Cell cycle-dependent modulation of telomerase activity in tumor cells

Telomerase is a ribonucleoprotein complex that is thought to add telomeric repeats onto the ends of chromosomes during the replicative phase of the cell cycle. We tested this hypothesis by arresting human tumor cell lines at different stages of the cell cycle. Induction of quiescence by serum deprivation did not affect telomerase activity. Cells arrested at the G1/S phase of the cell cycle showed similar levels of telomerase to asynchronous cultures; progression through the S phase was associated with increased telomerase activity. The highest level of telomerase activity was detected in S-phase cells. In contrast, cells arrested at G2/M phase of the cell cycle were almost devoid of telomerase activity. Diverse cell cycle blockers, including transforming growth factor beta1 and cytotoxic agents, also caused inhibition of telomerase activity. These results establish a direct link between telomerase activity and progression through the cell cycle.

Bcl-2 expression regulates sodium butyrate-induced apoptosis in human MCF-7 breast cancer cells

Sodium butyrate (butyrate) is a potent growth inhibitor and differentiating agent for many cell types, including breast cancer cells. Programmed cell death, or apoptosis, is a physiological mechanism of cell death that is dependent on both preexisting proteins and de novo protein synthesis. In the studies presented here, we investigated the role of apoptosis in the growth regulation of human MCF-7 breast cancer cells by sodium butyrate. We report that butyrate treatment of breast cancer MCF-7 cells causes a nonreversible growth inhibition by inducing apoptosis in a time- and dose-dependent manner. Treatment of MCF-7 cells for as little as 12 h with butyrate caused a 5.6-fold induction in apoptotic cell death, which continued to increase up to 27-fold by 48 h treatment. The butyrate-induced apoptosis in MCF-7 cells was closely linked with the down-regulation of expression of Bcl-2 mRNA and Bcl-2 protein, a gene product known to be involved in the regulation of apoptosis in mammalian cells. The observed relationship between the down-regulation of Bcl-2 and induction of apoptosis was not causal because stable overexpression of Bcl-2 resulted in protection of MCF-7 cells from the cytotoxic morphological changes and growth-inhibitory effects of butyrate (15% growth inhibition compared to 60% growth inhibition in the parental cells). In addition, Bcl-2-overexpressing MCF-7 cells exhibited a significant suppression in butyrate-induced stimulation of apoptosis (5-fold increase in apoptosis compared to 27-fold in parental MCF-7 cells). These findings demonstrate that the levels of Bcl-2 expression regulate the butyrate-induced apoptosis in breast cancer cells and that butyrate may potentially be useful in sensitizing the breast cancer cells to chemotherapy-induced apoptosis.

Purification and characterization of a pregnancy-associated protein: TJ6s

PROBLEM

Characterization of the soluble form of a novel protein, TJ6 (TJ6s) with immune suppressive activity from murine fetoplacental units.

METHOD

Preferential ammonium sulfate precipitation, gel filtration and ion-exchange chromatography were employed to purify the protein TJ6s from murine fetoplacental units using an anti-peptide antibody as a detection tool. Biological activity of the purified protein was studied in lymphocyte proliferation assays.

RESULTS

Purified TJ6s has a M(r) of approximately 18 kDa as evidenced by SDS-PAGE in both reducing and non reducing conditions. It exerted a strong anti-proliferative activity in both anti-CD3 and Con A proliferation lymphocyte proliferation assays but not in a PHA assay, suggesting that the anti-proliferative effects on T cells are exerted only on cells specifically activated directly through T cell receptor complex.

CONCLUSION

The results indicate that TJ6s is a novel anti-proliferative protein that has many of the characteristics that are considered necessary for survival of the fetal allograft.

Noninvasive acceleration measurements to characterize knee arthritis and chondromalacia

Devising techniques and instrumentation for early detection of knee arthritis and chondromalacia presents a challenge in the domain of biomedical engineering. The purpose of the present investigation was to characterize normal knees and knees affected by osteoarthritis, rheumatoid arthritis, and chondromalacia using a set of noninvasive acceleration measurements. Ultraminiature accelerometers were placed on the skin over the patella in four groups of subjects, and acceleration measurements were obtained during leg rotation. Acceleration measurements were significantly different in the four groups of subjects in the time and frequency domains. Power spectral analysis revealed that the average power was significantly different for these groups over a 100-500 Hz range. Noninvasive acceleration measurements can characterize the normal, arthritis, and chondromalacia knees. However, a study on a larger group of subjects is indicated.

Neutralization of pathophysiological manifestations of Russell's viper envenoming by antivenom raised against gamma-irradiated toxoid

Rabbits were immunized against gamma-irradiated (100 krads) Russell's viper venom toxoid adsorbed to aluminium phosphate gel. The antivenom (0.1 ml) neutralized 5 LD50, 8 minimum hemorrhagic doses (MHD) and 14 minimum necrotic doses (MND) of venom. The coagulant and protease activities of the viper venom were neutralized more effectively than phospholipase A activity, by the toxoid antivenom.

Neutralization potency of Russell's viper venom toxoid antivenom, as compared with standard antivenom

Rabbits were immunized with gamma (gamma) irradiated Russell's viper venom toxoid, adsorbed to aluminium phosphate adjuvant. Antibody (raised against toxoid inoculation) titer was compared to a commercial antivenom on the basis of its ability to neutralize hemorrhagic, necrotic and lethal effects of viper venom. Toxoid immunization (on day 0, 15 and 30) produced antivenom which showed approximately one-third antilethal, half antihemorrhagic and antinecrotic titers as compared to those of the commercial hyperimmunized, concentrated horse antivenom.

Epidemiology of snake bite in the district of Burdwan, West Bengal

An epidemiological field survey on snake bite was conducted on 26 randomly selected villages with a population of 18,892 in the district of Burdwan, West Bengal to assess the magnitude of the problem in a decade (1980-1989). Total number of snake bite, number of presumably poisonous snake bite and deaths due to snake bite poisoning were 307, 48 and 31 respectively. The death rate among snake bite victims was 10.09%. Males (54.72%) were bitten more than females (45.23%) and highest incidence of snake bite was found in the age group of 21-30 years and during the months of July and August. Majority of the snake bites (53%) were encountered in the lower extremities. Among the snake bite patients 201 (65.47% went to the traditional healers (ozhas) and 68 (22.14%) persons received hospital treatment, while 12 (3.09%) people neither went to the ozhas nor to hospital and 26 (8.46%) persons went to hospital after consulting the ozhas. If the present data are extrapolated for the total population of the district, average number of snake bite and death per year would be 7,857 (0.16%) and 793 (0.016%) respectively. Deaths due to snake bite per 100,000 population varied from 5.28 to 31.75 (average 16.4) over 10 years.

Active immunization of rabbit with gamma irradiated Russell's viper venom toxoid

Russell's viper venom detoxified by gamma (gamma)-radiation (100 kR or 200 kR) was used as a toxoid for active immunization of rabbits following a short or long schedule of immunization without any adjuvant. Effective neutralization of venom toxin by immune sera of rabbits was observed with both schedules. Sera of rabbits immunized with 100 kR irradiated venom toxoid (100 kR toxoid antisera) were more potent than 200 kR toxoid antisera. The presence of antibody in the immune sera was detected by immunoelectrophoresis. The effect of gamma-radiation on some enzymes and venom protein profiles was studied. Phosphodiesterase, protease and hyaluronidase were inhibited by radiation though phospholipase A activity remained unaffected. Radiation did not produce any gross change in the protein profile of crude viper venom. Phosphodiesterase and protease activities of viper venom were neutralized more effectively by 100 kR toxoid antisera in the short schedule than in the long schedule of immunization.

Antisticking protein factors in buffalo blood serum

Buffalo blood serum is a potent source of antisticking factor (ASF) that inhibits with high affinity adhesion of goat epididymal spermatozoa to the glass surface of hemocytometer counting chamber. The serum is also capable of inhibiting glass-sticking of spermatozoa of the buffalo, ram, and bull. The serum ASF activity is nondialyzable and stable to heat treatment at 100 degrees C for two minutes. The activity of the serum ASF was lost completely when treated with trypsin (50 micrograms/ml) at 37 degrees C for thirty minutes indicating the polypeptide nature of the ASF. Serum ASF activity consists of at least two factors (A and B) as shown by concanavalin A-agarose affinity chromatography. ASF-A and -B represent nearly 75% and 25% of the total serum ASF activity. ASF-B is a glycoprotein as it binds with high affinity to concanavalin A. The sera of species such as man, goat, and rat possess ASF activity.

Stimulation of forward motility of goat cauda epididymal spermatozoa by a serum glycoprotein factor

Blood sera of humans, rats, goats, and buffalo have been shown to possess a forward motility-stimulating factor (FMSF) that markedly stimulated goat cauda epididymal sperm forward motility, as assayed by a microscopic method in the presence of epididymal plasma (1.2 mg protein/ml) that had sufficient anti-sticking activity to eliminate the possibility of cell-sticking artifacts in motility assays. The specific activity of FMSF was greatest in buffalo blood serum compared to the sera of the other species. Buffalo serum at a concentration as low as 8.5 mg protein/ml induced forward motility in nearly 45% of the cells. The buffalo serum FMSF was heat-stable, nondialyzable, and sensitive to the action of trypsin. Purified proteins--casein, serum albumin, ovalbumin, myoglobin, and beta-lactoglobulin--showed little or relatively low FMSF activity. FMSF is a glycoprotein, as it binds with high affinity to concanavalin A-agarose. A major portion of the serum protein (approx. 70%) did not bind to the affinity matrix, and this unretained serum protein fraction showed little FMSF activity. The FMSF activity of buffalo serum was confirmed by estimating sperm forward motility spectrophotometrically: an objective method of assessing sperm motility.

Endoscopic removal of impacted Sengstaken-Blakemore tube

In developing countries, the Sengstaken-Blakemore tube (SB tube) is one of the common treatment modalities for controlling hemorrhages from bleeding esophageal varices. Its use is accompanied by numerous complications. An unusual complication is impaction of a SB tube and its endoscopic removal is described.

Hypersensitivity reaction after barium meal examination

Hypersensitivity reactions can occur after the administration of barium products and all caused by one of the many additives. These reactions are extremely unusual. Authors report on a patient who developed urticaria shortly after a conventional barium examination.