Mepolizumab in children and adolescents with severe eosinophilic asthma not eligible for omalizumab: a single Center experience.

BACKGROUND: Mepolizumab is an anti-interleukin-5 monoclonal antibody shown to reduce asthma exacerbations in adults and adolescents with severe eosinophilic asthma. AIM: To assess the impact of mepolizumab on children and adolescents over 12 months by examining steroid usage, asthma-related hospitalizations, Asthma Control Test (ACT) scores, fractional exhaled nitric oxide concentration (FeNO), forced expiratory volume in 1 s (FEV1), mid expiratory flow (FEF25-75%), and blood eosinophil count. METHODS: Retrospective analysis performed between October 2015 and December 2022. Data was reviewed 12 months before and after commencing mepolizumab. Mepolizumab was offered if the patient had severe eosinophilic asthma and were unresponsive to or ineligible for omalizumab. RESULTS: Sixteen participants (age 7-17, 8 males, 8 females) received subcutaneous mepolizumab monthly with no serious adverse reactions. Incidence of hospital admissions fell significantly (IRR 0.33, p = 0.007). Among the 11 patients receiving daily oral corticosteroids, 3 were weaned off daily oral steroids and 3 patients' daily dose was significantly reduced (mean Δ-0.095 ± 0.071 mg/kg, p = 0.0012). Eosinophil count was decreased (mean Δ-0.85 x 109/L, p < 0.001). There was no significant change in mean overall steroid burden per patient (mean Δ-1445.63 ± 1603.18 mg, p = 0.10), ACT scores (mean Δ2.88 ± 6.71, p = 0.17), FEV1 z-scores (mean Δ-0.99 ± 1.88, p = 0.053), FEF25-75% z-scores (mean Δ-0.65 ± 1.61, p = 0.13), FeNO (mean Δ-20.09 ± 80.86, p = 0.34), or number of courses of oral steroids given for asthma attacks (IRR 0.71, p = 0.09). CONCLUSION: Among children and adolescents with severe eosinophilic asthma ineligible for or not responsive to omalizumab, mepolizumab therapy exhibited significant reduction in rate of asthma-related hospitalizations and significant decrease in daily steroid dosage.

In vitro comparison of methods for sampling copper-based antimicrobial surfaces.

IMPORTANCE: Self-sanitizing surfaces such as copper (Cu) are increasingly used on high-touch surfaces to prevent the spread of harmful viruses and bacteria. Being able to monitor the antimicrobial properties of Cu is fundamental in measuring its antimicrobial efficacy. Thorough investigations into reliable methods to enumerate bacteria from self-sanitizing surfaces are lacking in the literature. This study demonstrates that direct use of Petrifilm on Cu surfaces most likely revives stressed and dying bacteria, which induces increased bacterial counts. This phenomenon was not observed with indirect collection methods. Studies assessing time-kill kinetics or long-term efficacy of Cu should consider the impact of the collection method chosen.

Calcicole behaviour of Callisthene fasciculata Mart., an Al-accumulating species from the Brazilian Cerrado.

Most aluminium (Al)-accumulating species are found on soils with high Al saturation and low Ca availability (Ca poor). Callisthene fasciculata Mart. (Vochysiaceae), however, is an Al-accumulating tree restricted to Ca-rich soils with low Al saturation in the Brazilian Cerrado savanna. Here we tested its calcicole behaviour, and the possible role of organic acids in detoxification of Al during the early stages of plant development. We assessed growth, dry mass, nutrients, Al and organic acids in seedlings grown for 50 days on two contrasting Cerrado soils; one with high Ca concentrations and low Al saturation and the other with low Ca availability and high Al saturation. Relative to plants on Ca-rich soil, plants on Ca-poor soil had necrotic spots and bronzing of leaves. Roots and shoots contained reduced concentrations of P and Cu, but higher concentrations of Fe, Al and citrate. Despite lower concentrations in the soil, Ca and Mg increased in shoots. Shoot concentrations of oxalate were also higher. We confirmed C. fasciculata as an Al-accumulating species with calcicole behaviour. The increased concentrations of organic acids in plants with higher Al accumulation suggest that high availability of soluble Al does not prevent occurrence of this species on soils with high Al saturation. Instead, the absence of C. fasciculata from Ca-poor soils is probably due to imbalances in tissue Fe, Cu and Zn imposed by this soil type.

Viable but Nonculturable and Persister Cells Coexist Stochastically and Are Induced by Human Serum.

Dormancy holds a vital role in the ecological dynamics of microorganisms. Specifically, entry into dormancy allows cells to withstand times of stress while maintaining the potential for reentry into an active existence. The viable but nonculturable (VBNC) state and antibiotic persistence are two well-recognized conditions of dormancy demonstrated to contribute to bacterial stress tolerance and, as a consequence, yield populations that are tolerant to high-dose antibiotics. Aside from this commonality, more evidence is being presented that indicates the relatedness of these two states. Here, we demonstrate that VBNC cells are present during persister isolation experiments, further indicating that these cells coexist and are induced by the same conditions. Interestingly, we reveal that VBNC cells can exist stochastically in unstressed growing cultures, a finding that is characteristic of persisters. Furthermore, human serum induces the formation of both VBNC cells and persisters, a finding not previously described for either dormancy state. Lastly, we describe the role of toxin-antitoxin systems (TAS) in the induction of the VBNC state and report that these TAS, which are classically implicated in persister cell formation, are also induced during incubation in human serum. This study provides evidence for the recently proposed "dormancy continuum hypothesis" and substantiates the physical and molecular relatedness of VBNC and persister cells in a standardized model organism. Notably, these results provide new evidence for the clinical significance of VBNC and persister cells.

Quorum-sensing linked RNA interference for dynamic metabolic pathway control in Saccharomyces cerevisiae.

Some of the most productive metabolic engineering strategies involve genetic modifications that cause severe metabolic burden on the host cell. Growth-limiting genetic modifications can be more effective if they are 'switched on' after a population growth phase has been completed. To address this problem we have engineered dynamic regulation using a previously developed synthetic quorum sensing circuit in Saccharomyces cerevisiae. The circuit autonomously triggers gene expression at a high population density, and was linked with an RNA interference module to enable target gene silencing. As a demonstration the circuit was used to control flux through the shikimate pathway for the production of para-hydroxybenzoic acid (PHBA). Dynamic RNA repression allowed gene knock-downs which were identified by elementary flux mode analysis as highly productive but with low biomass formation to be implemented after a population growth phase, resulting in the highest published PHBA titer in yeast (1.1mM).

Long-term impacts of selective logging on two Amazonian tree species with contrasting ecological and reproductive characteristics: inferences from Eco-gene model simulations.

The impact of logging and subsequent recovery after logging is predicted to vary depending on specific life history traits of the logged species. The Eco-gene simulation model was used to evaluate the long-term impacts of selective logging over 300 years on two contrasting Brazilian Amazon tree species, Dipteryx odorata and Jacaranda copaia. D. odorata (Leguminosae), a slow growing climax tree, occurs at very low densities, whereas J. copaia (Bignoniaceae) is a fast growing pioneer tree that occurs at high densities. Microsatellite multilocus genotypes of the pre-logging populations were used as data inputs for the Eco-gene model and post-logging genetic data was used to verify the output from the simulations. Overall, under current Brazilian forest management regulations, there were neither short nor long-term impacts on J. copaia. By contrast, D. odorata cannot be sustainably logged under current regulations, a sustainable scenario was achieved by increasing the minimum cutting diameter at breast height from 50 to 100 cm over 30-year logging cycles. Genetic parameters were only slightly affected by selective logging, with reductions in the numbers of alleles and single genotypes. In the short term, the loss of alleles seen in J. copaia simulations was the same as in real data, whereas fewer alleles were lost in D. odorata simulations than in the field. The different impacts and periods of recovery for each species support the idea that ecological and genetic information are essential at species, ecological guild or reproductive group levels to help derive sustainable management scenarios for tropical forests.

Next-generation sequencing can reveal in vitro-generated PCR crossover products: some artifactual sequences correspond to HLA alleles in the IMGT/HLA database.

The high-resolution human leukocyte antigen (HLA) genotyping assay that we developed using 454 sequencing and Conexio software uses generic polymerase chain reaction (PCR) primers for DRB exon 2. Occasionally, we observed low abundance DRB amplicon sequences that resulted from in vitro PCR 'crossing over' between DRB1 and DRB3/4/5. These hybrid sequences, revealed by the clonal sequencing property of the 454 system, were generally observed at a read depth of 5%-10% of the true alleles. They usually contained at least one mismatch with the IMGT/HLA database, and consequently, were easily recognizable and did not cause a problem for HLA genotyping. Sometimes, however, these artifactual sequences matched a rare allele and the automatic genotype assignment was incorrect. These observations raised two issues: (1) could PCR conditions be modified to reduce such artifacts? and (2) could some of the rare alleles listed in the IMGT/HLA database be artifacts rather than true alleles? Because PCR crossing over occurs during late cycles of PCR, we compared DRB genotypes resulting from 28 and (our standard) 35 cycles of PCR. For all 21 cell line DNAs amplified for 35 cycles, crossover products were detected. In 33% of the cases, these hybrid sequences corresponded to named alleles. With amplification for only 28 cycles, these artifactual sequences were not detectable. To investigate whether some rare alleles in the IMGT/HLA database might be due to PCR artifacts, we analyzed four samples obtained from the investigators who submitted the sequences. In three cases, the sequences were generated from true alleles. In one case, our 454 sequencing revealed an error in the previously submitted sequence.

Pseudo-outbreak of Legionella pneumophila serogroup 8 infection associated with a contaminated ice machine in a bronchoscopy suite.

OBJECTIVE: To investigate the marked increase noted over an 8-month period in the number of Legionella pneumophila isolates recovered from bronchoalveolar lavage fluid specimens obtained during bronchoscopy in our healthcare system. SETTING: Bronchoscopy suite that serves a 580-bed tertiary care center and a large, multisite, faculty practice plan with approximately 2 million outpatient visits per year. METHODS: Cultures of environmental specimens from the bronchoscopy suite were performed, including samples from the air and water filters, bronchoscopes, and the ice machine, with the aim of identifying Legionella species. Specimens were filtered and acid-treated and then inoculated on buffered charcoal yeast extract agar. Serogrouping was performed on all isolates recovered from patient and environmental samples. RESULTS: All L. pneumophila isolates recovered from patients were serogroup 8, a serogroup that is not usually recovered in our facility. An epidemiologic investigation of the bronchoscopy suite revealed the ice machine to be contaminated with L. pneumophila serogroup 8. Patients were exposed to the organism as a result of a recently adopted practice in the bronchoscopy suite that involved directly immersing uncapped syringes of sterile saline in contaminated ice baths during the procedures. At least 1 patient was ill as a result of the pseudo-outbreak. Molecular typing of isolates recovered from patient and environmental samples revealed that the isolates were indistinguishable. CONCLUSIONS: Extensive cleaning of the ice machine and replacement of the machine's water filter ended the pseudo-outbreak. This episode emphasizes the importance of using aseptic technique when performing invasive procedures, such as bronchoscopies. It also demonstrates the importance of reviewing procedures in all patient areas to ensure compliance with facility policies for providing a safe patient environment.

Evaluation of adhesion formation, mesh fixation strength, and hydroxyproline content after intraabdominal placement of polytetrafluoroethylene mesh secured using titanium spiral tacks, nitinol anchors, and polypropylene suture or polyglactin 910 suture.

BACKGROUND: The purpose of this study is to evaluate fixation methods for polytetrafluoroethylene (ePTFE) mesh with an in vivo model of laparoscopic ventral hernia repair. METHODS: In 40 New Zealand white rabbits, a 4 x 4-cm ePTFE mesh (n = 80, two per animal) was attached to an intact peritoneum with polyglactin 910 (PG 910) (n = 20) or polypropylene (PP) (n = 20) suture, titanium spiral tacks (TS) (n = 20), or nitinol anchors (NA) (n = 20). Mesh was harvested at 8 and 16 weeks for fixation strength testing, adhesion assessment, and collagen (hydroxyproline) content. Fixation strength on day 0 was determined with mesh attached to harvested abdominal wall. Statistical significance was determined as p < 0.05. RESULTS: There was no difference in fixation strength between PP (39.1 N) and PG 910 (40.0 N) sutures at time zero. At week 8, PP (25.7 N) was significantly stronger (p < 0.05) than PG 910 (11.4 N) suture, but not at week 16. The fixation strength of TS and NA (day 0, 15.4 vs 7.4 N; week 8, 17.5 vs 15.3 N; week 16, 19.1 vs 13.8 N) was not significantly different. Fixation with PP suture was significantly (p < 0.05) stronger than that with TS and NA at day 0 (39.1, 15.4, and 7.4 N, respectively) but not at weeks 8 or 16. The fixation strength of suture decreased significantly (p < 0.05) from day 0 to week 16 (PP: day 0 = 39.1 N, week 8 = 25.7 N, week 16 = 21.4 N; PG 910: day 0 = 40.0 N, week 8 = 11.4 N, week 16 = 12.8 N). The fixation strength of NA and TS did not change significantly (NA: day 0 = 7.4 N, week 8 = 15.3 N, week 16 = 13.8 N; TS: week 0 = 15.4 N, week 8 = 17.5 N, week 16 = 19.1 N). There were no differences in adhesion area based on fixation device used; however, there were more (p < 0.05) mesh samples using NA with adhesions compared to TS and adhesion tenacity was greater (p < 0.05) compared to that of TS, PP, and PG. Hydroxyproline content at weeks 8 and 16 was similar for all fixation devices. CONCLUSIONS: The initial fixation strength for nonabsorbable suture is significantly greater than that of the metallic fixation devices, but after 8 weeks there is no difference. Laparoscopic ventral hernia repair without transabdominal suture fixation may be predisposed to acute failure. The metallic devices have similar fixation strength, although the incidence of adhesions and tenacity of adhesions appear to be greater with the nitinol anchors. Since these devices have similar fixation strengths and most likely provide adequate supplementation to transabdominal sutures for mesh fixation after laparoscopic ventral hernia repair, their use should be based on other factors, such as their propensity for adhesions, ease of application, and cost.

Haemotoxicity of thiamphenicol in the BALB/c mouse and Wistar Hanover rat.

Chloramphenicol (CAP) is haemotoxic in man, inducing two forms of toxicity. First, a commonly-occurring, dose-related, reversible bone marrow depression, which develops during treatment. Second, a rarer aplastic anaemia (AA), developing after treatment, is irreversible, and often fatal. Thiamphenicol (TAP) was developed as a replacement for CAP; however, there are no toxicological investigations in the mouse or rat on the dose-related haemotoxicity of TAP, in repeat dose gavage studies. Therefore, we have conducted a comprehensive investigation in these species, administering TAP for 7-17 days, to define haematological changes. Female BALB/c mice were gavaged with TAP, daily for 7-17 days at 400-1500 mg/kg; female Wistar Hanover rats were dosed with TAP daily at 50-375 mg/kg for 9 or 10 days. Haematological changes were studied at 1, 7 and 14 days post-dosing. In mice at day 1, TAP caused decreases in RBC, HCT and Hb; reticulocytes and platelets were reduced; changes were dose-related and reversible. Marrow cell counts were reduced; marrow was hypocellular, with erythroid depletion and progenitor cell vacuolation; the myeloid/erythroid (M:E) ratio was increased. In the rat, changes were not as clear-cut; there was anaemia with indications of reduced reticulocyte and platelet counts, and evidence of decreased neutrophils and lymphocytes. Marrow erythroid cells were decreased, precursor cells vacuolated, and the M:E ratio increased. We conclude that TAP induced haematological changes in the mouse and rat, parallelling the dose-dependent, reversible marrow depression reported in man; TAP is more haemotoxic in the rat than in the mouse.

Studies on the haemotoxicity of chloramphenicol succinate in the Dunkin Hartley guinea pig.

In man, chloramphenicol (CAP), induces two major haemotoxic effects. First, a reversible, dose-related reticulocytopenia and anaemia developing during treatment. Second, a non-dose-related aplastic anaemia (AA), developing weeks after treatment, is often irreversible and fatal. In previous studies, we developed a mouse model of the reversible reticulocytopenia/anaemia using CAP succinate (CAPS); attempts to induce AA in the mouse with CAPS were unsuccessful; in the rat, CAPS induced only minimal haemotoxicity. We therefore wished to investigate haematological changes caused by CAPS in a third rodent, particularly in relation to the induction of significant 'late stage' bone marrow depression (AA). Female guinea pigs were gavaged with CAPS in three experiments. In a dose ranging study, CAPS (at 2500 and 3500 mg/kg) was administered daily for 9 days, and blood examined at 1 day post dosing. CAPS induced increased erythrocyte values (an apparent haemoconcentration effect), and reduced reticulocytes and femoral marrow nucleated cell counts (FNCC). In a second experiment, CAPS was given at 333, 666 and 1000 mg/kg (13 days); haematological changes were compared with results from the initial study, with evidence of dose-related effects. In a final experiment, CAPS was administered (825 mg/kg, 16 days) and blood studied at 1, 12, 28 and 63 days post dosing. At day 1, erythrocyte values were decreased (NS), and reticulocytes and FNCC were reduced; the marrow was hypocellular with erythroid depletion. At 12 and 28 days, values returned towards the normal range. At 63 days, parameters were normal. Thus, CAPS (825 mg/kg for 16 days) induced changes comparable to the reversible bone marrow depression seen in man; but there was no evidence of 'late stage' (i.e. at 63 days) marrow depression, as would be seen in a developing or overt marrow aplasia (AA). The guinea pig (like the mouse) is a model for the early events, but is not a good model for CAP-induced AA in man.

An assessment of chloramphenicol and thiamphenicol in the induction of aplastic anaemia in the BALB/c mouse.

The potential of the antibiotics chloramphenicol succinate (CAPS) and thiamphenicol (TAP) to induce aplastic anaemia in the female BALB/c mouse was investigated. CAPS was administered at 2000 mg/kg, and TAP at 850 mg/kg, daily by gavage, for 17 days. At 1, 13, 22, 41, 98 and 179 days after the final dose of each antibiotic, mice (n = 4 or 5) were sampled for haematological examination and haematopoietic stem cell assays. Both CAPS and TAP induced significant reductions in red blood cell count, haematocrit and haemoglobin values at day 1 post dosing; counts of colony-forming units-erythroid and colony-forming units-granulocyte-macrophage, were similarly significantly decreased at this time. All these reduced parameters returned towards normal at days 13 and 22. At days 41, 98 and 179, results for all haematological values and stem cell assays in both CAPS- and TAP-treated mice compared with the controls; there was no evidence of a reduction in peripheral blood values or bone marrow parameters at the later sampling points, as would be expected in a developing or overt bone marrow aplasia. We therefore consider that the administration of CAPS and TAP, which have been associated with the development of aplastic anaemia in man, induce a reversible anaemia, but not a chronic bone marrow aplasia, when given at haemotoxic dose levels for 17 days in the BALB/c mouse.

Development and validation of an NMR-based identity assay for bacterial polysaccharides.

A method utilizing NMR spectroscopy has been developed to confirm the identity of bacterial polysaccharides used to formulate a polyvalent pneumococcal polysaccharide vaccine. The method is based on 600 MHz proton NMR spectra of individual serotype-specific polysaccharides. A portion of the anomeric region of each spectrum (5.89 to 4.64 ppm) is compared to spectra generated for designated reference samples for each polysaccharide of interest. The selected region offers a spectral window that is unique to a given polysaccharide and is sensitive to any structural alteration of the repeating units. The similarity of any two spectral profiles is evaluated using a correlation coefficient (rho), where rho >/= 0.95 between a sample and reference profile indicates a positive identification of the sample polysaccharide. This method has been shown to be extremely selective in its ability to discriminate between serotype-specific polysaccharides, some of which differ by no more than a single glycosidic linkage. Furthermore, the method is rapid and does not require extensive sample manipulations or pretreatments. The method was validated as a qualitative identity assay and will be incorporated into routine quality control testing of polysaccharide powders to be used in preparation of the polyvalent pneumococcal vaccine PNEUMOVAX 23. The specificity and reproducibility of the NMR-based identity assay is superior to the currently used colorimetric assays and can be readily adapted for use with other bacterial polysaccharide preparations as well.

Haemotoxicity of chloramphenicol succinate in the CD-1 mouse and Wistar Hanover rat.

1. Chloramphenicol has been widely used in the treatment of serious infections including typhoid fever and meningitis. However, the drug is haemotoxic in man inducing firstly, a reversible, dose-dependent anaemia which develops during treatment, secondly, an often fatal aplastic anaemia with pancytopenia and acellular marrow, and thirdly, leukaemia. 2. We investigated the haemotoxicity of chloramphenicol succinate (CAPS) in female CD-1 mice in repeat dose studies, to compare the response with the reversible anaemia reported in man. Studies in male Wistar Hanover rats were also carried out. 3. CAPS was gavaged daily to mice at dose levels from 800 - 2000 mg/kg for seven days. Values were significantly reduced for reticulocytes at 1700 and 2000 mg/kg, and for erythrocytes (RBC), haematocrit (HCT), and haemoglobin (Hb) at 2000 mg/kg. Platelet and white blood cell (WBC) counts were unaffected. 4. Mice were dosed with CAPS at 1400 mg/kg for 10 days and sampled at 1, 4 and 15 days after the last dose. At day 1 post dosing, RBC, HCT and Hb values were significantly reduced, but returned to normal (or above normal) by day 4 or 15. 5. CAPS from 2000 - 4000 mg/kg was gavaged to rats daily for 19 days. Hb values were significantly lower at 3600 and 4000 mg/kg; reticulocytes were not reduced. WBC and platelet counts, in general, were unaffected. 6. Levels of apoptosis in marrow mononuclear cells were increased in CAPS-treated mice, but not in CAPS-treated rats. Serum biochemistry parameters, in general, showed few changes of toxicological significance. 7. We conclude that the administration of CAPS to CD-1 mice induced haematological changes showing close parallels with the chloramphenicol-induced reversible anaemia seen in man.

Effects of citrated whole blood transfusion in response to hemorrhage.

BACKGROUND AND PURPOSE: Standard treatment for massive hemorrhage in dogs is infusion of whole blood or of packed red blood cells with fresh frozen plasma if whole blood is not available. Although most whole blood is collected using a citrate-based anticoagulant, knowledge of citrate's relevant non-anticoagulant effects is not widespread. Citrate's anticoagulant activity is achieved through chelation of divalent metal cations (e.g., magnesium, calcium), which may exacerbate cardiovascular and metabolic insults attributable to hemorrhage. METHODS: Blood pressures, gas tensions, metabolites, and electrolytes; myocardial metabolites, pressures, and contractility; cardiac output; and left cranial descending and circumflex coronary artery flows were measured in 21 anesthetized dogs after hemorrhage was induced by collection of blood into a citrated reservoir to mean arterial pressure of 45 mm Hg for approximately 60 min (until arterial lactate concentration was 7.0 mmol/L), followed by a 1-h transfusion and 2 h of maintenance. RESULTS: Arterial ionized calcium concentration, total peripheral resistance, and myocardial function decreased significantly during hemorrhage. All aforementioned responses but myocardial function continued to decrease during the initial 20 min of transfusion, then began to recover. Total peripheral resistance and end-systolic elastance were the only factors significantly related to calcium concentration. CONCLUSION: Transfusion with citrated whole blood may significantly alter calcium concentration, negatively affecting myocardial and vascular function.

Prospective multivariate analysis of donor monoethylglycine xylidide (MEGX) testing in liver transplantation. Transplantation Society of Michigan Scientific Studies Committee.

Measurement of the metabolism of lidocaine to MEGX by the hepatic cytochrome P450 system has been proposed as a means to assess liver function and metabolic activity of cadaveric organ donors. This prospective study of 102 potential liver donors from the State of Michigan sought to determine the role of MEGX determinations alone and in conjunction with traditional measures of donor acceptability. High MEGX values (> 80 microg/L) did not correlate with the acceptability of donor livers, and had no significant association with early posttransplant graft function, as determined by SGOT, SGPT, alkaline phosphatase, bilirubin, prothrombin time, or bile production. However, livers procured from donors with high MEGX values had improved actuarial graft survival when compared to low MEGX donors at 30 d (95% vs. 84%) and at 1 yr (68% vs. 43%) (p < 0.04). Multivariate analysis demonstrated a significant independent association of both shorter cold ischemic time and high MEGX value with improved graft survival (p < 0.002). We conclude that the MEGX test offers limited incremental value in predicting early function of donor livers when used in conjunction with traditional criteria of clinical evaluation, laboratory tests, and histology. However, knowledge of the results of MEGX determinations may be of value in predicting graft survival after liver transplantation.

The myelotoxicity of chloramphenicol: in vitro and in vivo studies: II: In vivo myelotoxicity in the B6C3F1 mouse.

1. Chloramphenicol continues to be widely used in many parts of the world despite its known haematotoxicity. Until now, elucidation of the mechanisms involved and any attempt at amelioration of the toxic effects have been hampered by the lack of an animal model. 2. In this study neither acute nor chronic administration of chloramphenicol as its succinate ester in the drinking water produced anaemia in mice as assessed by changes in peripheral blood parameters. 3. Chloramphenicol could not be detected in the bone marrow when the antibiotic was administered either in the drinking water or by gavage, although it was detected in the serum. 4. In marrow taken from mice after chloramphenicol succinate administration and cultured in vitro, depression of the differentiation of immature committed erythroid progenitors occurred 15 min after administration of the antibiotic by gavage. However, recovery was beginning to occur at 48 h after administration of chloramphenicol succinate at 50 and 200 mg/kg and this was then followed by an 'overshoot' response at the higher dose. A toxic effect was therefore achieved in the bone marrow but this was probably masked in the peripheral blood by enhanced proliferation. 5. Morphological evidence of apoptosis was seen in erythroid and myeloid precursors in mice treated with 200 mg/kg. 6. The data suggest that the effect of chloramphenicol was at the differentiation stage of the committed marrow progenitor cells rather than at the replication stage of the stem cells and therefore this response appears to mimic the reversible bone marrow depression seen in the treated patient.

Premature coronary artery disease associated with a disruptive mutation in the estrogen receptor gene in a man.

BACKGROUND: While estrogens protect against coronary artery disease in women, it is unclear whether they influence cardiovascular function in men. The present report describes coronary vascular abnormalities and the lipoprotein profile of a male patient with estrogen insensitivity caused by a disruptive mutation in the estrogen-receptor gene. METHODS AND RESULTS: Stress thallium scintigraphy, echocardiography, and electron-beam computed tomography (CT) scanning of the coronary arteries and detailed lipoprotein analysis were performed. Electron-beam CT scanning of the coronary arteries showed calcium in the left anterior descending artery. Lipoprotein analysis showed relatively low levels of total (130 mg/dL), LDL (97 mg/dL), and HDL (34 mg/dL) cholesterol; apolipoprotein A-I (91.7 mg/dL); and lipoprotein(a) (4.1 nmol/L), but normal levels of triglycerides (97 mg/dL) and pre-beta-1-HDL cholesterol (61 microg/mL). CONCLUSIONS: The absence of functional estrogen receptors may be a novel risk factor for coronary artery disease in men.