Effect of tidal regime on the thermal tolerance of the marine gastropod Lunella smaragda (Gmelin 1791).

The tidal cycle around New Zealand results in spring low tides consistently occurring during the hottest part of the day (mid-afternoon) in north-eastern New Zealand, and during the cooler dawn/dusk periods in the north-west of the country. We hypothesised that due to mid-afternoon spring low tides, intertidal populations residing at north-eastern sites would show greater thermotolerance than their north-west conspecifics. To test this we used the marine gastropod, Lunella smaragda, which were collected from sites on both the East and West coasts of the Auckland region and exposed to an acute heat shock. Thermotolerance was measured as survivorship (LT50), drop down time (time to heat coma) and thermal stability of the anaerobic energy producing enzyme Tauropine dehydrogenase. Furthermore, temperature loggers were deployed at each site so as to record and compare thermal regimes among sites. A strong temperature spike associated with spring low tide was found at all sites, and maximal temperatures of all East coast sites were higher than West coast sites (in some case by up to 10°C). In terms of thermotolerance, mortality of L. smaragda occurred at 42°C leading to 100% mortality at 45°C. However, comparison of LT50 showed snails were equally thermotolerant regardless of site of collection. Similar results were found in TDH thermal stability with animals from all sites showing an approximately 80% decrease in enzyme activity after 10min exposure to 42°C. Whilst drop down times were different among sites these were correlated with animal size as opposed to site of collection. Thus, East coast populations of L. smaragda appear no more thermotolerant than their West coast counterparts. Such a result is concerning as maximal temperatures at East coast sites already exceed the LT50 values of L. smaragda recorded in the lab suggesting these populations have less of a thermal safety margin.

At least one in three people with Type 2 diabetes mellitus referred to a diabetes centre has symptomatic obstructive sleep apnoea.

AIMS: To investigate the prevalence of symptomatic obstructive sleep apnoea in unselected patients with Type 2 diabetes referred to a tertiary diabetes clinic. METHODS: In a cross-sectional design, all newly referred patients were offered a stepwise screening for obstructive sleep apnoea with: (1) The Berlin questionnaire; then, if indicative: (2) overnight home monitoring with the ApneaLink™ device. Patients with an apnoea-hypopnoea index ≥ 5/h were offered referral for diagnostic polygraphy and treatment initiation. RESULTS: A total of 200 patients participated (61% men; age 59.6 ± 10.5 years, diabetes duration 8.3 ± 6.3 years and BMI 31.7 ± 6.7 kg/m²). According to the questionnaire, 106 patients showed 'high risk' of obstructive sleep apnoea, and 72 of these were referred to polygraphy based on ApneaLink screening corresponding to a prevalence of symptomatic obstructive sleep apnoea of 39%. Patients with symptomatic obstructive sleep apnoea had significantly higher BMI, poorer glycaemic control and lower plasma HDL cholesterol levels as compared with patients unlikely to have obstructive sleep apnoea. The groups were not different with respect to sex, age, diabetes duration, blood pressure, diabetic complications or medication use. In multiple regression analyses, age, BMI and HDL cholesterol levels were all significant, independent predictors of obstructive sleep apnoea. CONCLUSIONS: At least one third of people with Type 2 diabetes referred to a diabetes clinic in Denmark has symptomatic obstructive sleep apnoea. Our data suggest higher age, a compromised plasma lipid profile and a more obese phenotype in patients with Type 2 diabetes who have obstructive sleep apnoea, highlighting the need to focus on screening and treatment of obstructive sleep apnoea in these patients.

Elective caesarean section at 38 weeks versus 39 weeks: neonatal and maternal outcomes in a randomised controlled trial.

OBJECTIVES: To investigate whether elective caesarean section before 39 completed weeks of gestation increases the risk of adverse neonatal or maternal outcomes. DESIGN: Randomised controlled multicentre open-label trial. SETTING: Seven Danish tertiary hospitals from March 2009 to June 2011. POPULATION: Women with uncomplicated pregnancies, a single fetus, and a date of delivery estimated by ultrasound scheduled for delivery by elective caesarean section. METHODS: Perinatal outcomes after elective caesarean section scheduled at a gestational age of 38 weeks and 3 days versus 39 weeks and 3 days (in both groups ±2 days). MAIN OUTCOME MEASURES: The primary outcome was neonatal intensive care unit (NICU) admission within 48 hours of birth. Secondary outcomes were neonatal depression, NICU admission within 7 days, NICU length of stay, neonatal treatment, and maternal surgical or postpartum adverse events. RESULTS: Among women scheduled for elective caesarean section at 38⁺³ weeks 88/635 neonates (13.9%) were admitted to the NICU, whereas in the 39⁺³ weeks group 76/637 neonates (11.9%) were admitted (relative risk [RR] 0.86, 95% confidence interval [95% CI] 0.65-1.15). Neonatal treatment with continuous oxygen for more than 1 day (RR 0.31; 95% CI 0.10-0.94) and maternal bleeding of more than 500 ml (RR 0.79; 95% CI 0.63-0.99) were less frequent in the 39 weeks group, but these findings were insignificant after adjustment for multiple comparisons. The risk of adverse neonatal or maternal outcomes, or a maternal composite outcome (RR 1.1; 95% CI 0.79-1.53) was similar in the two intervention groups. CONCLUSIONS: This study found no significant reduction in neonatal admission rate after ECS scheduled at 39 weeks compared with 38 weeks of gestation.

Identification of a novel UTY-encoded minor histocompatibility antigen.

Minor histocompatibility antigens (mHags) encoded by the Y-chromosome (H-Y-mHags) are known to play a pivotal role in allogeneic haematopoietic cell transplantation (HCT) involving female donors and male recipients. We present a new H-Y-mHag, YYNAFHWAI (UTY(139-147)), encoded by the UTY gene and presented by HLA-A*24:02. Briefly, short peptide stretches encompassing multiple putative H-Y-mHags were designed using a bioinformatics predictor of peptide-HLA binding, NetMHCpan. These peptides were used to screen for peptide-specific HLA-restricted T cell responses in peripheral blood mononuclear cells obtained post-HCT from male recipients of female donor grafts. In one of these recipients, a CD8+ T cell response was observed against a peptide stretch encoded by the UTY gene. Another bioinformatics tool, HLArestrictor, was used to identify the optimal peptide and HLA-restriction element. Using peptide/HLA tetramers, the specificity of the CD8+ T cell response was successfully validated as being HLA-A*24:02-restricted and directed against the male UTY(139-147) peptide. Functional analysis of these T cells demonstrated male UTY(139-147) peptide-specific cytokine secretion (IFNγ, TNFα and MIP-1ß) and cytotoxic degranulation (CD107a). In contrast, no responses were seen when the T cells were stimulated with patient tumour cells alone. CD8+ T cells specific for this new H-Y-mHag were found in three of five HLA-A*24:02-positive male recipients of female donor HCT grafts available for this study.

Safety of Bifidobacterium breve, Bif195, employing a human exercise-induced intestinal permeability model: a randomised, double-blinded, placebo-controlled, parallel group trial.

We have previously shown that the probiotic Bifidobacterium breve strain Bif195 alleviates mucosal injury including ulcer formation in the upper intestine induced by non-steroid anti-inflammatory drugs (NSAIDs). Here, we report additional safety use of Bif195 in 126 healthy humans undergoing an exercise-induced intestinal permeability challenge in a double-blinded, placebo-controlled randomised 6-week intervention trial. Intestinal permeability was assessed by urinary lactulose/rhamnose (L/R) ratio. L/R ratio, plasma intestinal fatty acid binding protein (I-FABP) and gastrointestinal symptom rating scale (GSRS) questionnaire were measured resting and after a 1 h treadmill challenge, prior to and at the end of the intervention. To be able to compare the equivalence of resting state at baseline, of this cohort of well-trained subjects, to non-trained subjects, a cohort of 63 healthy and non-trained subjects (<2 h/week of endurance sports) was included. Study subjects (well-trained) were 35.7% women with a mean age and body mass index (in kg/m2) of 35.0 years and 24.8, respectively. There were no differences between the Bif195 and placebo groups in effects on L/R ratio, I-FABP and GSRS questionnaire score. In addition, there were no differences between Bif195 and placebo in number of adverse events and change in cytokines, liver or kidney biomarkers. The exercise model successfully induced intestinal permeability by statistically significantly increasing L/R ratio by ~100% (P<0.0001) and cytokines after the exercise challenge. No significant difference was found between well-trained and non-trained subjects in baseline resting L/R ratio. In conclusion, the reported cytoprotective effects of Bif195 are unlikely to be primarily related to small bowel permeability, and the safety of Bif195 in individuals with increased permeability is supported by the present data. ClinicalTrials.gov: NCT03027583.

Effects of environmental factors on microbial induced calcium carbonate precipitation.

AIMS: To gain an understanding of the environmental factors that affect the growth of the bacterium Sporosarcina pasteurii, the metabolism of the bacterium and the calcium carbonate precipitation induced by this bacterium to optimally implement the biological treatment process, microbial induced calcium carbonate precipitation (MICP), in situ. METHODS AND RESULTS: Soil column and batch tests were used to assess the effect of likely subsurface environmental factors on the MICP treatment process. Microbial growth and mineral precipitation were evaluated in freshwater and seawater. Environmental conditions that may influence the ureolytic activity of the bacteria, such as ammonium concentration and oxygen availability, as well as the ureolytic activities of viable and lysed cells were assessed. Treatment formulation and injection rate, as well as soil particle characteristics are other factors that were evaluated for impact on uniform induction of cementation within the soils. CONCLUSIONS: The results of the study presented herein indicate that the biological treatment process is equally robust over a wide range of soil types, concentrations of ammonium chloride and salinities ranging from distilled water to full seawater; on the time scale of an hour, it is not diminished by the absence of oxygen or lysis of cells containing the urease enzyme. SIGNIFICANCE AND IMPACT OF STUDY: This study advances the biological treatment process MICP towards field implementation by addressing key environmental hurdles faced with during the upscaling process.

Insulin resistance induced by physical inactivity is associated with multiple transcriptional changes in skeletal muscle in young men.

Physical inactivity is a risk factor for insulin resistance. We examined the effect of 9 days of bed rest on basal and insulin-stimulated expression of genes potentially involved in insulin action by applying hypothesis-generating microarray in parallel with candidate gene real-time PCR approaches in 20 healthy young men. Furthermore, we investigated whether bed rest affected DNA methylation in the promoter region of the peroxisome proliferator-activated receptor-γ coactivator-1α (PPARGC1A) gene. Subjects were reexamined after 4 wk of retraining. We found that bed rest induced insulin resistance and altered the expression of more than 4,500 genes. These changes were only partly normalized after 4 wk of retraining. Pathway analyses revealed significant downregulation of 34 pathways, predominantly those of genes associated with mitochondrial function, including PPARGC1A. Despite induction of insulin resistance, bed rest resulted in a paradoxically increased response to acute insulin stimulation in the general expression of genes, particularly those involved in inflammation and endoplasmatic reticulum (ER) stress. Furthermore, bed rest changed gene expressions of several insulin resistance and diabetes candidate genes. We also observed a trend toward increased PPARGC1A DNA methylation after bed rest. We conclude that impaired expression of PPARGC1A and other genes involved in mitochondrial function as well as a paradoxically increased response to insulin of genes involved in inflammation and ER stress may contribute to the development of insulin resistance induced by bed rest. Lack of complete normalization of changes after 4 wk of retraining underscores the importance of maintaining a minimum of daily physical activity.

Nutrients cause grassland biomass to outpace herbivory.

Human activities are transforming grassland biomass via changing climate, elemental nutrients, and herbivory. Theory predicts that food-limited herbivores will consume any additional biomass stimulated by nutrient inputs ('consumer-controlled'). Alternatively, nutrient supply is predicted to increase biomass where herbivores alter community composition or are limited by factors other than food ('resource-controlled'). Using an experiment replicated in 58 grasslands spanning six continents, we show that nutrient addition and vertebrate herbivore exclusion each caused sustained increases in aboveground live biomass over a decade, but consumer control was weak. However, at sites with high vertebrate grazing intensity or domestic livestock, herbivores consumed the additional fertilization-induced biomass, supporting the consumer-controlled prediction. Herbivores most effectively reduced the additional live biomass at sites with low precipitation or high ambient soil nitrogen. Overall, these experimental results suggest that grassland biomass will outstrip wild herbivore control as human activities increase elemental nutrient supply, with widespread consequences for grazing and fire risk.

Clearance of circulating gamma-glutamyltransferase by the hepatic galactose receptor. Variability in clearance rate due to carbohydrate heterogeneity of the enzyme.

The clearance and organ uptake of gamma-glutamyltransferase was studied by injecting the purified human liver enzyme intravenously in the rat. The enzyme was almost exclusively taken up by liver hepatocytes with a rapid initial uptake. The clearance was significantly inhibited by asialofetuin as well as by galactose and fucose. The uptake of neuraminidase-treated enzyme was much more rapid than that of the native enzyme. Subfractions of gamma-glutamyltransferase obtained by lectin affinity chromatography revealed significant differences in clearance rates. The data strongly indicates that the uptake of circulating gamma-glutamyltransferase involves the galactose (asialo-glycoprotein) receptor of the parenchymal cells, and that the heterogeneity of gamma-glutamyltransferase results in varying clearance rates.

Improved vaccination response during ranitidine treatment, and increased plasma histamine concentrations, in patients with B cell chronic lymphocytic leukemia.

Patients with B cell chronic lymphocytic leukemia (B-CLL) have decreased capacity to mount relevant antibody responses upon immunization, and development of hypogammaglobulinemia is part of the natural history of the disease. We investigated the influence of histamine type-2 (H2) receptor blockade by ranitidine on the in vivo antibody production in B-CLL patients following vaccination. Anti-polysaccharide antibodies in B-CLL patients, vaccinated with a tetanus-toxoid conjugated vaccine against Haemophilus influenzae type-B (Hib), reached long-term protective levels in more than 90% of B-CLL patients randomized to ranitidine treatment, as compared to 43% of the untreated patients (P = 0.024). No difference in the response to vaccination against influenza virus types A and B protein could be detected between the two groups. Plasma histamine levels were 2-fold to 20-fold higher in 23 out of 31 B-CLL patients, compared to normal controls, and these levels showed a significant positive correlation to disease duration. These findings indicate the possibility of improving in vivo antibody production against a highly relevant pathogen in B-CLL patients by histamine type-2 receptor blockade, and the combined finding of an immune-stimulatory effect of ranitidine and increased plasma histamine levels, strongly suggests the involvement of histamine in the pathogenesis of B-CLL immunodeficiency.

Serum lipoprotein inhibitors of granulopoiesis in human bone marrow cultures.

Ammonium sulphate fractionation of human serum showed that two fractions contained an inhibitor of cluster and colony formation in agar cultures of human bone marrow cells. Further investigations demonstrated this inhibition to be caused by lipoproteins. When freshly prepared, only light density lipoproteins (LDL) were found to be inhibitory. During storage, very light density lipoproteins (VLDL) acquired inhibitory activity, while high density lipoproteins (HDL) did not show any inhibition of human bone marrow cultures. The possibility of toxic degradation of lipoproteins as an explanation for the inhibition was investigated by preincubation of human marrow cells with lipoproteins for 6 hours (37 degrees C) after storage of the lipoproteins under nitrogen (4 degrees C) for various intervals up to 48 days. Preincubation was found to be non-toxic (viable cell counts) and without colony/cluster-reducing ability for incubated marrow cells compared to controls. Addition of lipoproteins to mouse marrow cells and Ehrlich ascites tumour cells resulted in no change in colony formation by Ehrlich cells, whereas mouse marrow cells were inhibited, but to a lesser degree than human marrow cells.

Micropore filters for sterile filtration may leach toxic compounds affecting cell cultures (HL 60).

Reduction in HL-60 cell growth could be traced unexpectedly to sterile filtration procedures. To circumvent this problem, 11 available brands of micropore filters (five prepacked and six to be packed and autoclaved) were investigated with the aim of finding the least toxic product. Samples of 10 ml of RPMI 1640 medium with 10% fetal calf serum added were filtered through four filters of each brand to detect even small amounts of leached toxic compounds. HL-60 cells were cultured in these filtered media for three days and the results compared with cultures using unfiltered medium. A large variation in growth inhibition was found between the filters investigated, ranging from 0% to about 90%. The growth inhibition was due to leaching of toxic compounds, as revealed by viability test, reseeding, and direct microscopy. Adsorption of essential proteins to the micropore filters was found for only one of the filters investigated in this study.

Development and application of a sensitive radioimmunoassay for human granulocyte-macrophage colony-stimulating factor able to measure normal concentrations in blood.

A radioimmunoassay (RIA) for human granulocyte-macrophage colony-stimulating factor (GM-CSf) was developed based on antibodies from rabbits immunized with glycosylated recombinant human (rh) GM-CSF. The antibodies are specific for human GM-CSF and do not crossreact with other human hematopoietic growth factors or mouse GM-CSF. The antibodies also react with nonglycosylated rhGM-CSF, so E. coli-derived rhGM-CSF can be assayed as well. The RIA has a measuring range of about 10 to 200 pg/mL. Normal blood was found to contain 13 to 24 pg/mL (95% limits) with a mean of 18.5 pg/mL (n = 34). Monoclonal antibodies against GM-CSF could remove GM-CSF from normal human serum, thus ensuring that the GM-CSF measured in serum is real and does not represent nonspecific reactivity with our polyclonal rabbit antibodies. While previously published methods have been unable to measure GM-CSF in human serum under normal conditions, our more sensitive RIA does confirm the presence of small amounts of GM-CSF in serum or plasma and can therefore be used to detect fluctuations of GM-CSF in health and in disease.

Constitutive and modulated cytokine expression in two permanent human bone marrow stromal cell lines.

We present a detailed analysis of cytokine expression patterns of the two permanent human bone marrow stromal cell lines, L87/4 and L88/5. These cell lines, previously established in our laboratory, are highly radiotolerant without cell detachment and support long-term cultures of CD(34+)-enriched human cord blood cells. RT-PCR analysis of 22 different cytokines or cytokine receptor mRNAs showed an almost identical expression pattern in the two stromal cell lines compared to primary human Dexter-type stroma. Since stromal feeder lines employed in long-term cultures usually are irradiated and grown in media containing corticosteroids, we analyzed the impact of irradiation and dexamethasone on cytokine production in the two cell lines by RT-PCR, Northern blot analysis, bioassays, and RIAs. By RT-PCR analysis, constitutive mRNA expression of c-kit, G-CSF, GM-CSF, IL-1 beta, IL-6, IL-7, IL-8, IL-11, Kit ligand (KL), LIF, M-CSF, MIP-1 alpha, TGF-beta, and TNF-alpha was demonstrated in both cell lines, with L87/4 a more potent cytokine producer than L88/5. Northern blot data showed an increase in mRNA levels for GM-CSF, IL-1 beta, and LIF by irradiation and IL-1 alpha treatment in both cell lines. IL-1 alpha-induced GM-CSF, IL-1 beta, IL-6, IL-11, and LIF mRNA levels were reduced by the addition of dexamethasone, whereas dexamethasone had no influence on the amounts of IL-1 alpha-induced G-CSF mRNA. L87/4 and, to a lower extent, L88/5 cells showed dexamethasone-dependent increases in KL mRNA, while KL mRNA levels were not stimulated by IL-1 alpha.

Immediate bromodeoxyuridine labelling of unseparated human bone marrow cells ex vivo is superior to labelling after routine laboratory processing.

It is important to evaluate the proliferation of bone marrow cells in several disease conditions and during treatment of patients with for example cytokines. Labelling with bromodeoxyuridine (BrdUrd), immunocytochemical staining with anti-BrdUrd antibody and analysis by flow cytometry provides a reliable and reproducible technique for estimation of the fraction of cells that incorporated BrdUrd into DNA during S-phase. We have compared immediate BrdUrd labelling of unseparated bone marrow cells with the previously used labelling in the laboratory after routine separation of the mononuclear cells. Bone marrow aspirates from seven lymphoma patients without bone marrow involvement were studied with these two methods. We found higher BrdUrd labelling indices (LI) in the mononuclear cells, when cells were labelled immediately. A large variation in LI was found between patients. Our results suggest that ex vivo BrdUrd labelling of bone marrow cells should be performed immediately after aspiration and before separation, because these data are closer to values reported from in vivo labelling with BrdUrd.

Increased cellular hypoxia and reduced proliferation of both normal and leukaemic cells during progression of acute myeloid leukaemia in rats.

The microenvironmental changes in the bone marrow, spleen and liver during progression of the transplantable promyelocytic leukaemia in the Brown Norwegian rat (BNML) have been studied. We used flow cytometry to estimate cellular hypoxia and proliferation based on in vivo pulse-labelling with a mixture of 2-nitroimidazole linked to theophylline (NITP) and bromodeoxyuridine (BrdUrd). The leukaemic cells were identified with the RM124 antibody. In rats inoculated with leukaemic cells the fraction of RM124+ cells was significantly increased from day 20 onwards in the spleen and from day 27 in the bone marrow and liver, reaching a level of 65-87% in these organs at day 32. At day 32, the NITP+ fraction of RM124+ cells had increased significantly in the bone marrow and spleen to 88% and 90%, respectively. The corresponding fractions of NITP+ normal cells reached 63% and 65%, respectively. From day 13 to day 32, the DNA-synthesizing (BrdUrd+) fraction of RM124+ cells in the bone marrow decreased significantly from 52% to 25%, and of normal cells from about 20% to 6%. In the bone marrow and spleen at day 27 and 32, the S-phase and G2/M-phase fractions according to DNA content were higher for the NITP+ than for the NITP- cells. This could partly be explained by an impaired cell cycle progression due to hypoxia. Nevertheless, we found indications of leukaemic cells that were simultaneously labelled with NITP and BrdUrd, in the bone marrow and spleen. These latter findings suggest that in contrast to normal cells some of the leukaemic cells can proliferate even during hypoxia, and this subpopulation may consequently renew and expand the leukaemic cell load.

24,25-dihydroxy vitamin D3 treatment inhibits parathyroid-stimulated adenylate cyclase in iliac crest biopsies from uremic patients.

Renal osteodystrophy with increased bone resorption is a major clinical problem in patients with chronic renal failure. Previous reports have shown that treatment with 24,25-dihydroxy vitamin D3 (24,25(OH)2D3) may result in decreased bone resorption. The present study addresses basic mechanisms for the action of 24,25(OH)2D3 in bone of patients with elevated serum parathyroid hormone (PTH) levels due to chronic renal disease. Twenty-four patients 56 +/- 17 years old (mean +/- SE) with chronic kidney disease in the predialytic state (serum creatinine > 150 mumol/l) and elevated serum midregion PTH > 1.2 micrograms/l were randomly assigned to oral treatment with either 1,25-dihydroxy vitamin D3 (1,25(OH)2D3) (0.25-0.50 microgram/day), 24,25(OH)2D3 (daily dose of 15 micrograms), or a combination of the two vitamin D3 analogs. The control group received calcium carbonate (maximal dosage of 1 g x 3). Selected variables in serum and urine as well as hormone sensitive adenylate cyclase (AC) in iliac crest biopsies were assessed before treatment and during follow-up after two and six months. Serum levels of 1,25(OH)2D3 and 24,25(OH)2D3 were significantly (P < 0.05) increased after two and six months in the respective treatment groups. Net bone PTH-enhanced AC (PTH-AC) fell abruptly (P < 0.01) after two months of treatment and was nearly abolished (P < 0.01) after six months with 24,25(OH)2D3 given alone or in combination with 1,25(OH)2D3. An inverse relationship (r = -0.57, P < 0.05, n = 48) between net PTH-AC in bone and serum levels of 24,25(OH)2D3 was demonstrated. In all groups, serum total calcium (s-Ca) was maintained within normal range.(ABSTRACT TRUNCATED AT 250 WORDS)

Serum gamma-glutamyltransferase and alkaline phosphatase during experimental liver metastases. Detection of tumour-specific isoforms and factors affecting their serum levels.

Tumour-specific isoenzymes and tumour markers in serum are potentially useful in the detection and monitoring of liver metastases. An experimental rat model was used in the search for such isoenzymes and to study factors affecting their serum levels. Splenic injection of CC531 colon carcinoma cells in syngeneic WagRij rats caused liver metastases after 3 weeks with concomitant and significant increases in serum levels of gamma-glutamyltransferase (GT) and alkaline phosphatase (ALP). The presence of tumour-specific isoforms of both enzymes, as well as increased amounts of the liver isoform of ALP, were demonstrated in serum. The serum levels of the tumour variants were clearly related to their elimination rates from the circulation. Thus, the slow clearance of the tumour ALP resulted in high serum levels of this isoform, compared with the more rapid elimination of tumour GT and its lower serum level. When using another colon carcinoma cell line (DHD/K12), metastatic to liver in BD IX rats, no increases in serum GT were detected. This was related to the rapid elimination from the circulation of the GT variant from the DHD/K12 metastatic tissue. The relatively high amount of the tumour ALP isoform detected in serum during growth of the CC531 liver metastases indicated that this isoform could be useful as a marker of tumour growth.

Changes in the activities of cytidine deaminase during differentiation of HL60 cells induced by 1,25 dihydroxy D3.

The activities of the enzymes cytidine deaminase (CDD), deoxycytidine kinase (dCK), adenosine deaminase (ADA), and purine nucleoside phosphorylase (PNP), have been investigated in the promyelocytic leukemia cell line HL60. The activities of the enzymes corresponded well with that seen in acute myeloid leukemia cells except, that the CDD activity was very low in the HL60 cells. Induction of differentiation in HL60 cells by 1,25 dihydroxy D3 resulted in an increase in CDD from 12 to 247 nmol/h/mg and a decrease in ADA from 1326 to 896 nmol/h/mg, while the activities of dCK, and PNP were unchanged. Retinoic acid, another used inducer of differentiation, gave no changes of the enzyme activities. The increase in CDD activity induced by 1,25 dihydroxy D3 was prevented by inhibition of protein synthesis, whereas inhibition of proliferation of the cells did not abolish the increase of CDD. The changes correspond well with the differences seen between immature and mature myeloid cells. The results may have consequences for the interpretation of results obtained with cytostatics, which are metabolized by the enzymes.