Antitumor activity of five new platinum complexes having a glycolate leaving ligand

In an attempt to develop a new anticancer platinum complex with greater or equivalent antitumor activity but reduced side effects compared with cisplatin (CDDP), a series of new platinum complexes having a glycolate leaving ligand was synthesized. Among them, five complexes were selected for further development on the basis of adequate water solubility, low nephrotoxicity and high antitumor activity in a murine system. The chemosensitivity of these five complexes was examined in MTT assay against two human pulmonary adenocarcinoma cell lines, PC-9 and PC-14, and two human stomach adenocarcinoma cell lines, MKN-45 and KATO III. Their IC50 and relative antitumor activity (RAA) values were compared with those of CDDP and 254-S, a second-generation platinum complex with a glycolate leaving ligand under phase III clinical trial. The lowest mean IC50 value was observed in CDDP, followed by SKI 2034R and SKI 2033R. In this study, the antitumor activity was evaluated in terms of RAA values and SKI 2034R showed the highest RAA value. The order of RAA values was SKI 2034R > CDDP > SKI 2032R > SKI 2033R > SKI 2030R > SKI 2029R > 254-S. Based on the RAA order, we have recommended SKI 2034R as the most promising candidate for further development of a clinically useful platinum complex.

Loop diathermy and cold-knife conization in patients with cervical intraepithelial neoplasia: a comparative study

One hundred and sixty-eight cases of cervical conization were performed for cervical intraepithelial neoplasia (CIN) in a 32-month study. The indications for conization were unsatisfactory colposcopic finding, abnormal epithelium that extended into the endocervical canal, a microinvasive cervical cancer, and significant discrepancy among cytology, colposcopy, and/or punch biopsy histology. In the early period of the study, conization was done by the cold-knife method (N = 107), whereas loop diathermy was used in the latter part of the study (N = 61). Both groups were similar in terms of age, indications for conization, and size of cervical cone specimens. Loop diathermy conization was done in a significantly shorter time (5.7 +/- 1.8 minute vs 15.2 +/- 6.1 minute)(P < 0.05) than cold-knife conization. However, the difference in the postoperative complications between loop diathermy(3.0%) and cold-knife conization(4.7%) was not significant. The incidence rate of residual CIN III lesions in the subsequent hysterectomy specimens, found by histological documentation on these specimens was 25.0 and 26.1 percent after loop diathermy and cold-knife conization respectively. These results suggest that loop diathermy is much easier to perform and a more time-conserving treatment modality than cold-knife conization in the management of patients with cervical intraepithelial neoplasia.

Bronchoalveolar lavage fluid phospholipase A2 activities are increased in human adult respiratory distress syndrome

The role of phospholipase A2 (PLA2) in lung injury in humans is unclear. Previous studies have failed to identify an increase in PLA2 activity in bronchoalveolar lavage fluids (BALF) of patients with the adult respiratory distress syndrome (ARDS). In this study, increased phospholipase A2 (PLA2) activity was detected in BALF from patients with ARDS. PLA2 levels in BALF correlated positively with lung injury score in patients with lung disease. BALF PLA2 activity in patients with ARDS was resolved into heparin binding and nonbinding activities. Both PLA2 activities were increased in BALF of ARDS patients. The PLA2 activity that bound to heparin was identified as a group II PLA2 by its chromatographic characteristics, its inhibition by dithiothreitol, its substrate specificity, and its approximate molecular mass of 14 kDa. The second PLA2 activity was further purified and found to require Ca2+ at a concentration > 2 x 10(-4) M for activity. This form of PLA2 exhibited a neutral and broad pH optimum (pH 6.0-8.0) and hydrolyzed both phosphatidylethanolamine and phosphatidylcholine effectively. Its apparent molecular mass was estimated to be 80-90 kDa. Neither anti-pancreatic PLA2 antiserum nor anti-pig spleen cytosolic 100-kDa PLA2 antiserum immunoprecipitated the enzymatic activity. Thus at least two forms of PLA2 are increased in activity in BALF of patients with ARDS, a group II PLA2 and a biochemically and immunochemically form distinct from group I, group II, and cytosolic PLA2. Increased lung PLA2 activity may be important for the pathophysiology of ARDS.

The role of the 34-kDa subunit of human replication protein A in simian virus 40 DNA replication in vitro

Human replication protein A (RPA) is a three subunit protein complex involved in DNA replication, repair, and recombination. We investigated the role of the 34-kDa subunit (p34) of RPA in DNA replication by generating a series of p34 mutants. While deletion of the N-terminal domain of p34 prevented its phosphorylation by both cyclin-dependent kinase (Cdk) and DNA-dependent kinase, a double point mutant that lacks the major phosphorylation sites for Cdk could be phosphorylated by DNA-dependent kinase. In simian virus 40 (SV40) DNA replication, RPA containing either of these mutants functioned as efficiently as wild-type RPA. However, mutant RPA containing C-terminally deleted p34 was only marginally active. This indicates that the C-terminal region, but not the phosphorylation domain of p34, is necessary for RPA function in DNA replication. Furthermore, RPA containing the C-terminally deleted p34 mutant could stimulate DNA polymerase alpha, and bind to single-stranded DNAs but was limited in its ability to unwind DNA or interact with SV40 large T antigen (T Ag). These results suggest that RPA p34 interacts with SV40 T Ag during the initiation of SV40 DNA replication and may be necessary for DNA unwinding.

Characterization of a novel phospholipase A2 activity in human brain

Phospholipases A2 (PLA2) are a family of enzymes that catalyze the removal of fatty acid residues from phosphoglycerides. The enzyme is postulated to be involved in several human brain disorders, although little is known regarding the status of PLA2 activity in human CNS. We therefore have characterized some aspects of the PLA2 activity present in the temporal cortex of human brain. More PLA2 activity was found in the membrane (particulate) fraction than in the cytosolic fraction. The enzyme could be solubilized from particulate material using 1 M potassium chloride, and was capable of hydrolyzing choline phosphoglyceride (CPG) and ethanolamine phosphoglyceride (EPG), with a preference (approximately eightfold) for EPG over CPG. When the solubilized particulate enzyme was subjected to gel filtration chromatography, PLA2 activity eluted in a high molecular mass fraction (approximately 180 kDa). PLA2 activity was weakly stimulated by dithiothreitol, strongly stimulated by millimolar concentrations of calcium ions, and inhibited by brief heat treatment at 57 degrees C, bromophenacyl bromide, the arachidonic acid derivative AACOCF3, gamma-linolenoyl amide, and N-methyl gamma-linolenoyl amide. Thus, whereas the human brain enzyme(s) characterized in our study displays some of the characteristics of previously characterized PLA2s, it differs in several key features.

Comparison of rates of infection of two methods of emergency ventricular drainage

The rates of infection of two methods of external ventricular drainage in use at Atkinson Morley's Hospital--namely, (a) percutaneous drainage with Rickham reservoirs and (b) tunnelled ventriculostomies--were compared in this retrospective review. Percutaneous drainage of CSF with Rickham reservoirs was associated with a 27% rate of infection as identified by positive microbiological cultures; tunnelled ventriculostomy catheters had a 10% infection rate. The difference in the infection rate between the two methods was statistically significant (P < 0.015). Other variables examined, including the age and sex of the patients and the reasons for ventricular drainage, were not associated with an increased rate of infection. Most infections from either method were caused by a coagulase negative staphylococcus. The average duration of ventricular drainage before identification of positive cultures was 5.7 days for Rickham reservoirs and 6.0 days for ventriculostomies.

Heparin-enhanced plasma phospholipase A2 activity and prostacyclin synthesis in patients undergoing cardiac surgery

Although eicosanoid production contributes to physiological and pathophysiological consequences of cardiopulmonary bypass (CPB), the mechanisms accounting for the enhanced eicosanoid production have not been defined. Plasma phospholipase A2 (PLA2) activity, 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha), and thromboxane B2 (TXB2) levels were measured at various times during cardiac surgery. Plasma PLA2 activity increased after systemic heparinization, before CPB. This was highly correlated with concurrent increases in plasma 6-keto-PGF1 alpha, TXB2 concentrations did not increase with heparin administration but did increase significantly after initiation of CPB. High plasma PLA2 activity, 6-keto-PGF1 alpha, and TXB2 concentrations were measured throughout the CPB period. Protamine, administered to neutralize the heparin, caused an acute reduction of both plasma PLA2 activity and plasma 6-keto-PGF1 alpha, but no change in plasma TXB2 concentrations. Thus the ratio of TXB2 to 6-keto-PGF1 alpha increased significantly after protamine administration. Enhanced plasma PLA2 activity was also measured in patients with lower doses of heparin used clinically for nonsurgical applications. Human plasma PLA2 was identified as group II PLA2 by its sensitivity to deoxycholate and dithiothreitol, its substrate specificity, and its elution characteristics on heparin affinity chromatography. Heparin addition to PMNs in vitro resulted in dose-dependent increases in cellular PLA2 activity and release of PLA2. The PLA2 released from the PMN had characteristics similar to those of post-heparin plasma PLA2. In conclusion, plasma PLA2 activity and 6-keto-PGF1 alpha concentrations are markedly enhanced with systemic heparinization. Part of the anticoagulant and vasodilating effects of heparin may be due to increased plasma prostacyclin (PGI2) levels. In addition the pulmonary vasoconstriction sometimes associated with protamine infusion during cardiac surgery might be due to decreased plasma PLA2 activity, with an associated increased TXB2/6-keto-PGF1 alpha ratio.

The appearance, density, and distribution of Merkel cells in human embryonic and fetal skin: their relation to sweat gland and hair follicle development

The density and distribution of Merkel cells in human embryonic and fetal skin were studied using an immunolabeling technique on epidermal and dermal sheets obtained by ethylenediamine tetraacetic acid separation. Merkel cells were identified by the known cytokeratin markers CK20 and CK18. Merkel cells showed CK20 immunoreactivity as early as 56 d estimated gestational age (EGA) in the palmar epidermis (133.11 +/- 44.27 cells/mm2). The density increased rapidly, reaching a maximum of more than 1400 cells/mm2 at 80-90 d EGA. At this stage, the cells became distributed along the primary epidermal ridges. In the palmar epidermis of fetuses older than 100 d EGA, the distribution of Merkel cells showed the same pattern, but the density then decreased gradually. Merkel cells were not observed in ductal and glandular portions of eccrine sweat glands. In the epidermal sheets of hairy skin, a few cells were first seen in the fetus at 75 d EGA. At 100 d EGA, only a few Merkel cells were observed, mostly in the hair pegs and bulbous hair pegs. In the older fetus, ring-like arrangements and aggregates of Merkel cells were prominent in the infundibulum and bulge of hair follicles, respectively. Merkel cells were both globular and dendritic in shape. The ratio of dendritic to globular cells increased gradually until the period of highest Merkel cell density in both the glabrous and hairy skin. All Merkel cells located in the dermis were globular in shape. In accord with the results obtained, we postulate that Merkel cells may have some functional role in the formation and proliferation of eccrine sweat glands and hair follicle anlagen in developing skin.

In vitro antitumor activity of a new platinum complex, cis-malonato [(4R,5R)-4,5-bis(aminomethyl)-2-isopropyl-1,3-dioxolane] platinum (II) (SKI 2053R), against human lung and stomach cancer cell lines

The in vitro antitumor activity of a new platinum complex, cis-malonato[(4R,5R)-4,5-bis(aminomethyl)-2-isopropyl-1,3-dioxolan e] platinum(II) (SKI 2053R, NSC D644591), cisplatin (CDDP) and carboplatin (CBDCA) was determined against two human lung cancer (PC-9 and PC-14) and two human stomach cancer (MKN-45 and KATO III) cell lines by human tumor clonogenic assay. The activity of SKI 2053R was compared with those of CDDP and CBDCA in terms of relative antitumor activity (RAA, peak plasma concentration/IC50). Mean IC50 values (microgram/ml) of SKI 2053R, CDDP and CBDCA were 6.4 +/- 0.8, 1.8 +/- 0.7 and 20.6 +/- 12.2, respectively. The RAAs of SKI 2053R, CDDP and CBDCA were 1.6 +/- 0.4, 2.0 +/- 0.8 and 1.2 +/- 0.6, respectively. The differences in these values were not statistically significant. The results, demonstrating that antitumor activity of SKI 2053R is similar to those of CDDP and CBDCA, suggest that SKI 2053R is an interesting candidate for further development as a new anticancer drug.

Acral lentiginous melanoma

OBJECTIVE

To analyze whether the histologic subtype acral lentiginous melanoma confers independent prognostic significance.

DESIGN

Case series retrospective review.

SETTING

Academic surgical practice.

PATIENTS OR OTHER PARTICIPANTS

Fifty-six patients with histologically confirmed acral lentiginous melanoma identified from patients with malignant melanoma consecutively treated by the faculty of the Department of Surgical Oncology at the University of Illinois at Chicago.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Lymph node metastases, disease-free survival, and overall concurrent or subsequent survival.

RESULTS

The average age of our patients with acral lentiginous melanoma was 61.1 years. Thirty-four (61%) were white, and the remaining 22 (39%) were African-American, Hispanic, or Asian. Thirty (54%) were male and 26 (46%) were female. The primary tumor occurred on the lower extremity in 46 (82%) of the cases and on the upper extremity in the remaining 10 (18%). Twenty-four primary tumors (43%) were greater than 4.00 mm thick. Analyzed by means of a logistic regression model, the rate of lymph node metastases did not significantly differ among patients with acral lentiginous melanoma, superficial spreading melanoma, and nodular malignant melanoma. Furthermore, when corrected for tumor thickness, disease-free and overall survival were the same for the three histologic groups. Multifactorial analysis identified only thickness as a prognostic variable for disease-free survival and overall survival.

CONCLUSIONS

Despite the greater age, diverse ethnic background, and distinctive tumor characteristics of our patients with acral lentiginous melanoma, this histologic subtype does not, in itself, affect the outcome of these patients.

Antitumor activity of cis-malonato[(4R,5R)-4,5-bis(aminomethyl)-2- isopropyl-1,3-dioxolane]platinum(II), a new platinum analogue, as an anticancer agent

The in vitro and in vivo antitumor activity of a new antitumor platinum complex, cis-malonato[(4R, 5R)-4,5- bis(aminomethyl)-2-isopropyl-1,3-dioxolane]platinum(II) (SKI2053R, NSC D644591), were evaluated and compared with those of cisplatin (CDDP) and carboplatin (CBDCA) using murine tumors. SKI 2053R was highly active in vitro against both L1210 murine leukemia and its CDDP-resistant subline, L1210/DDP; the relative resistances were 20.0-, 14.5-, and 2.7-fold for CDDP, CBDCA, and SKI 2053R, respectively. SKI 2053R showed activity comparable with or superior to either CDDP or CBDCA in mice implanted with L1210. In mice implanted with L1210/DDP, as compared with CBDCA, SKI 2053R showed high values for the percentage of treated survivors relative to controls and for numbers of cured mice, whereas CDDP had virtually no activity. In mice implanted with P388, all three drugs were highly active, but the intensity of activity was shown to be ranked in the following order: SKI 2053R > CDDP > CBDCA. The antitumor activity of SKI 2053R against Lewis lung carcinoma was comparable with that of both CDDP and CBDCA. The antitumor activity of SKI 2053R was further investigated against two human tumor xenografts, KATO III (stomach adenocarcinoma) and WiDr (colon adenocarcinoma), implanted s.c. in nude mice and was compared with that of CDDP. In SKI 2053R-treated groups, the time required for a mean tumor weight of 1,000 mg was 33.1 days in KATO III xenografts and 35.0 days in WiDr xenografts as compared with 30.2 and 27.2 days in CDDP-treated groups, respectively. SKI 2053R achieved growth-inhibition rates comparable with those of CDDP against KATO III (65% versus 59%) and WiDr xenografts (64% versus 54%) on day 35. These results indicate that SKI 2053R is an attractive candidate for further development as a clinically useful anticancer drug.

Analysis of proliferative grade in glial neoplasms using antibodies to the Ki-67 defined antigen and PCNA in formalin fixed, deparaffinized tissues

In an effort to optimize immunocytochemical methods to evaluate cell kinetics in brain tumors, we studied two newly-developed antibodies which react with formalin resistant epitopes of Proliferating Cellular Nuclear Antigen (PCNA) and Ki-67. These results were compared with standard flow cytometric cell cycle data from the same tumor specimens to determine if these methods correlate with each other, and whether retrospective analysis using these antibodies is feasible for cell kinetic analysis of brain tumors. Thirty-one specimens of glial tumors submitted for flow cytometry during 1992 were also reacted with antibodies to PCNA (PC-10) and Ki-67 (MIB-1). Flow cytometry scores for S-phase Fraction were compared with immunocytochemical scores for both antibodies, using an arbitrary rating of 1 (low, < 4%), 2 (intermediate, 4-6%), 3 (high, > 6%), and 1 (< 25% positive), 2 (26-75% positive), 3 (> 75% positive), respectively. MIB-1 results were found to correlate significantly with the S-phase fraction as determined by flow cytometry. The MIB-1 data showed a trend toward underestimating, i.e., lower scores, the proliferative index compared with flow cytometry. There was less of a correlation between PC-10 antibody scores and flow cytometry S-phase fraction, as PC-10 immunostaining typically overestimated the proliferative rate of brain tumors when compared with flow cytometry. There was an exact correlation between PC-10 and MIB-1 in only 4 cases, whereas in the remaining specimens, PC-10 results were always higher than MIB-1.(ABSTRACT TRUNCATED AT 250 WORDS)

Marker values at the time of an AIDS diagnosis

In this paper statistical methods are proposed to estimate the distribution of a CD4 T-cell number at the time of a clinical AIDS endpoint from serial measurements of CD4 T-cell values in a cohort study. The statistical formulation of the problem is that of survival analysis with interval censored data, but in which the endpoints are obtained with measurement error. A measurement error likelihood is developed, assuming normality of the CD4 distribution at AIDS. A maximum likelihood estimation procedure and a Gibbs sampling approach are implemented.

General pharmacology of cis-malonato[4R,5R)-4,5-bis-(aminomethyl)-2-isopropyl-1,3- dioxolane]platinum(II)

The general pharmacological properties of cis-malonato-[(4R,5R)-4,5- bis(aminomethyl)-2-isopropyl-1.3-dioxolane]platinum(II) (SKI 2053R, CAS 146665-77-2), a new potential anticancer agent, were investigated in mice, rats, guinea pigs, rabbits, cats and dogs. Intravenous administration of SKI 2053R had no effect on the central nervous system. SKI 2053R had no effect on the autonomic nervous system and smooth muscles except that it slightly inhibited the spontaneous motility of isolated rabbit ileum at a concentration of 5 x 10(-5) g/ml. SKI 2053R did not adversely affect the respiratory-cardiovascular system, gastrointestinal system, neuromuscular junction, or renal function. SKI 2053R did not significantly alter the levels of serum glucose, serum free fatty acid and plasma lactate, and did not induce hemolysis. SKI 2053R did not affect blood coagulation mechanism and liver function. SKI 2053R did not exhibit anti-inflammatory activity. It was observed that SKI 2053R increased the formation of hemolytic plaque by spleen cells of sensitized mice at high doses (10 mg/kg and 35 mg/kg). Therefore, it is concluded from these general pharmacological studies that SKI 2053R at the doses showing antitumor activity does not induce severe adverse effects on the central nervous, autonomic nervous, respiratory-cardiovascular, gastrointestinal, peripheral nervous, and other systems in experimental animals.

Role of 100-kDa cytosolic PLA2 in ACh-induced contraction of cat esophageal circular muscle

We have shown that acetylcholine (ACh)-induced contraction of esophageal circular muscle cells is mediated by activation of protein kinase C (PKC). We now examine the role of phospholipase A2 (PLA2). ACh increases [3H]arachidonic acid release in esophageal but not in lower esophageal sphincter (LES) muscle. In addition, ACh-induced contraction of esophageal but not of LES cells was reduced by the PLA2 antagonist dimethyleicosadienoic acid and by antiserum to a 100-kDa cytosolic PLA2 (cPLA2). These data suggest that the 100-kDa cPLA2 plays a role in ACh-induced contraction of esophageal but not of LES muscle. In esophageal cells, arachidonic acid produced by PLA2 caused little contraction by itself but potentiated contraction induced by the PKC agonist diacylglycerol (DAG). The free fatty acids linoleic acid and linolenic acid also potentiated DAG-induced contraction. Indomethacin and nordihydroguaiaretic acid had no effect on arachidonic acid-induced potentiation of DAG. The potentiation of DAG-induced contraction by arachidonic acid was inhibited by the PKC inhibitor H-7, but it was not affected by the calmodulin inhibitor CGS-9343B. We conclude that a 100-kDa cPLA2 participates in ACh-induced esophageal contraction by producing arachidonic acid and potentiating DAG-induced activation of a PKC-dependent pathway.

The utilization of Doppler ultrasonography with color flow mapping in the diagnosis and evaluation of malignant trophoblastic tumors

The Doppler ultrasound with color flow mapping image has been recently applied for the evaluation of gynecologic diseases, in particular, malignant trophoblastic tumors with the characteristic abundant blood flow. Doppler color flow mapping of uterine artery and intratumoral blood vessels was performed at a regular interval in all 26 patients including 3 cases of lost for follow up. Systolic/diastolic (S/D) ratio representing blood flow was measured in 19 cases of malignant trophoblastic tumors and 7 cases of hydatidiform mole diagnosed at the department of Obstetrics and Gynecology, Yonsei University, College of Medicine. The initial mean S/D ratio and standard deviation(SD) of uterine artery in 11 remitted and 5 non-remitted patients were 2.72 +/- 1.31 and 2.69 +/- 1.80, respectively. No significant difference was noted between two groups. However, the final S/D ratio of uterine artery in remitted group showed significantly higher values than non-remitted group, of which values were 6.23 +/- 2.38 and 3.08 +/- 1.54, respectively (P < 0.05). In aspect of blood flow changes in malignant trophoblastic tumors after chemotherapy, remitted group showed entirely disappeared blood flow, while non-remitted group had persistent blood flow. The mean S/D ratio and SD measured in hydatidiform mole patients were 5.43 +/- 1.65, of which value reflects higher resistance than malignant trophoblastic tumors. Also blood flow was not detected in all cases. This study suggests that color flow mapping Doppler ultrasound can be a useful method in diagnosing and monitoring the treatment in malignant trophoblastic tumors along with the conventional serum beta-hCG titration.

Unilateral vestibular schwannoma in a child with prior orbital rhabdomyosarcoma

In the absence of neurofibromatosis, vestibular schwannomas (acoustic neuromas) are rarely found in children. We report a case of a 13-year-old boy who presented with unilateral vestibular schwannoma 11 years after resection of an orbital rhabdomyosarcoma. The coincidence of these tumors has not been previously reported.

Clinical analysis of 40 cases of childhood-onset Behçet's disease

Behçet's disease is a chronic, relapsing, idiopathic, multi-system condition characterized by mucocutaneous, ocular, gastrointestinal, articular, vascular, urogenital, and neurologic involvement. Usually the onset occurs between 20 and 30 years of age; it is very uncommon in children. We analyzed 40 cases of childhood-onset Behçet's disease. The male:female ratio was 0.67. The most frequent major sign was oral ulceration, appearing in all patients. Other major signs were genital ulcers (33 patients), skin lesions (29), and ocular lesions (11). The average time interval between the initial oral ulceration and the second major manifestation was 8.8 years. After the second major manifestation, the third and fourth features rapidly developed within one to two years. The most frequent minor sign was arthritis, occurring in 11 of 40 patients. Intestinal, neurologic, and renal involvement was also present. From our results, we concluded that oral ulceration, which is the most common initial manifestation, should not be neglected in children, since it may signal Behçet's disease.

Synthesis and antitumor activity of a series of [2-substituted-4,5-bis(aminomethyl)-1,3-dioxolane]platinum(II) complexes

The synthesis, physical properties, antitumor activity, structure-activity relationships, and nephrotoxicity of a series of [2-substituted-4,5-bis(aminomethyl)-1,3-dioxolane]platinum(II) complexes are described. The 42 platinum(II) complexes having a seven-membered ring structure in this series have been prepared and characterized by 1H NMR, 13C NMR, IR, FAB-MS, and elemental analysis. All members of the series were designed to have a 1,3-dioxolane ring moiety in their carrier ligands to increase water solubility. The solubility of platinum complexes was related to the nature of leaving ligands and 2-substituents in the 4,5-bis(aminomethyl)-1,3-dioxolane carrier ligands. In general, compounds having two different R1 and R2 substituents in the 4,5-bis(aminomethyl)-1,3-dioxolane moiety were more water-soluble than those having the same substituents. Most members of this series showed the excellent antitumor activity against murine L1210 leukemia cells transplanted in mice and were superior to cisplatin and carboplatin. The (4R,5R)-stereoisomer 1a-h exhibited the higher antitumor activity than the corresponding (4S,5S)-stereoisomer 2a-h in the (1,1-cyclobutanedicarboxylato)platinum(II) complexes. The (glycolato)-platinum(II) complexes were highly cytotoxic toward four human stomach cancer cell lines, SNU-1, SNU-5, SNU-16, and NCI-N87, and among them, complexes 3d-g were even more cytotoxic than cisplatin. The (malonato)platinum(II) complex 1m and the (glycolato)platinum(II) complexes 3d-g were selected for further studies based on the greater in vivo and in vitro antitumor activity and desirable physical properties. The complexes 3e-g were almost equally cytotoxic to cisplatin toward human stomach cancer cell lines, KATO-III and MKN-45, and a human non-small cell lung cancer cell line, PC14. In contrast with cisplatin and carboplatin, five complexes selected significantly increased in life span in mice transplanted with cisplatin-resistant L1210 cells. Nephrotoxicity studies in ICR mice indicated that serum BUN and creatinine levels were not elevated when five complexes were given at a dose equal to 1.5 times the optimal dose determined in the in vivo L1210 screening system.

Annexin-I inhibits phospholipase A2 by specific interaction, not by substrate depletion

Annexin-I is a calcium dependent phospholipid binding and phospholipase A2 (PLA2) inhibitory protein. A 'substrate depletion' model has been proposed for the mechanism of PLA2 inhibition by annexin-I in studies with 14 to 18 kDa PLA2s. Herein, we have studied the inhibition mechanism using 100 kDa cytosolic PLA2 from porcine spleen. The inhibition has been measured at various substrate and calcium ion concentrations. The pattern of PLA2 inhibition by annexin-I was consistent with a 'specific interaction' mechanism rather than the 'substrate depletion' model. Apparent contraction with previous studies can be explained by the calcium-dependent binding of annexin-I to the substrate.