Body composition and muscle constituents during weight loss: studies in obese patients following gastroplasty.

BACKGROUND: The influence of rapid and prolonged weight loss on body composition and muscle constituents in the obese patient is not well known. There are serious complications related to rapid and prolonged weight loss. It is of general interest to increase the understanding of the mechanisms and consequences of significant weight loss in man. METHODS: In 40 obese patients, the body composition and muscle constituents were studied before and during 1 year of weight loss following gastroplasty. The study was undertaken in two groups (A and B) of obese patients, comprising 32 women and eight men, body weight 82-175 kg and aged 24-49 years. Mean BMI in group A and B was 45 (W/H(2)) and 43 (W/H(2)) respectively. Body composition was assessed by total body potassium measurements and muscle constituents were determined by analyses of muscle specimens obtained percutaneously. RESULTS: The preoperative body composition was found to be equal parts of lean body mass and body fat. Preoperatively, muscle constituents revealed a higher protein content per cell and a lower potassium concentration related to fat-free solids. The loss of 18-28% body fat and lean body mass occurred in equal proportions during the first 3 postoperative months of rapid weight loss, followed by a continuous decrease of body fat but not of lean body mass. The concentrations of proteins and potassium per muscle cell revealed a reduction during the period of rapid weight loss. The RNA/DNA ratio 1 year after surgery was still reduced, indicating a low protein synthesis rate. CONCLUSIONS: Preoperatively mean body fat accounted for 50% of the body weight in obese patients. Following weight loss, body fat, lean body mass and concentrations of proteins were reduced compared to preoperative values. After the period of rapid weight loss, with reduction of lean body mass and body fat in parallel, a progressive reduction of body fat was observed whereas the lean body mass did not decrease further. Protein synthesis rate was still low 12 months after surgery.

Blocking of MHC class I antigens on leukemic B-cells enhances their conjugate formation with cytotoxic lymphocytes and their susceptibility to lysis.

The role of major histocompatibility complex (MHC) class I antigens and adhesion molecules (AM) in the resistance of leukemic B-cells to cell-mediated cytotoxicity was investigated using cells from eight patients with B-chronic lymphocytic leukemia (B-CLL) and six patients with immunocytoma (IC). Both CLL and IC cells were completely resistant to natural killer (NK) and lymphokine activated killer (LAK) cytotoxicity and no binding to effector cells was observed, irrespectively of AM expression. Blocking of MHC class I antigens with monoclonal antibodies or their temporary elimination from leukemic B-cell surface by acid treatment resulted in a significant (p < 0.005) increase in both conjugate formation and susceptibility to lysis, thus suggesting the relevance of MHC class I expression on leukemic B-cells for the NK/LAK resistance phenomenon.

Leukotrienes and lipoxins--new potential performers in the regulation of human myelopoiesis.

Leukotrienes and lipoxins are bioactive lipoxygenase products formed by leukocytes alone or in collaboration with other cells. While the physiological role of lipoxins remains to be clarified, accumulating evidence shows that leukotrienes are important mediators in asthma and inflammation. Consequently, recent clinical trials with leukotriene D4 receptor antagonists and 5-lipoxygenase inhibitors have demonstrated marked reduction of airway symptoms in asthmatic patients. In addition, both leukotrienes and lipoxins have been indicated as modulators of cell proliferation. This article reviews recent findings suggesting that these compounds may also participate in the regulation of human myelopoiesis. Such a role is conceivable since leukotrienes and lipoxins can be produced by bone marrow cells and potently modulate GM-CSF-induced myeloid stem cell proliferation.

The quandary of cancer prevention.

The incidence and mortality due to the major cancers such as lung, breast, colon-rectum, prostate, and ovary have changed very little over the past 20-30 years, in spite of the introduction of important new treatments and apparent prolongation of survival of patients with these cancers. The new strategies focus on earlier detection and primary prevention of cancer. Three approaches for prevention are receiving increasing prominence as an approach to reducing the incidence of cancer: (1) control of common source environmental carcinogens, (2) modification of personal health behavior believed to increase or decrease the risk of cancer, and (3) identification of specific genotypes that increase the risk of cancer. All of these approaches offer some hope of reducing cancer incidence and morbidity. All will be costly and, therefore, require careful evaluation. It is likely that the changes in personal health behaviors will have the greatest overall impact on cancer incidence. Identification of specific genotypes will be of importance for high risk families. At present, it is unlikely that control of environmental common sources will substantially reduce cancer incidence without better measures of exposure and risk of disease.

Methodological aspects of DNA image cytometry in normal bone marrow smears.

The possibility of using DNA image cytometry in hematological material was evaluated in 27 Feulgen stained normal bone marrow smears. The 95% normal limits of DNA index (DI) determined separately for each cell population in bone marrow were 0.89-1.15, 0.93-1.09 and 0.92-1.12 for blasts, granulocytes and lymphocytes, respectively. The mean DI for blasts, granulocytes and lymphocytes was 1.02, 1.01 and 1.02, respectively. In the blasts population the mean percentage of cells in S+G2/M phase was 38.1% (S.D. 12.9%, range 14.3-65.6%), whereas the corresponding values for granulocytes and lymphocytes were below 1%. Calculation of DI and G0/G1 C.V. obtained in bone marrow smears subjected to Feulgen hydrolysis (5 N HCl, 22 degrees C) for different periods of time revealed the presence of a plateau of results between 60 and 120 min for all of the cell types. The intraobserver and interobserver reproducibility was confirmed by duplicate measurements of each subpopulation (P > 0.05). A comparison of DI and G0/G1 C.V. using smears from the same donors stained with the Feulgen method either straight away or after destaining from May-Grunwald-Giemsa confirmed that destained smears can be used, provided applying appropriately prepared reference cells. We conclude that image cytometry can be used reliably to analyze DNA content in hematological material.

Conjugate formation by leukemic blasts from acute myeloid leukemia with cytotoxic lymphocytes.

Conjugate formation by AML blasts with fresh peripheral blood lymphocytes (PBL) and lymphokine activated killer (LAK) effectors was studied by flow cytometry. Leukemic blasts formed very low numbers of conjugates with fresh PBL and were resistant to natural killer (NK) cytotoxicity. When LAK effectors were used a significant increase in conjugate formation was observed, which in the majority of cases was followed by an increased killing. There was a positive correlation between the percentages of conjugates formed by AML blasts with LAK effectors and the susceptibility to lysis. No significant difference in binding activity between the CD3+ and CD56+ LAK subpopulations was found. There was no correlation between the expression of ICAM-1, LFA-3 and Transferrin receptor (CD71) and the conjugate formation. The blocking of CD71 on the control K562 cell line reduced the conjugate formation with LAK effectors but no such effect could be observed with CD71+ AML blasts.

Variation in DNA content of immature normal bone marrow cells.

A variability in DNA content detected was found with image cytometry, in immature bone marrow cells from 13 healthy donors (median age 31 yr). The mean coefficient of variation (C.V.) of the DNA content was found to be significantly (P = 0.0002) higher in immature blasts and promyelocytes than in mature granulocytes, lymphocytes, and monocytes. The finding was not due to high DNA contents secondary to DNA-synthesis in immature cells, since the percentage of such cells with a reduced DNA content was also significantly (P = 0.0424-0.0002) increased. The error of the method expressed as the variance of multiple measurements has been found to be 0.0002-0.0004. A staining error has been found for some hydrolysis times, but not for times between 60 and 120 minutes. A measuring error was found for an average of 1.38 to 3.38% of the cells. If many normal cells with DNA-aneuploidy are sterile, this would explain the present findings as well as previous ones about intra-marrow cell death, and also the fact that the variability in DNA content could not be detected with cytogenetic or flow cytometric methods.

Comparative absorption of ferrous and heme-iron with meals in normal and iron deficient subjects.

The relative intestinal absorption of heme- and non heme-iron in connection with a standardized test meal was studied in a group of fertile women given 16 mg Fe in the form of FeSO4 and 2 mg Fe in the form of hemoglobin. Both in normal subjects and in women with iron deficiency, the heme-iron was significantly better absorbed (16.13% +/- S.D. 8.0 vs 4.59 +/- 3.4, p < 0.01 and 22.03 +/- 8.9 vs 9.45 +/- 7.8, p < 0.05). For targeted prophylaxis of iron deficiency with small, side-effect-free doses, heme-iron is thus a valuable component which increases the absorption by about 40%. Heme-iron does not cause high concentrations in the intestinal lumen of free radical inducing, possibly harmful ferric iron.

Formation and effects of leukotrienes and lipoxins in human bone marrow.

The present results demonstrate leukotriene and lipoxin synthesis in human bone marrow and link these findings to biological effects in the same tissue. However, the mechanisms behind the described effects on myeloid progenitor cell growth are presently unknown. It is conceivable that both leukotrienes and lipoxins may act through modulation of endogenous cytokine production. However, it should be noted, that these lipoxygenase products totally failed to induce colony growth in the absence of GM-CSF. Moreover, the role of lipoxins in the bone marrow needs to be further clarified, since LXA4 induced both synergistic (with GM-CSF) and antagonistic (with LTC4) effects on progenitor cell growth. A possible pathophysiological role for leukotrienes and lipoxins may be suggested in chronic myelogenous leukemia. Thus, the capacity of hematological cells from CML patients to synthesize LTC4 was significantly increased. In addition, we have recently reported that CML platelets possessed a markedly decreased ability to participate in transcellular synthesis of the potential inhibitors of myelopoiesis, LXA4 and 5(S),12(S)-diHETE (Stenke et al., 1991b). Moreover, the production of these compounds was totally abolished in platelets obtained from CML patients in blastic crisis. Further studies should aim at defining the mechanisms behind the regulatory actions of leukotrienes and lipoxins in normal and leukemic human myelopoiesis.

Comparison of acute myeloid leukemia occurring de novo or preceded by a myelodysplastic stage: differences in cellular DNA content.

The DNA content of bone marrow cells in patients with acute leukemia preceded by a myelodysplastic stage (MDS-AML) was compared to that in patients with de novo AML. We studied granulocytes, lymphocytes, monocytes, and blasts/promyelocytes from Feulgen-stained bone marrow smears of 11 patients with de novo AML, ten patients with MDS-AML, and 13 apparently healthy controls. The mean amount of DNA per cell (DNA index; DI) in each cell population was determined using a digital video-based image-analyzing system (CAS-100). Analysis of variance (F test) showed a significant difference in the DNA content between de novo AML on one hand and MDS-AML and controls on the other as regards to blasts/promyelocytes (P < 0.01), lymphocytes (P < 0.05), and monocytes (P < 0.01), respectively. In three of 11 (27%) patients with de novo AML, a lower than normal limit DI was found both in immature and mature bone marrow cells. Patients with MDS-AML had those of DI values similar to normal controls. In consequence, a significantly reduced mean DI was found in patients with de novo AML in blasts/promyelocytes (P < 0.01), and monocytes (P < 0.05) compared to both normal controls and MDS-AML. Together with data published separately, suggesting differences in granulocyte morphology, clonality, and HLA-DR expression, these data suggest biological differences between the two diseases.

DNA image analysis in childhood acute lymphoblastic leukemia.

DNA index (DI) and percentages of cells in S and G2/M phase were determined in Feulgen stained nuclei of blasts from 31 cases of childhood ALL at diagnosis. In 6 cases the results of DNA analysis and cytogenetics were concordant showing hyperdiploidy. Two other cases with normal karyotype were revealed as DNA aneuploid with image analysis. Cases with cytogenetic abnormalities like translocation, deletion or presence of single or double supernumerary chromosomes had DI within normal ranges. Nine ALL cases (29%) were found to be DNA aneuploid--8 hyperdiploid and 1 hypodiploid. The percentages of cells in S and G2/M phase for blasts from bone marrow (mean 17.6%) were significantly higher than those estimated in the peripheral blood (mean 1.57%). We conclude that analysis by image cytometry can detect aneuploid DNA content even in cases, which showed a normal karyotype and provides new information concerning the biological aspects of leukemic blasts.

Binding of leukaemic blasts to various subpopulations of lymphokine-activated killer cells.

Conjugate formation by natural killer (NK)-resistant and NK-sensitive leukaemic cell lines with fresh and IL-2-stimulated (lymphokine-activated killer, LAK) peripheral blood lymphocytes (PBL) was studied by a flow cytofluorometry method with double staining. A significant difference in binding of NK-resistant T-cell lymphoma (HuT 78) and NK-sensitive myeloid (K562) blasts to fresh PBL was observed (P < 0.01). Activation of lymphocytes with IL-2 resulted in a significant increase of binding and killing of both K562 and HuT 78. However, in the case of blasts from NK-resistant cell line Daudi a similar conjugate formation with fresh PBL and LAK effectors was observed, despite a significant increase in killing. Various subpopulations of LAK effectors (CD3, CD16 and CD56 positive) displayed similar binding activity towards myeloid (K562) and lymphoid (Raji) blasts, which shows that conjugate formation occurs not only with NK-cell-derived, but also with T-cell-derived LAK cells. The blocking of CD71 antigen (transferrin receptor) on K562 blasts inhibited binding of cytotoxic lymphocytes, which was mostly due to the blocking of binding of CD56+ subpopulation. Our results indicate that the resistance of leukaemic blasts to cell-mediated cytotoxicity may depend on different (and probably several) steps of this process.

Stimulation of human myelopoiesis by leukotrienes B4 and C4: interactions with granulocyte-macrophage colony-stimulating factor.

The regulatory role of leukotrienes (LT) on human myelopoiesis was investigated. Mononuclear bone marrow cells from 31 healthy donors were cultivated in the presence of suboptimal concentrations of recombinant granulocyte-macrophage colony-stimulating factor (GM-CSF) for 10 days in semisolid agar. The addition of LTC4 or LTB4 to the cultures dose-dependently stimulated myeloid stem cell proliferation. Maximal effects were observed at 10(-8) mol/L, at which LTC4 induced a 91% +/- 23% (mean +/- SEM; P = .004) and LTB4 a 73% +/- 22% (P = .008) increase in colony formation. In contrast, addition of the LTB4 isomer 5(S), 12(S)-diHETE did not affect the growth. LTD4 exerted a weak potentiating effect on progenitor proliferation (17% +/- 7% growth stimulation at 10(-10) mol/L; P = .034), whereas LTE4 was without consistent effect. Furthermore, LTC4-induced stimulation of colony formation was insensitive to the LTD4 antagonist ICI 198615. The dual lipoxygenase and prostaglandin endoperoxide synthase inhibitor CL42A potently suppressed the proliferation of myeloid colonies, a suppression that could be reversed by parallel addition of LTB4 or LTC4. The results suggest that both LTB4 and LTC4 possess strong and specific synergistic stimulatory effects on GM-CSF-induced human myeloid progenitor cell growth.