Search PubMed⌕ Search

Biomedical subjects

C Wallis

Publications and source records attributed to C Wallis.

151 records · Page 9Linked to original sources
PubMed1965

Thermostabilization and thermosensitization of herpesvirus.

Wallis, Craig (Baylor University College of Medicine, Houston, Tex.), and Joseph L. Melnick. Thermostabilization and thermosensitization of herpesvirus. J. Bacteriol. 90:1632-1637. 1965.-Herpesvirus, long considered as one of the most thermolabile of viruses, was stabilized by 1 m Na(2)SO(4) or Na(2)HPO(4) so that it withstood heating at 50 C, but the virus was not protected by 1 m MgCl(2), MgSO(4), or KH(2)PO(4), or 2 m KCl or NaCl; 1 m Na(2)SO(4) also stabilized herpesvirus at 25 and 37 C. In contrast, herpesvirus was made extremely thermosensitive in the presence of isotonic salt concentrations or of isotonic tris(hydroxymethyl)aminomethane buffer, especially at pH 7.2 or above. Partially purified virus was relatively thermostable when suspended in distilled water at pH 7.2, but in Earle's salt solution the virus immediately became thermosensitive. As found in tissue culture harvests, herpesvirus was thermolabile, but the virus was rendered stable at 50 C by simple dilution in distilled water. Protection by proteins or amino acids, generally accepted as virus-stabilizing agents, did not seem to be the result of a direct effect upon herpesvirus. The present data suggest that the added proteins counteract in part thermosensitizing effects of the salts contained in the virus harvest.

Culture Media↗
PubMed1965

A rapid plaque method using vertical tube cultures for titration of viruses and neutralizing antibodies.

Standard methods for titrating and typing enteroviruses and other viruses, or for assaying antibodies against them, are based on observation of metabolic inhibition of infected cells or on direct microscopic reading of cytopathogenic effects. Incubation of cell cultures for at least a week, with two or three readings during this period, is usually required before assessment is completed. This report describes a vertical-tube method in which cell monolayers are confined to the bottom end of a serological tube; an agar overlay is used after virus or virus-serum inoculation. The reduced monolayer area allows seeding with only about 30% of the cells required for standard tube cultures, and 5% of those required for plaque assay in bottle cultures. The new method requires only a single macroscopic reading one to three days after the test is set up. This method has proved economical, simple and rapid in epidemiological studies on rapidly growing viruses of the entero-, reo-, herpes-, myxo- and poxvirus groups, and for tests of the genetic markers of live poliovirus vaccine.

Culture Techniques↗
PubMedDate not supplied

Prevalence of canine cataract: preliminary results of a cross-sectional study.

OBJECTIVE: In this study 2000 dogs were examined ophthalmoscopically to determine presence of cataract. MATERIALS AND METHODS: The dogs examined were predominantly from veterinary hospital populations but also from the Waltham Center For Pet Nutrition, rehoming charities and breeding kennels. Prevalence of cataract was thus determined for different age groups (year cohorts). The age at which prevalence of cataract was 50% (C50) was determined indirectly from a fitted prevalence curve. RESULTS: The mean +/- standard deviation of C50 for all dogs in the study was 9.4 +/- 3.3 years. All dogs over 13.5 years were affected by some degree of lens opacity. C50 was determined for animals of different genders and different breeds. For dogs of six breeds sufficient data were available for calculation of breed-specific C50. In these dogs C50 was positively correlated with longevity with a least squares correlation coefficient of 0.74. CONCLUSION: The study yields novel findings regarding the prevalence and incidence of cataract in the dog and forms the basis for considerable further work on the epidemiology and pathophysiology of age-related cataract in the dog.

Age Factors↗
PubMedDate not supplied

Problems related to the use of serum and trypsin in the growth of monkey kidney cells.

A function of serum in the growth medium for primary monkey kidney cells has been shown to be inhibition of proteolytic enzymes. Serum inactivates the residual trypsin remaining from enzymatic digestion of the kidneys and the proteolytic enzymes subsequently synthesized by the cells. Freshly trypsinized cells could be grown to monolayers in the absence of serum provided that they were repeatedly washed to remove residual trypsin. In the absence of serum, cell growth ceased on the 4-5th day after initiation of the culture, at which time the culture fluids became active proteolytically. When the 5th day fluids were replaced with fresh serum-free medium, cell growth was accelerated and a monolayer was attained by the 7th day. If cells were grown in the absence of whole serum but in the presence of medium containing alpha globulins or fetuin which inhibit both trypsin and cell proteases, such cultures grew as well as cultures containing serum. The sterilization of trypsin for use in digestion of tissues and cell cultures poses a serious problem. After filtration through 0.22 micron filters, trypsin preparations may still contain adventitious viruses, mycoplasma and minute forms of pseudomonas and other bacteria or bacteria-produced toxins, which pass the membrane pores. A process of purifying and sterilizing trypsin without deleteriously affecting its proteolytic activity is described.

Animals↗
PubMedDate not supplied

Setting up an HIV-testing service with same-day results.

The advent of human immunodeficiency virus (HIV) has meant that the speciality of genito-urinary medicine has had to respond promptly and decisively in order to limit the extent of infection. This paper describes how a unit has made its service more adaptable to clients' needs to encourage people to come forward for HIV tests. The results of the study reported demonstrate the demand for this service.

AIDS Serodiagnosis↗
PubMedDate not supplied

Cystic fibrosis: paediatric aspects.

With a comprehensive team approach and attention to early intervention, most infants with cystic fibrosis (CF) born in the 1990s will reach and contribute successfully to adult life. Our perception of CF has evolved from a lethal disease in childhood to a chronic disorder with increased mortality in adulthood. This article examines some of the issues involved in ensuring that children with CF achieve these goals, with special emphasis on the maintenance of health and the prevention of disease progression.

Adolescent↗