Mammalian cell mutant requiring cholesterol and unsaturated fatty acid for growth

A mutant requiring both cholesterol and oleate for growth has been isolated from mutagenized Chinese hamster ovary cells. By comparison with wild-type cells, sterol and unsaturated fatty acid biosynthetic activities in the mutant cells grown in fetal calf serum medium appear to be nearly intact. However, whole-cell radioactive acetate, mevalonate, dihydrolanosterol, and stearate incorporation studies show that sterol synthesis from acetate, lanosterol demethylation, and fatty acid desaturation are defective in the mutant cells grown in delipidated serum medium. In vitro enzyme assays with crude cell extracts demonstrated that beta-hydroxy-beta-methylglutaryl-coenzyme A reductase is not induced in the mutant. These experiments were substantiated by gas/liquid chromatographic analyses which showed the sterol content and the percentage unsaturated fatty acids in mutant cells to be drastically reduced when the cells are grown in delipidated serum medium. A spontaneous revertant exhibiting prototrophic growth in lipid-free medium has been isolated from 50 X 10(6) mutant cells. All three defects in this revertant reverted back in parallel, which suggests that these three biosynthetic activities may be controlled by a common regulatory mechanism.

Co-circulation of two influenza A (H3N2) antigenic variants detected by virus surveillance in individual communities

From March through June 1977 a total of 31 influenza A (H3N2) viruses were isolated from students with respiratory disease who were seen at the student health service on the Berkeley campus of the University of California, and 32 influenza A (H3N2) viruses were isolated from persons who participated in a city-wide febrile respiratory disease surveillance program in Seattle. The antigenic specificity of the hemagglutinin was determined for each isolate by hemagglutination inhibition testing with sera from ferrets infected with prototype strains A/Victoria/3/75 and A/Texas/1/77. In each of the three months, April, May and June, A/Victoria/3/75-like and A/Texas/1/77-like viruses were identified among isolates from both communities, and the numbers of isolates of the two antigenic variants from patients seen with influenza-like illnesses were similar. The findings emphasize the need to examine multiple isolates even from within single communities to determine the antigenic specificity of current strains of influenza virus.

Intestinal infection and toxin production by Clostridium botulinum as one cause of sudden infant death syndrome

The spontaneous production of botulinum toxin in the infant gut by ingested Clostridium botulinum organisms is the underlying cause of infant botulism, recognised as an infectious disease only in late 1976. Because of the recognition of the pathophysiology of this disease and because the known potency and action of botulinum toxin can lead to rapid respiratory arrest, it appeared possible that the in-vivo production of botulinum toxin could cause the sudden death of some infants. To test this hypothesis, serum, selected tissues, and bowel contents from 280 dead infants were examined for the presence of C. botulinum toxin and/or organsisms. We found C. botulinum organisms in 10 infants, all of whom died suddenly and unexpectedly. 9 of these deaths were classified by the forensic pathologist as sudden infant death syndrome (S.I.D.S. or crib death). In 2 of these 10 sudden deaths both C. botulinum organisms and botulinum toxin were identified, and from the spleen of 1, C. botulinum organisms were isolated. Faecal specimens from 160 age-matched healthy infants who served as controls in studies of inpatient infant botulism cases were negative for both C. botulinum organisms and toxin, except for one specimen that contained only C. botulinum type A organisms. The 9 S.I.D.S. cases with evidence of C. botulinum infection comprised 4.3% of the 211 S.I.D.S. cases examined over 12 months. These findings suggest that intestinal production of botulinum toxin by C. botulinum is one cause of S.I.D.S. The strikingly similar age-distribution of 62 inpatient infant botulism cases and the 211 S.I.D.S. cases is also consistent with this concept. The possibility that in-vivo production of botulinum toxin may account for a larger proportion of S.I.D.S. cases is discussed.

Testing of hypoxic cell radiosensitizers in vivo

Use has been made of the transplantable KHT sarcoma in C3H mice to test the in vivo effectiveness of some 2-, 4-, and 5-nitroimidazoles as hypoxic cell radiosensitizers. A comparison of the in vivo versus the in vitro sensitizing ability of misonidazole and metronidazole indicates some differences, probably due to drug delivery problems in vivo. The relative sensitizing abilities of eight 2-nitroimidazoles, two 4-nigroimidazoles and two 5-nitroimidazoles are compared on the basis of the amount of drug injected and the plasma levels obtained.

Infant botulism. Epidemiological, clinical, and laboratory aspects

Clostridium botulinum organisms and toxin were identified in the feces of six infants, aged 5 to 20 weeks, who had illnesses clinically consistent with botulism. Five of the infants lived in California and became ill within a six-month period in 1976; one infant became ill in New Jersey in 1975. Three cases were type A botulism, and three were type B. No source of ingested botulinal toxin could be found in any case. However, one infant with type B botulism had ingested a food containing C botulinum type B organisms, and no toxin was found in it. The clinical findings in these cases include constipation, weak sucking and crying ability, pooled oral secretions, cranial nerve deficits, generalized weakness, and, on occasion, sudden apnea. A characteristic electromyographic pattern termed "brief, small, abundant, motor-unit action potentials" (BSAP) was observed. The sources of C botulinum toxin for these six infants is thought to have been in vivo (gastrointestinal) production following ingestion of C botulinum organisms. Studies are underway to determine the full clinical spectrum, incidence, and potential public health importance of this infectious disease newly recognized in infants.

Responses of guinea pigs to infections with strains of Venezuelan encephalitis virus, and correlations with equine virulence

Five equine-virulent strains of Venezuelan encephalitis (VE) virus consistently killed guinea pigs (strain English short hair) inoculated subcutaneously, whereas ten equine benign strains did not. Two enzootic eastern Panamanian and Colombian strains of hemagglutination-inhibition antigenic subtype I-D and of undetermined virulence for equine animals also killed guinea pigs. This subtype of VE virus may represent an excpetion to a positive correlation between equine virulence and guinea pig lethality since another strain of ts subtype has been reported to be benign in horses inoculated subcutaneously. Within the strains tested, viruses of subtypes I-ABC and I-D were lethal for guinea pigs, and viruses of other subtypes were benign. There was no correlation between guinea pig and human virulence of VE strains.

Stimulation of erythroblast maturation in vitro by sphingolipids

A lipid factor previously isolated from leukocytes and found to stimulate basophilic erythroblast formation in an in vitro system of incubated rabbit bone marrow cells has been analyzed by thin-layer chromatography, gas-liquid chromatography, and gas-liquid chromatography-mass spectrometry. The biologically active components are sphingosine ceramides of tetracosanoic and dehydrotetracosanoic acids. Tests of a series of related ceramides show a high degree of structural specificity for the C(24)-V-acyl compounds with significant but markedly lower activity of the C(22) analog. Commercially available sphingomyelin shows activity comparable to that of the tetracosanoic acid ceramide. Sphingosine and tetracosanic acid supplied in equimolar amounts have negligible activity. The results, in the context of other findings, suggest a possible supportive role of plasma ceramides and sphingomyelins in red cell maturation.

The epidemiology of influenza in California, 1968-1973

Influenza is one of the most common acute febrile respiratory diseases in adults. Epidemics caused by influenza viruses occur every few years. When such epidemics are in progress, the medical community, the general public and the news media seek information regarding the presence, spread and severity of influenza. The methods and findings of the Influenza Surveillance System in California for the years 1968 through 1973 should be of interest generally. This period spans the total California experience with the type A Hong Kong variant (A/Hong Kong/1/68 [H(3)N(2)]), and the first appearance of the English strain of type A influenza virus (A/England/42/72 [H(3)N(2)]). The surveillance of influenza during this period showed that there were major epidemics in Calfornia only during the state's first experience with the type A Hong Kong variant in 1968-69, and with the English strain in 1972-73. Problems and limitations in influenza surveillance do exist. Nonetheless, the major surveillance indices used (school absenteeism, laboratory data and deaths from pneumonia and influenza) are reliable and sensitive indicators of general trends of influenza virus activity. These indices are most useful in comparing the relative severity of influenza epidemics. However, since these indices usually lag several weeks behind the occurrence of disease, this lag must be considered in making estimates of current incidence trends based on these indices.

Botulism--diagnosis, management and public health considerations

Botulism is an uncommon but often fatal disease associated with ingestion of a potent neurotoxin present in improperly preserved foods. Exposures to commercially preserved foods with an odd or peculiar taste almost never represent exposure to botulism toxin. Improperly prepared home-canned products which are tasted or consumed without heating are more likely to be associated with botulism. The management of suspect and confirmed cases of botulism is presented by medical epidemiologists in the State Department of Public Health, Bureau of Communicable Disease Control, to provide physicians in California with a practical approach to this problem.

Epidemiology of viral hepatitis in California, 1950-1970

Epidemiologic patterns of type A (infectious) and type B (serum) hepatitis in California from 1950 to 1970 are presented. During this period hepatitis incidence increased greatly among teenagers and young adults but no significant increase occurred in other age groups. Much of this age-specific increase is related to the increasing drug abuse problem during the last decade. Other factors which possibly contribute to the current pattern of hepatitis in California are the overcrowding and inadequate sanitary facilities among a portion of young people between the ages of 15 and 30. Until these factors change or effective vaccines are developed, viral hepatitis will continue to be a significant public health problem.

Importation of Shiga bacillus dysentery into California. Clinical and public health significance

Concurrent with the regional epidemic of classic Shiga dysentery in Central America during 1969 and 1970, a pronounced increase in the isolation of Shigella dysenteriae type 1 was noted in California. A retrospective study of 20 cases diagnosed in California in 1969 and 1970 revealed that 18 of the patients had traveled to Central America or Mexico during or immediately before the onset of symptoms. Sixteen were known to have been admitted to hospital; there was one death. Despite the concern that such importations might result in epidemics in this country among groups living in crowded, unsanitary settings, no definite secondary transmission was identified in this study. The problems of differential diagnosis, laboratory isolation of the agent, chemotherapy, and epidemic control are discussed.

The need for routine rubella antibody testing of women

Results of rubella antibody tests performed by the California State Viral and Rickettsial Disease Laboratory on blood specimens collected in 1968 and 1969 from school children and women of childbearing age showed a slightly lower prevalence of rubella antibody in California than reported from most other areas of the United States. Among women of childbearing age, rubella hemagglutination-inhibition (hi) antibody was found in 72 percent of those tested in California compared with 80 percent to 90 percent in other areas of the country. Rubella antibody testing services offered by the State Virus Laboratory included situations in which a pregnant woman was exposed to a suspected case of rubella. It was shown that very few of these exposures constitute a significant risk to the fetus as most of the women already possessed antibody to rubella from past infection and in many instances the exposures were not to actual cases of rubella. The results of this study emphasized the urgency of obtaining blood specimens from pregnant women as soon as possible after exposure to rubella or development of symptoms of rubella. The urgency and anxiety attending these situations can largely be obviated if routine rubella antibody testing of women is carried out prior to pregnancy or at the first prenatal visit.

Complications of rubella immunization in children

A rubella vaccine, prepared in dog kidney cell culture, was given to 4,734 primary school children in one California county in May, 1970. Adverse reactions of arthritis, arthralgia and paresthesia were reported two to eight weeks later. Paresthesia was a very prominent complaint and showed a peculiar diurnal pattern. Objective findings in a group of symptomatic children who came to medical attention were limited to tender, swollen, small joints. Rubella virus was isolated from throat swabs from two children with symptoms 38 and 43 days after immunization.A sample telephone survey of immunized and non-immunized children was conducted two to three months after the vaccination program to estimate the frequency, type, and distribution of reactions. Approximately 7 percent of inoculated children had symptoms subsequent to vaccination. Almost no reactions were found in the control group. There was a preponderance of girls affected, but symptoms appeared to be more severe in boys. The highest complication rate was found in the youngest age group. These reactions should be brought to the attention of medical groups and the public, but since these reactions are usually mild and self-limited, ongoing immunization programs need not be altered.