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Biomedical subjects

A Palumbo

Publications and source records attributed to A Palumbo.

At least 55 records · Page 3Linked to original sources
PubMed1997

Multiple myeloma: reduced plasma cell contamination in peripheral blood progenitor cell collections performed after repeated high-dose chemotherapy courses.

The possibility of reducing tumour cell contamination by cytotoxic drug courses prior to peripheral blood progenitor cell (PBPC) collection was evaluated in two consecutives groups of multiple myeloma (MM) patient candidates for autograft. All patients were at disease onset and received two VAD (vincristine, doxorubicin and dexamethasone) courses as initial debulking. In the first group (44 patients), mobilization and harvest were performed 'upfront', after a single cyclophosphamide (CY) administration of 4 g/m2; in the second group (17 patients), PBPC were collected at the end of a high-dose sequential chemotherapy programme, including: CY 5 g/m2, etoposide (VP16) 2 g/m2, a chemotherapy-free interval with three courses of high-dose dexamethasone, a final mobilizing CY at 7 g/m2. G-CSF was given following each high-dose cytotoxic drug. Cytofluorimetric analysis was performed to quantify progenitors (CD34+ cells) and plasma cells, identified by the high CD38 expression and/or CD38 and CD138 coexpression. Large amounts of PBPC were collected in either group (median harvested CD34+/kg: 15.8 x 10(6) and 13.4 x 10(6), respectively; P=0.9). Circulating plasma cells were significantly higher in patients mobilized 'upfront' compared to those who received the high-dose sequence (median peak values of CD38bright/microl: 39 and 10, respectively; P=0.02); a similar difference was observed in the amount of contaminating plasma cells in the harvest products (median CD38bright/kg: 7.4 x 10(6) and 1.3 x 10(6), respectively; P=0.02). The results demonstrate that an in vivo purging approach is feasible in myeloma patients through repeated high-dose chemotherapy courses; this may provide less-contaminated material suitable for further in vitro purging procedures.

Adult↗
PubMed1997

Conventional induction treatments do not influence overall survival in multiple myeloma.

A retrospective analysis was performed on two subsequent myeloma patient series treated with the same conventional induction treatments, melphalan and prednisone or alternating VMCP/VBAP: 273 were enrolled in the multicentre M83 trial (M83 trial group) from 1983 to 1986; 160 were referred to a single institution (Haemat. To group) from 1986 to 1994. Response to treatment was very similar in the two groups (53% v 50.3%). Remission duration curves merely overlapped (median 20 v 21 months). However, overall survival was significantly longer in the Haemat. To group (43.2 v 33 months, P < 0.04). This difference was due to a prolonged period from relapse or progression to death (21 v 8 months, P < 0.01; 20.8 v 7 months, P < 0.009). Prolonged survival was also observed in poor-prognosis patients with a serum beta2-microglobulin level > 3 mg/l, in the Haemat. To group (31.8 v 24.2 months, P < 0.04). The same induction treatments produced almost identical response rate and remission duration in both groups, but overall survival was 10 months longer for one group. However, it could be argued that treatment salvage modalities and support therapies have been improved in a decade. Lastly, induction treatments did not influence overall survival.

Adult↗
PubMed1997

Specific cellular localization of tyrosinase mRNA during Ciona intestinalis larval development.

A Ciona intestinalis cDNA clone that encodes a protein highly homologous to other tyrosinases was isolated. Northern blot analysis showed that expression of Ciona tyrosinase starts at the early neurula stage and continues throughout the tail-bud and tadpole larval stages. The earliest tyrosinase expression was detected, by in situ hybridization, at the neural plate stage, in pigment precursor cells located along the two neural folds, in the animal region of the embryo. In the course of embryonic development the strong hybridization signal was always localized, within the rostral part of the developing brain, in the pigment precursor cells and was later detected in the otolith and ocellus. These results are discussed in relation to tyrosinase as an early marker of neural induction.

Amino Acid Sequence↗
PubMed1997

Selective incorporation of the prototype melanoma seeker thiourea into nascent melanin: a chemical insight.

The mechanism of selective incorporation of thiourea into melanotic melanoma was investigated by model experiments in which the effect of the compound was examined at various stages of melanogenesis in vitro. Up to 50% inhibition of dopachrome formation was observed in the tyrosinase-dopa reaction in the presence of thiourea at a 2:1 molar ratio with respect to the substrate. Under these conditions, a major product was formed which was isolated and identified as a 1:1 dopa-thiourea adduct (adduct I). Subsequent stages of the oxidation were characterized by the development of a yellow chromophore (lambdamax 440-460nm), virtually identical to that obtained by separate oxidation of the adduct I. A less remarkable effect of thiourea was observed on the oxidative polymerization of 5,6-dihydroxyindole (DHI) and 5,6-dihydroxyindole-2-carboxylic acid (DHICA) which was apparent on spectrophotometric and high pressure liquid chromatography (HPLC) analysis. Radiolabelling experiments with 14C-thiourea showed that the label was initially incorporated into the adduct I, while in the subsequent stages of the oxidation it was associated with pigmented materials which escaped direct analysis. Incorporation of labelled thiourea into dopa-melanins was found to be significantly higher than incorporation into synthetic pigments from indole precursors. These results provide a chemical basis for the interpretation of the selective accumulation of thiourea in those melanoma areas with high rates of melanin synthesis seen in autoradiographic experiments.

Antineoplastic Agents↗
PubMed1996

Mechanism of selective incorporation of the melanoma seeker 2-thiouracil into growing melanin.

The mechanism of selective incorporation of 2-thiouracil (TU), a highly specific melanoma seeker, into growing melanins was investigated both in vitro and in vivo. Methods used included direct analysis of the melanins, by evaluation of the absorption at 350 nm (A350) and chemical degradation coupled with HPLC quantitation of pigment makers, i.e., pyrrole-2,3-dicarboxylic acid (PDCA) and pyrrole-2,3,5-tricarboxylic acid (PTCA), as well as biosynthetic experiments involving tyrosinase-catalyzed oxidation of DOPA, 5,6-dihydroxyindole (DHI), and 5,6-dihydroxyindole-2-carboxylic acid (DHICA). Injection of radiolabeled TU into melanoma-bearing mice resulted in a rapid incorporation of the drug into the tumor pigment, with a substantial decrease in A350 and in PTCA yields. Similar changes in the absorption properties were observed in biosynthetic melanins prepared in the presence of TU, whereas the yields of PTCA and PDCA varied depending on the pigment precursor used. When incubated with DOPA in the presence of tyrosinase, TU profoundly modified the normal course of melanogenesis, favoring formation of a complex mixture of addition products consisting mainly of 6-S-thiouracil-DOPA as well as DHI-TU adducts. The latter were obtained in larger amounts by enzymatic oxidation of DHI in the presence of TU and were identified as the 3- and 2-substituted adducts 1 and 2, the dimer 3, and the trimer 4. Similar reactions carried out on DHICA yielded the 4-substituted adduct 5, the dimer 6, and the trimer 7. A new mechanistic scheme for the incorporation of TU into growing melanin is proposed, which envisages nucleophilic attack of the thioureylene moiety of TU to transient quinonoid intermediates in the melanin pathway, chiefly dopaquinone and 5,6-indolequinones, followed by entrainment of the resulting adducts into the growing pigment via oxidative copolymerization with DHICA and/or DHI.

Animals↗
PubMed1996

[Double cardiac fibroma in a newborn infant].

The authors describe the autopsy finding of two fibromas within the left ventricular wall of a five-day-old newborn. Histochemistry and immunohistochemistry showed the lesion as a purely fibroblastic proliferation, with intense elastic fibers formation and secondary morphological alteration and biological damage of the pre-existing muscular fibers. The authors, on the basis of the phases of the cardiac metamers development and of myocardial tissue differentiation, exclude any relationship with disembryogenetic factors, and hence the hamartomatous origin of the lesion, despite their onset in the first months of intrauterine growth.

Fatal Outcome↗
PubMed1995

Iron- and peroxide-dependent conjugation of dopamine with cysteine: oxidative routes to the novel brain metabolite 5-S-cysteinyldopamine.

The mechanism of formation of 5-S-cysteinyldopamine (5-S-CDA), a putative index of oxidative stress in dopaminergic regions of the brain, was investigated by comparing the ability of a number of neurochemically relevant oxidising systems to promote the conjugation of dopamine with cysteine in vitro. Autoxidation of the catecholamine proceeds at relatively slow rate in the physiological pH range, and is little affected by 1 mM Fe(2+)-EDTA complex. In the presence of cysteine, however, the Fe(2+)-induced autoxidation is hastened, affording little amounts of 5-S-CDA. Formation of the adduct is completely suppressed by ascorbic acid. Hydrogen peroxide, in the presence of Fe(2+)-EDTA (Fenton-type oxidation) or peroxidase, promotes a relatively efficient conversion of dopamine to 5-S-CDA and the minor isomer 2-S-CDA. Noteworthy, 15-hydroperoxyeicosatetraenoic acid (arachidonic acid hydroperoxide, HPETE), in the presence of Fe(2+)-EDTA complex, can also mediate 5-S-CDA formation, whilst superoxide radicals are little effective. Overall, these results suggest that ferrous ions, hydrogen peroxide and lipoperoxides may play an important role in 5-S-CDA generation.

Brain↗
PubMed1995

Peroxidase activity in the ink gland of Sepia officinalis and partial nucleotide sequence of a candidate cDNA encoding the enzyme.

A peroxidase was partially purified from the ink gland of the cuttlefish Sepia officinalis. This enzyme acts on guaiacol and I- as substrates and is inhibited by cyanide and azide. By using the PCR technique we have isolated and sequenced a cDNA clone encoding a protein homologous to other animal peroxidases. These results are discussed in relation to the possible involvement of peroxidase in the biosynthesis of melanin.

Amino Acid Sequence↗
PubMed1995

The reproducibility of the postcoital test: a prospective study.

OBJECTIVE: To determine the reproducibility of the postcoital test among trained observers. METHODS: Twenty-eight infertile patients presenting to the Brigham and Women's Hospital over a 1-year period were recruited for the study. After a standardized collection of specimens for the postcoital test, four fellowship-trained reproductive endocrinologists evaluated six postcoital test characteristics and gave their overall impression of the test. Each observer was blinded to the patients' identities and clinical histories as well as to the ratings of the other observers. The six characteristics included an assessment of the cervical mucus by ferning, cellularity, spinnbarkeit, and consistency, and of sperm by total count per high power field and percent motility. Scoring was adapted from World Health Organization (WHO) criteria for semen-cervical mucus interaction. Statistical analysis included the kappa statistic to determine agreement among observers for postcoital test characteristics and the Mantel-Haenszel test to determine the association between overall impression and the other test characteristics. RESULTS: Agreement among the four observers was best for sperm number and motility (39% of cases) and worst for cellularity, spinnbarkeit, and overall test impression (11, 14, and 14% of cases, respectively). The kappa statistic ranged from a low of 0.13 for cellularity, demonstrating poor reliability (95% confidence interval [CI] 0.03-0.23), to a high of 0.51 for sperm number, demonstrating fair reliability (95% CI 0.41-0.60). Only sperm number and percent motility were significantly associated with the overall impression (P < .001). CONCLUSIONS: In a blinded study, the characteristics of the postcoital test were found to have poor to fair reproducibility among trained observers using a standardized WHO scoring system. The observers' overall impressions of test quality correlated with sperm number and motility only. We question the validity of the postcoital test as a diagnostic tool in the evaluation of infertility.

Adult↗
PubMed1995

Retinoic acid inhibits the growth of human myeloma cells in vitro.

Retinoic acid has been shown to induce growth inhibition in a variety of cell types including human myeloma cell lines. Bone marrow plasma cells from 31 multiple myeloma (MM) patients were cultured to investigate the activity of 13-cis-retinoic acid (cRA), all-trans-retinoic acid (tRA), interferon-alpha (IFN-alpha), interferon-gamma (IFN-gamma), and dexamethasone (DEX), alone or in combination, on in vitro proliferation and immunoglobulin (Ig) secretion. Both cRA and tRA inhibited proliferation: the labelling index (LI) of treated cultures/controls, was 0.47 +/- 0.05 (mean +/- standard error mean, M +/- SEM) P < 0.0001, and 0.67 +/- 0.04 (M +/- SEM), P < 0.0001, respectively. The inhibitory effect of cRA was significantly superior to tRA (P = 0.0129) and IFN-alpha, similar to IFN-gamma and DEX. The combinations of cRA + IFN alpha, tRA + IFN-gamma, tRA + DEX did not show any synergistic effect on myeloma proliferation. In contrast, the combination cRA + DEX (0.29 +/- 0.04, M +/- SEM) markedly increased the effect of both cRA and DEX used as single agents. Ig synthesis was not significantly affected by CRA, tRA, IFN-gamma and the combination tRA + IFN-gamma. As expected, only IFN-alpha (P = 0.002) and DEX (P < 0.001) inhibited Ig production. The combinations cRA + IFN-alpha, cRA + DEX and tRA + DEX decreased Ig secretion to the same extent as IFN-alpha and DEX alone respectively. In conclusion, our data indicate that tRA and especially cRA strongly inhibited plasma cell proliferation but had no effect on Ig synthesis. The combination of cRA + DEX showed the highest degree of inhibitory activity of all cytokines, alone or in combination.

Antibodies, Neoplasm↗
PubMed1995

Impaired D-myo-inositol 1,4,5-triphosphate generation from cord blood polymorphonuclear leukocytes.

D-myo-Inositol 1,4,5-triphosphate (IP3) is a key second messenger in many cells, including macrophages, T and B cells, and neutrophils, in which it regulates free intracellular calcium ion levels. In human polymorphonuclear leukocytes the rise of intracellular [Ca2+] is the signal that activates a number of functions such as adherence, aggregation, chemotaxis, and degranulation, which are typically depressed in newborn infants. IP3 generation can be stimulated by N-formyl-methionyl-leucylphenylalanine (fMLP) tripeptide, which mimics the naturally occurring bacterial oligopeptides. In this study both neonatal and adult polymorphonuclear leukocytes were stimulated by fMLP (1 x 10(-6) M) and the levels of IP3 were assayed by a specific radiometric method. The time course of IP3 generation was studied for up to 60 s in a total of 10 samples. The response appeared reduced in cord blood samples. To confirm this observation, we extended our study to a larger number of samples, quantitating [IP3] at the time peak of 10 s. As expected IP3 generation was significantly (F test, p < 0.0001, n = 39) lower in newborns than in adults (means +/- SD = 0.64 +/- 0.25; 1.26 +/- 0.36, ng/10(6) cells, respectively). Besides soluble stimulus, neutrophils were treated with a particulate stimulus, namely serum-treated zymosan, which is also able to stimulate IP3 synthesis from polymorphonuclear leukocytes. Serum-treated zymosan produced a prolonged elevation in the level of IP3, reaching a plateau within 120 s in both cord blood and in control samples.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

Interferon-gamma in multiple myeloma.

Biological heterogeneity is a characteristic of multiple myeloma. A dysregulated cytokine network underlies the various phases of the disease. Numerous cytokines, either promoting or inhibiting plasma cell growth, are involved in tumor control. Interferon-gamma (IFN-gamma) showed the most powerful inhibiting activity on myeloma cell proliferation. This effect was demonstrated on IL-6 dependent myeloma cell lines, but not on IL-6 independent ones. It was also evident on fresh explanted bone marrow myeloma cells. The antiproliferative effect of IFN-gamma seems mainly due to the inhibition of IL-6, the central myeloma growth factor. IL-6 inhibition may occur at various levels: a downregulation of IL-6 receptor has been reported, and also a block of the IL-6 signal transduction pathway via interaction with cytoplasmic proteins such as p91 has been suggested. Our findings showed that IFN-gamma strongly inhibited myeloma cell proliferation to the same extent as dexamethasone (DEX), whereas interferon-alpha (IFN-alpha) inhibited Ig secretion. The combined use of interferons (IFNs) showed inhibitory activities both on proliferation and Ig synthesis that paralleled the effects of DEX. In some cases, IFN-gamma was also shown to augment monoclonal immunoglobulin secretion suggesting a possible differentiating activity on plasma cells. The in vitro data encouraged pilot studies to evaluate the in vivo antitumor effects of IFN-gamma.(ABSTRACT TRUNCATED AT 250 WORDS)

Cell Division↗
PubMed1995

The ovarian renin-angiotensin system. A paracrine-intracrine regulator of ovarian function.

We present a review that considers the regulation of ovarian function by the ovarian renin-angiotensin system. Evidence is presented that shows the ovarian renin-angiotensin system can regulate normal ovarian function by paracrine and intracrine mechanisms. In addition, the complexity that is inherent in the renin-angiotensin system conferred by multiple biological angiotensin peptides and multiple receptors is discussed. Evidence that a dysfunctional OVRAS induces ovarian pathology such as polycystic ovarian disease is also presented.

Animals↗
PubMed1994

Specific incorporation of 2-thiouracil into biological melanins.

2-Thiouracil (TU), an antithyroid drug, is generally recognized as a highly specific melanoma seeker owing to its capability of being selectively accumulated into active melanin-producing tissues. We recently reported evidence that in vitro TU is capable of reacting with dopaquinone (DQ), an early intermediate in melanin biosynthesis, to give an addition product characterized as 6-S-thiouracildopa (TD). However, several aspects of the mechanism of the uptake of TU into melanin in vivo still need to be clarified. We report here the extremely rapid incorporation of [2-14C]thiouracil into melanoma tumors growing subcutaneously in mice and show its selective accumulation into melanin by isolation and purification of the pigment fraction. Formation of the TD adduct in the tumor was examined by HPLC analysis of the soluble fractions of the tissue homogenates: however, no trace of TD could be detected on account of its rapid oxidation by the melanogenic enzyme tyrosinase, as evidenced by in vitro kinetic measurements. Monitoring the course of the tyrosinase-catalyzed oxidation of 5,6-dihydroxyindole (DHI) and 5,6-dihydroxyindole-2-carboxylic acid (DHICA) in the presence of TU, at various molar ratios, provided evidence for the ability of the drug to affect melanogenesis by interaction with biosynthetic intermediates beyond the DQ stage, suggesting other possible modes for its chemical binding to the growing pigment.

Animals↗
PubMed1994

A new dopachrome-rearranging enzyme from the ejected ink of the cuttlefish Sepia officinalis.

A melanogenic enzyme catalysing the rearrangement of dopachrome has been identified in the ejected ink of the cuttlefish Sepia officinalis. This enzyme occurs as a heat-labile protein which co-migrates with tyrosinase under a variety of chromatographic and electrophoretic conditions. On SDS/PAGE it shows like a single band with an approx. molecular mass of 85 kDa. The enzyme possesses high substrate specificity, acting on L-dopachrome (Km = 1 mM at pH 6.8) and on L-alpha-methyl-dopachrome, but not on D-dopachrome, L-dopachrome methyl ester, dopaminochrome and adrenochrome. Significant inhibition of the catalytic activity was observed with tropolone and L-mimosine. H.p.1.c. analysis of the enzyme-catalysed rearrangement of L-dopachrome revealed the quantitative formation of the decarboxylated product, 5,6-dihydroxyindole. These results point to marked differences between melanogenesis in cephalopod pigment cells and in melanocytes, which may have important implications in relation to the use of sepiomelanin as a model for studies of mammalian melanins.

Animals↗
PubMed1994

The inherent cytotoxicity of melanin precursors: a revision.

The potential cytotoxicity of the melanogenic intermediates DOPA, (L-3,4-dihydroxyphenylalanine) and DHI (5,6-dihydroxyindole) has long been recognized and exploited as a targeting concept in experimental melanoma therapy. In recent years, however, a novel branchpoint in the melanin biosynthetic pathway has been shown to divert the metabolism of DOPAchrome to a carboxylated derivative termed DHICA (DHI-2-carboxylic acid) rather than to DHI. In order to evaluate the biological implications of this regulatory control, we have reexamined the inherent cytotoxicity of DHICA versus DHI on different cell lines. We found that under the usual conditions of the biological assay, the apparent cytotoxicity of the two indoles reflect their instability in the culture medium, the less stable DHI being generally more toxic than DHICA to melanoma cells and nonmelanocytic cells. Moreover, the observed cytotoxic effects increased with the time of incubation and were markedly reduced by the addition of catalase to the medium, suggesting that they were probably due to the generation of reactive oxygen species (particularly H2O2) during the autoxidation of the melanin precursors outside the cells. To circumvent this problem, we then tested the diacetylated derivatives of DHI and DHICA (DAI and DAICA) which are sufficiently stable until taken up into the cells whereupon they may be converted by endogenous esterases back to the parent indoles. Although DAI proved to be cytotoxic for nonmelanocytic cells, it had no detectable activity on melanoma cells, whereas DAICA showed no effect on any of the cells examined. These results, when combined with other studies, point to a reconsideration of the inherent cytotoxicity of the 5,6-dihydroxyindoles, as well as DOPA, to melanin producing cells.

3T3 Cells↗