Electromagnetic behavior of dielectric objects on metallic periodically nanostructured substrates

In this research, we investigate the electromagnetic behavior of a metallic thin-film with a periodic array of subwavelength apertures when dielectric objects are located on it. The influence of size, geometry and optical properties of the objects on the transmission spectra is numerically analyzed. We study the sensitivity of this system to changes in the refractive index of the illuminated volume induced by the presence of objects with sizes from hundreds of nanometers (submicron-sized objects) to a few microns (micron-sized objects). Parameters such as the object volume within the penetration depth of the surface plasmon in the buffer medium or the contact surface between the object and the nanostructured substrate strongly affect the sensitivity. The proposed system models the presence of objects and their detection through the spectral shifts undergone by the transmission spectra. Also, we demonstrate that these can be used for obtaining information about the refractive index of a micron-sized object immersed in a buffer and located on the nanostructured sensitive surface. We believe that results found in this study can help biomedical researchers and experimentalists in the process of detecting and monitoring biological organisms of large sizes (notably, cells).

Case-control study and meta-analysis of low density lipoprotein receptor-related protein gene exon 3 polymorphism in Alzheimer's disease

The low density lipoprotein receptor-related protein (LRP) may influence both the clearance and the production of beta-amyloid peptide and thus plays a role in Alzheimer's disease (AD) pathogenesis. Previous studies, although inconsistent, have suggested that the LRP exon 3 CC genotype contributes to the risk of AD. A case-control study utilizing a clinically well-defined group of 305 sporadic AD patients and 304 control subjects was performed to test this association in an ethnically homogeneous population from Spain. In the current study, the LRP CC genotype was not over-represented in AD patients compared to non-demented controls. A meta-analysis of previous studies revealed a weak correlation of LRP CC genotype with AD (odds ratio of 1.35, P=0.01).

Antiapoptotic protein Bcl-xL is up-regulated during megakaryocytic differentiation of CD34+ progenitors but is absent from senescent megakaryocytes

OBJECTIVE

The expression of Bcl-x(L) has been shown to be regulated during the maturation process of different hematopoietic cell lineages (i.e., erythroid cells, neutrophils, monocytes/macrophages). In the present study, we examined the expression of Bcl-x(L) in megakaryocytes derived from CD34(+) progenitors and in the megakaryoblastic cell line UT7.

MATERIALS AND METHODS

Expression of Bcl-x(L) was analyzed in CD41(+) cells cultured in the presence of thrombopoietin and in UT7 cells treated with phorbol diester by Western blot, flow cytometry, and immunocytochemistry analysis. Apoptosis was determined at different culture times by terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling and propidium iodide uptake.

RESULTS

Bcl-x(L) but not Bcl-2 was up-regulated in the megakaryocytic population (CD41(+)) during the first 15 days of culture, which was consistent with the pattern of Bcl-x(L) expression in UT7 cells differentiated to megakaryocytes by incubation with phorbol diester. However, by day 20 of culture, the levels of Bcl-x(L) in CD41(+) cells were greatly reduced, and this expression pattern was accompanied by an increase in the number of apoptotic cells. At this culture time, we detected the presence of cytoplasmic fragments resembling proplatelets with prominent Bcl-x immunostaining, most likely due to the Bcl-x(L) isoform, in close proximity to Bcl-x(-) senescent megakaryocytes. The presence of Bcl-x(L) but not of Bcl-2 in platelets was confirmed by Western blot analysis.

CONCLUSION

Although little is known regarding the functional significance of survival proteins within the megakaryocytic compartment, the changes in the Bcl-x(L) expression pattern observed in UT7 and CD41(+) cells may play a role in the survival of developing megakaryocytes and the lifespan of mature platelets.

The --491 TT apolipoprotein E promoter polymorphism is associated with reduced risk for sporadic Alzheimer's disease

Homozygosity for the A allele of the -491 A/T apolipoprotein E (APOE) promoter polymorphism has recently been reported to be associated with sporadic Alzheimer's disease (AD). Two hundred and fifty one patients with AD and an equal number of controls derived from the same region in a Spanish population, were genotyped for -491 A/T and epsilon2/epsilon3/epsilon4 APOE polymorphisms. We did not detect an elevated -491 AA genotype frequency when comparing AD cases to controls. In contrast, persons homozygous for the T allele were at a significantly reduced risk of AD (odds ratio of 0.10, P=0.006). Multiple logistic regression analysis indicated that the -491 TT polymorphism added information on the risk of AD which was independent of that of the APOE epsilon4 allele.

Telomerase activity in pulmonary neuroendocrine tumors: correlation with histologic subtype (MS-0060)

The authors measured telomerase activity using the telomeric repeat amplification protocol-enzyme-linked immunosorbent assay method in 13 neuroendocrine pulmonary neoplasms and in non-neoplastic frozen lung samples from the same patients. These cases belonged to the complete neuroendocrine neoplastic spectrum: four typical carcinoids, three atypical carcinoids, four large cell neuroendocrine lung carcinomas, and two small cell lung carcinomas. The authors performed the same assay for 52 non-neoplastic lung tissues from the surgical files in their department (negative controls). They verified the presence (or absence) of neoplastic tissue in every case by looking at one frozen section done in the same tissue used for telomerase assay. The telomerase activity level in non-neoplastic tissues (mean, 182 A450nm U) was similar to that obtained in the typical carcinoids (mean, 104.5 A450nm U). All neuroendocrine tumors but the typical carcinoids showed high levels of telomerase activity (mean, 1,750.8 A450nm U). According to the telomerase hypothesis, typical carcinoid cells are mortal pre-M2 stage cells, but atypical carcinoid, large cell neuroendocrine lung carcinoma, and small cell lung carcinoma cells are immortal post-M2 stage cells. This finding may be of important prognostic significance in these kinds of tumors. Measurement of enzyme activity with a good morphologic control could be necessary in telomerase activity assay.

[The prevalence of the Cys282Tyr mutation in the hemochromatosis gene in Cantabria in patients diagnosed with hereditary hemochromatosis]

BACKGROUND

The aim of our study was to evaluate the prevalence of Cys282Tyr mutation in patients with genetic haemochromatosis (GH) in Cantabria.

PATIENTS AND METHODS

The HFE Cys282Tyr mutation was determined in a cohort of 60 patients with GH and 213 controls.

RESULTS

The frequency of the Cys282Tyr mutation in control individuals was 4.4%. Sixty-seven percent of patients with GH were homozygous for the Cys282Tyr mutation. Twenty-seven percent of patients were normal at Cys282Tyr loci.

CONCLUSIONS

The prevalence of the Cys282Tyr mutation in patients with GH in Cantabria, Spain, seems to be lower than in North America and in North Europe patients.

Apoptosis and polycythemia vera

Polycythemia vera is an acquired clonal myeloproliferative disorder characterized by increased numbers of erythroid cells, often with a concomitant rise in neutrophils and/or megakaryocytes. Normally, erythropoietin is essential for the survival and proliferation of erythroid progenitors; however in polycythemia vera the erythroid progenitor cells can survive and develop in the absence of erythropoietin. Members of the Bcl-2 family of apoptosis regulators have been shown to mediate the erythropoietin-dependent survival of erythroid cells. In this article, recent advances in understanding the mechanisms used by erythroid progenitors from patients with polycythemia vera to control apoptosis, are discussed.

Constitutive activation of Stat3 signaling confers resistance to apoptosis in human U266 myeloma cells

Interleukin 6 (IL-6) is the major survival factor for myeloma tumor cells and induces signaling through the STAT proteins. We report that one STAT family member, Stat3, is constitutively activated in bone marrow mononuclear cells from patients with multiple myeloma and in the IL-6-dependent human myeloma cell line U266. Moreover, U266 cells are inherently resistant to Fas-mediated apoptosis and express high levels of the antiapoptotic protein Bcl-xL. Blocking IL-6 receptor signaling from Janus kinases to the Stat3 protein inhibits Bcl-xL expression and induces apoptosis, demonstrating that Stat3 signaling is essential for the survival of myeloma tumor cells. These findings provide evidence that constitutively activated Stat3 signaling contributes to the pathogenesis of multiple myeloma by preventing apoptosis.

Diagnosis of the CMT1A duplication by PCR based detection of a novel junction fragment

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The c-erbA alpha protooncogene induces apoptosis in glial cells via a protein kinase C- and bcl-2-suppressible mechanism

The c-erbA protooncogene encodes the thyroid hormone (3,5,3'-triiodothyronine; T3) receptor alpha1 (TR alpha1). c-erbA/TR alpha1 is expressed in many cell types including glial cells, particularly in the immature state. We show here by morphological and biochemical criteria that c-erbA induces apoptosis of glial B3.1 cells in serum-deprived conditions. This effect is mostly T3 independent. Growth factors such as platelet-derived growth factor, basic fibroblast growth factor, or transforming growth factor-alpha prevent B3.1 + TR alpha1 cell death. Protein kinase C (PKC) activators also prevent the apoptosis phenomenon, an effect that was blocked by the PKC-specific inhibitor GF109203X. Expression of an exogenous bcl-2 gene led also to B3.1 + TR alpha1 cell survival. Neither a series of inhibitors including GF109203X nor T3 inhibits bcl-2 action, indicating that bcl-2 blocks a downstream step in the death-promoting process. B3.1 + TR alpha1 cell apoptosis is not blocked by caspase-1 or poly-ADP-ribosyltransferase inhibitors, suggesting that the activation of these classic pathways is not involved in the apoptotic mechanism. In addition, direct interaction with specific neuronal cells but not incubation with their conditioned medium inhibits also apoptosis of B3.1 + TR alpha1 cells. Our results show that c-erbA promotes an apoptotic process in glial B3.1 cells that is suppressible by PKC activation and bcl-2, probably by distinct mechanisms.

Expression of Bcl-x in erythroid precursors from patients with polycythemia vera

BACKGROUND

Deregulating the expression of Bcl-xL, an inhibitor of apoptosis, in an erythropoietin-dependent erythroblast cell line averts apoptosis induced by the withdrawal of erythropoietin. Since in polycythemia vera an abnormal clone of erythroid progenitors is independent of erythropoietin, we investigated whether the endogenous expression of Bcl-xL was deregulated in these cells.

METHODS

Erythroid colonies from patients with polycythemia vera and normal subjects were cultured in the presence and absence of erythropoietin and assessed by immunocytochemical and flow-cytometric analysis with anti-Bcl-x antibodies that recognize the two species of Bcl-x (Bcl-xL and Bcl-xS). Reverse-transcriptase-polymerase-chain-reaction analysis was used to determine which one of the two species was responsible for anti-Bcl-x staining. Bone marrow mononuclear cells from 8 healthy bone marrow donors, 14 patients with polycythemia vera, 19 patients with other myeloproliferative syndromes, and 12 patients with secondary erythrocytosis were analyzed by flow cytometry with antibodies against Bcl-x and glycophorin A, an erythroid marker.

RESULTS

Erythroid cells from patients with polycythemia vera survived in vitro without erythropoietin, and this finding correlated with the expression of Bcl-x protein (Bcl-xL messenger RNA was the main species of Bcl-x found), even in mature erythroblasts that normally do not express Bcl-x. The mean (+/-SD) percentage of cells positive for both glycophorin A and Bcl-x in the 14 patients with polycythemia vera (21.8+/-3.6 percent) was significantly higher than that in 8 normal donors (6.62+/-1.58 percent), 12 patients with secondary erythrocytosis (6.87+/-1.95 percent), 9 patients with essential thrombocythemia (3.81+/-0.97 percent), and 10 patients with chronic myeloid leukemia (2.7+/-0.41 percent).

CONCLUSIONS

Deregulated expression of Bcl-x may contribute to the erythropoietin-independent survival of erythroid-lineage cells in polycythemia vera and thereby contribute to the pathogenesis of this disease.

Gender effect on apolipoprotein E epsilon4 allele-associated risk for sporadic Alzheimer's disease

INTRODUCTION

The role of gender in Alzheimer's disease (AD), and its possible interaction with apolipoprotein E (apoE), has been controversial.

MATERIAL AND METHODS

ApoE allelic frequencies and the effect of apoE epsilon4 allele dosage on risk and age at onset of AD were evaluated, separately for men and women, in 100 patients with sporadic AD and 100 age-matched controls.

RESULTS

The distribution of apoE alleles and the odds ratio for AD, when associated with 1 or 2 epsilon4 alleles, were not statistically different between men and women. No effect of the dosage of the epsilon4 allele was found on the age at onset of dementia in the 2 sex groups.

CONCLUSION

Our data suggest that the relation of the apoE genotype to AD is not dependent on sex.

The expression of Bcl-x is downregulated during differentiation of human hematopoietic progenitor cells along the granulocyte but not the monocyte/macrophage lineage

Expression of the apoptosis inhibitory protein Bcl-x was studied in CD34+ hematopoietic precursor cells and in the promyelocytic leukemia cell line HL-60. The enriched population of CD34+ cells (more than 95%) was cultured in the presence of stem cell factor, interleukin-3 (IL-3), IL-6, and either granulocyte colony-stimulating factor or macrophage colony-stimulating factor to achieve granulocyte or monocyte/macrophage differentiation, respectively. The expression of Bcl-x increased in the early stages of both differentiation pathways. However, by day 21 of culture mature granulocytes were Bcl-x-negative, whereas monocytes/macrophages either maintained or increased the expression of Bcl-x. The pattern of Bcl-x expression in the differentiated CD34+ cells was similar to that observed in HL-60 cells differentiated along the granulocyte lineage (induced by incubation with retinoic acid), or along the monocyte/macrophage lineage (induced by incubation with phorbol diester). The bcl-x transcript predominant in HL-60 and CD34+ cells differentiated into monocytes/macrophages was bcl-xL. Although little is yet known regarding the functional significance of Bcl-x within the granulomonocytic compartment, marked changes in the pattern of its expression, as observed during granulomonocytic differentiation of HL-60 and CD34+ cells, are likely to alter the life span of mature granulocytes and monocytes/macrophages.

Selective induction of apoptosis in cancer cells by the ether lipid ET-18-OCH3 (Edelfosine): molecular structure requirements, cellular uptake, and protection by Bcl-2 and Bcl-X(L)

The ether lipid 1-O-octadecyl-2-O-methyl-rac-glycero-3-phosphocholine (ET-18-OCH3; Edelfosine) has been shown to be a rapid inducer of apoptosis in human leukemic cells and has been considered as a promising drug in cancer treatment. Here we have found that ET-18-OCH3 induced apoptosis not only in human tumor cell lines but also in primary tumor cell cultures from cancer patients. Human leukemic cells were highly sensitive to ET-18-OCH3, whereas normal cells remained unaffected. Among the distinct modifications of the ET-18-OCH3 molecule assayed, we found that substitutions in positions sn-2 and sn-3 of the glycerol backbone resulted in a complete loss of its capacity to induce apoptosis, highlighting the importance of the molecular structure of ET-18-OCH3 in its apoptotic effect. Induction of apoptosis by ET-18-OCH3 was very well correlated with the uptake of this ether lipid. ET-18-OCH3-resistant 3T3 fibroblasts became sensitive and incorporated significant amounts of the ether lipid following transformation with the SV40 virus. ET-18-OCH3-induced apoptosis as well as ET-18-OCH3 uptake were not mediated through binding of the ether lipid to the platelet-activating factor receptor. Overexpression of bcl-2 or bcl-xL by gene transfer in the human erythroleukemic HEL cells abrogated apoptosis induced by ET-18-OCH3. ET-18-OCH3 did not affect the expression of bcl-2, bcl-xL, or bax in HEL and HL-60 human leukemic cells but induced expression of c-myc, an important effector of apoptosis in several systems. Thus, ET-18-OCH3 behaves as a potent and highly selective antitumor drug able to induce an apoptotic pathway of cell death in tumor cells but not in nonmalignant cells.

A1 demonstrates restricted tissue distribution during embryonic development and functions to protect against cell death

Members of the bcl-2 gene family are essential regulators of cell survival in a wide range of biological processes. A1, a member of the family, is known to be expressed in certain adult tissues. However, the precise tissue distribution and function of A1 remains poorly understood. We show here that A1 is expressed in multiple tissues during murine embryonic development. In the embryo, A1 was detected first at embryonic day 11.5 in liver, brain, and limbs. At day 13.5 of gestation, A1 expression was observed in the central nervous system, liver, perichondrium, and digital zones of developing limbs in a pattern different from that of bcl-X. In the central nervous system of 15.5-day embryos, A1 was expressed at high levels in the ventricular zone and cortical plate of brain cortex. Significantly, the interdigital zones of limbs and the intermediate region of the developing brain cortex, two sites associated with extensive cell death, were devoid of A1 and bcl-X. The expression of A1 was retained in many adult tissues. To assess the ability of A1 to modulate cell death, stable transfectants expressing different amounts of A1 protein were generated in K562 cells. Expression of A1 was associated with retardation of apoptotic cell death induced by actinomycin D and cycloheximide as well as by okadaic acid. Confocal microscopy showed that the A1 protein was localized to the cytoplasm in a pattern similar to that of Bcl-2. These results demonstrate that the expression of A1 is wider than previously reported in adult tissues. Furthermore, its distribution in multiple tissues of the embryo suggests that A1 plays a role in the regulation of physiological cell death during embryonic development.

Erythropoietin can promote erythroid progenitor survival by repressing apoptosis through Bcl-XL and Bcl-2

Erythropoietin (Epo), the hormone that is the principal regulator of red blood cell production, interacts with high-affinity receptors on the surface of erythroid progenitor cells and maintains their survival. Epo has been shown to promote cell viability by repressing apoptosis; however, the molecular mechanism involved is unclear. In the present studies we have examined whether Epo acts as a survival factor through the regulation of the bcl-2 family of apoptosis-regulatory genes. We addressed this issue in HCD-57, a murine erythroid progenitor cell line that requires Epo for proliferation and survival. When HCD-57 cells were cultured in the absence of Epo, Bcl-2 and Bcl-XL but not Bax were downregulated, and the cells underwent apoptotic cell death. HCD-57 cells infected with a retroviral vector encoding human Bcl-XL or Bcl-2 rapidly stopped proliferating but remained viable in the absence of Epo. Furthermore, endogenous levels of bcl-2 and bcl-XL were downregulated after Epo withdrawal in HCD-57 cells that remained viable through ectopic expression of human Bcl-XL, further indicating that Epo specifically maintains the expression of bcl-2 and bcl-XL. We also show that HCD-57 rescued from apoptosis by ectopic expression of Bcl-XL can undergo erythroid differentiation in the absence of Epo, demonstrating that a survival signal but not Epo itself is necessary for erythroid differentiation of HCD-57 progenitor cells. Thus, we propose a model whereby Epo functions as a survival factor by repressing apoptosis through Bcl-XL and Bcl-2 during proliferation and differentiation of erythroid progenitors.

Apoptosis induced by erythroid differentiation of human leukemia cell lines is inhibited by Bcl-XL

The induction of tumor cell differentiation represents an attractive strategy for the treatment of a wide range of malignancies. Differentiation of HL-60 promyelocytic leukemia cells towards neutrophils or monocytes has been shown to induce apoptotic cell death, which is inhibited by bcl-2 over-expression. However, the role of the bcl-2 gene family during erythroid differentiation of human leukemia cells remains unknown. We found that human erythroleukemia (HEL) and K562, two leukemia cell lines that undergo erythroid differentiation do not express Bcl-2, but express Bcl-XL, a related protein that functions as an inhibitor of apoptosis. Differentiation of HEL or K562 cells with inducers of erythroid differentiation (hemin, retinoic acid, or transforming growth factor-beta) was accompanied by progressive cell death and degradation of genomic DNA into oligonucleosomal fragments. The loss of cellular viability was associated with downregulation of bcl-xL mRNA and protein. In contrast, the levels of Bax, another Bcl-2 family member implicated in apoptosis remained unaltered. Constitutive expression of Bcl-XL by gene transfer inhibited apoptosis triggered by erythroid differentiation of HEL K562 cells. Yet, Bcl-XL did not alter the expression of epsilon-globin, which is induced during erythoid differentiation of HEL and K562 cells, arguing that apoptosis and differentiation can be uncoupled by Bcl-XL. These results indicate that Bcl-XL acts as an antiapoptosis protein in leukemia cells that undergo erythroid differentiation and that downregulation of bcl-x is a component of the apoptotic response that is coupled to differentiation in human leukemia cells.

A mutation unique in serine protease inhibitors (serpins) identified in a family with type II hereditary angioneurotic edema

BACKGROUND

Hereditary angioneurotic edema (HANE) is an autosomal dominant disease due to genetic alterations at the C1 inhibitor gene. Mutations within the C1 inhibitor gene are responsible for the molecular defect in type II HANE. Most of the dysfunctional proteins result from mutations involving the Arg-444 (the P-1 site of the reactive center) or amino acids NH2-terminal to the reactive center.

MATERIALS AND METHODS

We have studied a Spanish family with type II HANE by using polymerase chain reaction (PCR) to amplify the exon eight of the C1 inhibitor gene. The purified 338-bp PCR product was subcloned and transformed into competent cells. After overnight cultures, we extracted the cloning vector from the positive colonies and sequenced both strands of the PCR product from each patient and healthy members of the family.

RESULTS

We show that affected individuals in this family have a missense mutation, changing an adenine to cytosine in the codon 445. This substitution changes threonine at the P-1' site of the reactive center to a proline. This mutation generates a new restriction site, recognized by Bsi YI.

CONCLUSIONS

To our knowledge, this is the first molecular defect characterized in a Spanish family with type II HANE, and to date, this is the first reported mutation at the P-1' site of the reactive center in individuals with type II HANE. This new mutation located at the reactive center emphasizes once more time the enormous heterogeneity of this gene.

Expression and functional role of nitric oxide synthase in osteoblast-like cells

Nitric oxide synthases (NOS) are enzymes that produce nitric oxide (NO) from L-arginine in a reaction yielding citrulline as a coproduct. Nitric oxide modulates the activity of a wide variety of cells, but little is known about its effects on bone cells. In the present study we report that the NOS inhibitor NG-monomethyl-L-arginine (NMMA) induced a dose-dependent inhibitory effect on the proliferation of the osteoblast-like cell lines MG63 and ROS 17/2.8. The inhibitory effect was prevented by increasing L-arginine concentrations in the medium and by the NO donor sodium nitroprusside. Likewise, NMMA inhibited interleukin-6 secretion, independently of its effect on cell number. NOS expression by MG63 cells was confirmed by measuring their ability to metabolize radiolabeled L-arginine to citrulline. NOS bioactivity was detected in unstimulated cells, but was markedly increased by stimulating the cells with cytokines, lipopolysaccharide, or 1,25-dihydroxyvitamin D3. NOS activity was partially dependent upon the presence of calcium in the medium. Furthermore, constitutive-type NOS (c-NOS) and inducible-type NOS (i-NOS) mRNA expression was detected in ROS 17/2.8 cells after reverse transcription and polymerase chain reaction amplification. In conclusion, osteoblast-like cells express c-NOS and i-NOS, and NOS activity seems to play an important role in the regulation of cell proliferation and function.

Interleukin-4 as a bone regulatory factor: effects on murine osteoblast-like cells

Bone remodelling is regulated at the local level by an incompletely elucidated cytokine network. In the present study we have determined the effect of interleukin-4 (IL-4), a cytokine produced by T lymphocytes and other cells, on the activity of murine osteoblasts. IL-4 (0.1-10 ng/ml) did not influence the proliferation rate of the osteoblast-like cell line MC3T3, but inhibited the expression of alkaline phosphatase. In long-term cultures supplemented with ascorbic acid and glycerophosphate such an effect was accompanied by a retardation of matrix mineralization. IL-4 also stimulated M-CSF expression by MC3T3 cells, both at the RNA and bioactivity levels. However, no stimulation of IL-1, IL-6, GM-CSF or PGE2 production was observed. An IL-4-induced inhibition of alkaline phosphatase expression and retardation of mineralization was also found in cultures of primary osteoblast-like cells isolated from neonatal mice calvariae. These results suggest that IL-4, probably released by cells within the bone marrow, may locally influence the activity of bone-forming cells.

Regulation and function of Bcl-2 during differentiation-induced cell death in HL-60 promyelocytic cells

Polymorphonuclear leukocytes are generated by differentiation of early myeloid precursors. Once fully differentiated, blood neutrophils are programmed to die rapidly and are removed by tissue macrophages. In normal myeloid cells, the death mechanism seems to be coupled to the differentiation pathway and is accomplished by a process termed apoptosis. In the present study, we have examined the role of Bcl-2 in the differentiation pathways of the promyelocytic cell line HL-60. Treatment of HL-60 with retinoic acid or phorbol ester, which induced neutrophil or macrophage-like cell differentiation, respectively, resulted in progressive loss of cellular viability and internucleosomal DNA degradation. In HL-60, differentiation and apoptosis were coupled to down-regulation of the Bcl-2 protein. Overexpression of Bcl-2 by gene transfer inhibited apoptosis triggered by terminal differentiation of HL-60. Yet, Bcl-2 did not alter the expression of surface markers or other phenotypic changes that are induced upon myeloid differentiation. In contrast to HL-60, another immature myeloid cell line, K562, did not produce Bcl-2 but expressed a related protein, Bcl-xL, that functions as a repressor of apoptotic cell death. K562 has been shown to be relatively resistant to a variety of apoptotic stimuli. Incubation of HL-60 and K562 with inhibitors of macromolecular synthesis induced apoptosis, which appeared earlier in HL-60 than in K562. Interestingly, Bcl-2 overexpression protected K562 cells from apoptosis induced by inhibitor of macromolecular synthesis but it had little or no effect on HL-60 cells. We conclude that although differentiation and apoptosis proceed simultaneously, they can be uncoupled by expression of Bcl-2. Down-regulation of Bcl-2 appears to be part of the differentiation pathway and may serve to facilitate the apoptotic response.

Measurement of protein HC (alpha 1 microglobulin) and protein HC-IgA complex in different body fluids

Protein HC and protein HC-IgA complex were measured in 18 different types of fluid sample from healthy subjects and patients with different illnesses to determine if the concentrations of protein HC and protein HC-IgA complexes could be used to monitor certain diseases, when measured separately. The normal values for HC ranged from between 0.30 mg/l in saliva and 11.7 mg/l in blood plasma. HC-IgA complex has a greater range, from undetectable concentrations (urine, colostrum, and cervical mucus) up to 59.2 mg/l in blood plasma. Undetectable concentrations of HC-IgA complex were also shown in serum from patients with IgA immune deficiency and in cerebrospinal fluid from patients with multiple sclerosis. Increased concentrations of HC were noted in bronchoalveolar fluid from a patient with pulmonary alveolar proteinosis, serum from patients with Behcet's syndrome, and in synovial fluid from patients with gout, chondrocalcinosis, and rheumatoid arthritis. On the other hand, the concentrations of HC-IgA complex were raised only in those patients with pulmonary alveolar proteinosis or rheumatoid arthritis.

The primary structure of the cytotoxin restrictocin

The complete amino acid sequence of the single polypeptide chain of cytotoxin restrictocin has been determined. Its structure was established by automated Edman degradation of the intact molecule reduced and [14C]carboxymethylated and of fragments obtained by chemical cleavage of the protein with cyanogen bromide and BNPS-skatole and by enzymatic cleavage of the polypeptide chain with trypsin. The molecule consists of 149 amino acid residues with a calculated relative molecular mass of 16836. The protein presents two disulfide bridges, one between cysteine residues at positions 5 and 147 and the other one formed by cysteine residues at positions 75 and 131. The amino acid sequence of restrictocin shows a high degree of homology (86%) with that of the cytotoxin named alpha-sarcin.