pH-dependent fusion between the Semliki Forest virus membrane and liposomes

Semliki Forest virus was mixed with liposomes containing phosphatidylcholine,phosphatidylethanolamine, sphingomyelin, and cholesterol. When the pH of the mixture was dropped to 6 or below, rapid fusion between the membranes of the virus and the liposomes occurred, resulting in the transfer of viral nucleocapsids into the liposomes. Fusion was demonstrated biochemically by trapping RNase or trypsin within the liposomes. Trapped RNase digested the viral RNA into acid-soluble form, providing a simple quantitative assay for fusion. Trapped trypsin digested the viral capsid protein. Fusion was also demonstrated by electron microscopy as the formation of large vesicles containing viral glycoproteins on the surface and nucleocapsids inside. The efficiency of fusion was 91 +/- 6%. In addition to low pH, it required that the viral glycoproteins be intact. In the target liposomes, cholesterol (but none of the individual phospholipids) was essential. Divalent cations were not required. Our previous studies with tissue culture cells indicated that the final step in the penetration of the Semliki Forest virus genome into host cells might involve a fusion event between the membrane of lysosomally trapped viruses and the lysosomal membrane [Helenius, A., Kartenbeck, J., Simons, K. & Fries, E. (1980) J. Cell Biol, 84, 404--420]. The data presented here are fully compatible with this hypothesis.

Silver recovery--departmental management approach

Silver from spent fixing solutions offers a challenge to recover consistently the maximum possible grams of silver per square metre, resulting in a high financial return. It also helps in keeping a clean environment, whilst assisting in the maintenance of silver stocks. The benefits of control in management of silver recovery have been demonstrated using the high current density electrolytic method. While this system is expensive, the high prices paid for silver very quickly repay the initial cost. Thereafter with the exception of a small collection charge the return is considerable.

Muscle and adipose cell development in mice selected for postweaning growth rate

Genetic selection for postweaning growth rate between 3 and 6 weeks of age resulted in significant changes in body weight, semimembranosus muscle weight, and epididymal fat pad weights. Body weights at 15 weeks of age ranged from 24.9 gm for the Low line (slow growth) mice and 59.4 gm for the High line mice (rapid growth). Total muscle DNA content was decreased in Low line mice and increased in High line mice when compared to Control mice (random bred). RNA to DNA and protein to DNA ratios were not significantly affected by growth rate selection pressure. Selection for high or low growth rate appeared to affect the development of muscle by altering the amount of DNA synthesized, suggesting that growth hormone status was altered by this type of selection. Adipose cell number was reduced in the Low line and increased in the High line when compared to Control mice. Adipose cell size was increased in High line mice when compared to Low and Control lines. The role of adipose cell development in supporting growth selection success is suggested.

Effects of cigarette smoke on elastase secretion by murine macrophages

Mice were chronically exposed to cigarette smoke for various time periods up to 4 weeks. As a consequence of the exposure, there was an increase in the number of alveolar macrophages obtained from the lungs of these mice. Light microscopic examination of cultured cells revealed increased numbers of highly pleomorphic cells filled with pigmented residues of cigarette smoke. These cells were more mitotically active, with a five fold increase in the number of alveolar colony-forming cells compared to the controls. When macrophages derived from mice exposed to cigarette smoke were cultured at high density in the absence of serum, they secreted significantly greater amounts of elastase than did the same number of control macrophages. At concentrations as low as 0.50 micrograms/ml, cycloheximide reversibly inhibited elastase secretion from both the control and experimental cultures. The effects of cigarette smoke inhalation on elastase secretion by alveolar macrophages do not appear to be a direct effect of cigarette smoke on these cells. Exposure of normal mouse macrophages in vitro to pulses of aqueous extracts of cigarette smoke, while significantly increasing secretion of elastase by peritoneal exudative macrophages, did not augment that of resident or exudative alveolar macrophages. These results suggest that the increased elastase secretion observed with the use of cultured macrophages derived from mice exposed to cigarette smoke is the result of either indirect activation of resident macrophages or the recruitment of a highly activated exudative population into the lungs of the exposed animals.

Long-term atrial pacing for sinus node disease with output-terminal programmagle pacemakers

Long-term transvenous atrial pacing for symptomatic sinus node disease, in the absence of atrioventricular conduction disease, confers the advantages of increased cardiac performance and probable freedom from systemic thromboembolism. Conventional ventricular pacing has been preferred, however, because of the complications of atrial pacing, mainly those of electrical and mechanical instability of currently available atrial electrodes. These complications have been circumvented with a new pacemaker, programmable for output terminal. This has allowed the institution of atrial pacing in seven patients, with its attendant advantages and the ability to reprogram noninvasively to ventricular pacing should atrial pacing fail. Such reprogramming has been accomplished without difficulty in one patient who developed second-degree atrioventricular block and one with electrode microdisplacement.

The 1976 influenza epidemic in Melbourne

Some aspects of the 1976 influenza epidemic are described and compared with findings in previous years. Rapid diagnostic techniques gave encouraging results, but were less sensitive than conventional techniques. A higher rate of virus isolation was obtained from nasopharyngeal aspirates than from pooled nose and throat swabs.

The effectiveness of prophylactic brain irradiation in small cell carcinoma of the lung: a Southwest Oncology Group study

Brain involvement in small cell carcinoma of the lung is a common phenomenon occurring in from 29 to 45% of patients. Because of this, it was suggested that prophylactic brain irradiation be made a part of treatment plans for small cell carcinoma. In December 1974, the Southwest Oncology Group (SWOG) began treating patients with combination chemotherapy and irradiation of both the primary lesion and whole brain. In two years, there were 390 patients entered into the study. In patients with extensive disease only 6 of 152 prophylactically irradiated patients developed CNS signs or symptoms of CNS recurrence. In limited disease, 6 of 88 prophylactically treated patients had CNS recurrence and in only 4 was this the site of initial failure. We feel prophylactic brain irradiation in small cell carcinoma of the lung is of benefit.

Disulfiram implantation. A placebo-controlled trial with two-year follow-up

Ten alcoholics implanted with disulfiram had longer periods of abstinence after treatment than did 10 alcoholics implanted with placebo; 7 of the disulfiram-implanted patients experienced a disulfiram-ethanol reaction in uncontrolled drinking situations, while none of the placebo-implanted patients did.

Diagnosis of uveo-parotid fever by 67Ga-citrate imaging

67Ga-citrate scan from skull to mid-abdomen showed increased uptake in both parotid glands, mediastinum, lungs, uvei and/or enlarged lacrimal glands. The differential diagnosis of the positive radiogallium scan is discussed with emphasis on the value of the extrathoracic findings. Tissue diagnosis confirmed the imaging diagnosis of sarcoidosis. The case illustrates the usefulness of double radionuclide study--67Ga and 99mTc-MAA--and of the tomographic scanner in defining the spread of the active granulomatous disease.

A 'profile' of immune responsiveness in multiple sclerosis

An 'immunological profile' of various indices of B-cell function and T-cell function was developed for the 'early' case of multiple sclerosis (MS). This was compared against two groups of controls comprising age and sex-matched healthy subjects, and patients with other disabling neurological diseases (CNS controls) who were matched for age, sex, and type and duration of disability. Some indices of humoral immune responsiveness, such as the induced primary response to monomeric flagellin and the 'resting' levels of antibody to measles and rubella viruses, showed significant augmentation. Cellular immune deficits were attributed to an illness effect per se because (a) cell-mediated immunity was depressed, but only when compared with that of healthy subjects and not when compared with that of the CNS controls, and (b) transformation responses of lymphocytes to viral antigens were inversely related to disability status. The abnormalities in humoral immune responses demonstrable in this study do not provide an explanation for this disease; if there is a relevant 'immunological fault', the nature of this needs to be sought from within the neuraxis rather than from the systemic circulation.