DNA methylation and genetic inactivation at thymidine kinase locus: two different mechanisms for silencing autosomal genes.

Patterns of methylation of CpG dinucleotides in the promoter region of the thymidine kinase (TK) gene in wild-type and TK-deficient Chinese hamster cell lines were studied. Whereas wild-type cells were unmethylated, three conventionally derived TK-deficient cell lines were all almost completely methylated in the promoter region. Demethylation at a number of different CpG sites was observed upon selection for reexpression of the TK gene. Of thirteen HhaI (GCGC) or HpaII (CCGG) sites studied, the highest correlation between absence of methylation and at least partial TK activity was obtained at one HhaI site within 20 bp of the putative cap site. Silencing in the three conventionally derived mutants is therefore accompanied by hypermethylation of the promoter-associated CpG-rich island. We contrast this situation with another type of silencing event, in which TK was coordinately inactivated at a high frequency with at least one other linked allele. Methylation of the promoter region of TK was not associated with this event, but two lines of evidence suggested a role for methylation at sites other than in the promoter region of TK.

Molecular characterization of 15 rearrangements among 90 human in vivo somatic mutants shows that deletions predominate.

Ninety hypoxanthine phosphoribosyltransferase-deficient mutants were isolated from lymphocytes of 31 individuals drawn from both control populations and populations exposed to low doses of ionizing radiation. Southern analysis of the DNA revealed altered hybridization patterns in 15 mutants. Of these, 14 changes consisted of deletions of 2 to 40 kilobases or more.

New approach in the treatment of prostate cancer: complete instead of partial withdrawal of androgens.

To completely eliminate androgens of both testicular and adrenal origin, 37 previously untreated patients with advanced (stages C or D) prostatic cancer received the combination therapy using an LHRH agonist (HOE-766) and a pure antiandrogen (RU-23908). The response criteria developed by the National Prostatic Cancer Project were used. A positive response (assessed by bone scan and/or serum prostatic acid phosphatase measured by radioimmunoassay was observed in 29 of the 30 cases who could be evaluated by these objective criteria (97%). The objective response was parallel to a rapid and marked improvement of the clinical signs and symptoms related to prostate cancer (prostatism, bone pain, and general well being). In marked contrast, the same combination therapy applied to patients previously treated with high doses of diethylstilbestrol (13 patients) showed a positive objective response in only 55% of cases. In 23 previously castrated patients showing relapse, an objective response was seen in only 25% of cases after neutralization of adrenal androgens by the antiandrogen. Previous treatment with chlorotrianisene (TACE) had no detectable effect on prostatic cancer and patients having previously received such treatment had a rate of positive response similar to previously untreated patients (five of five). In the previously untreated patients receiving the combination therapy, a 60% fall in serum prostatic acid phosphatase was observed as early as five days after starting treatment, at a time when the serum androgen concentration was 100% to 200% above control. Combined treatment with the pure antiandrogen completely prevents flare-up of the disease, a complication previously found in a significant proportion of patients treated with an LHRH agonist alone. The present data show that complete withdrawal of androgens by combined hormonal therapy with the LHRH agonist (or castration) and a pure antiandrogen leads to a positive objective response in more than 95% of cases as opposed to 60%-70% as reported by many groups using the previous partial hormonal therapy (castration or high doses of estrogens). Adrenal androgens are most likely responsible for this difference. The present study also shows that the proportion of androgen-sensitive cells decreases from more than 95% in untreated patients to 25% to 55% after previous partial hormonal therapy. Such data clearly indicate that the previous partial hormonal therapy exclusively aimed at neutralizing testicular androgens left 25% to 55% of cancer cells having a relatively low sensitivity to androgens in a hormonal milieu compatible with their continuous growth. No clinical or biochemical side effect could be detected except those related to reduced serum androgen levels.(ABSTRACT TRUNCATED AT 400 WORDS)

Comparative hypnotic activity of single doses of loprazolam, flurazepam, and placebo.

Loprazolam is a benzodiazepine derivative which possesses, in animals, a potent hypnotic effect. In a double-blind single-dose study, three dose levels of loprazolam (0.5, 1.0, and 2.0 mg) were compared to each other as well as to 15 mg flurazepam and placebo in 60 insomniac outpatients. The 0.5- and 1.0-mg doses demonstrated hypnotic potency comparable to that of flurazepam, and all three treatments were superior to placebo. The hypnotic effect of the 2-mg dose of loprazolam was significantly greater than that of the other treatments, but at this dose, patients experienced significantly more side effects and morning hangover.

A placebo-controlled trial of floctafenine (idarac) against enteric-coated acetylsalicylic acid in osteoarthritic patients.

A double-blind placebo-controlled trial was carried out in 30 out-patients with osteoarthritis of knee and hip. The therapeutic value of flactafenine 1.2 g daily, a new oral non-narcotic analgesic agent, was compared with that of enteric-coated acetylsalicylic acid (ACSA) (Rougier Inc.--enteric-coated acetylsalicylic acid, tablets of 650 mg) 2.6 g daily. Every patient successively received the three medications for six weeks according to a Latin-square design. An objective index of improvement of hips and knees was developed and applied to this study. In both objective and subjective assessments of the disease, floctafenine was found to be approximately equivalent to or superior to ACSA and superior to placebo. Both drugs were clinically well tolerated. A consistant but slight decrease in both haemoglobin and red-blood-cell count under floctafenine and ASA was found to be statistically but not clinically significant.