Antitumor activity of immunoconjugates composed of boanmycin and monoclonal antibody

Boanmycin (bleomycin A6, BM), an antitumor antibiotic, was conjugated to monoclonal antibodies including R19, H111 and CCT2. The immunoconjugates exhibited selective cytotoxicity to related target cells including cecum cancer Hce-8693 cells, liver cancer BEL-7402 cells and leukemia CEM cells. They were highly effective against related human tumor xenografts in nude mice, and the inhibition rates by the conjugates were much higher than those by free BM. The inhibition rate by R19-BM conjugate against human cecum cancer xenografts reached 90%. BY immunoelectron microscopy, CCT2-BM conjugate showed specific binding and internalization in leukemia CEM cells. The results indicate that boanmycin-monoclonal antibody immunoconjugates are highly active both in vitro and in vivo.

Uptake of a neurotoxin-candidate, (R)-1,2-dimethyl-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline into human dopaminergic neuroblastoma SH-SY5Y cells by dopamine transport system

Uptake of catechol isoquinolines to dopamine cells was studied using human dopaminergic neuroblastoma SH-SY5Y cells. Only (R)-1,2-methyl-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline [(R)-1,2-DiMeDHTIQ] was transported by dopamine uptake system, while (S)-1,2-DiMeDHTIQ, (R)- and (S)-1-methyl-6,7-dihydroxy-tetrahydroisoquinoline, and 1,2-dimethyl-6,7-dihydroxyisoquinolinum ion were not. Kinetical study showed that the uptake of (R)-1,2-DiMeDHTIQ followed the Michaelis-Menten equation, and the values of the Michaelis constant and the maximal velocity were obtained to be 102.6 +/- 36.9 microM and 66.0 +/- 2.8 pmol/min/mg protein. Dopamine was found to inhibit (R)-1,2-DiMeDHTIQ uptake competitively. These results suggest that the selective uptake by dopamine transporter may account for the specific neurotoxicity of (R)-1,2-DiMeDHTIQ to dopamine neurons.

Influence of pregnancy on ANF release from isolated atria

Isolated perfused right atria were prepared from virgin cycling rats and from rats at 7, 14, and 21 days of pregnancy. Intraluminal pressure was raised from the basal control level (atmospheric) to 4, 6, and 10 cmH2O. Basal and stretch-induced release of atrial natriuretic factor (ANF) into the perfusate was measured by radioimmunoassay. When atria derived from unmated and from 7-day pregnant rats were distended, mean ANF secretion into the perfusion medium increased by 64 +/- 16 and 89 +/- 31 pg/ml at the highest distending pressure of 10 mmHg. (Mean basal secretion for the two groups was 196 +/- 104 and 181 +/- 63 pg/ml, respectively.) However, at 14 and 21 days, distension failed to elicit any significant increase in ANF release. There was no significant difference between the groups with respect to basal secretion of ANF, nor did pregnancy influence atrial compliance or volume. The slopes of the pressure-volume curves for atria derived from virgin, 7-, 14-, and 21-day-pregnant rats were 0.76 +/- 0.17, 0.623 +/- 0.178, 0.811 +/- 0.177, and 1.050 +/- 0.173, respectively. These results are in agreement with our findings in vivo that plasma ANF levels are elevated at 7 days of pregnancy but that, despite the progressive increase in intravascular volume, they decrease to control levels at 14 and 21 days. Our latest data suggest that this fall is a result of changes in the secretory characteristics of the atrial tissue itself and not necessarily of pregnancy-induced changes in atrial filling.

Electro-oculogram of retinal vein occlusion

Twenty five cases, including 26 eyes with retinal vein occlusion (RVO) were examined by means of the electro-oculogram. The results showed that 23 of the 26 eyes suffering from RVO exhibited abnormalities of the electro-oculogram (EOG). The potential difference and Arden ratio in the RVO eyes were lower than those in the normal eyes (P < 0.01). The more the visual acuity of ill eyes was decreased, the higher the abnormal rate of EOG in ill eyes was. 14 eyes had the visual acuity less than 0.1, whose EOGs were abnormal. Six eyes had the visual acuity from 0.2 to 0.4, in which the EOGs of 5 eyes were abnormal. Six eyes had the visual acuity more than 0.5, among which the EOGs of 4 eyes were abnormal. Based on the above observations, it may be considered that the circulatory disturbance resulting from RVO damages not only the internal layer but also the external layer of the retina. We suggest that EOG is a useful method for distinguishing lesions caused by RVO and may reflect the functional condition of the outer layer of the retina.

Antigen processing: where tumor-specific T-cell responses begin

It is well established that tumor-specific CD8+ T cells have the capacity to prevent and cure malignancies in animals under experimental conditions. This has raised expectations that it will prove possible to achieve similar successes with human cancers. CD8+ T cells recognize peptides of 8-10 residues derived from cytosolic proteins that are bound to the class I molecules of the major histocompatibility complex. To most effectively manipulate the T-cell response to tumor cells, it is essential to understand the means by which the peptide-class I complex is created in cells. An overview of this process is provided with an emphasis toward the recent findings made by our laboratory.

Renal response to atrial stretch during pregnancy in conscious rats

Chronic indwelling balloons were placed at the junction of the right atrium and the right superior vena cava of virgin female rats. The renal response to discrete standardized atrial stretch was tested in the conscious animals. The rats were then mated, and the renal response was retested at days 7, 14, and 20 of pregnancy. On day 21, the rats were killed, and the pressure-volume relationship of the right atria was measured. In response to atrial stretch, there was an increase in urine volume, urine sodium output, and urine potassium output and a decrease in free water clearance in the virgin rats. Subsequent to mating, these responses were completely abolished at all stages of pregnancy. The renal responses to atrial stretch were also abolished during pseudopregnancy. Central venous pressure did not change when the intracardiac balloons were inflated; there were also no changes in resting central venous pressure during pregnancy. There were no significant changes in unstressed atrial volume or in atrial compliance during pregnancy.

Synthesis and antitumor activity of ammine/amine platinum(II) and (IV) complexes

Dimeric platinum complexes, [Pt(RNH2)I2]2 (where R = H, methyl, ethyl, isopropyl, cyclopropyl, cyclobutyl, cyclopentyl, and cyclohexyl), have been synthesized by reactions of diiodoplatinum compounds with perchloric acid in water/ethanol solutions. The dimerization varies from several hours to a few days depending upon the length of the carbon chain in the alkylamines and the process can be conveniently monitored by 195Pt NMR spectroscopy. All these dimers exhibit two closely separated resonances around -4000 ppm (vs K2PtCl4 at -1620 ppm) in dimethylformamide. Reactions of [Pt(NH3)I2]2 with alkylamines do not yield the desired mixed ammine/amine complexes, which are obtained subsequently by treatment of the alkylamine dimer [Pt(RNH2)I2]2 with ammonium hydroxide in water. By using this latter procedure, a novel class of ammine/amine platinum complexes of the type PtII(NH3)(RNH2)Cl2, PtIV(NH3)(RNH2)X2A2, and PtIV(NH3)(RNH2)(CBDCA)A2.H2O, where X2 = chloro or 1,1-cyclobutanedicarboxylato (CBDCA), A = OH, Cl, or OCOCH3, have been synthesized and characterized by elemental analysis, infrared, and 195Pt NMR spectroscopic techniques. The alicyclic ammine/amine Pt(II) complexes, where R is C3-C6 were selected as representative of the class to undergo antitumor evaluations. The compounds had excellent activity against murine leukemic L1210/0 cells with cyclobutylamine-, cyclopentylamine- and cyclohexylamine-containing complexes demonstrating cytotoxicity superior to that of the clinically established cisplatin.

Splenic control of intravascular volume in the rat

1. We tested the hypothesis that hypervolaemia causes an increase in intrasplenic filtration of cell-free fluid out of the vasculature. To this end we developed a preparation in the anaesthetized rat whereby the splenic vein could be non-occlusively cannulated. 2. Haematocrit and plasma protein concentrations were measured in the splenic afferent and efferent blood supplies. 3. In response to volume loading with saline (1% body weight), there was a sustained increase in the arterial-venous differential of haematocrit, i.e. there was a relative increase in the haematocrit of the blood draining from the spleen. There was no such change in plasma protein concentration. By contrast, this degree of volume loading had no effect on the haematocrit of blood passing through the hindquarters of the animal. 4. Following volume expansion, there was no significant difference in the protein concentration of the plasma and the lymph fluid collected from the splenic lymphatic duct. 5. Distension of the superior vena caval-right atrial junction by means of a small inflatable balloon, caused a similar increase in the splenic venous haematocrit, and again, no change in plasma protein concentration. 6. We interpret these results to mean that, in response to expansion of the intravascular space, there is increased intrasplenic filtration of plasma out of the blood and into the lymphatic system.

Preparation, characterization, and antitumor activity of new ethylenediamine platinum(IV) complexes containing mixed carboxylate ligands

A series of ethylenediamine platinum(IV) complexes of the type PtIV(en)XA2 and PtIV(en)X'2A2, where X = 1,1-cyclobutanedicarboxylato or malonato, X' = chloro, cyclobutanecarboxylato, cyclopentanecarboxylato, or cyclohexanecarboxylato, and A = acetato or trifluoroacetato were synthesized and characterized by elemental analysis, infrared, and NMR (13C and 195Pt) spectroscopic techniques. These compounds had good to excellent antitumor activity against murine leukemia L1210 cells. Complexes with axial trifluoroacetate groups were superior to those with acetate ligands. Those possessing both axial trifluoroacetate groups and monodentate bis-carboxylate ligands in the equatorial positions were the most active in the series investigated.

The influence of reproductive hormones on ANF release by rat atria

The effects of subcutaneous (sc) administration of estradiol (50 micrograms/100 microliters/day x 10 day) or testosterone (15 mg/100 microliters twice a week x 2 weeks) on ANF release were examined in isolated perfused rat atria. The concentration of ANF in the perfusate was measured by radioimmunoassay, under basal conditions (atrial wall unstressed), and during atrial distention (intraluminal pressure raised to 4, 6, and 10 cm water). In both male and female control (vehicle-injected) groups, increased atrial pressure resulting in distention of the atrium caused a significant increase in ANF release. Estradiol increased basal secretion of ANF but did not influence stretch-induced stimulation of ANF secretion. By contrast, although testosterone did not affect basal secretion, it completely abolished the stretch-induced increase in ANF secretion. Neither estradiol nor testosterone affected atrial compliance.

Rapid inactivation of endothelin-1 by a carboxypeptidase-like enzyme purified from rat kidney

A survey of various rat tissues showed that the kidney had the highest endothelin degradation enzyme activity. An enzyme that effectively inactivated endothelin-1 was purified from soluble kidney extracts. This enzyme appeared to contain two subunits with molecular weights of 34 kDa and 21 kDa. It displayed carboxypeptidase-like properties and cleaved off the carboxyl terminal tryptophan of endothelin-1. These results agree with the findings that endothelin-1 is cleared efficiently by the kidney and suggest that this enzyme plays a role in the homeostasis of circulating endothelin-1.

Soluble endothelin degradation enzyme activities in various rat tissues

From soluble extract of rat kidney we have previously identified an endothelin degradation enzyme that rapidly and specifically cleaves off the C-terminal tryptophan of endothelin-1, resulting in a peptide that is three orders of magnitude weaker in potency than endothelin-1 in causing smooth muscle contraction. The tissue distribution of this enzyme was examined, and the soluble extracts of rat kidney were found to contain the highest enzyme activity, followed by the spleen and the liver. In contrast, no enzyme activity was detected in the soluble extracts of brain, heart, and lung. The biochemical properties of the partially purified enzyme from kidney were further investigated. The optimal pH of the enzyme was between 5 and 7. The endothelin degrading activity was effectively blocked by thiol protease inhibitors such as benzyloxycarbonyl-Phe-Ala-diazomethyl ketone and p-hydroxymercuribenzoic acid, as well as by phenylmethylsulfonyl fluoride, but not by metalloprotease and other serine protease inhibitors. This enzyme displayed a clear difference in substrate specificity when compared with other thiol proteases such as cathepsin B, cathepsin H, and cathepsin L, known to be present in the kidney. These results suggest that a novel protease with endothelin degrading activity is widely distributed in a number of tissues.

A soluble protease identified from rat kidney degrades endothelin-1 but not proendothelin-1

Endothelin-1 (ET-1) is a potent peptidic vasoconstrictor. This peptide has been shown to be cleared rapidly by the kidney. The purpose of the present study was to assess the involvement of renal proteolytic enzymes in the clearance/degradation of ET-1. Incubation of ET-1 with the cytosolic fraction of rat kidney homogenate resulted in a decrease of contractile activity on rabbit aortic rings when compared to the untreated ET-1. This cytosolic fraction was chromatographed by anion-exchange and concanavalin A columns. The partially purified enzyme cleaved off the C-terminal tryptophan of ET-1 rapidly, resulting in a peptide which is three orders of magnitude weaker in potency than ET-1 in causing smooth muscle contraction. In contrast, proendothelin-1 was not degraded by this endothelin degradation enzyme (EDE). The effects of EDE on other vasoactive peptides were also examined. The C-terminal tyrosine of atrial natriuretic peptide was cleaved by EDE, but the biological activity of the resulting peptide was not significantly changed. Angiotensin II was not a substrate for EDE. The EDE was shown to be different from both carboxypeptidases A and B based on the HPLC analysis of the degradation products of ET-1 produced by these enzymes. In addition, these enzymes displayed different sensitivities toward a carboxypeptidase inhibitor from potato tuber. These results suggest that this previously unidentified enzyme inactivates ET-1 effectively and that it may play a role in modulating the levels of ET-1 in the kidney.

The influence of calcium on ANF release in the isolated rat atrium

We developed an in vitro model of the isolated, perfused rat atrium with which to examine the mechanisms linking muscular stretch to atrial natriuretic factor (ANF) secretion. It was shown that an increase in atrial pressure causing distension of the atria is associated with a rise in ANF secretion correlating with the degree of pressure load. Pressure-induced ANF secretion is enhanced by the calcium blocker nifedipine or omission of calcium from the perfusion buffer. The changes in atrial volume in response to a given pressure load are also more pronounced in the absence of calcium or following the addition of the calcium blocker. These data suggest that in nonbeating atria, stretch-induced ANF secretion does not rely on calcium influx.

Cosegregation of blood pressure with angiotensin converting enzyme and atrial natriuretic peptide receptor genes using Dahl salt–sensitive rats

We have evaluated the genes for angiotensin converting enzyme (ACE) and guanylyl cyclase A/atrial natriuretic peptide receptor (GCA) for genetic effects on blood pressure response to high salt diet. In F2 rats derived from Milan normotensive and Dahl salt-hypertension sensitive (S) rats, both ACE and GCA cosegregated with blood pressure, and rats that were homozygous for the S allele at both the ACE and GCA loci had inordinately high blood pressure. In F2 derived from Wistar Kyoto (WKY) and S rats, GCA revealed positive cosegregation with blood pressure, but ACE did not. We conclude that certain alleles at the GCA and ACE loci (or at loci closely linked to them) have a significant genetic impact on blood pressure response to high salt in specific rat strains.

Aggregative adherence fimbriae I of enteroaggregative Escherichia coli mediate adherence to HEp-2 cells and hemagglutination of human erythrocytes

Strains of enteroaggregative Escherichia coli (EAggEC) have been implicated in several studies as important agents of persistent diarrhea among infants in the developing world. We have previously shown that the aggregative adherence (AA) property of EAggEC is associated with the presence of a 60-MDa plasmid which confers AA when introduced into E. coli HB101. Here, we report the cloning of the AA determinant from EAggEC strain 17-2 into the 21.5-kb cosmid vector pCVD301. TnphoA mutagenesis of the AA cosmid clone pJPN31 implicated an AA region of approximately 12 kb. Transmission electron microscopy of HB101 (pJPN31) revealed the presence of bundle-forming fimbriae, which were absent in AA- TnphoA insertion mutants. The presence of these fimbriae, AA, and hemagglutination (HA) of human erythrocytes were all concurrently lost by single-insertion mutations. A 14-kDa protein was seen on polyacrylamide gel electrophoresis and Western blotting (immunoblotting) of surface shear preparations from fimbriated clones. Twelve of nineteen volunteers fed EAggEC 17-2 developed rises in antibodies to the 14-kDa protein as determined by Western blot. We have termed the cloned bundle-forming fimbriae aggregative adherence fimbriae I (AAF/I); positivity with a previously described EAggEC probe and human erythrocyte HA appear to correlate with the presence of AAF/I.

Identification and partial purification of a thiol endothelin-converting enzyme from porcine aortic endothelial cells

Endothelin is a potent peptide vasoconstrictor. The final step in the processing of endothelin has been postulated to be the cleavage of the Trp21-Val22 peptide bond in proendothelin by a putative endothelin-converting enzyme. A soluble extract of primary porcine aortic endothelial cells was found to contain an enzyme activity that converted proendothelin-1 (proET-1) to an endothelin-1 (ET-1)-like peptide as determined by the rabbit aortic ring contraction assay. This enzyme was partially purified by DE52 ion-exchange chromatography. Incubation of proET-1 with the partially purified enzyme generated a product which had a retention time on HPLC identical to that of authentic ET-1. Further analysis of the product showed that it caused contraction of rabbit aortic rings, had a molecular weight identical to ET-1 as measured by fast atom bombardment mass spectrometry, and competed for [125I]ET-1 binding in an RIA using specific antibodies which recognize the carboxy terminal tryptophan of ET-1. The enzyme activity could be inhibited by thiol protease inhibitors such as Z-phe-pheCHN2 and p-hydroxymercuribenzoate, but not by serine- or metalloprotease inhibitors. The optimal pH for the enzymatic activity was between 7.0 and 7.5, and no activity was detected at pH 4.0. These results demonstrate that this thiol protease is a potential endothelin-converting enzyme.

Intermixing of resident Golgi membrane proteins in rat-hamster polykaryons appears to depend on organelle coalescence

We have used the synchronized formation of a mixed cytoplasm upon heterokaryon formation as a model for investigating the cisternal-specific transport of resident proteins between neighboring Golgi apparatus. Rat NRK and hamster 15B cells were fused by UV-inactivated Sindbis virus and then incubated for various time periods in the presence of cycloheximide. The resident Golgi apparatus proteins, rat GIMPc and Golgp 125, were localized with species-specific monoclonal antibodies. Immunofluorescent colocalization of rat and hamster Golgi membrane proteins was observed with a t1/2 of 1.75 h at 37 degrees C. Colocalization of resident, but not transient, Golgi membrane protein was concomitant with formation of a large extended Golgi complex and was accompanied by the acquisition of endoglycosidase H resistance by preexisting Golgp 125. Dispersal of the extended Golgi complex by nocodazole revealed that colocalization of resident Golgi proteins was due to intermixing of proteins in the same Golgi element rather than overlapping of closely apposed Golgi structures. Incubation of the polykaryons at 20 degrees C inhibited both the colocalization of GIMPc and Golgp 125 and the formation of an extended Golgi complex. Little change in the number of cisternae/stack in cross sections of the Golgi apparatus was observed upon cell fusion, and in the extended Golgi complex the hamster resident protein remained localized to one side of the Golgi stack. Surprisingly, the morphological identity of the rat and hamster Golgi units appeared to be maintained in the heterokaryons. These results suggest that the intermixing of resident Golgi membrane proteins requires direct physical continuity between Golgi elements and that resident Golgi membrane proteins are preferentially excluded from the non-clathrin-coated transport vesicles budding from Golgi cisternae.

[Bullous retinal detachment and its classification of fluorescence angiography]

Nineteen cases with (27 eyes) of bullous retinal detachment, male (24 eyes), female (3 eyes), were reported. The age of onset was from 16 to 46, mean 36.7. All of them underwent fundus fluorescence angiography (FFA). According to the results of FFA, it could be divided into two types of fluorescence angiograph changes were seen: type I, multiple pigmental epithelial damage at posterior pole, it consisted of twelve cases (16 eyes); type II, extensive pigmental epithelial damage at posterior pole, it consisted of seven cases (11 eyes). The treatments consist: medicine; medicine and photocoagulation; combined medicine, transscleral drainage and photocoagulation. Among 27 eyes, 20 had their vision improved after treatment, 4 eyes unchanged and 3 eyes decreased in vision. 22 eyes obtained their retinal reattachment (81.4%). The diagnosis, differential diagnosis, classification and treatment are discussed.

Incidence and mortality rates of myocardial infarction in Chinese workers aged 40-59 in relation to coronary risk factors. Results of a Chinese prospective study (Wuhan Study) in comparison to the Göttingen Risk Incidence and Prevalence Study (GRIPS)

Some 2045 male Chinese industrial workers aged 40-59 years living in the city of Wuhan in the People's Republic of China were examined for coronary risk factors in the year 1983. The investigation included a patient history, clinical examination, and ECG and laboratory tests, with special attention to serum lipids. After 5 years, a follow-up investigation of the study group was carried out. The results were compared to the similarly designed German GRIPS project. In comparison to the German population, significantly lower levels for total-, LDL-, and VLDL-cholesterol, apolipoprotein B, triglycerides, uric acid, body mass index, and diastolic blood pressure were found in China. The percentage of smokers, however, was remarkably higher in China than in the Federal Republic of Germany. During the 5 year observation period in the Chinese sample, four subjects suffered from sudden death and four from nonfatal myocardial infarction; in the German study group three times as many fatal myocardial infarction and cases of sudden death and 7.5 times as many nonfatal myocardial infarctions were recorded. Nonfatal coronary heart disease and peripheral vascular disease were also observed less often in China. The incidence of cerebrovascular diseases was 1.5 times higher in China than in Germany. Whereas in Germany, total-, and LDL-cholesterol values were the major distinguishing parameters between infarction and reference groups, in China these values have thus far had no significant influence on the level of risk. Instead in the Chinese incidence group, significantly higher levels for blood pressure, body mass index, uric acid, and the ratio LDL/HDL-cholesterol were found.

[Inhibitory effect of bleomycin A6 on human colon cancer xenografts in nude mice]

As evaluated by clonogenic assay, bleomycin A6 was found to be highly active against established human cancer cell lines derived from colon cancer (HT-29) and cecum cancer (Hce-8693). These human cancer cells have been serially transplanted in nude mice. At a tolerable dosage level, bleomycin A6 exerted remarkable growth inhibition on human colon cancer HT-29 and cecum cancer Hce-8693 xenografts (approximately 90% inhibition). No histopathological changes were found in the organs of treated animals. Compared on the basis of equitoxic doses (1/9 LD50), bleomycin A6 exerted much stronger growth inhibition against colon cancer HT-29 xenografts in nude mice than 5-fluorouracil and mitomycin C, with inhibition rates of 82%, 12% and 53%, respectively. More extensive necrosis was found in tumors treated with bleomycin A6 than in those treated with mitomycin C or 5-fluorouracil. The ratio values of non-necrotic tumor tissue to whole tumor tissue for bleomycin A6, mitomycin C and 5-fluorouracil were 0.33, 0.65 and 0.57, respectively. These observations indicate that bleomycin A6 is a potent antitumor agent against colon cancer xenografts and may be useful in human colon cancer chemotherapy.