Peripheral photocoagulation in the treatment of disc neovascularization

Forty-two eyes in 30 patients with disc neovascularization were treated by the method of extensive photocoagulation of the retinal periphery (ablation). Total obliteration of disc neovascularization was accomplished in 76% of eyes treated. Partial regression was noted in 21% of eyes treated. There were only 2 major complications--traction retinal detachment and one major hemorrhage--in this series. Feeder-frond treatment was necessary to obliterate recurrent disc neovascularization in 2 eyes. It is concluded that therapy is efficacious in the treatment of papillary neovascularization.

[Effect on macrophages of acute stress induced in mice by local irradiation]

In examining the role of radiation in inducing immunosuppression in tumor-bearing Mice it has been shown that the experimental acute stress inadvertently generated by the procedure is profoundly immunosuppressive. It would appear that monocytes under the influence of glucocorticoïds are sequestered in the spleen. This monocyte immobilisation leads to rapid suppression of local inflammatory reactions including delayed hypersensitivity. The increased number of marcrophages in the spleen is co-incident with non-specific non T cell splenocyte anti-tumour activity. Stress induced suppression of inflammation is prevented by previous adrenalectomy and restored by hydrocortisone.

Differential activation of hepatitis B DNA polymerase by detergent and salt

Three patterns of activity were evident when the differential activation of the DNA polymerase associated with serum Dane particles by nonionic detergent and salt was investigated. The patterns were obtained by plotting the increase in enzyme activity mediated by the detergent Nonidet P-40 (NP-40) in increasing concentrations of KCl compared to the activity observed in the absence of detergent. The pattern of differential activity of hepatitis B (HB) DNA polymerase in detergent and salt was altered by subjecting the HBAg preparations to shearing forces. Hepatitis B DNA polymerase activity was stable even in NP-40 concentrations as high as 10%. In addition to hepatitis B DNA polymerase, DNA polymerase activated by calf thymus DNA was found in pellets containing Dane particles. The latter DNA polymerase activity was also activated by NP-40 and was not decreased by DNAse; this DNA polymerase coprecipitated with hepatitis B antigen (HBAg) upon addition of anti-HBs. However, the DNA polymerase activated by calf thymus DNA was inhibited by 0.4 M KCl. Electron microscopic observations of serum Dane particles in 0.4 M KCl showed no alterations of morphology of these particles when compared to particles in low-salt buffer. The data indicated that KCl activated HB DNA polymerase by a different mechanism from that of shear or NP-40, which removed the surface antigen coat from the Dane particles.

Growth stimulating activity in bovine pituitary extract specific for a rat mammary carcinoma cell line

We report the isolation of a bovine pituitary growth factor (MGF) for a rat mammary carcinoma cell line, 64-24, which was isolated from a highly hormone-dependent mammary tumor. The MGF has been partially purified by a series of Diaflo ultrafiltration membrane sievings, isoelectric focusing and Sephadex columns. The MGF has a molecular weight of approximately 1,000 to 2,000 daltons and has a U.V. absorption spectrum typical for a polypeptide. Its isoelectric point is approximately pH 3.8-4.0. The factor is heat stable. The growth stimulating activity of the MGF does not stimulate other rat cell lines (22-1, RMG or HTC lines) but is specific for the 64-24 mammary tumor cell line. The MGF is not among previously reported pituitary hormones or growth factors.

Observations on the core particle of hepatitis B virus and the DNA polymerase associated with hepatitis B antigen

Several methods are presented for the purification of core particles of hepatitis B virus (HBV) from nuclei of infected human hepatocytes. No endogenous DNA polymerase activity was found in any of the preparations of core particles even when circular double and single stranded DNAs were used as exogenous templates. The DNA polymerase activity associated with serum HB Ag was not stimulated by circular DNAs. Sodium dodecyl sulfate (SDS) at concentrations of greater than or equal to 0.1% inhibited the DNA polymerase activity of serum HB Ag. Exogenous templates such as native and activated calf thymus and Micrococcus lysodeikticus DNAs did not stimulate the DNA polymerase of serum HB Ag even in the presence of low concentrations of SDS. It is suggested that the DNA polymerase associated the HB Ag is specific for its own DNA as template.

Retinal vascular lesions in two patients with prolapsed mitral valve leaflets

Two patients with retinal vascular lesions had mid-late systolic clicks on cardiac auscultation, suggesting the diagnosis of prolapsed mitral valve. The first patient demonstrated an inferonasal arteriolar branch occlusion secondary to embolization; the second patient had a central vein occlusion with multiple hemorrhages, glial proliferative tissue, and retinal neovascularization. This report describes the association between the prolapsed mitral valve syndrome and retinal vascular lesions.

Purification of naked intranuclear particles from human liver infected by hepatitis B virus

The isolation and purification of the naked intranuclear particles of a human liver infected with hepatitis B virus is described. The particles had a diameter of 27-28 nm, were hexagonal, and showed the presence of capsomeres and spikes with lengths of 7-10 nm projecting from the surfaces. The particles formed cubic arrays with center-to-center distances of 40-42 nm. The overall particle symmetry was icosahedral. The ultraviolet absorption spectrum of the particles showed a peak at 264 nm with a shoulder at 280 nm. Endogenous DNA polymerase activity was not detected in fractions containing particles. DNA polymerase activity was present when activated DNA or d(A-T)(n) was used as exogenous template.