DNA double-stranded breaks induce histone H2AX phosphorylation on serine 139.

When mammalian cell cultures or mice are exposed to ionizing radiation in survivable or lethal amounts, novel mass components are found in the histone H2A region of two-dimensional gels. Collectively referred to as gamma, these components are formed in vivo by several procedures that introduce double-stranded breaks into DNA. gamma-Components, which appeared to be the only major novel components detected by mass or 32PO4 incorporation on acetic acid-urea-Triton X-100-acetic acid-urea-cetyltrimethylammonium bromide or SDS-acetic acid-urea-cetyltrimethylammonium bromide gels after exposure of cells to ionizing radiation, are shown to be histone H2AX species that have been phosphorylated specifically at serine 139. gamma-H2AX appears rapidly after exposure of cell cultures to ionizing radiation; half-maximal amounts are reached by 1 min and maximal amounts by 10 min. At the maximum, approximately 1% of the H2AX becomes gamma-phosphorylated per gray of ionizing radiation, a finding that indicates that 35 DNA double-stranded breaks, the number introduced by each gray into the 6 x 10(9) base pairs of a mammalian G1 genome, leads to the gamma-phosphorylation of H2AX distributed over 1% of the chromatin. Thus, about 0.03% of the chromatin appears to be involved per DNA double-stranded break. This value, which corresponds to about 2 x 10(6) base pairs of DNA per double-stranded break, indicates that large amounts of chromatin are involved with each DNA double-stranded break. Thus, gamma-H2AX formation is a rapid and sensitive cellular response to the presence of DNA double-stranded breaks, a response that may provide insight into higher order chromatin structures.

The interpretation of marker protein assays: a critical appraisal in clinical studies and a xenograft model.

Although useful in the management of malignant testicular tumours, alphafoetoprotein and human chromonic gonadotrophin are not perfect parameters of tumour bulk. In a series of 65 patients with marker-positive advanced disease, 23 showed the phenomenon of discordance of markers or dissociation from tumour response. Transplantable human malignant teratoma xenografts were established in immune-suppressed mice as models of the human disease. In the model system, it was demonstrated that tumour AFP concentration was reflected by AFP titres in the blood, but that tumour AFP (or blood AFP) did not correlate well with tumour size. One xenograft line illustrated the evolution of marker-negative tumour cells from a patient who was initially AFP-positive.

Vitamin B12 binding protein as a tumour marker for hepatocellular carcinoma.

Grossly raised levels of tumour related vitamin B12 binding protein, reflected by rises in serum vitamin B12 and unsaturated vitamin B12 binding capacity (UBBC), were found in three of 44 patients with hepatocellular carcinoma. All three were HBsAg negative and had normal serum alpha fetoprotein levels. The patients did not have underlying cirrhosis and the tumours contained characteristic intracellular inclusions. In the first patient the UBBC level fell during a partial remission induced by adriamycin therapy and in the second patient UBBC levels rose with progression of her disease. In the third patient serum B12 binding protein levels fell after tumour resection. Assay and subsequent monitoring of serum vitamin B12 and UBCC may prove valuable in the assessment and follow-up of some patients with hepatocellular carcinoma whose alpha fetoprotein levels are normal.

Serum-alpha1-fetoprotein in patients with testicular tumours.

Serum-alpha1-fetoprotein (A.F.P.) was assayed in 88 men with testicular teratomas and 34 with seminomas. 61% of teratoma patients with clinically evident disease had serum-A.F.P. greater than 25 ng/ml, whilst it is highly unlikely that any patient with a pure seminoma had a titre above this level. A.F.P. concentrations correlated with response to radiotherapy and chemotherapy and predicted relapse in some patients. Serum-A.F.P. should be measured in all patients with testicular tumours.

Prognostic value of serum alpha-fetoprotein in fulminant hepatic failure including patients treated by charcoal haemoperfusion.

Serum alpha-fetoprotein (AFP) levels have been measured sequentially by a radio-immunoassay method in 64 patients with fulminant hepatic failure. In 15 of the 64 patients (23%) AFP levels were raised but in only two did they exceed 500 ng/ml. Of the 23 survivors 11 (48%) had raised AFP levels compared with four of the 41 (9-8%) fatal cases (P less than 0-005). This rise in AFP levels was found early after the development of grade IV coma and constitutes an encouraging prognostic sign at a time when the liver function tests and EEG are unhelpful. A radioimmunoassay must be used if these small but significant rises in plasma concentration are to be detected. Twelve patients survived without showing a rise in plasma AFP at anytime during the illness. The four fatal cases who had raised AFP levels all had serious complications of fulminant hepatic failure. Charcoal haemoperfusion did not seem to increase the survival of AFP negative patients.

Choriocarcinoma after hydatidiform mole. Studies related to effectiveness of follow-up practice after hydatidiform mole.

Chemotherapy, in conjunction with other methods of treatment, was used in 100 patients with invasive hydatidiform mole or choriocarcinoma following mole. When treatment was instituted within two to six months of the antecedent mole serious drug resistance was not encountered, drug toxicity was slight, the duration of treatment was comparatively short, and sustained remissions were obtained in 57 out of 60 patients. When the start of chemotherapy was delayed beyond six months drug resistance occurred in many instances, toxicity was often severe, the duration of treatment was much longer, and sustained remissions were obtained in 22 out of 40 patients.The practice of giving prophylactic chemotherapy to all patients with mole is not established as effective or safe. Differences in the social background to hydatidiform mole in different geographical areas may be such that conclusions based on evidence from one area are not necessarily applicable to another.Careful follow-up after mole remains essential, though present methods often fail to ensure recognition of choriocarcinoma while it is still curable. Standard qualitative and quantitative methods for detecting the continued excretion of chorionic gonadotrophin, though useful, are sometimes too insensitive. It is suggested that to supplement local arrangements some form of centralized or regionalized follow-up service based on notification of patients with hydatidiform mole, and making use of radioimmunoassays for chorionic gonadotrophin, could reduce deaths attributable to late diagnosis.