Marine litter footprint in the Azores Islands: A climatological perspective.

Marine litter (ML) consists of any item of anthropogenic origin that has been lost, discarded or intentionally disposed of into the environment, being acknowledged as a worldwide environmental and ecological threat. In the last decade, there has been an attempt across different sectors to tackle, reduce and mitigate sources of litter. In this study, meso and macrodebris between 2 and 30 cm was recorded and classified in two established study areas (Porto Pim and Conceição beaches), throughout five monitoring years (2012-2018). The litter abundance, density and weighted average by abundance were evaluated in eight main categories: plastics, cloths/fabrics, glass, metals, rubber, processed lumber, other and large. Field surveys provided evidence that plastic represented 95% of all litter. ML abundance was treated as an "environmental variable" and used to determine its anomalies, temporal trends and forecasts. Results from this time-series addressed possible periodic oscillations and density peaks of litter. Reference values of ML presence were obtained and could potentially be used for developing a diagnostic tool for anthropogenic pollution in the Azores.

Reversal of multidrug resistance by the P-glycoprotein modulator, LY335979, from the bench to the clinic.

Multidrug resistance may be conferred by P-glycoprotein (Pgp, ABCB1) or the multidrug resistance associated protein (MRP). These membrane proteins are members of the ATP binding cassette transporter superfamily and are responsible for the removal from the cell of several anticancer agents including doxorubicin. Modulators can inhibit these transporters. LY335979 is among the most potent modulators of Pgp with a Ki of 59 nM. LY335979 is selective for Pgp, and does not modulate MRP-mediated resistance by MRP1 (ABCC1) and MRP2 (ABCC2). LY335979 significantly enhanced the survival of mice implanted with Pgp-expressing murine leukemia (P388/ADR) when administered in combination with either daunorubicin, doxorubicin or etoposide. Coadministration of LY335979 with paclitaxel compared to paclitaxel alone significantly reduced the tumor mass of the Pgp-expressing UCLA-P3.003VLB lung carcinoma in a xenograph model and delayed the development of tumors in mice implanted with the parental drug-sensitive UCLA-P3 tumor. LY335979 was without significant effect on the pharmacokinetics of these anticancer agents. This may be due impart to its poor inhibition of four major cytochrome P450 isozymes important in metabolizing doxorubicin and other oncolytics. The selectivity and potency of this modulator allows the clinical evaluation of the role of Pgp in multidrug resistance. LY335979 is currently in clinical trials.

Reversal of resistance in multidrug resistance protein (MRP1)-overexpressing cells by LY329146.

The benzothiophene LY329146 reverses the drug resistance phenotype in multidrug resistance protein (MRP1)-overexpressing cells when dosed in combination with MRP1-associated oncolytics doxorubicin and vincristine. Additionally, LY329146 inhibited MRP1-mediated uptake of the MRP1 substrate LTC4 into membrane vesicles prepared from MRP1-overexpressing cells.

Sonography compared with radiography in revealing acute rib fracture.

OBJECTIVE: This study was undertaken to compare the sensitivities of sonography and radiography for revealing acute rib fracture. SUBJECTS AND METHODS: Chest radiography and rib sonography were performed on 50 patients with suspected rib fractures. Sonography was performed with a 9- or 12-MHz linear transducer. Fractures were identified by a disruption of the anterior margin of the rib, costochondral junction, or costal cartilage. The incidence, location, and degree of displacement of fractures revealed by radiography and sonography were compared. Sonography was performed again after 3 weeks in 37 subjects. RESULTS: At presentation, radiographs revealed eight rib fractures in six (12%) of 50 patients and sonography revealed 83 rib fractures in 39 (78%) of 50 patients. Seventy-four (89%) of the 83 sonographically detected fractures were located in the rib, four (5%) were located at the costochondral junction, and five (6%) in the costal cartilage. Repeated sonography after 3 weeks showed evidence of healing in all reexamined fractures. Combining sonography at presentation and after 3 weeks, 88% of subjects had sustained a fracture. CONCLUSION: Sonography reveals more fractures than does radiography and will reveal fractures in most patients presenting with suspected rib fracture. Further scientific studies are needed to clarify the appropriate role for sonography in rib fracture detection.

Selectivity of the multidrug resistance modulator, LY335979, for P-glycoprotein and effect on cytochrome P-450 activities.

Overexpression of ATP-dependent drug efflux pumps, P-glycoprotein (Pgp) or multidrug resistance-associated protein (MRP), confers multidrug resistance to tumor cells. Modulators of multidrug resistance block the action of these pumps, thereby sensitizing cells to oncolytics. A potent Pgp modulator is LY335979, which fully sensitizes Pgp-expressing cells at 0.1 microM in cytotoxicity assays and for which Pgp has an affinity of 59 nM. The present study examines its effect on MRP1-mediated drug resistance and cytochrome P-450 (CYP) activity and its ability to serve as a Pgp substrate. Drug resistance was examined with HL60/ADR and MRP1-transfected HeLa-T5 cells. Drug cytotoxicity was unaffected by 1 microM LY335979; leukotriene C4 uptake into HeLa-T5 membrane vesicles was unaffected. Because the substrate specificity of Pgp and CYP3A overlap, the effect of LY335979 on the 1'-hydroxylation of midazolam by CYP3A in human liver microsomes was examined. The apparent K(i) was 3.8 microM, approximately 60-fold higher than the affinity of Pgp for LY335979. The modulator's effect on Pgp was evaluated with Pgp-overexpressing CEM/vinblastine (VLB)(100) and parental CCRF-CEM cells. Both cell lines accumulated [(3)H]LY335979 equally well and did not efflux [(3)H]LY335979 during a 3-h incubation, indicating that it is not a substrate of Pgp. Equilibrium-binding studies with CEM/VLB(100) plasma membranes and [(3)H]LY335979 showed that Pgp had a K(d) of 73 nM, which is in good agreement with the previously determined K(i) value. Thus, LY335979 is an extremely potent Pgp, and not MRP1 or MRP2, modulator and has a significantly lower affinity for CYP3A than for Pgp.

Pharmacological characterization of LY335979: a potent cyclopropyldibenzosuberane modulator of P-glycoprotein.

The above data indicate that LY335979 displays the following characteristics of an 'ideal modulator' of Pgp-mediated multidrug resistance: high affinity binding to Pgp, high potency for in vitro reversal of drug resistance, high therapeutic index (activity was demonstrated at doses ranging from 1-30 mg/kg) observed in in vivo antitumor efficacy experiments, and a lack of pharmacokinetic interactions that alter the plasma concentration of coadministered oncolytic agents. These desirable features strongly suggest that LY335979 is an exciting new clinical agent to test the hypothesis that inhibition of P-glycoprotein activity will result in reversal of multidrug resistance in human tumors.

Reversal of P-glycoprotein-mediated multidrug resistance by a potent cyclopropyldibenzosuberane modulator, LY335979.

Overexpression of P-glycoprotein (Pgp) by tumors results in multidrug resistance (MDR) to structurally unrelated oncolytics. MDR cells may be sensitized to these oncolytics when treated with a Pgp modulator. The present study evaluates LY335979 as a modulator both in vitro and in vivo. LY335979 (0.1 microM) fully restored sensitivity to vinblastine, doxorubicin (Dox), etoposide, and Taxol in CEM/VLB100 cells. LY335979 modulated Dox cytotoxicity even when LY335979 (0.5 microM) was removed 24 h prior to the cytotoxicity assay. LY335979 blocked [3H]azidopine photoaffinity labeling of the M(r) approximately 170,000 Pgp in CEM/VLB100 plasma membranes and competitively inhibited equilibrium binding of [3H]vinblastine to Pgp (Ki of approximately 0.06 microM). Treatment of mice bearing P388/ADR murine leukemia cells with LY335979 in combination with Dox or etoposide gave a significant increase in life span with no apparent alteration of pharmacokinetics. LY335979 also enhanced the antitumor activity of Taxol in a MDR human non-small cell lung carcinoma nude mouse xenograft model. Thus, LY335979 is an extremely potent, efficacious modulator that apparently lacks pharmacokinetic interactions with coadministered anticancer drugs and is, therefore, an exciting new agent for clinical evaluation for reversal of Pgp-associated MDR.

Novel acid labile COL1 trityl-linked difluoronucleoside immunoconjugates: synthesis, characterization, and biological activity.

LY207702 (1) is a difluorinated purine nucleoside that exhibits impressive antitumor activity in preclinical models. This agent, however, also possesses cardiotoxicity which limits the potential clinical utility of this novel drug candidate. We therefore developed linker chemistry whereby regioselective N6-tritylation of LY207702 (1) allowed this drug to be coupled to epsilon-lysine amino groups of mAb's reactive with human tumor-associated antigens. The resulting immunoconjugates 3 possessed conjugation ratios ranging from 5 to 7 mol of LY207702/mol of mAb, minimal aggregate content (5-10%), and good immunoreactivity. The electronic nature of substituents on the aromatic rings of the trityl group dictated the degree of acid lability of the trityl linker. Increased electronic stabilization of the transient trityl carbocation led to increase in the release rate of free drug, i.e., m-DMT 10a = p-DMT 10b > p-MMT 10d > p-T 10f. Consequently, the more acid labile DMT conjugates 3a and 3b proved to be the most potent cytotoxic agents, and the most stable p-T conjugate 3f exhibited the least antitumor activity when evaluated in vitro and in vivo. p-MeT-linked conjugate 3e, the most stable construct that retained excellent in vivo antitumor activity, was selected for more extensive evaluation. No detectable free drug or metabolite was observed in mouse plasma at a single intravenous dose of p-MeT conjugate 3e, which was consistent with its predicted stability under physiological conditions. This construct did, however, exhibit significant antigen-mediated antitumor activity in vivo. No cardiotoxicity was detected in mice dosed with conjugate 3e (6 mg/kg free drug content per day for 21 days) equivalent to approximately 8 times the total dose required for complete regression of well-established (approximately 1 g) HC1 human colon tumor xenografts in nude mice. Cardiotoxicity was induced in 20% of free drug 1 treated group at the equivalent dose. Cardiomyopathy was, however, observed when the dose of conjugate 3e was increased to 8 mg/kg per day for 21 days. These data suggest that antitumor activity of LY207702 (1) was maintained and its cardiotoxic potential reduced when this agent was administered to human tumor xenograft bearing nude mice as COL1-N6-p-MeT-207702 conjugate 3e.

Dextran modification of a Fab'--beta-lactamase conjugate modulated by variable pretreatment of Fab' with amine-blocking reagents.

The physical and pharmacological properties of proteins can be altered by chemical modification with polymers. Preliminary studies showed that attachment of oxidized dextran to the bacterial protein, beta-lactamase (beta L) effectively reduced in vivo immunogenicity in mice with no loss of enzymatic activity. This report describes a general method for differentially dextran modifying the Fab' component of a Fab'--beta-lactamase conjugate by the use of amine-blocking reagents. Methyl acetimidate (MeAcm) and the N-succinimidyl derivative of (methylsulfonyl)ethyl carbonate (NHS-Msc), reagents which can reversibly block primary amines, were used in model studies to modulate the level of available reactive amines on the F(ab')2 fragments of both the anti-carcinoembryonic antigen antibody, ZCE025, and the antitumor-associated glycoprotein-72 antibody, CC49. MeAcm had little or no effect on immunoreactivity and was maximally effective in modulating dextran attachment, while NHS-Msc was much less effective. A comparison of NHS-Msc and MeAcm is described. Treatment of F(ab')2 with 5-300 mM MeAcm prior to dextran treatment showed a proportional decline in the level of dextran attachment as well as intramolecular cross-linking of the protein by the dextran polymers (6 kDa or 33-mer). A conjugate of beta L coupled to MeAcm-treated ZCE025 Fab' [reduced F(ab')2] was constructed under standard conditions using sulfosuccinimidyl N-[(4-carboxycyclohexyl)methyl]maleimide. After dextran modification, this conjugate maintained good immunoreactivity and enzymatic activity. Biodistribution studies in tumor-bearing nude mice of dextranated and nondextranated conjugate showed comparable overall distribution profiles except that the clearance of the dextranated conjugate from both blood and tumor was delayed about 48-72 h.

Site-specific prodrug activation by antibody-beta-lactamase conjugates: preclinical investigation of the efficacy and toxicity of doxorubicin delivered by antibody directed catalysis.

Antibody directed catalysis (ADC), the catalytic conversion of prodrugs to drugs by enzymes localized at disease targets by appropriate monoclonal antibodies, has shown promise in the treatment of cancer in nude mouse xenograft models. We investigated this concept using antibody enzyme conjugates constructed from beta-lactamase and Fab's reactive with carcinoembryonic antigen, CEA, and tumor associated glycoprotein, TAG-72, to convert prodrugs that are cephalosporin sulfoxide derivatives into oncolytic drugs. Previous work focused on ADC delivery of the potent vinca alkaloid derivative desacetylvinblastine carboxhydrazide (DAVLBHYD). In the current study the ability of the system to deliver doxorubicin was tested in MCF7 breast carcinoma xenografts and OVCAR3 ovarian carcinoma xenografts, and in T380 and LS174T colon tumor xenografts for comparison with previous DAVLBHYD results. ADC enhanced the delivery of doxorubicin in the model systems investigated. Tumor growth suppression was equivalent to or greater than that observed with free doxorubicin at its maximum tolerated dose (MTD). In contrast to the DAVLBHYD results, ADC delivery of doxorubicin did not regress tumors, but did result in a substantial increase in the MTD.

High yield, site-specific coupling of N-terminally modified beta-lactamase to a proteolytically derived single-sulfhydryl murine Fab'.

The preparation of bispecific protein conjugates capable of performing diverse biological functions is an area of active investigation. Such conjugates are routinely prepared using techniques which employ random derivatization of lysine residues, but the overall utility of these methods is limited due to poor yields and heterogeneous conjugates. In this report we describe the development of site-specific linkage methodology for the chemical synthesis of a homogeneous enzyme-antibody Fab' conjugate with coupling efficiencies of at least 72%. The N-terminal threonine residue of beta-lactamase from the P99 strain of Enterobacter cloacae was oxidized to an aldehyde functional group under mild conditions with a 5-fold molar excess of sodium periodate. The murine Fab' with a single sulfhydryl at the hinge region was generated by further digestion of the peptic Fab' fragment with lysyl endopeptidase to remove a decapeptide containing two of the three cysteine residues. Coupling of the two modified proteins was accomplished through a bifunctional coupling reagent containing meleimide and aminooxy functional groups. Synthesis of the linker is described. Yields of 1:1 enzyme-Fab' were at least three times higher than for comparable random derivatization methods. Immunoreactivity and enzymatic activity were unaffected. Biodistribution studies showed a more favorable tumor to blood ratio with the site-specifically linked conjugate.

Site-specific prodrug activation by antibody-beta-lactamase conjugates: regression and long-term growth inhibition of human colon carcinoma xenograft models.

Antibody-directed catalysis (ADC) is a two-step method for the delivery of chemotherapeutic agents in which enzyme-antibody conjugate, prelocalized to antigen-bearing tumor cells, catalyzes the site-specific conversion of prodrug to drug. An ADC system consisting of F(ab')-beta-lactamase conjugates and a cephalosporin derivative of the oncolytic agent 4-desacetylvinblastine-3-carboxhydrazide was investigated. The ability of the system to mediate antitumor activity was compared with that of free drug given alone and with covalent drug-antibody conjugates in LS174T and T380 colon carcinoma xenografts in nude mice. Efficacy increased from moderate tumor growth inhibition by using free 4-desacetylvinblastine-3-carboxhydrazide to tumor regression and long-term stabilization with the ADC system. Labile covalent drug-antibody conjugates prepared from the same antibodies were less effective than ADC and required much higher antibody doses. The antigens KS1/4, carcinoembryonic antigen, and tumor-associated glycoprotein-72, TAG-72, present on the model cell lines, were chosen to investigate the effect of differences in subcellular location and expression heterogeneity on the efficacy of ADC delivery. Response was equivalent with the three tumor antigens. Hence, heterogeneous expression and membrane shedding of carcinoembryonic antigen and TAG-72, did not diminish the suitability of these antigens as targets for ADC therapy. In contrast, drug-antibody conjugate efficacy was more sensitive to subcellular location and heterogeneity. Thus, ADC is a highly effective form of immunochemotherapy in preclinical models, with applicability toward a variety of antigen targets.

Treatment of childhood acute lymphoblastic leukemia with protocol TCL-842 in Taiwan: the Taiwan Children's Cancer Study Group.

From March 1984 to May 1988, 212 children with acute lymphoblastic leukemia were enrolled on Protocol TCL-842. In all, 68 patients were classified as standard risk (SR), 56 as intermediate risk (IR), and 88 as high risk (HR) groups. Remission induction for all three groups consisted of vincristine (VCR), prednisolone (PRED) and L-asparaginase (L-Asp). One consolidation course with cyclophosphamide (CP) and cytarabine (AraC) was used for the SR and IR groups, and two courses were given to patients in the HR group. Central nervous system prophylaxis was randomized using either cranial irradiation 18 Gy + 5 intrathecal methotrexate (IT MTX) or triple IT with maintenance. Reinforcement cycles were employed periodically during maintenance therapy (basically 6-mercaptopurine+MTX) and varied among the three groups. Four-week oral PRED every 16 weeks was the sole reinforcement agent for SR. Two-week VCR+dexamethasone (DEX)+adriamycin CP cycles were used to reinforce IR and HR at different intervals. Five third-form cycles with VCR+DEX+AraC were used only for HR. Treatment was discontinued after three years in patients who achieved continuous complete remissions (CCR). Eight patients died during the induction phase and eight failed to achieve complete remission (CR). The CR rate for SR was 97%, for IR was 98% and for HR was 83.3%; the overall rate was 91.8%. As of 30 June 1991, 33 patients had dropped out, 12 had died during remission, and 52 had relapsed. Twenty-eight SR, 26 IR, and 29 HR patients remained in CCR with a median follow-up duration of 66 months (38-88 months).(ABSTRACT TRUNCATED AT 250 WORDS)

Childhood non-Hodgkin's lymphoma--results of treatment with ALL high-risk protocol.

Between August 1984 and September 1990, 13 children with non-Hodgkin's lymphoma (NHL) were treated with ALL high-risk protocol (5 with TCLSG 842 regimen and 8 with TPOG 882B protocol) at Taichung Veterans General Hospital. Diagnosis of NHL was confirmed by histology. Nine had lymphoblastic lymphoma, three had histiocytic lymphoma and one had small non-cleaved cell lymphoma, according to the Rappaport classification. After thorough clinical evaluation eight children were NHL stage IV; four were stage III; and one was stage II. All these children had received chemotherapy as acute lymphocytic leukemia (ALL) high-risk protocol for a total of three years, including central nervous system (CNS) prophylaxis. Of the 13 patients, 9 (69.2%) gained complete remission. Over-all survival rate was 46.2%, with a median interval of 36 months. The complete remission rate and survival rate for the nine children with lymphoblastic lymphoma was better at 77.7% & 66.6% respectively. Within the nonresponsive group, two failed to remit because of early withdrawal from the protocol; the other two patients were refractory to treatment. Relapse was noted in one patient. As to the side effects, neutropenic fever was the most common problem encountered (9 occurrences in 13 patients). Other major complications included severe mucositis, massive GI bleeding, intracranial thrombosis induced by l-asparaginase and tumor lysis syndrome. Childhood NHL is often of diffuse types in pathology, and most affected children have advanced diseases at diagnosis. Choosing an optimal treatment protocol is important for good treatment results.

In vivo antitumor activity of a monoclonal antibody-Vinca alkaloid immunoconjugate directed against a solid tumor membrane antigen characterized by heterogeneous expression and noninternalization of antibody-antigen complexes.

It is widely believed that antigen heterogeneity and noninternalization of antigen-antibody complexes will severely limit the antitumor activity of monoclonal antibody-drug conjugates. The B72.3 monoclonal antibody binds to a tumor-associated antigen which is heterogeneously expressed in human carcinomas (J. Schlom, Cancer Res., 46: 3225-3238, 1986). We therefore performed studies to assess the degree of internalization of B72.3 antibody-antigen complexes and the level of in vivo antitumor activity that could be achieved with B72.3 conjugated to 4-desacetyl vinblastine-3-carboxhydrazide. Internalization studies were performed on LS174T colorectal carcinoma and OVCAR-3 ovarian carcinoma cells using iodinated B72.3 as well as an iodinated antibody that binds to the human transferrin receptor, IIB21. These data indicated that, in contrast to HB-21, the B72.3 antigen-antibody complex was not internalized. The B72.3-Vinca alkaloid immunoconjugate demonstrated significant antitumor activity against LS174T xenografts, although complete regressions of established tumors were not achieved. Immunohistochemical analyses indicated that the B72.3 antigen was heterogeneously expressed in the LS174T xenografts and that tumor cells which were not killed by high doses of B72.3-Vinca also expressed the B72.3 antigen. These studies indicated that significant antitumor activity may be achieved by monoclonal antibody-drug conjugates even when antigen heterogeneity and noninternalization of antigen-antibody complexes are encountered. The data also suggested that the formulation of antibody-drug conjugate cocktails to counteract antigen heterogeneity may not be sufficient to eradicate all malignant cells within a solid tumor mass.

[Cyclosporin A for treatment in nephrotic syndrome of childhood--a preliminary report].

We treated five, three steroid resistant and 2 steroid dependent nephrotic syndrome with oral cyclosporin A and prednisolone. All children received more than eight weeks course of prednisolone, and were in a critically ill status from their nephrotic syndrome and by steroid-toxic side effects. Cyclosporin A was started at 7 mg/kg/day and titrated to maintain serum level of 150-250 ng/ml. Prednisolone was given initially at a dose of 1 mg/kg/day x 1 month, subsequently at a dose of 0.4 mg/kg/day x 1 month, then 0.2 mg/kg/day x 4 months. After a total course of six months, cyclosporin A was tapered to 3.5 mg/kg/day. Prednisolone was maintained at a dose of 0.2 mg/kg/day. Renal biopsies of the 3 steroid resistant children showed membranous glomerulonephritis with focal segmental glomerulosclerosis, focal segmental glomerulosclerosis and IgM nephropathy respectively. These three cases all went into complete remission within four weeks. Among them, one case relapsed twice within one year. Renal biopsies of the two steroid dependent children showed minimal change and focal segmental glomerulosclerosis respectively. These two cases went into complete remission within three weeks sustained up to a year. Side effects of cyclosporin A were observed in one patient with gum hypertrophy and two patients with hirsutism. Other side effects were not found. After cyclosporin A treatment for one year, the renal biopsy of the relapsing patient showed no interstitial fibrosis or tubular atrophy. In conclusion, cyclosporin A was found to be effective in steroid resistant and dependent patients. The duration of cyclosporin A treatment is so far unknown. It needs further evaluation in the future.

Continuous monitoring of intracranial pressure in Reye's syndrome--5 years experience.

Monitoring of intracranial pressure (ICP) and efforts to keep the ICP below the critical level are vital in the treatment of Reye's syndrome. Continuous monitoring of ICP was carried out in 21 cases of Reye's syndrome who were at or beyond stage III at the time of admission to the Veterans General Hospital, between January 1981 and August 1986. Seventeen had ICP ranging from 15 mmHg to 67 mmHg. Three patients died, 1 in stage V with an ICP of 67 mmHg received a craniectomy, and 2 others were in stage IV with ICP's of 66 mmHg and 25 mmHg, respectively. The fatality rate was 14% (3/21). Among 18 patients, 5 had moderate psychomotor retardation (PMR), 4 had severe PMR and 2 had mild PMR. The remaining 7 patients survived without sequelae. Blood exchange transfusion could further reduce ICP and seemed to improve neurologic outcome. Blood ammonia higher than 400 micrograms% is indicative of a bad prognosis. Hyperventilation was the most rapid and effective means of reducing moderate degrees of increased ICP. During intensive supportive care, we also found that coughing, endotracheal intubation, seizures, asynchronous respiration to an artificial respirator, suction of the airway and any painful stimulation caused further increases in ICP and worsened the situation. Care should be given to avoid these factors.

Daunorubicin coupled to monoclonal antibodies via a cis-aconitic anhydride linker: biochemical and cytotoxic properties revisited.

Daunorubicin (DNR) was coupled to monoclonal antibodies (Mab) reactive to breast tumor cells using the acid-labile linking agents cis-asonitic anhydride and two other non acid-labile analogs, glutaric anhydride and citraconic anhydride. The acid derivatives of DNR formed by reaction with the anhydrides were converted to their N-hydroxysuccinimide (NHS) active esters for coupling to MAb. The molar input of drug NHS ester to MAb ranged from 1:1 to 100:1. The resulting MAb-DNR conjugates were purified by gel filtration and analyzed by high performance liquid chromatography. Monomeric conjugates contained 0.2 to 11.0 moles of DNR/mole of MAb. No evidence of cell killing was observed up to a concentration of 10 micrograms/ml DNR bound to MAb, while DNR exhibited 50% killing of the breast tumor cell line MCF-7 at a concentration of 1 microgram/ml.

Tumor reactive cis-aconitylated monoclonal antibodies coupled to daunorubicin through a peptide spacer are unable to kill tumor cells.

Antibody-drug conjugates containing a linkage susceptible to lysosomal hydrolases were constructed by coupling peptide-daunorubicin (DNR) derivatives to MAb. Using a modification in the method of Trouet et al, peptide derivatives of DNR containing the sequences Ala-Leu and Ala-Leu-Ala-Leu linked to drug via their carboxy terminus were prepared. Cleavage of these derivatives by lysosomal enzymes resulting in the release of free DNR was demonstrated. Human antitumor MAb were derivatized with either succinic anhydride or cis-aconitic anhydride to introduce spacer arms for coupling. Binding studies showed that MAb with a decrease of 12-20 amino groups retained greater than 70% of their immunoreactivity, a level deemed acceptable for constructing conjugates. Derivatized and native MAb were conjugated to peptide-DNR via a carbodiimide mediated reaction. None of the conjugates displayed cytotoxicity toward target tumor cell lines in vitro.

[Retroperitoneal fibrosis in children].

A 13 year-old boy was hospitalized because of persisted fever had pallor for three months. Abdominal ultrasound, intravenous pyelogram, and abdominal computerized axial tomography scan disclosed a space occupying lesion located postero-superior to the bladder. Biopsies of the above lesion disclosed retroperitoneal fibrosis. Retroperitoneal fibrosis in children is very rare and has a wide variety of presentations and associated diseases. Treatment relief of obstruction when necessary.