Chain Growth Polycondensation as a Polymer Generating Reaction in the Synthesis of Oligo(p‐phenyleneethynylene)s with Low Polydispersity

Summary: The polycondensation of 1‐ethynyl‐2,5‐dihexyl‐4‐iodobenzene in the presence of 1‐ethynyl‐2,5‐dihexyl‐4‐(2‐phenylethynyl)benzene proceeds according to the mechanism of initiated chain growth polycondensation. It has allowed the synthesis of oligomers with a desired molecular weight and a narrow molecular weight distribution. The reasons for the side reaction leading to the formation of diyne compounds are revealed and the presumed mechanism is given. This opens prospects for the preparation of defectless poly(p‐phenyleneethynylene)s with required molecular weights and narrow molecular weight distributions.

     

Comparison of protein tyrosine phosphorylation and morphological changes induced by IL-2 and IL-3.

We constructed cell lines which can proliferate in response to IL-2 or IL-3 by introducing a wild-type and mutant forms of cDNAs encoding the human IL-2R p75 chain into an IL-3 dependent hematopoietic cell line which expresses the p55 chain of the IL-2R. We compared early events that were induced in these cells by IL-2 and IL-3. Analysis of protein tyrosine phosphorylation showed that two common protein bands, pp95 and pp90, were phosphorylated by stimulation of either IL-2 or IL-3, suggesting the possible sharing of part of a signal transduction pathway between IL-2R and IL-3R. Comparison of protein tyrosine phosphorylation profiles induced by IL-2 and IL-3 among a variety of cell lines revealed that the pp90 band is the common tyrosine phosphorylation substrate in the cell lines examined, although the general tyrosine phosphorylation pattern differed in each cell line. Mutant p75 molecules incapable of inducing tyrosine phosphorylation could bind and internalize IL-2, but could not support cell growth. We also found that swift changes of cytoskeletal protein organization are one of the early events caused by signal transduction through either IL-2R and IL-3R. Reorganization of cytoskeletal proteins seems to be associated with protein phosphorylation, as a significant portion of pp90 was found in a detergent-soluble fraction in IL-2 or IL-3 treated cells.     

Voltage-dependent ionic currents in solitary horizontal cells isolated from cat retina.

1. Horizontal cells of the cat retina were isolated by enzymatic dissociation. Two types of horizontal cells were identified: the axonless (A-type) horizontal cell having four to six thick, long (approximately 100 microns) dendrites, and the short-axon (B-type) horizontal cell having many (> 5) fine, short (approximately 30 microns) dendrites. 2. Membrane properties of isolated horizontal cells were analyzed under current-clamp and voltage-clamp conditions. In the A-type cell, the average resting potential was -55 mV and the mean membrane capacitance was 110 pF, whereas values in the B-type cell were -58 mV and 40 pF, respectively. The A-type cell showed long-lasting Ca spikes, but B-type cells had no Ca spikes. 3. Five types of voltage-dependent ionic currents were recorded: a sodium current (INa), a calcium current (ICa), and three types of potassium currents. Potassium currents consisted of potassium current through the inward rectifier (Ianomal), transient outward potassium current (IA), and potassium current through the delayed rectifier (IK(v)). INa was recorded only from A-type cells. Other currents were recorded from both types of cells. 4. INa activated when cells were depolarized from a holding potential (Vh) of -95 mV, and it was maximal at -25 mV. This current was blocked by tetrodotoxin. Approximately half of the A-type cells had INa, but no B-type cell had this current. 5. L-type ICa, an inward-going sustained current, was activated with depolarization more positive than -25 mV. Current amplitude reached a maximal value near 15 mV and became smaller with further depolarization.(ABSTRACT TRUNCATED AT 250 WORDS)     

Primary choriocarcinoma and human chorionic gonadotrophin‐producing giant cell carcinoma of the lung: are they independent entities?

AIMS: Human chorionic gonadotrophin (hCG) is a useful marker for chorionic proliferative disorders, such as choriocarcinoma. Although hCG synthesis in lung cancers is frequent, primary pulmonary choriocarcinoma (PCC) is rare. To clarify the differences between primary choriocarcinoma and hCG-producing giant cell carcinoma (GCC) of the lung, we compared the clinicopathological and immunohistochemical findings of these tumours. METHODS AND RESULTS: Three patients, one with PCC and two with hCG-producing GCC, were included in this study. They were all middle-aged men and habitual smokers. The growth of these tumours and the progression of the clinical courses were extremely rapid, and the patients all died within 8 months after the pulmonary tumours were found. Haemorrhagic appearance was a common macroscopic feature of the specimens obtained. Microscopically, both types of tumours mainly consisted of atypical polygonal cells. While PCC contained many syncytial trophoblast-like multinucleated cells that had strong immunoreactivity for anti-hCG, such cells were relatively few in hCG-producing GCC. These histological and immunohistochemical findings reflected the serum test result for hCG, which was higher in the case of PCC. CONCLUSIONS: There are a few differences between PCC and hCG-producing GCC, as described above. Reliable distinction between them seems to be difficult for pathologists and worthless for clinicians.     

Phenotyping of proliferating lymphocytes in angioimmunoblastic lymphadenopathy and related lesions by the double immunoenzymatic staining technique.

Biopsy specimens of lymph nodes with the histologic characteristics of angioimmunoblastic lymphadenopathy with dysproteinemia (AILD) were obtained from 9 cases (4 cases of AILD and 5 cases of AILD-like T lymphoma [AILD-T]) and histologically analyzed by the use of a double immunoenzymatic staining technique with the combination of a monoclonal antibody against lymphocyte membrane antigen and that against human DNA polymerase alpha (pol alpha), which is detectable in the nucleus of the cells in G1, S, and G2 phases. In all 9 cases, the pol alpha + proliferating cells had a peripheral T-cell phenotype with T11 and Leu-4 antigens, whereas proliferating B cells with B1 antigen were rarely observed. As for T-cell subset antigens, the proliferating T cells had T4+ helper/inducer phenotype in 7 cases, while T8+ suppressor/killer T cells proliferated in 2 cases, although a significant number of T4+ proliferating cells were also recognized. The study on malignant lymphomas that evolved in the 2 cases showed that the T-subset antigens on major proliferating tumor cells were the same as those found in the preceding AILD lesions, suggesting that lymphoma T cells originate from the AILD lesion. The results suggested that AILD without histologic manifestations of malignancy and AILD-T may be a neoplastic disease derived from either subset of peripheral T cells.     

Breast cancer with reactive multinucleated giant cells: report of three cases

We report here three cases of breast cancer with reactive multinucleated giant cells. The patients were among the 605 patients with breast cancer seen in the past 17 years at Tenri Hospital; the incidence of this variety of breast cancer was 0.5%. Enzyme histochemical and electron microscopic examination suggested that the giant cells were of histiocytic origin. However, results of immunohistochemical technique, S-100 protein, lysozyme, nonspecific cross-reacting antigen with carcinoembryonic antigen, alpha-1-antitrypsin, and alpha-1-antichymotrypsin, all currently used as markers of histiocytes, were negative. Because of the rarity of this variety of breast cancer, the biological significance of these unusual findings remains unknown.     

Rat costochondral cell characteristics on poly (L-lactide-co-epsilon-caprolactone) scaffolds

This study was designed to examine the adhesion, proliferation, and morphology of chondrocytes on new scaffolds; and to examine these cells histologically for the ability of the chondrocytes to maintain chondrogenic properties after subcutaneous implantation into nude mice. Both 75:25 poly (L-lactide-co-epsilon-caprolactone) (75PLC) and 50:50 poly (L-lactide-co-epsilon-capro-lactone) scaffold (50PLC) were tested as a scaffold for rat costochondral resting zone chondrocytes in comparison with a type I collagen sponge scaffold (collagen scaffold). Both of the poly (L-lactide-co-epsilon-caprolactone) scaffolds (75PLC and 50PLC) were coated with type I collagen solution and the effects of the collagen coat (hybrid-PLC) were also examined. The hybrid-75PLC bound the same number of cells as the collagen scaffold, whereas the 75PLC and the 50PLC bound 60% and 50% fewer cells than the collagen scaffold, respectively. The cell growth on the scaffolds progressed with culture time in all scaffolds. Cell morphology was assessed by scanning electron microscopy for differences in the structure of cellular interaction. Chondrocytes on every scaffold maintained a spherical shape. The hybrid-PLCs were superior to the PLCs with respect to the number of cells attached. The PLCs had an advantageous degradation characteristic in that they retained their original shape better than the collagen scaffold. Additionally, in the PLCs seeded, the cells retained their integrity 4 weeks after implantation, although the volume of collagen scaffold decreased by 50%.     

Tumor necrosis factor-alpha in the placenta is not elevated in pre-eclamptic patients despite its elevation in peripheral blood

PROBLEM: Tumor necrosis factor-alpha (TNF-alpha) is present in human placental and uterine cells at the early and late stages of gestation and promotes the regulation of trophoblast growth and invasion. We evaluated whether TNF-alpha levels in the placenta and blood of pre-eclamptic women differed from those with normal pregnancies. METHOD OF STUDY: The subjects were 39 pregnant women carrying single fetuses (21 normal-pregnant and 18 pre-eclamptic patients). Their average gestational age at entry was 38-39 weeks. Peripheral blood was collected before the onset of labor and separated serum was stored at -20 degrees C. A tissue segment of the placenta was cut and frozen in liquid nitrogen immediately after delivery at -80 degrees C. The frozen placental tissue was added to phosphate-buffered saline. The tissue was fully homogenized and centrifuged. Separated supernatant was stored at -80 degrees C. TNF-alpha levels in separated serum and TNF-alpha and total protein (TP) levels in separated supernatant were measured. The presence of TNF-alpha in the placenta was evaluated by immunohistochemistry in five pre-eclamptic and five normal-pregnant patients. RESULTS: Serum TNF-alpha levels were higher in pre-eclampsia than in normal pregnancies. However, TNF-alpha/TP levels in the placenta did not differ significantly between the two groups. As for TNF-alpha immunostaining of trophoblastic cells in the placenta, it was weak in three and moderate in two of the normal pregnancies, while it was absent in two, weak in one, and moderate in two in the pre-eclampsia group. CONCLUSIONS: We demonstrated no significant increase in TNF-alpha/TP levels in the placenta in pre-eclampsia despite a significant increase in serum TNF-alpha levels. There was no strong immunostaining for TNF-alpha detected by immunohistochemistry in the pre-eclampsia group. These findings suggest that TNF-alpha in the placenta is not a key cytokine to interfere with normal trophoblast invasion into the myometrium in pre-eclampsia, and that sources other than the placenta may contribute to the elevated levels of TNF-alpha found in the circulation of pre-eclamptic patients.