Acute and temporary inhibition of thymidine kinase in mouse bone marrow cells after low-dose exposure

Low-dose whole-body exposure of mice to less than 0.01 Gy gamma-rays causes inhibition of incorporation of thymidine or 5-iodo-2-deoxyuridine into DNA of bone-marrow cells in vitro; the effect is maximal in cells at 4 hours after exposure and then subsides within about 10 hours. This is due to the inhibition of cellular thymidine kinase, which gradually develops to a maximum at 4 hours after exposure and again subsides within the next 10 hours. This inhibition involves only 35 per cent of the entire cellular enzyme activity and, analogous to the depression of thymidine incorporation into the cells, is only seen when the cells are collected into medium that is buffered to 7.2-7.4 and contains about 1350 mg NaHCO3 per litre. Addition of NaHCO3 to the cell homogenate or to the high speed supernatant containing the enzyme, but not to intact cells, failed to produce enzyme inhibition. There is also no depression of 5-iodo-2-deoxyuridine uptake into the intact cells in vitro when the mice are irradiated either shortly before or after i.v. injection of 0.02 mg of procain chloride. The reversibility of the effect in vivo and in vitro suggests a particular enzyme control mechanism that may be non-specifically triggered by intracellular charges, such as peroxides, and may enhance repair.

[Fluorometholon/tetryzoline in the treatment of conjunctival irritation]

The clinical efficacy of Efemoline eyedrops [fluourometholone (0.1%) + tetryzoline (0.25%)] and of fluorometholone 0.1% was investigated in a double-blind controlled clinical trial in 35 patients (63 eyes) in treatment of the upper bulbus area and postoperatively after surgery for cataract, glaucoma and strabismus. Both drugs were effective inflammation inhibitors. The superiority of fluorometholone + tetryzoline over fluorometholone was evident: subjective symptoms improved much more quickly. No tendency toward elevation of intraocular pressure was found. The combined preparation was compatible and produced no side-effects.

Orientation of fibrin in strong magnetic fields

Magnetic field orientation can be considered as a new valuable technique for the study of fibrin. Birefringence measurements during polymerization in the magnetic field enables a new approach to study the mode of association of fibrin monomers. Stable fully oriented clots can be obtained for investigation of the three-dimensional and the secondary structures of the fibrin fiber. Such experiments could be useful to assess the structure of other biopolymers diamagnetically anisotropic.

Diagnosis of ruptured ectopic pregnancy with peritoneal lavage

A case of ruptured ectopic pregnancy with a nondiagnostic culdocentesis is presented. Diagnosis was made by using open diagnostic peritoneal lavage. The patient underwent laparotomy, left salpingectomy, and cornual resection, and had no postoperative complications. In selected patients with suspected ectopic pregnancy, peritoneal lavage may serve as a helpful diagnostic procedure.

Determination of half-dose depth in skin for soft x-rays

Unlike superficial x-rays, the soft x-rays normally used in dermatologic practice spare unaffected underlying organs during treatment of cutaneous malignancies. However, since the dose with depth from soft x-rays varies markedly, it is important to know this relationship for optimal therapeutic results. The peak kilovoltage, and thus the energy of the beam, is generally selected so that the dose to the base of the lesion is one-half the surface dose. An absorbed dose of 3,400 rads to the surface and a dose of about one-half this amount to the base of most malignant lesions is one standard protocol for optimal therapeutic results. An accurate value of half-depth dose in skin is therefore necessary and is readily obtained from ordinary half-value layer measurements using the technic described.

Genital infections with herpes simplex virus in a university student population

The frequency of clinically evident genital infections with herpes simplex virus among students attending a large urban public university was studied. One-hundred ninety-eight students experienced 222 episodes of this disease over a one-year period. The mean age of the students, both undergraduate and graduate, with the diagnosis of genital herpes ranged from 23.6 years for those with a single initial episode to 24.9 years for those with recurrent episodes. The male-to-female ratio and socioeconomic class of students with genital herpes were not significantly different from those of the general university population. The incidences of both initial and recurrent episodes of genital herpes were statistically significantly higher during the months of July through October (with the exception of September). Genital herpes was a frequently diagnosed sexually transmitted disease among this student population.

Laser Raman Spectroscopy of Fibrinogen and Fibrin

Raman spectroscopy is now a useful mean of estimating the secondary structure of proteins. The study of the Amide I and Amide III bands revealed an important increase in the β-sheet form of fibrin, compared with that of fibrinogen. This effect is accompanied by significant variations in the bands characteristic of aromatic chromophores. These observations favour the hypothesis (Hudry-Clergeon et al. 1975, Thromb. Res. 6, 533) that important structural events occur during the fibrinogenfibrin transition.

Laser Raman Spectroscopy of Fibrinogen and Fibrin

Raman spectroscopy is now a useful mean of estimating the secondary structure of proteins. The study of the Amide I and Amide III bands revealed an important increase in the β-sheet form of fibrin, compared with that of fibrinogen. This effect is accompanied by significant variations in the bands characteristic of aromatic chromophores. These observations favour the hypothesis (Hudry-Clergeon et al.1975, Thromb. Res. 6, 533) that important structural events occur during the fibrinogenfibrin transition.