Auger electron emission initiated by the creation of valence-band holes in graphene by positron annihilation.

Auger processes involving the filling of holes in the valence band are thought to make important contributions to the low-energy photoelectron and secondary electron spectrum from many solids. However, measurements of the energy spectrum and the efficiency with which electrons are emitted in this process remain elusive due to a large unrelated background resulting from primary beam-induced secondary electrons. Here, we report the direct measurement of the energy spectra of electrons emitted from single layer graphene as a result of the decay of deep holes in the valence band. These measurements were made possible by eliminating competing backgrounds by employing low-energy positrons (<1.25 eV) to create valence-band holes by annihilation. Our experimental results, supported by theoretical calculations, indicate that between 80 and 100% of the deep valence-band holes in graphene are filled via an Auger transition.

Advancements in cancer therapy with alpha-emitters: a review.

PURPOSE: This synopsis attempts to shed light on the progresses made in the field of cancer therapy using alpha-particles. HURDLES AND PROGRESSES: The rationale of selection of radionuclides focusing on comparison of alpha- and beta-emitters, the hurdles and their solutions, and recent developments are addressed. The efforts made in the field of alpha-radioimmunotherapy of hematologic malignancies are emphasized. A good deal of progress has been achieved in the past decade, and preclinical studies with a variety of radioimmunoconjugates with astatine and bismuth radioisotopes (At-211, Bi-212, and Bi-213) have generated encouraging results, providing an impetus for future clinical trials. CONCLUSION: The onset of early clinical trials with alpha-emitters will hopefully enable the cancer researchers to come up with extremely effective and highly specific "smart bombs" to target cancer cells.

Status of radioimmunotherapy in the new millennium.

This synopsis attempts to summarize progress made in radioimmunotherapy (RIT) by the end of the 20th century addressing the problems, possible solutions, and recent developments. The reduction of minimal residual disease in an adjuvant setting appears to be a feasible goal for RIT utilizing short-range alpha-emitters. RIT has been more successful in the radiosensitive hematologic malignancies, for example lymphomas and leukemias as compared with small solid tumors. Several radiopharmaceuticals seem near approval for RIT in patients with non-Hodgkin's lymphoma (NHL) as therapeutic responses, including complete responses, are common. Obstacles to successful RIT have been recognized and strategies to overcome these hurdles and to improve efficacy are continuously being developed resulting in encouraging outcome particularly with locoregional routes of administration in solid tumors. Systemic RIT for solid tumors will need manipulating the tumor-host to improve the tumor uptake and retention of radioimmunoconjugates (RICs). The utilization of radiometals, stable chelators, biodegradable linkers and bone marrow transplantation should be able to deliver the radiation dose required for successful treatment. In conjunction with additional synergistic agents, RIT is likely to have a great impact on the treatment of solid tumors. The ability to generate new constructs, such as bivalent antibodies or fusion proteins incorporating two different functional proteins opens exciting opportunities for new therapeutic modalities. These developments will hopefully offset the impediments to the successful use of RIT.

O-diphenoloxidase concentrations in leprosy.

O-diphenoloxidase activity was studied in 15 patients with lepromatous leprosy, 15 with tuberculois leprosy, and 15 controls. O-diphenoloxidase isolated from skin and serum samples of patients with lepromatous leprosy had the specificity of a bacterially derived enzyme and not that of a mammalian-derived enzyme. Only the patients who had lepromatous leprosy for over two years showed enzyme activity in serum, though all showed it in skin tissue. O-diphenoloxidase activity in serum may be a useful diagnostic marker of lepromatous leprosy.

Effect of 3,4-trans-2,2-dimethyl-3-phenyl-4-P-(beta-pyrrolidinoethoxy) phenyl -7-methoxy chroman (centchroman) on the biochemistry of the fallopian tube and uterus of rhesus monkeys (Macaca mulatta).

PIP: The biochemical effects of the nonsteroidal compound Centchroman were observed in healthy, adult, female rhesus monkeys. The compound was administered at the antifertility dose (.625 mg/kg) for 22 days in a cycle. No marked weight changes were seen in the Fallopian tube, ovary, adrenal or pituitary as a result of treatment. Uterine weight increased significantly, however (p less than .01). In the Fallopian tube, levels of glycogen and protein increased significantly (p less than .01), lactic acid decreased significantly (p less than .01), and nonprotein nitrogen was unchanged as a result of treatment. Similar changes were observed in the uterus, and in addition, total total phospholipid concentration rose significantly (p less than .01) in the uterus. The activities of beta-glucuronidase, acid and alkaline phosphatases and glucose-6-phosphate dehydrogenase (G-6-PD) in the Fallopian tube were unchanged due to treatment. Adenosine triphosphatase (ATPase) and malic dehydrogenase activities were significantly stimulated (p less than .01) and lactic dehydrogenase activity was significantly depressed (p less than .01). In the uterus, beta-glucuronidase and acid and alkaline phosphatase activity were unaltered, however, the activities of ATPase and the dehydrogenases of glucose-6-phosphate, lactate and malate were markedly increased (p less than .01). It is suggested that the antifertility effect of Centchroman may be due principally to the ability of the compound to elicit estrogen-like responses in the Fallopian tube and uterus.^ieng

Effect of 2-phenyl-3-p-(beta-pyrrolidinoethoxy) phenyl-beta-methoxy benzofuran hydrochloride (DBF) on the biochemistry of the fallopian tube and uterus of rhesus monkey (Macaca mulatta).

PIP: The effects of the nonsteroidal title compound (DBF) on the biochemical composition of the Fallopian tube and uterus were studied in the rhesus monkey. Monkeys received 2 mg/kg daily by mouth, which is the antifertility dose. The weight of the pituitary was significantly decreased (p less than .05) due to treatment, but the weights of the Fallopian tube, uterus, ovary and adrenal were unaltered. In both the Fallopian tube and uterus, DBF induced a significant increase (p less than .01) in the concentration of glycogen, protein and nonprotein nitrogen, and a significant decrease (p less than .01) in the concentration of lactic acid. The total phospholipid level in the uterus showed an increase (p less than .01) in the activities of adenasine triphosphatase (ATPase), malic dehydrogenase, acid and alkaline phosphatases, and glucose-6-phosphate dehydrogenase (G-6-PD) was seen. Lactic dehydrogenase activity fell (p less than .01) and the activity of beta-glucuronidase was unchanged. In the uterus, ATPase, malic dehydrogenase, alkaline phosphatase and lactic dehydrogenase activities increased significantly (p less than .01), beta-glucuronidase and acid phosphatase activities fell (p less than .01) and G-6-PD activity was unaltered. The antifertility effect of DBF may be due to its ability to elicit many biochemical effects similar to those induced by a typical estrogen.^ieng