TGF-alpha and EGF-receptor mRNAs in human oral cancers

Transforming growth factor alpha (TGF-alpha) and epidermal growth factor receptor (EGFR) have been shown to be present in most squamous cell carcinomas. Using the Syrian hamster oral cancer model, we have recently demonstrated the consistent presence of TGF-alpha and EGFR mRNAs in chemically transformed hamster oral keratinocytes. We now present evidence that in human oral cancer (in vivo and in vitro), TGF-alpha and EGFR mRNAs can also be consistently detected. No TGF-alpha mRNA can be detected in normal human oral epithelium by Northern blot analysis. These findings reinforce the use of the hamster cheek pouch as an experimental model for the study of oral cancer development, at least in reference to the possible participation of TGF-alpha in the malignant transformation process.

Use of resealed erythrocytes as delivery system for C-reactive protein (CRP) to generate macrophage-mediated tumoricidal activity

We have shown previously in several mouse tumor systems that multilamellar vesicles (MLV) are an effective delivery system for generation of macrophage-mediated tumoricidal activity by C-reactive protein (CRP). Here we show that resealed erythrocyte ghosts (red cell ghosts, RCG) can function in the same manner. CRP associated with red cell ghosts (CRP-RCG) inhibited established lung metastases of T241 fibrosarcoma in C57B1/6J mice. The degree of inhibition was comparable to that observed with CRP-MLV. In other experiments, peritoneal exudate cells, obtained from mice pretreated with CRP-RCG i.p., inhibited growth and pulmonary metastases of T241 tumor in the Winn neutralization assay. Similar results were obtained with MCA-38 colon carcinoma in the Winn assay. These studies indicate that erythrocytes deserve consideration as another delivery system for biological response modifiers.

Effect of thyroxine on immune response in C57Bl/6J mice

The effect of T4 treatment (40 micrograms, 5 times/week) on immune function in C57Bl/6J mice was studied. The primary antibody synthesis as measured by the plaque-forming cell (PFC) assay demonstrated significant suppression in mice treated with T4 for 30 days. Mitogen assays using PHA and Con A demonstrated significant suppression of cellular immune responses as measured by [3H]thymidine incorporation. The effect was reversed when the treatment was discontinued and a normal response reappeared after 14 days. Allogeneic skin grafts (donor A/J mice) showed prolonged survival (median survival time, 13.5 days) in T4-treated mice as compared to control untreated mice (median survival time, 11 days). Further experiments using Chromium 51 assay for delayed type hypersensitivity also showed suppressed response. These results suggest that treatment with T4, in the above doses and duration, cause immunosuppression in C57Bl/6J mice.

Turbidimetric assay of penicillin in feeds: addition of magnesium sulfate to eliminate chlortetracycline interference

The official AOAC method for extracting penicillin from feeds allows some chlortetracycline to be co-extracted if the latter is also present in the sample. This can cause a high bias in results obtained by using the turbidimetric assay in which the test organism is sensitive to both antibiotics. In this report, we show that magnesium ions can be used to circumvent the interference of chlortetracycline in the turbidimetric assay for penicillin.

Inhibition of lung metastases in mice bearing a malignant fibrosarcoma by treatment with liposomes containing human C-reactive protein

Recent studies suggest an immune modulator role for C-reactive protein (CRP). We have tested the effect of CRP in a tumor system designed for study of metastases. Fibrosarcoma T241 was implanted on one hind foot of syngeneic C57BL/6 mice. After 17 days, the tumor-bearing feet were amputated, and i.v. therapy of liposomes containing CRP or control reagents was started. Examination of the lungs on Day 35 showed that CRP:liposome-treated animals had significantly fewer and smaller metastases as compared with those in the control groups. Moreover, 38% of the animals in the former groups were completely free of metastases as compared with 0 to 2% of the controls. Significantly, enhanced survival was also noted in the CRP liposome-treated group. CRP may have biological response modifier" function of value in cancer therapy.

Inhibition of chlortetracycline activity by magnesium ions

Up to 50% of the antimicrobial activity of chlortetracycline (CTC) can be inhibited by the presence of MgSO4 in microbiological turbidimetric assays. From 50 to 200 mM MgSO4 inhibited CTC activity, and the relationship between CTC inhibition and MgSO4 concentration is linear. The possible mechanism of this inhibition and its potential implication are discussed.

Location of ribosome-binding sites in the nin5 region of bacteriophage lambda

Seven ribosome-binding sites on DNA have been located within the region defined by the nin5 deletion as well as several ribosome-binding sites on each side of the nin5 region. These were mapped by electron microscopy relative to the end points of the nin5 deletion and two Tn903 transposons, one inserted into gene Rz and another inserted near gene Q. These ribosomes binding sites within the nin5 region may correspond to polypeptide initiation sites for up to seven new dispensible lambda genes.

Serum alpha-tocopherol, lipids, potassium, and creatine phosphokinase in normal and malabsorption patients

Serum alpha-tocopherol, lipids, potassium, and creatine phosphokinase levels were measured in 20 adult male control patients and eight malabsorption patients. The malabsorption group had significantly lower serum alpha-tocopherol levels than the control group. This change was independent of serum total lipid levels that were not significantly different among the two groups. Serum potassium and creatine phosphokinase levels that are normally used to assess muscle pathology in man did not correlate with serum alpha-tocopherol levels in either the control of the malabsorption groups. Body mass indices that are directly related to adiposity of the individuals were calculated. Among the control patients, there was a significant increase in serum alpha-tocopherol and serum total lipids with increase in body mass index. Similar correlations did not exist in the malabsorption group. In the latter group serum alpha-tocopherol levels may have reached low enough levels to be independent of factors such as adiposity and serum total lipids.

Enhancing effect of thyroxine on tumor growth and metastases in syngeneic mouse tumor systems

We studied the effect of thyroxine treatment on tumor growth and metastases resulting from tumor implants on the hind feet of mice in two syngeneic systems. In control, untreated A/Jax mice, tumor Sarcoma 1 at Day 14 after implantation had average tumor weight of 582 +/- 60 (S.D.) mg and showed an incidence of 57% metastases to regional popliteal nodes and 5% metastases to thymus. In contrast, the thyroxine-treated group (40 microgram/mouse s.c., 5 times/week for 1 month) had an average tumor weight of 808 +/- 56 mg (p less than 0.001), and metastases to popliteal nodes and thymus were 90 and 35%, respectively. In another syngeneic tumor system, Lewis fibrosarcoma was implanted in C57BL/6J mice, and the tumor weight and metastatic index (derived from the number and size of the pulmonary tumor foci) were determined at Day 28. Again, the synthetic L-thyroxine treated group showed a significant enhancement tumor growth and metastatic index. The mean tumor weight in the treated group was 385 +/- 26 mg (control, 694 +/- 25 mg; p less than 0.005) and metastatic index was 84 +/- 29 (control, 30 +/- 25; p less than 0.001). Induced hypothyroidism (treatment with 131I, 100 microCi/mouse i.p.) showed the reverse effect on both tumor systems. These results suggest that both tumor systems are dependent on thyroid hormones for their growth and spread.

Effects of the immunosuppressive drug niridazole in isogeneic and allogeneic mouse tumor systems in vivo

In both isogeneic (Sarcoma 1 in A/JAX mice) and allogeneic (Sarcoma 180 in C57BL/6 mice) mouse tumor systems, treatment of the tumor-bearing mice with niridazole, an antiprarasitic drug, known to be a potent suppressor of cell mediated but not humoral immunity caused enhancement of metastases to regional popliteal nodes. Niridazole also inhibited tumor growth in vivo, as manifested by a significant decrease in the weight of the primary tumors. The enhancement of metastases is attributed to the suppression of cell-mediated immunity by the drug, but the mechanism of tumor-growth inhibition is not yet clear.

On the lack of host-cell reactivation of UV-irradiated phage T5. I. Interference of T5 infection with the host-cell reactivation of phage T1

UV-irradiated phage T5, in contrast to T1, T3 and T7, fail to display host-cell reactivation (HCR) when infecting excision-repair proficient Escherichia coli cells. Possible causes of this lack of HCR (which T5 shares with the T-even phages) have been investigated by studying HCR of T1 under conditions of superinfection by T5. Repair-proficient B/r cells were infected at low multiplicity with UV-irradiated phage T1 in the presence of 1.8 mg/ml caffeine and were superinfected after 15 min with heavily UV-irradiated T5 amber mutants at highly multiplicity. The caffeine, which is later diluted out, prevents any T1 repair prior to T5 superinfection, and UV (254 nm) irradiation of T5 with 144 J/m2 reduces the ability of this phage to exclude T1, thus permitting a reasonable fraction of the mixedly infected complexes to produce T1 progeny. Under these conditions, T5 superinfection causes loss of HCR in about 90% of the T1-producing complexes. Superinfection with unirradiated T5 likewise inhibits HCR of T1, but superinfection with irradiated T3 (a host-cell reactivable phage) does not. This indicates that the observed HCR inhibition of T1 results from T5 infection rather than from competition of irradiated foreign DNA for the excision-repair enzymes of the bacterial host. Employment of appropriate T5 amber mutants has shown that "first-step transfer" (FST) of T5 DNA (involving only 8% of the T5 genome) is sufficient for HCR inhibition, but that transfer of the remainder DNA in addition inhibits a previously described minor T1 recovery process. HCR inhibition of T1, and thus presumably lack of HCR in T5 itself, is ascribed to a substance which is produced either post infection by a gene located in the FST segment of the T5 genome, or which is transferred from extracellular T5 together with the FST DNA.