Molecular analysis and genotype-phenotype correlation of Diamond-Blackfan anemia.

Diamond-Blackfan anemia (DBA) features hypoplastic anemia and congenital malformations, largely caused by mutations in various ribosomal proteins. The aim of this study was to characterize the spectrum of genetic lesions causing DBA and identify genotypes that correlate with phenotypes of clinical significance. Seventy-four patients with DBA from across Canada were included. Nucleotide-level mutations or large deletions were identified in 10 ribosomal genes in 45 cases. The RPS19 mutation group was associated with higher requirement for chronic treatment for anemia than other DBA groups. Patients with RPS19 mutations, however, were more likely to maintain long-term corticosteroid response without requirement for further chronic transfusions. Conversely, patients with RPL11 mutations were less likely to need chronic treatment. Birth defects, including cardiac, skeletal, hand, cleft lip or palate and genitourinary malformations, also varied among the various genetic groups. Patients with RPS19 mutations had the fewest number of defects, while patients with RPL5 had the greatest number of birth defects. This is the first study to show differences between DBA genetic groups with regards to treatment. Previously unreported differences in the rate and types of birth defects were also identified. These data allow better patient counseling, a more personalized monitoring plan, and may also suggest differential functions of DBA genes on ribosome and extra-ribosomal functions.

ABCB1 polymorphisms predict imatinib response in chronic myeloid leukemia patients: a systematic review and meta-analysis.

Imatinib mesylate, a competitive tyrosine kinase inhibitor, is considered the first-line therapy drug for Ph+ chronic myeloid leukemia (CML). Three single-nucleotide polymorphisms (SNPs) in the ATP-binding cassette, subfamily B (MDR/TAP), member 1 gene (ABCB1/MDR1), c.1236C>T, c.2677G>T/A and c.3435C>T, have been shown to affect cellular transport/metabolism of imatinib. The associations between these SNPs and imatinib response in CML patients have been widely evaluated, but the results were inconsistent. To derive a conclusive assessment of the associations, we performed a meta-analysis by combining data from a total of 12 reports including 1826 patients. The results showed that the 2677G allele or 3435T allele predicted a worse response to imatinib in CML patients, whereas 1236CC genotype was associated with better response in CML patients from Asian region. In conclusion, this meta-analysis suggests that c.1236C>T, c.2677G>T/A and c.3435C>T can be served as predictive markers for the therapeutical use of imatinib in CML patients.

Human albumin eye drops as a therapeutic option for the management of keratoconjunctivitis sicca secondary to chronic graft-versus-host disease after stem-cell allografting.

BACKGROUND: Keratoconjunctivitis sicca from chronic graft-versus-host disease (cgvhd) after allogeneic stem cell transplantation is common, leading to severe corneal damage and blindness if not treated. We retrospectively examined the efficacy and safety of pooled human albumin eye drops (haeds) for symptom relief in 40 stem-cell transplantation patients after other alternatives had failed. METHODS: The Common Terminology Criteria for Adverse Events (version 4.0) and the cgvhd grading scale were used to compare response in the patients during January 2000 and July 2013. In addition, on days 1 and 30, the haeds were subjected to quality assurance testing for sterility, oncotic pressure, albumin measurement, viscosity, pH, and purity by protein electrophoresis. RESULTS: Use of haeds resulted in symptom relief for 37 patients (92.5%); 3 patients (7.5%) failed to improve with use of haeds (p ≤ 0.0001). Of the 37 patients having symptom relief, 7 (19%) improved from grade 3 to no dry eye symptoms. Proportionately, post-treatment symptom improvement by two grade levels, from 3 to 1 (70%), was significantly higher than improvement by one grade level, from 3 to 2 (11%) or from 2 to 1 (19%, p ≤ 0.0001). Time to symptom relief ranged from 2 weeks to 28 weeks. Of the 40 patients, 38 (95%) had no adverse reactions. Days 1 and 30 quality assurance testing results were equivalent. CONCLUSIONS: Complications of keratoconjunctivitis sicca were well managed and well tolerated with haeds when other remedies failed. Quality assurance testing confirmed that haeds were safe and stable in extreme conditions.

Phase 2 study of subcutaneous omacetaxine mepesuccinate for chronic-phase chronic myeloid leukemia patients resistant to or intolerant of tyrosine kinase inhibitors.

Omacetaxine mepesuccinate (omacetaxine) is a first-in-class cephalotaxine with a unique mode of action, independent of BCR-ABL, that has shown promising activity in patients with chronic myeloid leukemia (CML). This multicenter, noncomparative, open-label phase 2 study evaluated the efficacy and safety of subcutaneous omacetaxine in CML patients with resistance or intolerance to two or more tyrosine kinase inhibitors (TKIs); results in patients in chronic phase are reported here. Patients received subcutaneous omacetaxine 1.25 mg/m² twice daily days 1-14 every 28 days until hematologic response (up to a maximum of six cycles), then days 1-7 every 28 days as maintenance. Primary endpoints were rates of hematologic response lasting >8 weeks and major cytogenetic response (MCyR). Forty-six patients were enrolled: all had received imatinib, 83% had received dasatinib, and 57% nilotinib. A median 4.5 cycles of omacetaxine were administered (range, 1-36). Hematologic response was achieved or maintained in 31 patients (67%); median response duration was 7.0 months. Ten patients (22%) achieved MCyR, including 2 (4%) complete cytogenetic responses. Median progression-free survival was 7.0 months [95% confidence interval (CI), 5.9-8.9 months], and overall survival was 30.1 months (95% CI, 20.3 months-not reached). Grade 3/4 hematologic toxicity included thrombocytopenia (54%), neutropenia (48%), and anemia (33%). Nonhematologic adverse events were predominantly grade 1/2 and included diarrhea (44%), nausea (30%), fatigue (24%), pyrexia (20%), headache (20%), and asthenia (20%). Subcutaneous omacetaxine may offer clinical benefit to patients with chronic-phase CML with resistance or intolerance to multiple TKI therapies.

Case report of very late gastric cancer recurrence.

Very late recurrence of gastric cancer is rare. Here, we report a dramatic recurrence of gastric cancer, with isolated skeletal metastasis and bone marrow carcinomatosis, 22 years after the patient's initial presentation. Gastric cancer recurrence involving bone or bone marrow is also uncommon and associated with poor prognosis. Pathology from a bone marrow biopsy showed signet ring cell morphology. The patient in this case demonstrated a surprising response-lasting 11 months-to palliative chemotherapy with cisplatin and capecitabine. This case report and literature review describes the characteristics of late gastric cancer recurrence and an approach to the diagnosis and management of patients with bone metastasis or bone marrow carcinomatosis.

Cardiovascular events among recipients of hematopoietic stem cell transplantation-A systematic review and meta-analysis.

Cardiovascular diseases are an emerging cause of mortality and morbidity in survivors of hematopoietic stem cell transplantation (HSCT); however, the incidence of cardiovascular events (CVEs) in this population is not well described. This systematic review summarizes the evidence on the incidence of CVEs in HSCT recipients. Medline and Embase were searched from inception to December 2020. Inclusion criteria were cohort studies and phase 3 randomized controlled trials that reported CVEs among adults who underwent HSCT for hematological malignancies. After reviewing 8386 citations, 57 studies were included. The incidence of CVEs at 100 days was 0.19 (95% CI: 0.17-0.21) per 100 person-days after autologous HSCT and 0.06 (95% CI: 0.05-0.07) per 100 person-days after allogeneic HSCT. This higher incidence after autologous HSCT was driven by reports of arrhythmia from one population-based study in patients with multiple myeloma. The incidence of long-term CVEs was 3.98 (95% CI; 3.44-4.63) per 1000 person-years in survivors of autologous HSCT and 3.06 (95% CI; 2.69-3.48) per 1000 person-years in survivors of allogeneic HSCT. CVEs remain an important but under-reported cause of morbidity and mortality in recipients of HSCT. Future studies are required to better understand the incidence and risk factors for CVEs in HSCT recipients.

Genetic analysis of inherited bone marrow failure syndromes from one prospective, comprehensive and population-based cohort and identification of novel mutations.

INTRODUCTION: Inherited bone marrow failure syndromes (IBMFSs) often have substantial phenotypic overlap, thus genotyping is often critical for establishing a diagnosis. OBJECTIVES AND METHODS: To determine the genetic characteristics and mutation profiles of IBMFSs, a comprehensive population-based study that prospectively enrols all typical and atypical cases without bias is required. The Canadian Inherited Marrow Failure Study is such a study, and was used to extract clinical and genetic information for patients enrolled up to May 2010. RESULTS: Among the 259 primary patients with IBMFS enrolled in the study, the most prevalent categories were Diamond-Blackfan anaemia (44 patients), Fanconi anaemia (39) and Shwachman-Diamond syndrome (35). The estimated incidence of the primary IBMFSs was 64.5 per 10(6) births, with Fanconi anaemia having the highest incidence (11.4 cases per 10(6) births). A large number of patients (70) had haematological and non-haematological features that did not fulfil the diagnostic criteria of any specific IBMFS category. Disease-causing mutations were identified in 53.5% of the 142 patients tested, and in 16 different genes. Ten novel mutations in SBDS, RPL5, FANCA, FANCG, MPL and G6PT were identified. The most common mutations were nonsense (31 alleles) and splice site (28). Genetic heterogeneity of most IBMFSs was evident; however, the most commonly mutated gene was SBDS, followed by FANCA and RPS19. CONCLUSION: From this the largest published comprehensive cohort of IBMFSs, it can be concluded that recent advances have led to successful genotyping of about half of the patients. Establishing a genetic diagnosis is still challenging and there is a critical need to develop novel diagnostic tools.

Comparative analysis of Shwachman-Diamond syndrome to other inherited bone marrow failure syndromes and genotype-phenotype correlation.

Our knowledge of the phenotypes of inherited bone marrow failure syndromes (IBMFSs) derives from case reports or case series in which only one IBMFS was studied. However, the substantial phenotypic overlap necessitates comparative analysis between the IBMFSs. Shwachman-Diamond syndrome (SDS) is an IBMFS that the appreciation of what comprises its clinical phenotype is still evolving. In this analysis we used data on 125 patients from the Canadian Inherited Marrow Failure Study (CIMFS), which is a prospective multicenter population-based study. Thirty-four cases of SDS patients were analyzed and compared to other patients with the four most common IBMFSs on the CIMFS: Diamond Blackfan anemia, Fanconi anemia (FA), Kostmann/severe congenital neutropenia and dyskeratosis congenita (DC). The diagnosis of SDS, FA and DC was often delayed relative to symptoms onset; indicating a major need for improving tools to establish a rapid diagnosis. We identified multiple phenotypic differences between SDS and other IBMFSs, including several novel differences. SBDS biallelic mutations were less frequent than in previous reports (81%). Importantly, compared to patients with biallelic mutations, patients with wild type SBDS had more severe hematological disease but milder pancreatic disease. In conclusion, comprehensive study of the IBMFSs can provide useful comparative data between the disorders. SBDS-negative SDS patients may have more severe hematological failure and milder pancreatic disease.

Clinical relevance of vascular endothelial growth factor (VEGFA) and VEGF receptor (VEGFR2) gene polymorphism on the treatment outcome following imatinib therapy.

BACKGROUND: Imatinib could reverse marrow angiogenesis and decrease the plasma level of vascular endothelial growth factor (VEGF) in chronic myeloid leukemia (CML) patients. Methods, materials and patients: The current study investigated the impact of four vascular endothelial growth factor type A (VEGFA) and three vascular endothelial growth factor receptor type 2 (VEGFR2) gene polymorphisms on the outcomes of 228 CML patients following imatinib therapy. VEGFA genotypes such as -2578C>A (rs699947), -460T>C (rs833061), +405G>C (rs2010963) and +936C>T (rs3025039) loci and VEGFR2 genotypes (rs1531289, rs1870377 and rs2305948) were analyzed using matrix-assisted laser desorption/ionization time-of-flight-based method. RESULTS: In single marker analyses, strong correlations were noted between complete cytogenetic response (CCyR) and VEGFR2 genotypes (rs1531289/rs1870377), between treatment failure and VEGFR2 genotype (rs1870377) and between progression to advanced disease and VEGFA genotypes (rs699947/rs833061). Three haplotypes of VEGFR2 gene were generated as follows: GT (46.1%), AT (27.9%) and GA (25.7%). Haplotype analyses showed good correlations between VEGFR2 haplotype and CCyR and treatment failure to imatinib. Multivariate analyses confirmed strong correlations of VEGFR2 polymorphisms (especially rs1531289, rs1870377 or VEGFR2 haplotype) with CCyR, treatment failure and of VEGFA genotype (rs699947) with progression to advanced disease. CONCLUSION: The VEGFR2 gene polymorphism correlates with cytogenetic response, treatment failure following imatinib therapy for CML, while VEGFA genotype correlates with progression to advanced disease.

European LeukemiaNet 2020 recommendations for treating chronic myeloid leukemia.

The therapeutic landscape of chronic myeloid leukemia (CML) has profoundly changed over the past 7 years. Most patients with chronic phase (CP) now have a normal life expectancy. Another goal is achieving a stable deep molecular response (DMR) and discontinuing medication for treatment-free remission (TFR). The European LeukemiaNet convened an expert panel to critically evaluate and update the evidence to achieve these goals since its previous recommendations. First-line treatment is a tyrosine kinase inhibitor (TKI; imatinib brand or generic, dasatinib, nilotinib, and bosutinib are available first-line). Generic imatinib is the cost-effective initial treatment in CP. Various contraindications and side-effects of all TKIs should be considered. Patient risk status at diagnosis should be assessed with the new EUTOS long-term survival (ELTS)-score. Monitoring of response should be done by quantitative polymerase chain reaction whenever possible. A change of treatment is recommended when intolerance cannot be ameliorated or when molecular milestones are not reached. Greater than 10% BCR-ABL1 at 3 months indicates treatment failure when confirmed. Allogeneic transplantation continues to be a therapeutic option particularly for advanced phase CML. TKI treatment should be withheld during pregnancy. Treatment discontinuation may be considered in patients with durable DMR with the goal of achieving TFR.

Graft-versus-host disease following marrow transplantation for aplastic anemia: different impact of two GVHD prevention strategies.

Prevention of GVHD is one of the most desirable goals of BMT in aplastic anemia (AA). We reviewed the medical records of 24 consecutive patients treated with BMT for acquired AA using two different GVHD prevention strategies. Ten patients were given alemtuzumab-based GVHD prophylaxis (50-60 mg in three divided doses on days -8, -7 and -6), and 14 patients were given conventional GVHD prophylaxis with calcineurin inhibitors plus MTX before the introduction of the alemtuzumab-based protocols. The incidence of acute, chronic and 'serious GVHD' was significantly reduced in alemtuzumab-treated patients compared to conventionally treated patients [11 vs 64% (P=0.03), 0 vs 78% (P=0.002) and 0 vs 57% (P=0.007), respectively]. Engraftment time and rates of graft failure appeared similar in the two groups. A significantly higher proportion of alemtuzumab-treated patients developed CMV reactivation compared to control patients (83 vs 12%; P=0.03); none developed CMV disease. The rates of other infectious complications did not appear significantly different. Our data suggest that 50-60 mg of alemtuzumab given according to the current schedule significantly reduces the risk of GVHD without increasing the risk of graft failure or serious infections.

Blood and marrow transplantation in elderly acute myeloid leukaemia patients - older certainly is not better.

Acute myeloid leukaemia in the elderly is a disease with distinct biological properties, commonly associated with leukaemic cell treatment resistance and with an increased number of high-risk features, including concomitant myelodysplasia and poor-risk cytogenetic abnormalities such as monosomy 5 and 7. Complete remission rates after standard induction chemotherapy in patients above age 60 years are less than 50%, with long-term survival rates below 10%. Post-remission stem cell transplant therapies have not been studied extensively. Autologous transplants can result in an acceptable 3-year leukaemia-free survival rate of up to 47%, yet this procedure is applicable only to a small minority of patients. Myeloablative allogeneic transplants similarly show feasibility in selected few patients and in general are very toxic. Non-myeloablative allogeneic transplants are associated with reduced toxicity, but are plagued by an increased relapse rate. The latter strategy appears promising, but must be validated in larger, multi-centre prospective trials, in which outcomes are compared to non-transplant approaches.

Evidence of graft-versus-Waldenstrom's macroglobulinaemia effect after allogeneic stem cell transplantation: a single centre experience.

The role of allogeneic stem cell transplantation (SCT) in Waldenstrom's macroglobulinaemia (WM) is not yet clear, as published data on allogeneic SCT in WM are limited. We present a retrospective study of allogeneic SCT in five patients with WM. Median age was 56 years (range 40-60 years). All patients were heavily pretreated. Conditioning therapy with busulphan and cyclophosphamide was used for all patients and all were given cyclosporine and methotrexate for graft-versus-host disease prophylaxis. With a median follow-up of 32 months (range 2-43), all except one are alive and disease free. Progressive, delayed decline in serum IgM levels were noted in all the patients, suggesting an active graft-versus-Waldenstrom's effect. With the limited available data, it appears that allogeneic SCT is a useful treatment option for advanced WM.

Long-term follow-up of allogeneic bone marrow transplantation for patients with chronic phase chronic myeloid leukemia prepared with a regimen consisting of cyclophosphamide, cytarabine and single-dose total body irradiation conditioning.

We evaluated long-term toxicities and outcomes in 96 patients with chronic phase chronic myeloid leukemia treated with a single bone marrow allograft regimen. Conditioning was cytosine arabinoside, cyclophosphamide (120 mg/kg) and single fraction total body irradiation (500 cGy). Median follow-up was 12.8 years (0.4-19.9 years). Graft failure occurred in one patient, nonfatal veno-occlusive disease in 13 patients (14%). Overall incidences of acute (a) and chronic (c) graft-vs-host disease (GVHD) were 77 and 63%. The 100-day and 1-year transplant-related mortality (TRM) were 1 and 9.2%, respectively, with no change through 5 years. Five- and 10-year event-free survival rates were 56 and 49%, overall survival (OS) rates 72 and 70%, respectively. Forty patients have relapsed: 8 cytogenetic (20%), 10 hematologic (25%) and 22 molecular (55%). Most have been salvaged with donor-leukocyte infusion, second transplants and/or imatinib therapy. Survival was worse for patients transplanted >2 years from diagnosis (10-year OS 56 vs 78%, P=0.01), for patients over 50 years old (10-year OS 44 vs 75%, P=0.05) and for patients without cGVHD (10-year OS 53 vs 86%, P<0.001). This regimen resulted in successful engraftment, low risk of TRM and long-term survival. In an era when imatinib is first line therapy, this regimen offers a potentially low-toxicity, highly successful alternative in the event of poor imatinib response.

Recommendations of the canadian consensus group on the management of chronic myeloid leukemia.

Chronic myelogenous leukemia (cml) is a disease characterized by the expression of Bcr/Abl, an oncogenic protein tyrosine kinase, and by evolution over time from a relatively benign chronic phase to a rapidly fatal cml blast crisis. Until recently, the standard of care included potentially curative therapy with allogeneic stem cell transplantation, available only to a minority (about 10%) of patients, or medical therapy with interferon-α with or without cytarabine, which helped to prolong the chronic phase of the disease in a minority of patients. The availability of imatinib mesylate, a selective inhibitor of Bcr/Abl approved by Health Canada in 2001, has profoundly altered the clinical and laboratory management of cml. This change in practice has been reviewed by the Canadian Consensus Group on the Management of Chronic Myelogenous Leukemia and has resulted in a new set of recommendations for the optimal care of cml patients.

Relationship between neurocognitive functioning and medication management ability over the first 6 months following allogeneic stem cell transplantation.

Although neurocognitive impairment has been established as a major issue among cancer survivors, the real-world consequences of this impairment are unclear. This study investigated the relationship between neurocognitive functioning and medication management ability over time among 58 patients treated with allogeneic hematopoietic stem cell transplantation (HCT). Participants completed a neuropsychological test battery and a simulated medication management task at three time points: pre-transplant (T0), Day 100 (T1) and 6 months post transplant (T2). Neurocognitively impaired participants performed worse on the medication management task than neurocognitively normal participants at each time point, and were more likely to score in the impaired range of medication management ability post transplant (72% vs 20%, P<0.001 at T1; 67% vs 23%, P=0.013 at T2). In multivariate analyses, worse performance in executive functioning/working memory consistently predicted impaired medication management ability, even when controlling for sociodemographic and clinical confounders (odds ratio=0.89, 95% confidence interval (0.80, 0.98), P=0.023). Lower physical symptom distress also predicted impaired medication management ability, but this effect decreased over time. Self-reported cognitive problems were not correlated with medication management ability at any time point. Findings suggest that poor neurocognitive functioning, particularly in the domain of executive functioning/working memory, is associated with worse medication management ability within the first 6 months after allogeneic HCT.

Mitochondrial biogenesis in cultured mammalian cells. II. Mitochondrial protein and phospholipid synthesis in chloramphenicol-treated BHK-21 cells.

The effect of growth of BHK-21 cells in chloramphenicol on the synthesis of cellular proteins and phospholipids has been examined. The incorporation of leucine into total cellular proteins, or into the proteins of specific subcellular fractions are not significantly reduced by cell culture in the presence of chloramphenicol. In cells treated with cycloheximide, a small amount of chloramphenicol-sensitive labelling of protein was detected within the first hour of exposure to the drug. Chloramphenicol inhibits the incorporation of delta-amino-levulinic acid into hemoproteins, only if it is present during both the 48-h culturing and 4-h labelling period. De novo synthesis of cellular lipids as measured by pulse labelling with 32Pi or [3H]glycerol, is decreased in chloramphenicol-treated cells. This decrease is observed in all sub-cellular fractions, although the mitochondrial fraction is most affected. All phospholipids are affected, with diphosphatidylglycerol labelling reduced to the greatest extent. Although fatty acid synthesis is inhibited, the labelling of diphosphatidylglycerol with fatty acids is stimulated on chloramphenicol treatment.

Mitochondrial biogenesis in cultured mammalian cells. III. Synthesis of mitochondrial phospholipids by subcellular fractions isolated from normal and chloramphenicol-treated BHK-21 cells.

The capacity of subcellular fractions isolated from chloramphenicol-treated BHK-21 cells to synthesize various mitochondrial phospholipids in vitro and examined. Both mitochondria and microsomes showed the capacity to acylate sn-glycerol 3-phosphate and dihydroxyacetone phosphate to lysophosphatidic acid and acyldihydroxyacetone phosphate and subsequently to phosphatidic acid. Both processes are inhibited in mitochondria from chloramphenicol-treated cells. The synthesis of CDPdiacylglycerol in mitochondria or microsomes, and the synthesis of phosphatidylinositol and of phosphatidylcholine in microsomes were stimulated in treated cells. A slight stimulation was also observed in the synthesis of phosphatidylglycerol and diphosphatidylglycerol when the labelled precursor was sn-glycerol 3-phosphate in treated cells, although the process was inhibited with labelled glycerol as the precursor. Conversion of phosphatidylglycerol phosphate to phosphatidylglycerol by mitochondria was rate limiting unless the post-microsomal supernatant fraction was added. These results are discussed in regard to the observed inhibition of phospholipid synthesis in BHK-21 cells in culture by chloramphenicol.

Characterization of macrophage- and granulocyte-inducing proteins for normal and leukemic myeloid cells produced by the Krebs ascites tumor.

Medium from serum-free cultures of Krebs ascites tumor cells contains two macrophage and granulocyte inducing (MGI) activities that can act on the myeloid precursors of these hematopoietic cells. One activity, MGI-1, induced the formation of macrophage and granulocyte colonies from normal myeloid precursors. The second activity, MGI-2, induced macrophage and granulocyte differentiation in myeloid leukemic cells that no longer required MGI-1 for colony formation. The medium contained one species of MGI-1 and two species of MGI-2. One species of MGI-2, MGI-2A, copurified through five stages of purification with MGI-1, but separated from the other MGI-2 species, MGI-2B, at an early stage in purification. MGI-1, MGI-2A and MGI-2B were purified 1490, 1140 and 678-fold, respectively. When bands with biological activity gel from non-denaturing polyacrylamide gels were run on SDS-polyacrylamide gel electrophoresis, MGI-1 and MGI-2A activities were associated with similar Mr and each activity showed two bands, one of 23 000 and the other 25 000. MGI-2B activity showed one band with a Mr of 45 000. Secretion did not appear to involve glycosylation, none of the species bound to concanavalin A, soybean agglutinin, or wheat germ agglutinin agarose columns and they did not appear to contain carbohydrates. The assays for MGI-1 and MGI-2 activities were not affected by adding protease inhibitors. But MGI-2 was more readily destroyed by treatment with proteases and was more labile at high temperature and low pH than MGI-1. It is suggested that the level of cellular proteases may play a role in regulating the relative amounts of MGI-1 and MGI-2 that are present in vivo.

Mitochondrial biogenesis in cultured animal cells. I. Effect of chloramphenicol on morphology and mitochondrial respiratory enzymes.

The effects of chloramphenicol on the morphology and respiratory enzymes of BHK-21 cells in spinner culture have been examined with time. Cells treated with chloramphenicol double twice before growth ceases; these cells have increased size as measured by several techniques. Mitochondria are enlarged and appear to degenerate with prolonged treatment. Cytochrome c oxidase and succinate cytochrome c reductase activities are reduced while there is no decrease in the activities of monoamine oxidase, glutamate dehydrogenase or NADPH-cytochrome c reductase. Cytochromes aa3 and b disappear on treatment while cytochromes c + c1 appears to be unaffected. All these effects are reversible if chloramphenicol is removed within a limited period of time.