Specific immunosuppression by immunotoxins containing daunomycin

Daunomycin, when conjugated with a targeting antigen by an acid-sensitive spacer, remains inactive at the intravascular pH of 7 but becomes active after cleavage within the acidic lysosomal environment of the target cell. This observation made it possible to construct cytocidal compounds that caused antigen-specific suppression of murine lymphocyte function. When daunomycin was coupled to the hapten conjugate of ovalbumin by an acid-sensitive cis-aconityl group, it caused hapten-specific impairment of immunocompetence in murine B lymphocytes in vitro and in vivo. Furthermore, the response by T lymphocytes to concanavalin A in vitro was selectively eliminated by a conjugate between daunomycin plus the acid-sensitive spacer and a monoclonal antibody specific for T cells.

Transplacental micronucleus inducing ability of arecoline, a betel nut alkaloid, in mice

Arecoline, a major betel nut alkaloid, was tested for its effectiveness in inducing micronuclei in fetal mouse blood after transplacental exposure late in the gestation period. Positive results were obtained and a linear dose-response relationship was expressed when pregnant mice were treated with arecoline at dose levels of 20, 40 and 80 mg/kg and micronucleated polychromatic erythrocytes from fetal blood were subsequently analysed.

Induction of shape abnormality and unscheduled DNA synthesis by arecoline in the germ cells of mice

The ability of arecoline, an alkaloid of betel nut, to induce abnormality in the shape of sperm heads and unscheduled DNA synthesis (UDS) in the early spermatid stages of Swiss albino mice was studied. Treatment of mice with arecoline at the dose levels of 20, 40 and 80 mg/kg elicited dose-related increase in the number of abnormal sperm heads, as well as the unscheduled incorporation of [3H]thymidine into the DNA of early spermatids. Such increase in the production of abnormally shaped sperms and UDS response of the early spermatids following arecoline treatment expressed its genotoxic potential in the mouse germ cells.

Embryotoxicity of betel nuts in mice

The fetotoxic potential of betel nuts was investigated in Swiss albino mice. Total aqueous extracts of ripe betel nuts of unprocessed and processed varieties were administered to pregnant animals at dose levels of 1, 3 and 5 mg/day/mouse (27 +/- 1 g body wt) through days 6-15 of gestation. The dams were sacrificed prior to term and the fetuses were examined for morphological, visceral and skeletal anomalies. The treatments resulted in increased resorptions as well as dead fetuses. Fetal weight was adversely affected as indicated by the dose related reduction in average body weight of live fetuses. No major morphological, visceral and skeletal defects, apart from hematomas, curved tails and a few incidences of rib anomalies, were observed. There was, however, a dose-related decrease in the number of fetuses possessing ossified coccygeal vertebrae while an increase in the number of fetuses with unossified 5th metacarpals. This indicated a delay in skeletal maturity, particularly in those fetuses exposed prenatally to the betel nut extract of the unprocessed variety.

Heat transient related changes in stress-protein synthesis

A slow temperature transient from 37 to 42 degrees C over 3 hr instead of the usual rapid 4- to 7-min transient increases thermal resistance twofold in MTC tumor cells and yet reduces the rates of synthesis of the 70- and 22-kDa heat-stress proteins (hsp) immediately prior to and during expression of thermal resistance--2 to 8 hr after reaching 42 degrees C [S. P. Tomasovic, P. A. Steck, and D. Heitzman, Radiat. Res. 95, 399-413 (1983)]. However, examination of hsp synthesis at earlier times reaching 42 degrees C (0.5 to 2 hr) has revealed differential expression of the individual hsp that is dependent on the rate of heating. Within 30 min of reaching 42 degrees C, cells exposed to slow transients had higher rates of synthesis of the 112- and 90- but not the 70-kDa hsp. However, cells exposed to rapid transients had a higher rate of synthesis of the 70-kDa hsp by 1 hr after reaching 42 degrees C. The rate of synthesis of the 22-kDa hsp was similar in cells heated by either method. Rates of synthesis of the 112-, 90-, and 22-kDa hsp in cells exposed to rapid transients did not equal or surpass the rates for cells exposed to slow transients until between 2 and 3 hr of heating, just before expression of thermal resistance. Rate of heating also had differential effects on total protein synthesized and transport. The total protein synthesized was observed to be 40% higher in slow-transient-treated cells over the first 2 hr. Transport of an amino acid analog, aminoisobutyric acid, was significantly inhibited in rapid-transient cells immediately after reaching 42 degrees C and had not recovered 1 or 5 hr later. Similar to total protein synthesis transport in slow-transient-treated cells was unaffected. There was no significant difference between slow- and rapid-transient-treated cells in hsp degradation, cell-cycle distribution, or amino acid pool sizes in the first 4 to 6 hr after reaching 42 degrees C. These results suggest that although the ultimate thermal dose was about 10-fold higher under slow-transient conditions, the cells receiving this treatment made regulatory or metabolic adjustments, including altered hsp synthesis patterns, that reduced initial heat damage. Either the protection of total protein synthesis or that combined with higher initial rates of synthesis of some hsp could explain the previously reported increased initial D0, increased thermotolerance, and reductions in latter hsp synthesis rates seen following slow temperature transients.

Inhibitory action of Piper betle on the initiation of 7,12-dimethylbenz[a]anthracene-induced mammary carcinogenesis in rats

When an aqueous extract of the leaves of Piper betle, a medicinal plant, was given orally at different dose levels during the initiation phase of 7,12-dimethylbenz[a]anthracene (DMBA)-induced mammary carcinogenesis in rats, higher doses of the extract inhibited the emergence of tumors. However, when the extract was fed to the rats bearing DMBA-induced mammary tumors for 8 weeks, no appreciable degree of inhibition of tumor growth was noticed. Betel leaf extract at the dose levels used in the present study did not affect the body weight gain among rats.

Tumoral calcinosis. Report of a case in a one-year-old child

Tumoral calcinosis is a rare disease known as a progressively growing mass of calcific deposit at a periarticular area. The youngest reported case was the occurrence of the disease in a three-year-old child. This report describes tumoral calcinosis in the area of the knee in a one-year-old child and presents a brief review of the literature. As is usually the case, the blood chemistry was normal in the patient.