Germany's first Total Diet Study - Occurrence of non-dioxin-like polychlorinated biphenyls and polybrominated diphenyl ethers in foods

The occurrence of persistent organic pollutants like polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) in food represents a public health concern. The BfR MEAL Study was initiated to generate a comprehensive data base of occurrence data for chemicals in the most consumed foods in Germany. Non-dioxin-like PCBs (NDL-PCBs) and PBDEs were analysed in 300 foods, purchased and prepared representatively for the eating behaviour of the population in Germany. Highest levels of NDL-PCBs and PBDEs were detected in spiny dogfish, cod liver, herring, and eel. High NDL-PCB and PBDE levels were observed in other oily fish, wild boar meat, sheep liver, and high-fat dairy products. The comparison of food from conventional and organic production revealed higher NDL-PCB values in the food group 'meat and meat products' if produced organically. Occurrence data of this study will improve future dietary exposure and risk assessments in Germany.

Corrigendum to "The first German total diet study (BfR MEAL Study) confirms highest levels of dioxins and dioxin-like polychlorinated biphenyls in foods of animal origin title of article" [Food Chem.: X 16 (2022) 100459]

[This corrects the article DOI: 10.1016/j.fochx.2022.100459.].

The first German total diet study (BfR MEAL Study) confirms highest levels of dioxins and dioxin-like polychlorinated biphenyls in foods of animal origin

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Presentation of PCDD/F and dl-PCB data in 300 foods prepared as consumed in Germany.

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By wet weight, highest levels in fish products, fatty fish, sheep liver, and butter.

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By fat weight, highest levels in game, dairy products, and sheep meat.

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MEAL foods did not exceed EU maximum levels.

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Evaluation of the impact of regions and type of production.

The first German Total Diet Study, called the BfR MEAL Study, generated a comprehensive dataset of polychlorinated dibenzo-p-dioxins and -furans (PCDD/Fs) and dioxin-like polychlorinated biphenyls (dl-PCBs) in foods representative for the consumption habits in households in Germany. PCDD/Fs and dl-PCBs are persistent organic pollutants. Dietary intake is considered to be the most relevant exposure pathway for humans. Levels were examined in 300 foods that were prepared as typically consumed by the population in Germany. Highest PCDD/F and dl-PCB levels were detected in animal-based foods such as fish, butter, dairy products, liver, and meat. The comparison of conventionally and organically produced foods revealed a trend to slightly higher contents in organically produced foods. Sampling discriminated by region and season showed no major differences. Analysed occurrence data will improve future dietary exposure and food safety assessments in Germany.

Cardiac MRI findings to differentiate athlete's heart from hypertrophic (HCM), arrhythmogenic right ventricular (ARVC) and dilated (DCM) cardiomyopathy

To provide clinically relevant criteria for differentiation between the athlete’s heart and similar appearing hypertrophic (HCM), dilated (DCM), and arrhythmogenic right-ventricular cardiomyopathy (ARVC) in MRI. 40 top-level athletes were prospectively examined with cardiac MR (CMR) in two university centres and compared to retrospectively recruited patients diagnosed with HCM (n = 14), ARVC (n = 18), and DCM (n = 48). Analysed MR imaging parameters in the whole study cohort included morphology, functional parameters and late gadolinium enhancement (LGE). Mean left-ventricular enddiastolic volume index (LVEDVI) was high in athletes (105 ml/m²) but significantly lower compared to DCM (132 ml/m²; p = 0.001). Mean LV ejection fraction (EF) was 61% in athletes, below normal in 7 (18%) athletes vs. EF 29% in DCM, below normal in 46 (96%) patients (p < 0.0001). Mean RV-EF was 54% in athletes vs. 60% in HCM, 46% in ARVC, and 41% in DCM (p < 0.0001). Mean interventricular myocardial thickness was 10 mm in athletes vs. 12 mm in HCM (p = 0.0005), 9 mm in ARVC, and 9 mm in DCM. LGE was present in 1 (5%) athlete, 8 (57%) HCM, 10 (56%) ARVC, and 21 (44%) DCM patients (p < 0.0001). Healthy athletes’ hearts are characterized by both hypertrophy and dilation, low EF of both ventricles at rest, and increased interventricular septal thickness with a low prevalence of LGE. Differentiation of athlete’s heart from other non-ischemic cardiomyopathies in MRI can be challenging due to a significant overlap of characteristics also seen in HCM, ARVC, and DCM.

[Prevalence of the metabolic syndrome and its risk factors: results of a large work-site health assessment]

BACKGROUND

Facing the demographic change, cardiovascular risk factors have been assessed within an occupational checkup to establish health programs.

PATIENTS AND METHODS

From 2006 to 2007, anthropometric and blood parameters of 27 359 employees of a large company of the German automobile industry were collected aiming to determine the prevalence of metabolic syndrome (by NCEP ATP III) and its risk factors. Data from 3048 employees (fasting state) were analyzed (age: ∅ 39,4 ± 10,3 years, 81.4% males).

RESULTS

The most common risk factors were hypertension ≥ 130/85 mmHg (men [m]: 74,4%, 95%-confidence interval [CI] 73-76%, women [w]: 47,1%, 95%-CI 43-51%), elevated triglycerides (≥ 150 mg/dl; m: 32,8%, 95%-CI 31-35%, w: 13,8%, 95%-CI 11-17%) and waist-circumferences (> 102 cm for men: 15,1%, 95%-CI 14-17%; > 88 cm for women: 16,9%, 95%-CI 14-20%). The prevalence of metabolic syndrome (≥ 3 risk factors) was 11,7% (95%-CI 12-15%; m: 12,7%, 95%-CI 11-14%, w: 7,4%, 95%-CI 6-10%) increasing with physical inactivity and rising age up to 20%. The prevalence of hypertension in young (< 20 years) and elder men (≥ 50 years) was similarly high (79,1%, 95%-CI 70-86% vs. 79,9%, 95%-CI 75-82%).

CONCLUSION

The prevalence of metabolic syndrome in this sample is rather low, but 75% of the men and nearly 50% of the women had hypertension. Health programs should focus on this risk factor in particular.

Dioxin and dl-PCB exposure from food: the German LExUKon project

Polychlorinated dibenzo-p-dioxin and -furan (PCDD/F) and dioxin-like polychlorinated biphenyl (dl-PCB) exposure from food were estimated using new food consumption data from the recent German food consumption survey (Nationale Verzehrsstudie II - NVS II). Based on these comprehensive data, information on the consumption of 545 individual food items by the German population was derived. Concentrations of dioxin-like compounds in food were compiled from the German Food Monitoring Programme (GFMP), the German Dioxin Database, other German authority programmes, European countries' authority programmes and the published literature covering the years 2000-2010. By multiplication with consumption data, estimates of intake from food were determined. The main food groups contributing most to the intake of the general public are dairy products (including milk), meat and fish (including seafood), followed - due to high consumption - by the main group vegetables. The combined intake of PCDD/F and dl-PCB (as toxic equivalents - TEQ) from food was estimated to be 2.11/1.53 pg kg(-1) bw and day and 3.56/2.85 pg kg(-1) bw and day (upper/lower bound) for average and high-end consumers, respectively. The estimated intake of average consumers is close to a reference value derived by the Scientific Committee on Food in 2001. Uncertainties in these estimates pertain to the influence of values below the limit of quantification (upper/lower bound ratio) and some foods not considered due to the lack of contamination data.

Association of leptin and insulin with childhood obesity and retinal vessel diameters

OBJECTIVE

Childhood obesity is associated with an impaired retinal microcirculation. The aim of the study was to investigate the association between specific obesity-related biomarkers, physical fitness and retinal vessel diameters in school children.

DESIGN AND SUBJECTS

We studied 381 children aged 10-11 years (body mass index (BMI): 19.3±3.7 kg m(-2)) in a school-based setting.

MEASUREMENTS

Anthropometric measurements and blood sampling were conducted using standard protocols for children. The serum biomarkers leptin, adiponectin, insulin as well as interleukin-6 (IL-6) were analyzed. Physical fitness was determined by a six-item-test battery and physical activity by use of a questionnaire. Central retinal arteriolar equivalent (CRAE), central retinal venular equivalent (CRVE) and the arteriolar-to-venular diameter ratio (AVR) were assessed with a non-mydriatic vessel analyzer (SVA-T) using a computer-based program.

RESULTS

Compared with normal weight children (n=254), obese children (n=39) showed higher leptin (P<0.001), higher insulin (P<0.001), higher IL-6 (P<0.001) and lower adiponectin levels (P=0.013). Obese children demonstrated wider CRVE (P=0.041) and lower AVR (P<0.001). Higher leptin levels were associated with wider CRVE (P=0.032) and lower AVR (P=0.010), that was BMI dependent. Insulin levels were associated with arteriolar (P=0.045) and venular dilatation (P=0.034) after adjustment for BMI. No significant associations between adiponectin levels, IL-6 levels, physical fitness or physical activity and retinal vessel diameter were observed. Lower leptin levels were independently correlated with higher physical fitness (r=-0.33; P<0.001).

CONCLUSION

Leptin and insulin levels are associated with changes of the retinal microcirculation. Especially insulin seems to be a good target marker for the cardiometabolic risk assessment in children since elevated insulin levels are independently associated with microvascular end-organ alterations at an early stage. Lifestyle intervention studies are warranted to examine whether improvement of physical fitness or weight reduction can affect cardiometabolic risk markers and reverse alterations of the retinal microcirculation.

First wave of the influenza A/H1N1v pandemic in Switzerland

AIM

To describe the disease burden, clinical pattern and outcome of influenza-related cases presenting to a Swiss Emergency Department (ED), during the first wave of the 2009 pandemic.

METHODS

Retrospective analysis of prospectively collected data at the University Hospital of Basel, Switzerland. All patients presenting to the ED with influenza-like symptoms from June 1 to October 23, 2009, were studied. Rate of hospitalisation, demographic characteristics, symptoms, microbiological diagnoses and complications of influenza infection were analysed.

RESULTS

One tenth (808 of 8356 patients) of all non-trauma ED presentations, during the study period, were a result of suspected influenza-related illness. Influenza A/H1N1v infection accounted for 5% of these presentations. Patients aged 50 years or less accounted for 87% of these presentations and for 100% of A/H1N1v infection. The highest detection rate of A/H1N1v-infection occurred in July, and the highest rate of clinical presentations occurred in August 2009. Underlying medical disease was observed in 14% of all patients. The presence of fever, cough and myalgia was the prime clinical predictor for the presence of A/H1N1v infection. 16% of patients with this triad suffered from A/H1N1v.

CONCLUSION

Suspected A/H1N1v infection contributed to a considerable health care burden in Switzerland. However, the rate of true positivity was low (5%), hospitalisations rare (5%), and mortality did not occur. Therefore, the first wave of the A/H1N1v pandemic in Switzerland was rather media "hype" than real threat.

Long-term outcomes of high-dose therapy using busulfan, etoposide, and cyclophosphamide followed by allogeneic hematopoietic cell transplantation for patients with high-risk or advanced stages of myeloid malignancies

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Patients (pts) with high risk (HR) or advanced myeloid malignancies have limited effective treatment options. These include high-dose therapy followed by allogeneic hematopoietic cell transplantation (HCT). We report a single institution long-term follow-up of 96 pts, median age 50 (20–60) yrs, who received HLA matched related HCT between 1992 and 2007. All pts were treated with a uniform preparatory regimen: busulfan 16.0 mg/kg (d-8 to-5), etoposide 60mg/kg (d-4), cyclophosphamide 60mg/kg (d-2), and graft-versus-host-disease (GVHD) prophylaxis of cyclosporine and prednisone. Disease status at transplantation was induction failure (IF) acute myeloid leukemia (AML) (n = 10), HR AML in 1st complete remission (CR1) n = 11, in CR2 (n = 5), in CR3 (n = 2), relapsed refractory (RR) AML (n = 14), chronic myeloid leukemia (CML) in second chronic phase (n = 6), blast crisis (n = 2), myelofibrosis (n = 6), myeloproliferative disorders (n = 2), and MDS (n = 38). Thirty-six % (n = 35) of pts received bone marrow while 64 % (n = 61) received G-CSF mobilized peripheral blood mononuclear cells (PBMC). With a median follow up of 5.6 yrs (1.6–14.6 yrs) actuarial 5-year overall survival (OS) was 32% (95% CI 22–42%) and 5-year probability for freedom from progression (FFP) was 64% (95% CI 52%-76%). Relapse rate was 32% at 1 year and remained at 36% (95%CI 24%-48%) at 2 and 5 years with no further increase in relapse beyond two years. Non-relapse mortality (NRM) was 29 % (95% CI 20%5–38%) at day 100 and 39% (95% CI 29%-49%) at one yr. Cumulative incidence of acute (grade 3–4) and chronic GVHD was 28% (95% CI 19%-37%) and 38% (95% CI 24%-52%), respectively. There was no statistically significant difference in OS; 31% versus 32% (p = 0.89) or FFP 71% versus 60% (p = 0.29) for recipients of BM versus PBMC with similar results in IF and RR AML. These results confirm that pts with high-risk or advanced myeloid malignancies can achieve long-term survival following myeloablative allogeneic HCT with aggressive conditioning. Relapse and acute GVHD remain significant causes of mortality. Strategies to augment graft-versus-tumor reactions and reduce GVHD remain essential for improving long-term outcomes.

No significant financial relationships to disclose.

Nonmyeloablative hematopoietic cell transplantation (HCT) for treatment of patients (pts) with fludarabine-refractory chronic lymphocytic leukemia (CLL) results in prolonged median survival

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Background: Pts with fludarabine-refractory CLL have a poor prognosis with median survival of 12 months. A phase II trial of Campath resulted in median survival of 16 months. Curative alternatives are required. Methods: We previously reported 2-year overall survival (OS) of 60% for 64 pts treated with nonmyeloablative HCT from related (n=44) or unrelated (n=20) donors (Sorror. JCO, 2005). Those pts were refractory to fludarabine (88%) ± additional agents. Eligibility criteria, conditioning and immunosuppression regimens, and primary endpoint were previously described. Here, we extended the follow up to 38 (range: 10–74) months after HCT ( Table ). Results: Chronic extensive graft-versus-host disease (GVHD) at 3 years was 53% and non-relapse mortality (NRM) was 27%. Among 30 pts who achieved initial responses {25 complete (CR) and 5 partial (PR)}, one patient died while in CR from NRM, one patient with PR progressed, while remaining 28 pts continued alive and in remission. CR and relapse rate at 3 years were 54% and 32%, respectively. Unrelated recipients had a significantly higher CR rate than related recipients. Ten responding pts were tested for molecular eradication of their disease and all were negative at a median of 52 months. There were 6 deaths in this extended follow up, 5 from relapse/progression and one from pneumonia. Overall, 33 pts are alive; 24 in CR, 4 in PR, 2 with stable disease, and 3 with relapse/progression. Estimated 3-year rates of OS, disease-free survival (DFS), and NRM were 54%, 42%, and 27% respectively. In multivariate analysis, high pretransplant comorbidity scores predicted higher NRM and worse OS while bulky lymphadenopathy predicted increased risk of progression. Conclusion: Nonmyeloablative HCT resulted in an extended median survival of greater than 3 years for pts with fludarabine-refractory CLL. The use of unrelated grafts was associated with a trend toward better DFS.

[Table: see text]

No significant financial relationships to disclose.

Hematopoietic cell transplantation from related and unrelated donors after minimal conditioning as a curative treatment modality for severe paroxysmal nocturnal hemoglobinuria

Paroxysmal nocturnal hemoglobinuria (PNH) is a rare clonal disorder caused by a somatic mutation of the X-linked phosphatidylinositol glycan class A gene. Allogeneic hematopoietic cell transplantation (HCT) after high-dose conditioning is the only curative treatment; however, it is associated with high treatment-related mortality. Here, we report on allogeneic HCT for PNH after minimal conditioning. Seven adult patients with high-risk PNH underwent peripheral blood HCT from HLA-A-, -B-, -C-, -DRB1-, and -DQB1-matched related (n = 2) and unrelated (n = 5) donors. Conditioning included fludarabine 30 mg/m(2)/d on days -4 to -2 and 2 Gy of total body irradiation on day 0. After HCT, patients were given immunosuppressive therapy with oral cyclosporine starting on day -3 and mycophenolate mofetil starting on day 0. All 7 patients attained durable engraftment. After 28 days, a median of 77% (range, 53%-96%) T-cell donor chimerism was found in bone marrow and peripheral blood. T-cell chimerism increased to 91% (range, 76%-100%) on day +180 and to 100% in all surviving patients after 12 months. All 7 patients attained complete remissions of their disease. Four patients are alive 13 to 38 months after HCT. Three patients died of treatment-related mortality, 1 because of complications after acute pancreatitis and multiorgan failure, 1 because of infection related to chronic graft-versus-host disease (GVHD), and 1 because of bleeding after liver biopsy for late subacute/chronic GVHD. Allogeneic HCT from related and unrelated donors after minimal conditioning is a new and potentially curative option for patients with advanced PNH.

HIV-1 Nef associated PAK and PI3-kinases stimulate Akt-independent Bad-phosphorylation to induce anti-apoptotic signals

A highly conserved signaling property of Nef proteins encoded by human or simian immunodeficiency virus is the binding and activation of a PAK kinase whose function is unclear. Here we show that Nef-mediated p21-activated kinase (PAK) activation involves phosphatidylinositol 3-kinase, which acts upstream of PAK and is bound and activated by Nef similar to the manner of Polyoma virus middle T antigen. The Nef-associated phosphatidylinositol-3-PAK complex phosphorylated the pro-apoptotic Bad protein without involving the protein kinase B-Akt kinase, which is generally believed to inactivate Bad by serine phosphorylation. Consequently, Nef, but not a Nef mutant incapable of activating PAK, blocked apoptosis in T cells induced by serum starvation or HIV replication. Nef anti-apoptotic effects are likely a crucial mechanism for viral replication in the host and thus in AIDS pathogenesis.

Allogeneic stem cell transplantation (BMT) for AML and MDS following i.v. busulfan and cyclophosphamide (i.v. BuCy)

Pretransplant conditioning therapy with i.v. BuCy followed by allogeneic hematopoietic stem cell transplantation (BMT) was investigated in a phase II trial in patients with acute myeloid leukemia (AML) or myelodysplastic syndrome (MDS). We gave i.v. Bu at a dose of 0.8 mg/kg every 6h x 16 doses, followed by Cy 60 mg/kg daily for 2 days. Twenty-six AML patients (18 males/eight females) were treated, only eight of whom were in CR1. The rest were either refractory to induction chemotherapy (four patients) or in a more advanced stage of their disease (14 patients). In addition, nine patients with MDS (1M/8F) were treated. Their median age was 41 years (range 21-64). Engraftment to > or =500 neutrophils/microl was reached at 14 days (range 10-29 days) post BMT, and the median time of neutropenia was only 11 days (range 4-28 days). The most common regimen-related toxicity was grade 2-3 nausea. In the post-BMT period (including BMT day +30), two patients died, one each from pulmonary hemorrhage secondary to CMV pneumonia and hepatic veno-occlusive disease (VOD), for an early treatment-related mortality (TRM) of 5.7%. Three patients developed VOD and two of them died. There was no direct regimen-related pulmonary or neurologic toxicity. Overall, the clinical side-effect spectrum was analogous to what would be expected from a high-dose oral Bu-based regimen; there was no unique toxicity experienced with the used solvent system. The disease-free survival in the high-risk subgroup (all patients not in CR1) at 1 and 2 years post transplant was 44% and 31%, respectively. The 13 patients still alive in CR have been followed for a median of 24 months (range 18-32). Pharmacokinetic analysis showed very good interdose reproducibility, and limited interpatient variability in area under the plasma concentration vs time curve, peak concentration, and clearance of Bu after this i.v. formulation. We conclude, that this new i.v. Bu formulation is well tolerated; it has an impressive safety profile, and we suggest that it should be considered as appropriate replacement for oral busulfan in pretransplant conditioning therapy prior to allogeneic BMT for patients with AML or MDS.

[Real-time ultrasonic pregnancy diagnosis (B-mode) in sheep. 1. Frequent examinations during the first month of pregnancy]

Transrectal ultrasonography was performed on 63 ewes (four breeds) to determine the earliest day at which pregnancy, the first embryo, the number of embryos, the embryonal heartbeat and placentoms could be detected. The ewes were examined at intervals of two to three days on day 12/13 to 30 post breeding. An Aloka SSD 500 ultrasound unit was used with a 5-Mhz probe. The diagnosis of the pregnant ewes took place on day 17.6 +/- 1.8 p.c. The first embryo was detected on day 20.5 +/- 1.9 p.c., but not all of the embryos were counted accurately until day 26. The heartbeat of the embryos was detected on day 22.9 +/- 2.9 p.c. and placentoms on day 27.6 +/- 2.4 p.c. The influence of the breed on the results will be discussed. The proportion of sheep with a loss of embryos was 24.6% (partial loss of embryos 18.0%, total loss of embryos 6.6%). In conclusion, transrectal ultrasound is a good method to describe the early pregnancy in sheep.

[Optimization of embryo transfer programs in ewes by transrectal ultrasonographic ovary diagnosis (B-mode) in superovulated donors]

The aim of this study was to check the accuracy of transrectal ultrasonography for the ovary diagnosis in superovulated sheep during the estrus (n = 10) and on the day 8 after estrus (n = 10). The results were checked by laparoscopic ovary diagnosis. The real-time ultrasound unit CS-9100 OCULUS was used with a linear 7.5 MHz rectal probe. Transrectal ultrasonography was performed at sheep lying in their dorsal position. In 90% of the sheep it was possible to find both ovaries during the estrus and in 60% on the 8th day of the estrus cycle. Correlation for the number of follicle (diameter > or = 4 mm) per ovary during the estrus counted at ultrasonography and laparoscopy were 0.62 (p < 0.05) and for the number of corpora lutea per ovary on day 8 after estrus 0.97 (p < 0.05). The results suggest, that the ultrasonographic ovary diagnosis is an appropriate method to check the results of superovulation in embryo transfer programs. Non-responding or poorly responding donors can be selected.

Bone marrow transplantation for thalassemia. The USA experience

PURPOSE

We have reviewed the results of bone marrow transplantation in 30 patients with thalassemia major who were treated in the United States.

PATIENTS AND METHODS

Ten patients who underwent transplantation in Seattle and 20 patients from five other U.S. centers were identified through a survey of the International Bone Marrow Transplant Registry. These transplants were performed between November 1981 and April 1992 in patients with diverse ethnic backgrounds and ranged in age from 6 months to 14 years (median 4.0 years). Twenty-seven of the 30 patients received marrow from a human leukocyte antigen (HLA)-identical sibling or other family member, one patient received HLA-matched marrow from an unrelated donor, and two patients were given haploidentical but HLA-mismatched marrow from a related donor. Cytoreductive (preparative) therapy varied among institutions and pretransplant risk categories. In general, patients were given busulfan (12-24 mg/kg) or dimethylmyleran (5 mg/kg) in combination with cyclophosphamide (120-240 mg/kg). A subset of patients were given total body irradiation (TBI) at a dose of 720 cGy followed by cyclophosphamide (120 mg/kg).

RESULTS

Sixteen of 27 patients (59%) who received marrow from an HLA-identical family member are event-free survivors, with a duration of follow-up ranging from 2 months to > 10 years after transplantation. Six of these 27 patients (22%) had recurrence of thalassemia and five (19%) died. The estimated actuarial rate of thalassemia recurrence was 24% and the rate of event-free survival was 57%. Only one of the three patients who received marrow from HLA-nonidentical or unrelated donors survives event-free. Liver biopsies were not routinely performed before transplant. Thus, classification of patients into Lucarelli risk groups was not possible. A modified risk classification was devised by using liver size and iron status assessed by the regularity of chelation and the serum ferritin level. With use of this classification, there was no significant difference in event-free survival between transplant risk groups.

CONCLUSIONS

The findings observed in this small series of patients confirms that thalassemia can be cured with bone marrow transplantation. Although most patients are event-free survivors, a significant number experienced recurrence of their disease. A cooperative multicenter trial of U.S. transplant centers may be necessary to evaluate the use of marrow transplantation for thalassemia and to determine optimal treatment.

Efficient generation and characterization of tumor cell subclones with different adhesion pathways involved in cell lysis

BACKGROUND

Specific tumor cell recognition is required for optimal tumor directed therapy. Lymphokine activated killer (LAK) cells are able to recognize tumor targets specifically because LAK cells can distinguish between normal and tumor cells. This study was aimed at analyzing receptor molecules on tumor cells and their counter-receptor molecules on LAK cells. Cell lines which differ in the pathway by which LAK cell lysis is mediated are important for an analysis of receptor molecules.

METHODS

We adapted a novel method for efficient production of K562 clones in order to analyze the mechanisms by which target and effector receptor molecules mediate different LAK cell interactions. K562 cells were exposed to ethyl methanesulfonate (EMS) for mutagenization and addition of two rounds of irradiated LAK cells. Prior data demonstrated that irradiation does not effect cytolysis. Surviving cells were plated in methylcellulose and single colonies were obtained after ten days. Cells were washed, resuspended in medium, expanded and tested as targets in a 51Cr-release assay.

RESULTS

With this procedure a variety of clones could be generated easily and time-savingly. All twelve clones expressed the bcr/abl transcript, as determined by PCR, and were sensitive to LAK cell lysis. However, cell blockage studies revealed that K562 clones were generated with LAK cell recognition differing from parental K562. Antibody blockage showed that lysis of clone 5 (LEF 5) is partially mediated via the LFA-1/ICAM-1 pathway. ICAM-1 expression of this clone was similar to expression on K562, as determined by flow cytometry.

CONCLUSIONS

These clones are of great value for studying the receptor molecules involved in LAK--tumor cell interactions.

Culture of phenotypically defined hematopoietic stem cells and other progenitors at limiting dilution on Dexter monolayers

Highly enriched, phenotypically defined hematopoietic stem, Thy-1loLin-Sca-1+, and progenitor cell populations from mouse bone marrow (BM) were tested at limiting dilution for their ability to reconstitute Dexter monolayers. Several classes of BM cells can reconstitute Dexter cultures, first forming discrete "cobblestone" areas which then mature into colonies consisting primarily of maturing myeloid and erythroid cells. Most such colonies have a limited lifespan in culture. Only the Thy-1loLin-Sca-1+ cell fraction gives rise to colonies that survive longer than 3 weeks, which suggests that a limiting-dilution analysis for long-term reconstitution of Dexter cultures can serve as a quantitative measure of stem cell activity. Additional experiments were performed to assess the formation of new progenitor cells in reconstituted Dexter cultures. Again, only cultures seeded with the stem cell-enriched fraction contained expanded numbers of replatable WEHI-3 CM responsive colony-forming cells (CFU-GM). Quantitative analysis indicates that 97% of the replatable CFU-GM of whole BM is contributed by the Thy-1loLin-Sca-1+ cell fraction, again suggesting a potential stem cell-specific assay. Such quantitative in vitro assays might prove useful in characterization and isolation of human stem cells where in vivo assays are lacking.

Hemoglobin Great Lakes (beta 68 [E12] leucine replaced by histidine): a new high-affinity hemoglobin

Hemoglobin Great Lakes, beta 68 (E12) Leu replaced by His is a new high oxygen affinity hemoglobin variant discovered in a 29-yr-old female having numerous hospitalizations for thrombophlebitis associated with mild erythrocytosis. The mutant hemoglobin has normal stability and normal electrophoretic mobility, but increased oxygen affinity (P-50 16.1 mm Hg at 37 degrees C, pH 7.4) and reduced cooperativity. The abnormal beta-chain could be separated on globin chain chromatography on carboxymethyl/cellulose in spite of the normal electrophoretic mobility of the intact hemoglobin. The leucyl residue at beta 68th position (E12) is in the middle of E-helix, which is part of the heme pocket and next to the valine (E11), which is the heme binding site. The substitution of proline for leucine in hemoglobin Mizuho resulted in the distortion of tertiary structure of the beta-chains and lead to a serious instability of hemoglobin molecule. However, the substitution of this residue by histidine in hemoglobin Great Lakes is not associated with hemoglobin instability.