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Biomedical subjects

A A McLean

Publications and source records attributed to A A McLean.

At least 19 recordsLinked to original sources
PubMed1989

Practical considerations in the production, purification, and formulation of monoclonal antibodies for immunoscintigraphy and immunotherapy.

Issues associated with the large-scale production of monoclonal antibodies for pharmaceutical applications are examined. The development of a commercial monoclonal antibody production process involves much more than just scaling-up the laboratory process and making it cost-effective. It involves establishing the hybridoma cell bank with cells that are free of adventitious agents such as viruses and mycoplasma, that have stability in continuous culture for antibody-production rate and cell viability, and that do not have unusual or expensive media requirements. The style and mode of operation of the bioreactor used to produce the antibody must be explored. The antibody-based product must be processed to high levels of purity, and specific contaminants such as DNA and endotoxin must be reduced to extremely low levels. Appropriate labeling or drug conjugation chemistries must also be developed. The product must be formulated so that it has performance characteristics that are stable over a reasonable period of time. Adequate test procedures must be developed to assure product purity, activity, stability, and safety on a lot-to-lot-basis. Compliance with federal regulations, guidelines, and procedures must be guaranteed. In the coming decade, it is likely that the two arms of biotechnology, hybridoma technology and recombinant DNA technology, will be used together to generate unique protein molecules. These new reagents will face the same practical considerations summarized in this review.

Animals↗
PubMed1988

Factors regulating the secretion of lysophosphatidylcholine by rat hepatocytes compared with the synthesis and secretion of phosphatidylcholine and triacylglycerol. Effects of albumin, cycloheximide, verapamil, EGTA and chlorpromazine.

1. The synthesis and secretion of glycerolipid by monolayer cultures of rat hepatocytes was measured by determining the incorporations of [3H]glycerol, [3H]oleate and [14C]choline and by the absolute concentration of triacylglycerol. 2. The presence of albumin in the medium stimulated the accumulation of lysophosphatidylcholine in the medium by 11-13-fold. 3. Cycloheximide did not significantly alter the accumulation of lysophosphatidylcholine. 4. This process was particularly sensitive to inhibition by chlorpromazine and verapamil, compared with the secretion of triacylglycerol and phosphatidylcholine. By contrast, it was relatively less sensitive to EGTA. 5. It is suggested that intracellular Ca2+ may be important in the production of lysophosphatidylcholine, which then accumulates in the medium by binding to albumin. In vivo this lysophosphatidycholine may be a means of delivering choline and polyunsaturated fatty acids to other organs.

Albumins↗
PubMed1987

Prevalence of hepatitis B serologic markers in community hospital personnel.

The seroprevalence of hepatitis B markers among predominantly high-risk staff members and personnel of 31 community hospitals located throughout the United States was 8.4 per cent (greater than or equal to 5 per cent in 25 hospitals and greater than or equal to 10 per cent in 13 hospitals). Only two hospitals had seroprevalence rates less than or equal to 3 per cent. The institutional seroprevalence ranged from 0 per cent to 16.7 per cent, with a median of 8.2 per cent. Although there are limitations to this survey, the results suggest that the well established increased risk of contracting HBV infection among certain groups of health-care workers in urban teaching medical centers may also hold true for personnel in similar occupational and professional categories in community hospitals.

Hepatitis B↗
PubMed1987

Haemophilus influenzae type b polysaccharide-protein conjugate vaccine.

An Haemophilus influenzae type b capsular polysaccharide-protein conjugate has been prepared. The polysaccharide was coupled to the serotype II protein of group B meningococcus through the spacer 6-aminocaproic acid using cyanogen bromide and water soluble carbodiimide. The conjugate can be shown to be reproducible and is stable and highly immunogenic in mice and African green monkeys. Clinical evaluation of this conjugate in children 3 months to 4 years of age showed that it elicited an antibody titer to the polysaccharide moiety greater than 1000 ng/ml in children 8 months of age or older.

Animals↗
PubMed1985

Live Oka/Merck varicella vaccine in healthy children. Further clinical and laboratory assessment.

A clinical trial among 137 healthy children, ages 1 to 12 years, was conducted with four different doses (4,350, 870, 435, and 43 plaque-forming units [pfu]) of live Oka/Merck varicella vaccine to evaluate clinical reactions and selected laboratory parameters and to determine the minimum effective dose and induction time of antibody. The vaccine was well tolerated with no significant difference in the rate of reported symptoms by dose. The frequency of varicellalike rash was 3% (4/137); all rashes were mild. Serum aminotransferase values were essentially unchanged after vaccination. Minor variations found in platelet counts after vaccination were not associated with any bleeding, bruising, or clotting. Among initially seronegative children who received doses of 435 pfu or greater, 94% assayed at two weeks and 100% assayed at four or six weeks seroconverted. The geometric mean titers were similar for all four doses at six weeks. IgG and IgA responses were demonstrated with no relation to the vaccine dose.

Alanine Transaminase↗
PubMed1985

Hepatitis B vaccine: a review of the clinical data to date.

The CDC estimates that about 200,000 Americans become infected with HBV each year. About 200 die of fulminant hepatitis. Most importantly, 12,000 to 20,000 persons become chronically infected, placing themselves at increased risk of developing chronic sequelae such as cirrhosis and primary hepatocellular carcinoma and also putting their families and close personal contacts at risk of hepatitis B infection. An effective vaccine to protect against hepatitis B is currently available. The vaccine is produced according to a rigorous process known to kill HBV, the agent causing AIDS, and all other viruses known to be present in human plasma. Well-controlled clinical studies have shown the vaccine to be well tolerated, immunogenic, and highly effective in preventing hepatitis B. The benefits of vaccination are clear.

Acquired Immunodeficiency Syndrome↗
PubMed1985

Future vaccines.

Explore the source record for details and available documents.

Hepatitis A↗
PubMed1984

Clinical evaluation in healthy adults of a hepatitis B vaccine made by recombinant DNA.

A vaccine formulated from hepatitis B surface antigen (HBsAg) produced by a recombinant strain of the yeast Saccharomyces cerevisiae was administered to two groups of human volunteers composed of 37 healthy, low-risk adults. Each subject received a 10-micrograms dose of HBsAg at 0, 1, and 6 months. By one month, 27% to 40% of the vaccinees had antibody to HBsAg, and by three months 80% to 100% were antibody positive. Large boosts in titer followed the third dose at six months. The antibody formed is predominantly specific for the a determinant of HBsAg. There have been no serious reactions attributable to the vaccine. The most frequent complaint has been transient soreness at the injection site. As far as we know, this is the first reported use in man of a vaccine prepared by recombinant DNA technology.

Adult↗
PubMed1984

Live attenuated varicella virus vaccine. Efficacy trial in healthy children.

We conducted a double-blind, placebo-controlled efficacy trial of the live attenuated Oka/Merck varicella vaccine among 956 children between the ages of 1 and 14 years, with a negative clinical history of varicella. Of the 914 children who were serologically confirmed to be susceptible to varicella, 468 received vaccine and 446 received placebo. The vaccine produced few clinical reactions and was well tolerated. There was no clinical evidence of viral spread from vaccinated children to sibling controls. Approximately eight weeks after vaccination, 94 per cent of the initially seronegative children who received vaccine had detectable antibody to varicella. During the nine-month surveillance period, 39 clinically diagnosed cases of varicella, 38 of which were confirmed by laboratory tests, occurred among study participants. All 39 cases occurred in placebo recipients; no child who received vaccine contracted varicella. The vaccine was 100 per cent efficacious in preventing varicella in this population of healthy children (P less than 10(-9).

Adolescent↗
PubMed1984

Vaccine against human hepatitis B virus prepared from antigen derived from human hepatoma cells in culture.

Vaccine against human hepatitis B was prepared using antigen derived from hepatitis B carrier hepatoma cells grown in the interstices of a Diaflo hollow filter unit. Hepatitis B surface antigen (HBsAg) produced by these cells was purified by immune affinity chromatography, digestion with DNase and pepsin, and Sephadex G-150 separation. The Formalin-treated antigen was formulated in 20-micrograms dose on alum adjuvant with thimerosal added as a preservative. This cell culture vaccine was as potent as human plasma-derived vaccine as measured in a mouse potency assay. The vaccine proved safe in tests in chimpanzees and in human subjects who were in late stages of cancer of the central nervous system and who were receiving therapy for their condition. None of five subjects who received the vaccine developed untoward clinical reactions. Two of the subjects who received all three doses of vaccine developed antibody against HBsAg. Three persons, two given only the primary doses and one who was given all three doses but was lost to follow-up, demonstrated no response. The slow and relatively low antibody responses to the vaccine were similar to those in other immunosuppressed persons who were given vaccine of human plasma origin.

Animals↗
PubMed1983

The preparation and safety of hepatitis B vaccine.

Preparation of hepatitis B vaccine in our laboratories consists of a series of steps that include initial concentration of surface antigen by ammonium sulphate precipitation, followed by isopycnic banding and rate zonal centrifugation in a K-II centrifuge. The partially purified antigen concentrate is digested with pepsin at pH 2 and the antigen is unfolded in 8 M urea solution followed by renaturation. After gel filtration, the antigen is treated with formalin in I :4000 dilution, adsorbed on to alum, and preserved with thimerosal. The final product contains essentially pure hepatitis B surface antigen. The process relies both on physical elimination of infectious virus particles and treatment with highly viral-destructive reagents in the pepsin (pH 2), urea and formalin steps. The process is known to be highly destructive of all known viruses tested and to include procedures that are known to be highly destructive of representatives of all known groups of animal viral agents. The three-step process in inactivation provides a fail-safe system for establishing safety of the product. Tests in more than 20000 persons, who are under surveillance, have shown no untoward effect and have confirmed the safety of the product.

Animals↗
PubMed1983

Quality and safety of human hepatitis B vaccine.

Preparation of hepatitis B vaccine in our laboratories consists of a series of steps that include initial concentration of surface antigen by ammonium sulfate precipitation, followed by isopycnic banding and rate zonal centrifugation in a K-II centrifuge. The partially purified antigen concentrate is digested with pepsin at pH2 and the antigen is unfolded in 8M urea solution followed by renaturation. After gel filtration, the antigen is treated with formalin in 1:4000 dilution, adsorbed onto alum, and preserved with thimerosal. The final product contains essentially pure hepatitis B surface antigen. The process relies both on physical elimination of infectious virus particles and treatment with highly viral-destructive reagents in the pepsin, urea and formalin steps. The process is known to be highly destructive of all known viruses tested and to include procedures that are known to be highly destructive of representatives of all known groups of animal viral agents. The three-step process in inactivation provides a fail-safe system for establishing safety of the product. Tests in more than 20'000 persons, who are under surveillance, have shown no untoward effect and have confirmed the safety of the product.

Hepatitis B Vaccines↗
PubMed1983

Progress toward a live attenuated human hepatitis A virus vaccine.

Human hepatitis A virus (HAV) was first grown in cell cultures four and one-half years ago, enabling significant progress toward the development of HAV vaccines. Vaccine development in a number of laboratories has proceeded on three fronts: 1) live, attenuated vaccine of cell culture origin; 2) inactivated vaccine of cell culture origin; and 3) genetic recombinant vaccines. Our studies to date have focused most heavily on the development of a live, attenuated HAV vaccine, although we have also made a prototype killed HAV vaccine form infected marmoset liver which induced anti-HAV and solid immunity to infection in marmosets. HAV was attenuated in virulence for both marmosets and chimpanzees by serial passaging in fetal rhesus monkey kidney cells and human diploid embryonic lung fibroblasts. A number of variants were produced which showed different levels of virulence/attenuation in these animal models. Some variants showed desirable live vaccine-like properties (little or no induction of enzyme elevations; little or no liver histologic change; retention of anti-HAV induction capacity). Vaccinated animals were solidly immune to challenge with virulent HAV. Experimental vaccines have been prepared from several attenuated HAV variants and preliminary studies in humans are planned.

Animals↗
PubMed1982

Comparison of enzyme-linked immunosorbent assay and neutralization techniques for measurement of antibody to respiratory syncytial virus: implications for parenteral immunization with live virus vaccine.

The sensitivity of an enzyme-linked immunosorbent assay (ELISA) to detect low levels of antibody to respiratory syncytial (RS) virus was compared with a tube dilution neutralization test (NEUT) on sera obtained from children who received a parenteral live RS virus vaccine. Among the children who developed antibody in response to live RS virus vaccine. ELISA was as sensitive as NEUT at detecting antibody increases. Some children who did not have detectable prevaccine ELISA antibody possessed NEUT antibody; these children were generally less than 12 months old, suggesting that they had low levels of maternal antibody. Low levels of NEUT or ELISA antibody were associated with the absence of antibody increases after injection of live RS virus vaccine. The quantity of antibody stimulated by this live RS virus vaccine was small compared with that which was stimulated by naturally acquired RS virus infection. We concluded that ELISA is a satisfactory test for determining antibody to RS virus in vaccine field trials, given the understanding that low levels of preexisting antibody are not detected in some instances.

Antibodies, Viral↗