Foreign DNA sequences contained in lambda bacteriophage genomes integrated in mammalian DNA can be efficiently rescued into infectious phage particles by treatment of the mammalian DNA with lambda-packaging extracts prepared in E. coli. This system provides for rapid, non-selective recovery of stably integrated, chromosomal sequences into lambda phage for subsequent analysis in bacterial systems. Since rescue is prior to selection, mutations can be recovered from intact animals made transgenic for the phage-target gene sequences. Such approaches allow study of physiologically relevant aspects of mammalian mutagenesis at the molecular level.

Animals↗

PubMedDate not supplied

Expression of a mammalian Na-H exchanger in muscle fibres of the giant barnacle.

It is now well established that the internal pH (pHi) of mammalian cells is regulated by means of a plasma membrane transport system that exchanges extracellular Na+ for intracellular H+ (ref. 1). Furthermore, modulation of the activity of the Na-H exchanger seems to have a crucial role in the action of various mitogens and growth factors. The possibility that such a mammalian Na-H exchanger might be efficiently expressed in a giant invertebrate cell was suggested to us by recent results of Barnard and Miledi and colleagues, who demonstrated in frog oocytes the expression of various plasma membrane channels that presumably were encoded by the mammalian messenger RNA wih which the oocytes had been injected. We used muscle fibres of the giant barnacle, which normally have no demonstrable Na-H exchanger activity, and report here that, when injected with poly(A)+ RNA isolated from rabbit liver, the muscle fibres express a Na-H exchanger. No such expression is observed, however, when the injected material is pretreated with ribonuclease A. As hepatocytes are known to possess a Na-H exchanger, the most straightforward interpretation of our data is that a mammalian Na-H exchanger has been expressed in the muscle fibre of an invertebrate.

Animals↗

PubMedDate not supplied

Hans Zinsser: a tale of two cultures.

Hans Zinsser, president of the Society of American Bacteriologists in 1926, was known as much for his literary and textbook writing as for his scientific contributions. He was a widely known scientist and person of letters. His early interests in poetry and other forms of literature were maintained and developed during his career as a microbiologist, and his most enduring legacy is based on his writing about microbiology for a general readership as well as his reflective and philosophical autobiography.

History, 20th Century↗

PubMedDate not supplied

The Chinese Nail Murders: forensic medicine in Imperial China.

Robert van Gulik was a respected Dutch sinologist and author who first translated a collection of traditional Chinese detective stories into English and then created additional fictional stories based on the same characters and setting in the Tang dynasty. One of these stories, The Chinese Nail Murders, draws on van Gulik's professional interest in law and his knowledge of early Chinese works on forensic medicine. This novel develops a common theme in Chinese detective fiction, murder by a nail wound to the head. The difficulty in detection of this mode of violence posed a particular problem for the examining magistrate because postmortem examination was mostly limited to external observations. This essay compares the development of Chinese and Western forensic medicine in the context of the nail murder motif.

China↗

PubMedDate not supplied

Molecular epidemiology of DNA viruses: applications of restriction endonuclease cleavage site analysis.

Restriction endonucleases which cleave DNA at specific nucleotide sequences can be used to produce a set of DNA fragments of a viral genome which, when separated by gel electrophoresis, gives a characteristic "fingerprint" for that virus genome. This simple technique has been used to identify and classify DNA viruses of the herpes, adeno, and papova virus groups. Small variants within a given type (e.g., herpes simplex type I) are genetically stable and permit study and identification of individual strains of viruses. Such analyses have recently been applied to study the epidemiology of some DNA virus outbreaks. Restriction endonuclease fingerprinting provides a useful addition to methods for virus identification and classification.

Cytomegalovirus↗

PubMedDate not supplied

A bacterial mutagenicity study of rivanol, an acridine derivative used as an abortifacient.

We have used the forward mutation to resistance to 6 azauracil to test the mutagenicity of rivanol (6,9 diamino 2-ethoxy acridine) on Escherichia coli. Rivanol has been used to induce therapeutic abortions in midpregnancy and is considered safe and effective for this purpose. The findings reported here that rivanol, like other acridines, is a mutagen, at least in procaryotes, suggests that such use of rivanol be reconsidered in light of its possible genetic toxicity.

Abortifacient Agents↗

PubMedDate not supplied

Congruences in Chinese and Western medicine from 1830-1911: smallpox, plague and cholera.

A close examination of three examples, smallpox, plague and cholera, suggest that for acute infectious diseases the Chinese viewed the symptomatologies, the causes, and the rational treatments of these illnesses in many ways similar to that of their contemporary Western counterparts. Rather than holding an opposing, clashing or incongruent system of medical thoughts for these common, well-recognized infectious diseases, the Chinese were prepared, by a long tradition of ontological thinking, to be receptive to the adoption, incorporation or modification of Western medical ideas in the late nineteenth century.

Americas↗

PubMedDate not supplied

3'-Amino thymidine affinity matrix for the purification of herpes simplex virus thymidine kinase.

A simple procedure for preparation of an affinity resin with 3'-amino thymidine linked to the carboxyl residues on 6-amino-hexanoic agarose is described. We have used this column for a rapid and simple purification of the thymidine kinase encoded by the herpes simplex virus type 1 genome. This resin has two major advantages over the most widely use used resin made with thymidine-p-nitrophenyl phosphate: first it is easily obtainable, and second, it is not subject to destruction by phosphodiesterases. The two resins are very similar in behavior and the resin made with amino thymidine has allowed us to prepare large quantities of highly purified HSV TK for crystallization studies.

Chromatography, Affinity↗