Cytotoxicity of derivatives from dehydrocrotonin on V79 cells and Escherichia coli

New derivatives from dehydrocrotonin (DHC, compound I), with the same anti-ulcerogenic properties but less toxicity were synthesised by reducing the cyclohexenone moiety of DHC with NaBH(4) (compound II), by reducing the cyclohexenone and lactone moieties with LiAlH(4) (compound III) and by transforming the lactone moiety into an amide (compound IV) using dimethylamine. The cytotoxicity of these derivatives from DHC was assayed on V79 fibroblast cell line. Three independent endpoints for cytotoxicity were evaluated; namely, the nucleic acid content (NAC), tetrazolium reduction (MTT) and neutral red uptake (NRU). IC(50) values of 540 and 350 microM were obtained for compound II in the NRU and NAC tests, respectively. Compound III was less toxic than the other DHC derivatives (IC(50)=1800 microM) on V79 cells based on NAC assay. Compound IV showed an IC(50) ranging from 350 to 600 microM based on the three endpoints evaluated. The three compounds were less toxic on V79 cells than DHC. DHC, compounds II, III and IV did not change the respiration rate of Escherichia coli on the acute toxicity assay.

New rearrangement pattern after treatment of hairy-cell leukemia with 2-chlorodeoxyadenosine

Leukemic hairy cells are clonally proliferating B-lymphoid cells with clonal rearrangements of genes for immunoglobulin chains. We describe a patient with a new hairy-cell clone after treatment with 2-chlorodeoxyadenosine (2-CdA). In this patient, a single course of 2-CdA resulted in good partial remission of hairy-cell leukemia, but Southern blot analysis of bone marrow biopsies and polymerase chain reaction using seminested amplifications with consensus primers revealed a new rearranged band 4 months after therapy with 2-CdA. Four years after therapy, the patient is in complete clinical remission and both bands disappeared during follow-up. The new rearranged band might have been related to prior treatment of hairy-cell leukemia with 2-CdA.

Violacein cytotoxicity and induction of apoptosis in V79 cells

Violacein, a pigment produced by Chromobacterium violaceum, is reported to be a potential drug for the treatment of Chagas' disease. Violacein is also effective against leukemia and lymphoma cells in culture (IC50 10(-8) M). Changes in the nuclear acid content, 3-(4,5-dimethylthiazole-2-yl)-2,5-biphenyl tetrazolium bromide reduction and neutral red uptake in these cells were used to evaluate the cytotoxicity of violacein in V79 Chinese hamster (M-8) fibroblasts. Violacein was highly cytotoxic to V79 fibroblasts (IC50 5-12 microM). Using the TUNEL method and the Feulgen reaction coupled to image analysis, violacein (5 and 10 microM) was found to trigger apoptosis but not necrosis in V79 cells. The morphological changes seen in the nuclei of these cells included chromatin condensation and a decrease in deoxyribonucleic acid content. These results demonstrating that violacein induces apoptosis in V79 cells strengthen its potential as a therapeutic agent.

Cytotoxicity of prodigiosin and benznidazole on V79 cells

The cytotoxicity of prodigiosin, an antibiotic and potential trypanocide produced by Serratia marcescens, and Benznidazole, a trypanocidal drug, were assayed on V79 fibroblast cell line. Three independent endpoints for cytotoxicity were evaluated; namely, the nucleic acid content (NAC), MTT reduction and neutral red uptake (NRU). IC(50) values of 1-20 microM were obtained for prodigiosin in the NRU, MTT and NAC tests. Prodigiosin had greater trypanocidal activity (IC(50)=5 microM) than Nifurtimox (IC(50)=150 microM) a known trypanocide drug used in Chagas' disease therapy. Benznidazole was less toxic (IC(50)=2000 microM) than prodigiosin (IC(50)=1-20 microM) in V79 cells based on the MTT and NAC assays. Benznidazole stimulated the NRU until 2 mM. Indeed, the cell viability measured with the NRU was higher at all concentrations of benznidazole tested than that measured by MTT reduction and NAC assays.

Mammaglobin gene expression: a superior marker of breast cancer cells in peripheral blood in comparison to epidermal-growth-factor receptor and cytokeratin-19

Various molecular markers have been used for the detection of circulating breast cancer cells in blood by reverse transcriptase-polymerase chain reaction (RT-PCR). Using nested RT-PCR, we compared the specificity and sensitivity of human mammaglobin (hMAM), epidermal-growth-factor receptor (EGF-R), and cytokeratin 19 (CK-19) expression as markers for circulating carcinoma cells in the peripheral blood of patients with breast cancer. Blood samples from 12 patients with ductal carcinoma in situ, 133 patients with invasive breast cancer, 20 patients with hematological malignancies, 31 healthy volunteers, and tumor tissues from 40 patients with invasive breast cancer were screened for mRNA encoding hMAM, EGF-R, or CK-19 by nested RT-PCR. In all breast cancer tissues, mRNA for hMAM, EGF-R, and CK-19 was detectable. In blood samples from patients with invasive breast cancer, 11 (8%), 13 (10%), and 64 (48%) were positive for mRNA encoding hMAM, EGF-R, or CK-19, respectively. Blood samples from none of the healthy volunteers and patients with hematological disorders were positive for hMAM, while CK-19 mRNA was found in the blood of 12 (39%) healthy volunteers and transcripts for EGF-R and CK-19 were detectable in 5 (25%) and 2 (10%), respectively, of the patients with hematological malignancies. Only hMAM mRNA expression in blood correlated with clinical parameters such as nodal status, metastasis, and CA 15-3 serum levels. In summary, hMAM transcripts detectable in blood by RT-PCR represent the most specific molecular marker for hematogenous spread of breast cancer cells. With the nested RT-PCR method, aberrant EGF-R mRNA expression might occasionally be found in hematological malignancies, whereas CK-19 mRNA expression proved to be rather nonspecific. The prognostic value of hMAM RT-PCR-based tumor cell detection in peripheral blood should be further tested and validated in prospective studies.

Gastroprotective effect of essential oil from Croton cajucara Benth. (Euphorbiaceae)

The gastroprotective activity of the essential oil from the bark of Croton cajucara Benth (Euphorbiaceae) was assessed in three different models of experimentally induced gastric ulcer in mice. At oral dose of 100 mg/kg the essential oil reduced gastric lesions induced by hypothermic restraint stress and HCl/ethanol significantly. In the HCl/ethanol model a dose-dependent gastroprotective effect was found. Moreover, significant changes in gastric parameters such as pH, secretion rate and total gastric acid were found after intraduodenal administration of essential oil under ligated pylorus (Shay) conditions. The acute toxicity of essential oil was assessed in mice. The LD50 values were 9.3 and 680 mg/kg for oral and intraperitoneal administrations, respectively. The cytotoxicity of essential oil was studied also. A dose-dependent cell viability inhibition was found in V79 fibroblast cell cultures with an IC50 of 22.9 microg/ml. Our results support the pharmacological study of this essential oil.

Evaluation of in vitro toxicity of N,N-dimethyl-2-propen-1-amines isomers

The trypanocidal activities of cis-3-(4'-bromo[1,1'-biphenyl]-4-yl)- 3-(phenyl)-N,N-dimethyl-2-propen-1-amine (Vb) and cis-3-(4'-bromo[1,1'-biphenyl]-4-yl)-3-(4-bromophenyl)-N,N-dimethyl-2- propen-1-anine (Vg) appeared 6.3 and 3.5 fold more active than the trans-isomers, respectively. Multi-endpoints for toxicity were also applied. Neutral red uptake (NRU), tetrazolium salt reduction (MTT), DNA content on V79 fibroblast cell culture and acute toxicity von E. coli were measured. The IC50 through DNA contents was lower for the cis-isomers in both series of compounds 5b: 7.8 microM and 5g: 5.2 microM). NRU values for derivative 5b in isomeric mixture shows the same value as the isolated isomers however, in the case of 5g a more significant toxicity of the cis-isomer was found. MTT values show that 5g is more toxic than 5b. In both cases, the acute toxicity of the trans-isomers was higher than that of the cis-isomers.

Cytotoxicity of trans-dehydrocrotonin from Croton cajucara on V79 cells and rat hepatocytes

The cytotoxicity of trans-dehydrocrotonin (DHC), an antiulcerogenic diterpene from Croton cajucara (Euphorbiaceae), was assessed on a V79 fibroblast cell line and on rat hepatocytes. Three independent endpoints for cytotoxicity were evaluated: DNA content, MTT reduction and neutral red uptake (NRU). For the V79 cells IC50 values of 253 and 360 microM were obtained for the NRU and MTT tests. The cytotoxic effect of DHC was time exposure dependent and no ability to recover after treatment was observed. For the rat hepatocytes IC50 values of 8, 300 and 400 microM for the MTT, DNA and NRU assays were obtained. The greater toxicity observed for the MTT test was inhibited when the experiment was performed using non-fresh hepatocytes in an age-dependent fashion. The treatment of V79 cells with the conditioned medium resulting after hepatocyte incubation with DHC showed an enhancement of MTT reduction without any evident toxic effects on fibroblasts. These results suggest that DHC has basal cytotoxic effects as observed on V79 fibroblasts and expresses a selective cytotoxicity after its metabolization by the hepatocytes. The bioactivation of DHC is mediated by cytochrome P450 and could generate metabolites that have no toxicity for V79 fibroblasts.

Modulation of neopterin formation and tryptophan degradation by Th1- and Th2-derived cytokines in human monocytic cells

In order to examine the regulatory effects of major Th1-derived cytokines, such as IL-12, and Th2 cytokines, IL-4 and IL-10, on the formation of neopterin and degradation of tryptophan, two metabolic pathways induced by interferon-gamma (IFN-gamma) in human monocytes/macrophages, we investigated the human monocytic cell line THP-1, primary human macrophages, and peripheral blood mononuclear cells (PBMC). Neopterin formation and tryptophan degradation were induced similarly by IFN-gamma in all three cell types investigated, but the effects of interleukins were different between THP-1, primary macrophages and PBMC. In PBMC, but not in THP-1 cells and primary macrophages, IL-12 was found to be additive to the effects of IFN-gamma to superinduce neopterin formation and tryptophan degradation. IL-4 and IL-10 reduced the effects of IFN-gamma on monocytic cells, and both cytokines were additively antagonistic to IFN-gamma in PBMC and THP-1 cells. Finally, on preincubation, but not on addition of IL-12, the effects of IL-4 and IL-10 on PBMC could be abrogated, whereas no such effect was seen in THP-1 cells. The results show that IL-12 up-regulates neopterin formation and tryptophan degradation by inducing additional IFN-gamma production by Th1 cells, while a direct effect of IL-12 on monocytes/macrophages appears to be absent. Similarly, IL-4 and IL-10 inhibit neopterin production and tryptophan degradation in PBMC by down-regulating Th1-type cytokine production and possibly also via direct deactivation of IFN-gamma effects towards monocytes/macrophages. The results clearly show how Th1 cell-mediated immunity may be up- or down-regulated by endogenous cytokine production.

Solution structure of the recombinant oxidized rabbit uteroglobin using homonuclear and heteronuclear multidimensional NMR

Rabbit uteroglobin (rab-UG) is a 16-kDa homodimeric secretory protein with potent anti-inflammatory/immunomodulatory properties. Its physiological role is still unclear, although it was observed that several small hydrophobic molecules bind to the oxidized and the reduced uteroglobin. It is suggested that the formation and/or disruption of the two disulphide bridges not only regulates this binding itself, but also the affinity to the ligand. The determination of the solution structure has been started with the assignment of 1H, 15N and 13C resonances of the oxidized rabbit uteroglobin, based on several two-dimensional and three-dimensional homonuclear and heteronuclear double and triple resonance experiments. The assignment was possible with the overproduction of the wild-type as well as of uniformly 15N-labeled and 15N/13C-labeled samples of the recombinant protein. A complete assignment of 1H, 15N and 13C resonances, the secondary-structure elements and the tertiary structure in solution is presented. The tertiary solution structure was found to be in good agreement with the previously determined crystal structure of rab-UG and with the solution structure of human uteroglobin (h-UG). h-UG and rab-UG are extremely stable proteins within a wide range of pH and temperatures. Some of the binding characteristics of ligands of rab-UG and a mutant with all cysteine residues exchanged to serine residues are discussed.

Antiulcerogenic activity of trans-dehydrocrotonin from Croton cajucara

trans-Dehydrocrotonin (DHC), the major diterpene isolated from Croton cajucara Benth, was assayed for antiulcerogenic activity in four induced gastric ulcer models in the rat. At an oral dose of 100 mg/kg DHC showed a significant antiulcerogenic effect on ulcers induced by hypothermic restraint stress, ethanol, and pylorus ligature. No significant changes in indomethacin-induced gastric lesions or modifications in gastric parameters such as wall mucus, secretion rate, pH, and total acid content were found after DHC treatment. The acute toxicological effects of DHC were assessed in mice. The LD50 values were 876 mg/kg and 47.2 mg/kg for oral and intraperitoneal administrations, respectively. The cytotoxicity of DHC was also studied. A dose-dependent inhibition of cell viability was observed in V-79 fibroblast cell cultures with an IC50 of 240 microM. The high yields of DHC obtained from dried C. cajucara barks as well as its good antiulcerogenic activity and low toxicity support the pharmacological study of this compound as a potential new antiulcerogenic drug.

Patterns of hepatitis C viremia in patients receiving hemodialysis

OBJECTIVES

Chronic hepatitis C virus (HCV) infection is common in patients who receive hemodialysis (HD). The aim of this study was to determine the natural history of hepatitis C viremia and the clinical utility of quantitation and genotyping of HCV in this population of patients.

METHODS

Consecutive sera from two groups of HD patients who were HCV RNA positive, a group of 33 patients treated with interferon alfa (5 MU, three times a week for 4 months) and a group of 31 untreated patients, were analyzed by qualitative polymerase chain reaction, quantitative polymerase chain reaction, and a line probe assay for genotyping.

RESULTS

Serum HCV RNA was detected continuously in 20 of 31 untreated patients (65%), and 11 patients (35%) showed a fluctuating pattern of viremia with virus-free intervals of up to 4 wk. Twenty-five of 33 patients (76%) treated with interferon alfa became HCV RNA negative during therapy; eight of these 25 patients had a breakthrough, which was transient in seven patients and persistent in one. Of the remaining 24 end-of-treatment responders, 17 relapsed after completion of therapy, and seven (21%) had a sustained response with undetectable serum HCV RNA for 1 yr of follow-up. Initial serum HCV RNA levels in HD patients were generally low (median, 1 x 10(5) genome eq/ml). Sustained responders had significantly lower median levels of viremia (4 x 10(4) eq/ml) than relapsers and nonresponders (9 x 10(4) and 1.8 x 10(5) eq/ml, respectively). Genotyping revealed a predominance of genotype 1a (33%) and 1b (48%).

CONCLUSIONS

This study documents that fluctuating hepatitis C viremia with periods of undetectable HCV RNA is common and that low viral load predicts a sustained response to interferon therapy in HD patients. Diagnosis of chronic hepatitis C and monitoring of interferon therapy in HD patients should include initial HCV RNA quantitation and repeated qualitative measurements of HCV RNA.

Differentiation of primary and secondary cutaneous B-cell lymphoma by Southern blot analysis

Malignant B-cell lymphomas represent a heterogenous group of lymphoreticular disorders that involve the skin in about 20% of reported cases. Skin involvement may be primary or secondary (ie, the result of hematogenous spread). Primary cutaneous B-cell lymphomas (PCBCLs) are thought to take a comparatively favorable course, respond readily to nonaggressive treatment, and lack evidence of extracutaneous spread. Nine primary B-cell lymphomas (7 centrocytic or centroblastic follicular, 1 immunoblastic, 1 centroblastic), three secondary (follicular) cutaneous B-cell lymphomas (SCBCLs) and two pseudolymphomas were studied. Staging revealed that bone marrow was involved only in SCBCLs. Centrocytes were detected in blood smear preparations of all SCBCLs. All lymphomas were treated with local irradiation. Patients with primary centroblastic and immunoblastic cutaneous lymphomas and those with secondary lymphomas received additional chemotherapy. Pseudolymphomas were treated by simple excision. Patients were monitored on average for 55 months. During this period, no patients with PCBCLs exhibited cutaneous relapses or hematogenous spread. In contrast, all patients with SCBCLs experienced cutaneous relapses. Peripheral blood, bone marrow, and skin samples from all patients were subjected to Southern blot analysis using a JH probe. Clonal rearrangement was found in all skin samples investigated except specimens from pseudolymphomas. Peripheral blood and bone marrow samples were positive in SCBCLs (the rearrangement pattern was different from that of the skin samples for two of the three patients), whereas it was negative in all PCBCLs and pseudolymphomas. In conclusion, Southern blot analysis of peripheral blood may be useful in differential diagnosis of PCBCLs and SCBCLs and a prognostic marker. Furthermore, these data confirm the comparatively favorable clinical course of PCBCLs and suggest that in these cases, local irradiation can be considered adequate treatment, whereas SCBCLs require additional systemic therapy.

In vitro trypanocidal activities of a novel series of N, N-dimethyl-2-propen-1-amine derivative

The trypanocidal activity of several 3-(4'-bromo-[1,1-biphenyl]-4-yl) -3-(4-X-phenyl)-N,N-dimethyl-2-propen-1-amine derivatives of the three evolutionary stages of Trypanosoma cruzi, namely the bloodstream trypomastigote form and both the proliferative epimastigote and amastigote forms, were studied. For both proliferative forms of T. cruzi, total lysis occurred at 10-60 microM for trypomastigotes at 40-200 muM. The following order of susceptibility was established: amastigotes > epimastigotes > trypomastigotes. The most were the bromo (X = g) and unsubstituted (X = b) compounds, which had 13- and 8-fold higher activity against trypomastigotes, respectively, than nifurtimox. Cytotoxicity in the Chinese hamster V-79 cell line, measured as inhibition of cell proliferation showed that all the compounds had the same range of IC50 (7.0-12.4 muM). The halogen (X = a,g,h) and the unsubstituted derivatives (X = b) were the least toxic in the series together with the compound (X = f).

p53, Ki-ras, and DNA ploidy in human pancreatic ductal adenocarcinomas

Ki-ras mutations and DNA aneuploidy are common findings in human pancreatic ductal adenocarcinomas. An altered p53 tumor-suppressor gene has been suggested to cooperate with activated Ki-ras in malignant cellular transformation and could enhance genomic instability. We have investigated a panel of well-documented pancreatic carcinomas with defined ploidy and Ki-ras mutations for the presence and pattern of genetic alterations of the p53 gene, their coincidence with Ki-ras point mutations, and their correlation with DNA ploidy, tumor pathology, and clinical course. DNA was isolated from formalin-fixed and paraffin-embedded tumor tissue and polymerase-chain-reaction-amplified fragments of the p53 gene exons 5 to 9 were screened by the single-strand conformation polymorphism method. The positive cases were further examined for mutations by direct sequencing. Twenty-nine of seventy-one (41%) tumors showed mutations of the p53 gene, however, five tumors carried two mutations resulting in a total of 34/71 (48%) genetic alterations of the p53 gene. The majority were missense point mutations and distributed primarily within the evolutionary conserved domains (62%). Ten of Thirty-four (29%) affected the hotspot codons 248, 273, and 282, respectively, and 21/34 (62%) of the p53 gene mutations clustered on exons 7 and 8. Transitions (71%) predominated over transversions (15%), deletions were identified in 7/34 (21%) tumors. One third of the carcinomas showed both Ki-ras codon 12 and p53 gene mutations. p53 mutations correlated with distant metastasis (p < 0.05) and survival (p < 0.05). DNA triploidy was associated with a mutated Ki-ras gene (p < 0.05) as well as with double mutations of c-Ki-ras and p53 (p < 0.05). Unlike most other malignant tumors pancreatic ductal adenocarcinomas exhibit a significantly higher incidence of c-Ki-ras than p53 gene mutations. However, like other neoplasms p53 gene mutations seem to be associated with a metastatic phenotype possibly acquired during tumor progression.

Growth-inhibitory effect of 2-CdA on myeloid CFU-GM progenitors in normal human long-term bone marrow cultures and its compensation by G-CSF or IL-3

As neutropenia is a common side effect of treatment with 2-chlorodeoxyadenosine (2-CdA), we investigated the myelosuppressive action of 2-CdA in Dexter-type human long-term bone marrow cultures (LTBMCs). LTBMCs were incubated with varying doses of 2-CdA (5 to 20 nM/L) during the first week. At 20 and 10 nM/L 2-CdA, we found a marked reduction in colony-forming unit-granulocyte/macrophage (CFU-GM) production throughout the culture period of 7 weeks (maximum reduction to 3.5% of untreated control cultures with 20 nM/L and to 27.2% with 10 nM/L, respectively). Even the lowest 2-CdA dose tested (5 nM/L) strongly reduced the number of CFU-GM progenitors during the first 3 weeks (maximum reduction to 52.4% of untreated controls), but this effect was transient, and values had recovered to normal within in 5 weeks. 2-CdA was also shown to cause a dose-dependent decrease in long-term culture-initiating cell (LTCIC) detections after 5 weeks in culture (49.6% of control cultures with 10 nM/L 2-CdA and 14% with 20 nM/L 2-CdA, respectively). When 2-CdA was added to LTBMCs initiated on preformed irradiated stromal feeder layers, similar results on CFU-GM production were obtained, indicating that the effects observed were not secondary to effects on the formation of a supportive layer. In addition, IL-6-concentrations in the supernatant of LTBMCs measured at various intervals after the addition of fresh medium with or without 2-CdA showed no significant decrease in cultures treated with 2-CdA. As neutropenia has been shown to be associated with a small but significant risk of fatal infection, we subsequently investigated the reversal potential of the 2-CdA effect by addition of recombinant human granulocyte colony-stimulating factor (rhG-CSF) or rh interleukin-3 (rhIL-3). The weekly addition of 100 ng/mL rhG-CSF counteracted the 2-CdA-mediated decrease in CFU-GM numbers during the entire period of 7 weeks, reaching statistical significance from weeks 3 to 7 (p < 0.05). Addition of rhIL-3 (100 ng/mL) showed an enhancement of CFU-GM output in 2-CdA-treated cultures that resulted in their numbers exceeding those in control cultures (without 2-CdA) from weeks 1 to 5 (p < 0.05) with a maximum increase of 5.1-fold over the parallel control value at week 3.(ABSTRACT TRUNCATED AT 400 WORDS)

Effect of deoxycytidine on 2-chloro-deoxyadenosine-mediated growth inhibition of normal human erythroid and myeloid progenitor cells

The cytotoxic effect of chlorodeoxyadenosine (CdA) on lymphocytes and monocytes requires phosphorylation by the enzyme deoxycytidine kinase and can be antagonized by coadministration of deoxycytidine (dCyt), a competitive substrate of deoxycytidine kinase. It has also been shown for lymphocytes that coadministration of 3-aminobenzamide (3-ABA), an inhibitor of the enzyme poly-(ADP ribose) synthetase, is activated by CdA-mediated DNA strand breaks, consumes intracellular nicotinamide-dinucleotide (NAD) and can antagonize the lethal effect of CdA. Recent in vitro studies have shown that not only growth of lymphocytes and monocytes, but also colony formation by erythroid and myeloid progenitors derived from normal human bone marrow, is inhibited by CdA in a dose-dependent manner. In this study we examined the effect of various doses of dCyt (10(-6) to 10(-3) M) on CdA-mediated growth inhibition of erythroid and myeloid progenitor cells in vitro. Our results show that colony formation by human bone marrow-derived progenitor cells--CFU-E (colony-forming unit erythroid), BFU-E (burst-forming unit erythroid) and CFU-GM (colony-forming unit granulocyte/macrophage)-in semisolid medium is protected by a high, but clinically achievable and non-toxic, concentration of dCyt (> 10(-4) M) against the inhibitory effects of coadministered high concentrations of CdA. The protective effect of dCyt was markedly different on the various subclasses of progenitor cells, however. Thus, with coadministration of 10(-4) M dCyt, the CFU-E colony formation could be restored to almost 100% despite the presence of high concentrations of CdA (160 nM) compared to control cultures, whereas the colony formation of BFU-E and CFU-GM was restored to only 50%. At a concentration of 10(-3) M dCyt, colony formation of BFU-E and CFU-GM was raised to 80% of control cultures even in the presence of high concentrations of CdA (160 nM). Further experiments in which 3-ABA was coadministered to CdA-treated cultures showed that in all concentrations tested (0.3 to 5 mM) 3-ABA was not able to prevent CdA-mediated cytotoxicity on bone marrow progenitors. Based on these studies, we suggest that the CdA toxicity on CFU-E is mainly mediated by phosphorylation by deoxycytidine kinase, whereas additional mechanisms may be operative in BFU-E and CFU-GM. Considerable biochemical differences seem to exist between hematopoietic stem cells on the one hand and lymphocytes and monocytes from peripheral blood on the other.

Mixed colony formation in vitro by the heterogeneous compartment of multipotential progenitors in human bone marrow

The physiology of the human haemopoietic primitive progenitor populations can be studied in normal and disease states by clonal in vitro cultures in which the primitive progenitor cells proliferate and differentiate to form mixed colonies. For many applications it is essential that such assays detect a high proportion of primitive progenitor cells. We describe an in vitro assay which detects a high incidence of human CD34+ multipotential progenitor cells. Bone marrow mononuclear cells (MNC) or selected CD34+ cells were plated at low cell concentrations in semisolid agar cultures with synergizing growth factor combinations. The optimum growth factor combination of conditioned medium from Mia PaCa-2 cells (Mia-CM), recombinant granulocyte-macrophage colony-stimulating factor and recombinant stem cell factor (SCF) supported the formation of macroscopic (> or = mm) colonies (97% of which were multilineage), at an average incidence of 250/10(5) MNC. The colony-forming cells (human colony-forming unit, type A) detected, showed a low cycling status (7.3%) and the macroscopic colonies had a high replating efficiency (46%), reflecting their probable primitive nature. This assay should prove invaluable, for studies on the regulation of proliferation of the multipotential compartment and in studies involving the assessment of these cells in transplantation and neoplastic disease.

Inhibitory effect of 2-chlorodeoxyadenosine on granulocytic, erythroid, and T-lymphocytic colony growth

Previous studies have shown that 2-chloro-2'-deoxyadenosine (CdA) is markedly toxic to normal and malignant human lymphocytes in vitro and in vivo. Recent clinical trials have shown that CdA is a very promising drug for the treatment of lymphoid malignancies. The present investigations were designed to test the effect of CdA on the in vitro clonal growth of both myeloid progenitors and T-lymphocyte colony-forming cells (CFU-TL) obtained from normal human bone marrow and peripheral blood. Cells were exposed to CdA in doses up to 1280 nmol/L. To reduce indirect effects of CdA mediated by accessory cells, monocyte- and T-lymphocyte-depleted bone marrow cells were used for our investigations. The results show a marked inhibition of myeloid progenitor and lymphocyte colony-forming cells in a dose-dependent manner, correlating with maturation stage in that the immature progenitor cells are more sensitive to this drug. Furthermore, our studies suggest that a sequence of metabolic events previously described for lymphocytes may be operative in myeloid progenitor cells because a minimal exposure time of 48 hours is required to obtain a marked inhibition. CdA toxicity was proposed to be linked with phosphorylation by deoxycytidine-kinase (E.C. 2.7.1.74), the levels of which have been found to be high in lymphocytes, but low in granulocytes. However, the marked inhibition of myeloid progenitor cells shown in these studies suggests that other factors such as modulation of the effect of CdA by the ambient levels of other deoxynucleosides might influence the apparent sensitivity of myeloid cells.

Biotinylated antibodies bound to streptavidin beads: a versatile solid matrix for immunoassays

Streptavidin was covalently bound to commercially available polyacrylamide beads (3-10 microns diameter) by peptide bond formation between the carboxyl groups on the solid matrix and the amino groups of the soluble protein. Biotinylated antibody or lectin was linked to the polyacrylamide beads via the streptavidin molecules. Immunoassays for human IgA1, IgA2, IgE, and vitronectin were developed utilizing the antibody or lectin as a capture ligand. The protein being assayed was quantitated colorimetrically at 492 nm via horseradish peroxidase-conjugated antibodies.

An immunoassay for the determination of total IgA subclass antibodies in human serum

An enzyme immunoassay capable of determining total IgA1 and IgA2 concentrations in human serum has been developed. Subclass-specific monoclonal antibodies are bound to polyacrylamide bead-conjugated anti-mouse immunoglobulin antibodies. Bound IgA is detected with an anti-IgA peroxidase conjugate and the standard curve is linear in the region 0.25 - 2.0 micrograms/ml. Coefficient of variation values range from 0.24 - 5.77% for the IgA1 standard curve and from 0.86 - 5.92% for the IgA2 standard curve. Inter-assay variation for the IgA1 and IgA2 control sample values were 8.2% and 13.4%, respectively.

A rapid procedure for the purification of IgA1 and IgA2 subclasses from normal human serum using protein G and jackfruit lectin (jacalin) affinity chromatography

Immunoglobulin A (IgA) from pooled normal human sera was purified using antibody and protein G affinity chromatography and gel filtration high-pressure liquid chromatography (HPLC). This high purity product was separated into IgA1 and IgA2 subclasses utilizing the agarose-bound lectin 'jacalin'. Evaluation of product homogeneity by immunological testing confirmed greater than 95% purity. The total IgA1 and IgA2 recovered from sera was approximately 26% of the initial antibody present.

An enzyme immunoassay for the determination of low levels of IgA in human serum

An enzyme immunoassay (EIA) has been developed which facilitates the detection of low levels of immunoglobulin A in human serum. IgA is captured by an anti-IgA antibody linked to micron-sized polyacrylamide beads and subsequently detected by an anti-IgA horseradish peroxidase conjugate. The standard curve is linear in the region between 25-1000 ng/ml IgA. The assay is particularly suited to measure IgA antibodies in sera from IgA-deficient individuals and IgA contaminants in blood products.

Bacterial chemistry-III: preliminary studies on trypanosomal activities of Chromobacterium violaceum products

It has been found that the pigment-I from Chromobacterium violaceum, 3-[1,2-dihydro5-(5-hydroxy-1H-indol-3-yl)-2-oxo-3H-pyrrol-3-yli diene] 1,3-dihydro-2H-indol-2-one, has trypanocide activity. The formylated derivatives, pigment-III, immobilized 100% of the Trypanosoma cruzi at a level of 46 microM after 48 h of interaction with a total growth inhibition in the same period. Pigment-I exhibited low toxicity and a DNA synthesis inhibition similar to that of Nifurtimox, a known trypanocide compound.

Synergistic effect of chlorpromazine and alkanals on the human red blood cells

The hemolysis of human red cells in the presence of chlorpromazine and 2-methylpropanal, or propanal, has been studied by a spectrophotometric method. A strong synergistic effect was observed concomitant to the quenching of photon emission. The synergistic effect is consistent with the view that triplet excited species generated from a hemoprotein-catalyzed aerobic oxidation of aldehydes promotes "in situ" the photooxidation of chlorpromazine leading to products which have shown hemolytic effects. This view is supported by protection, albeit weak, offered by energy acceptors such as eosin and the 9,10-dibromoanthracene-2-sulfonate ion.

Excited indole-3-aldehyde from the peroxidase-catalyzed aerobic oxidation of indole-3-acetic acid. Reaction with and energy transfer to transfer ribonucleic acid

The horseradish peroxidase catalyzed aerobic oxidation of the auxin indole-3-acetic acid generates triplet indole-3-aldehyde in high yield. The excited species is quenched by oxygen with formation of singlet oxygen, which is responsible for the observed photon emission and can be trapped by suitable agents. tRNA dramatically enhances the emission as a result of energy transfer from triplet indole-3-aldehyde to a 4-thiouridine group in tRNA. Triplet indole-3-aldehyde also adds covalently to tRNA. The results provide a possible mechanism for the auxin-tRNA interaction in vivo.