid differentiation kinetics in vivo under normal and anemic stress conditions.

Our current understanding of the kinetics and dynamics of erythroid differentiation is based almost entirely on the ex vivo expansion of cultured hematopoietic progenitor cells. In this study, we used an erythroid-specific, inducible transgenic mouse line to investigate for the first time, the in vivo erythroid differentiation kinetics under steady-state conditions. We demonstrated that bipotent premegakaroycyte/erythroid (PreMegE) progenitor cells differentiate into erythroid-committed proerythroblast/basophilic erythroblasts (ProBasoE) after 6.6 days under steady-state conditions. During this process, each differentiation phase (from PreMegE to precolony forming unit-erythroid [PreCFU-E], PreCFU-E to CFU-E, and CFU-E to ProBasoE) took ∼2 days in vivo. Upon challenge with 5-flurouracil (5-FU), which leads to the induction of stress erythropoiesis, erythroid maturation time was reduced from 6.6 to 4.7 days. Furthermore, anemia induced in 5-FU-treated mice was shown to be due not only to depleted bone marrow erythroid progenitor stores but also to a block in reticulocyte exit from the bone marrow into the circulation, which differed from the mechanism induced by acute blood loss.