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Biomedical subjects

P Albrecht

Publications and source records attributed to P Albrecht.

At least 55 records · Page 3Linked to original sources
PubMed1994

Immunization of 6 and 9 month old infants with AIK-C, Edmonston-Zagreb, Leningrad-16 and Schwarz strains of measles vaccine.

BACKGROUND: Measles kills more than 1 million infants per year and is particularly lethal in infants < 1 year old in developing countries. Recent reports have suggested that measles vaccines of different strains and titre differ in their immunogenicity in young infants. We sought to identify strains and titres of measles vaccines which would be effective in 6 and 9 month old infants. METHODS: We conducted a randomized trial of AIK-C, Edmonston-Zagreb (EZ), Leningrad-16 and Schwarz strains of measles vaccine at different titres in 1202 6 month old and 1250 9 month old infants. Antibody levels were measured by haemagglutination inhibition assay. Seroconversion was defined as a change from seronegative to seropositive or a fourfold rise in titre above the expected level after antibody decay (assumed antibody half-life = 6 weeks). Chi-square tests were used to compare seroconversion rates and rates of adverse reactions among the groups. Comparison of geometric mean titres (GMT) was done by the Student's t-test. RESULTS: No severe or unusual adverse reactions occurred during the 6 weeks after vaccination. All strains induced high seroconversion rates in 9 month old infants. In 6 month olds, medium- and standard-titre AIK-C induced the highest rates of seroconversion. Antibody titres at 6 weeks after vaccination were highest in recipients of Schwartz vaccine and lowest for EZ vaccine recipients. CONCLUSIONS: Standard-titre AIK-C may be more effective than other measles vaccine strains for early measles immunization and should be evaluated further for efficacy, long-term immunogenicity, and long-term safety.

Antibodies, Viral↗
PubMed1993

Quantitation of D antigen content in inactivated poliovirus vaccine derived from wild-type or sabin strains.

The enzyme-linked immunosorbent assay (ELISA) is currently the in vitro method for the measurement of the D antigen content of inactivated poliovirus vaccines (IPV) of greatest interest. The sensitivity and specificity of the test is dependent on the antibodies selected for use. We evaluated monoclonal and polyclonal antibodies for specificity to D antigen and wild or attenuated (Sabin) strains used in vaccine production. When used as detection antibodies the types 1 and 2 monoclonal antibodies raised against wild-type poliovirus strains were D antigen-specific and cross-reactive with the corresponding Sabin strains. The type 3 monoclonal antibody was weakly cross-reactive with Sabin type 3 vaccine. In contrast, polyclonal antibodies were less D antigen-specific, but reacted equally well with wild-type and Sabin strain vaccines. The ELISA using monoclonal antibodies was shown to be highly reproducible. Reactivity with these monoclonal antibodies implies that a D-specific neutralizing epitope of each respective poliovirus type has been preserved in the inactivation process. Evaluation with additional neutralizing D antigen-specific monoclonal antibodies may be necessary to determine whether reactivity with one epitope of each type in an in vitro test is sufficient to predict potency of the vaccine in humans.

Animals↗
PubMed1993

Investigation of a measles outbreak in a fully vaccinated school population including serum studies before and after revaccination.

A measles outbreak in early 1989 among approximately 4200 students at a high school and two intermediate schools in suburban Houston, TX, was investigated to evaluate reasons for vaccine failure and to predict the efficacy of a booster dose of measles vaccine. Seventy-seven cases occurred (71 at the high school, 6 at intermediate schools; attack rate, 3.2 and 0.3%, respectively). Vaccination in the first year of life an 13 to 14 years since last vaccination were independent risk factors for being a case. Forty-three (18%) of 239 sera collected from students just before revaccination during the outbreak were negative by enzyme immunoassay; a neutralization assay confirmed these 43 lacked antibody predicting protection against measles infection. Of 43 enzyme immunoassay-negative students 24 gave another blood sample 9 to 10 months after revaccination. Revaccination appeared to reduce the portion of all students with neutralization titers predicting susceptibility to measles illness with rash from 7.9% to 3.0% and left the portion predicted to be susceptible to illness without rash unchanged (45%).

Adolescent↗
PubMed1993

[The bactericidal effect of oxybuprocaine. A possible cause of false negative results in bronchoalveolar lavage].

New approaches in the diagnosis of pneumonia, especially in intensive care units, are quantitative cultures of bronchoalveolar (BAL) fluid or the protected specimen brush. The sensitivity of these methods, however, has often been found to be as low as 50-60%. One possible explanation for the low sensitivity of these diagnostic tools is the antimicrobial activity of local anaesthetics used in bronchoscopy. Therefore, we investigated the bactericidal properties of oxybuprocaine, a topical anaesthetic used for bronchoscopy in our clinic, in order to test the reliability of specimens obtained from BAL. METHODS. The bactericidal activity of oxybuprocaine in concentrations of 1%, 0.1%, 0.05% and 0.01% was tested by constructing time-kill curves for Streptococcus pneumoniae, Hemophilus influenzae, Pseudomonas aeruginosa and Escherichia coli. Five stains of each bacterial species were tested. The inoculum size was 10(4) ml, and bacteria were counted after 10, 20, 30, 60 and 120 min. RESULTS. The resulting time-kill curves are demonstrated in Figs. 1-4. The most sensitive bacteria were S. pneumoniae and H. influenzae, in which significant bactericidal activity could be shown even with a 0.01% solution of oxybuprocaine. E. coli and P. aeruginosa were also inhibited, but only at the highest concentration of 1%. CONCLUSIONS. The use of local anaesthetics before material is taken for culture, e.g. from BAL, may give rise to false-negative results and should therefore be avoided or reduced. For each local anaesthetic used in bronchoscopy, the concentrations that can be used without the risk of false-negative results should be determined.

Anesthetics, Local↗
PubMed1992

Persistence of measles antibody after revaccination.

To evaluate persistence of measles antibody after revaccination, antibody levels were measured 6 years after revaccination of 40 hemagglutination-inhibition (HAI) antibody-negative students who had participated in a serosurvey in Massachusetts. Twelve subjects who had been HAI antibody-positive and were not revaccinated were included as a comparison group. Before revaccination, 7 revaccinees had no detectable plaque reduction neutralization (PRN) antibody (group 1) and 33 had low levels of PRN antibody (group 2). Three weeks after revaccination, all in group 1 and 30 (90%) of 33 in group 2 had developed a fourfold or greater rise in PRN antibody. Six years after revaccination, all subjects had PRN-detectable antibody. However, 12 in group 2 (36%) had antibody titers less than or equal to 1:120 compared with none in group 1 (P less than .01). Persons without PRN antibody will respond to revaccination and maintain protective antibody titers. In contrast, persons with low levels of PRN antibody may respond initially to revaccination, but their antibody titers may fall again to low levels.

Adolescent↗
PubMed1991

Successful immunization of infants at 6 months of age with high dose Edmonston-Zagreb measles vaccine. Cite Soleil/JHU Project Team.

A group of 2097 Haitian infants 6 to 11 months of age were randomized to receive Schwarz or Edmonston-Zagreb strain measles vaccines containing 10- to 500-fold more vaccine viral particles than standard potency vaccines. No unusual adverse reactions were noted. Edmonston-Zagreb vaccines were more effective than equivalent doses of Schwarz vaccines as measured by the proportion of vaccinated children with measles antibody concentrations greater than or equal to 200 mIU/ml 2 months after vaccination and the persistence of antibody at 18 to 24 months of age. High titer Edmonston-Zagreb vaccine administered at 6 months of age induced antibody concentrations greater than or equal to 200 mIU/ml in 83% of infants by plaque reduction neutralization and 93% of infants by enzyme-linked immunosorbent assay with high rates of antibody persistence at 12 to 24 months of age. The World Health Organization recommends high titer Edmonston-Zagreb measles vaccines for routine use at 6 months of age in areas where measles is an important cause of mortality in young infants.

Antibodies, Viral↗
PubMed1991

Transfer function analysis of the circulation: unique insights into cardiovascular regulation.

We have demonstrated previously that transfer function analysis can be used to precisely characterize the respiratory sinus arrhythmia (RSA) in normal humans. To further investigate the role of the autonomic nervous system in RSA and to understand the complex links between respiratory activity and arterial pressure, we determined the transfer functions between respiration, heart rate (HR), and phasic, systolic, diastolic, and pulse arterial pressures in 14 healthy subjects during 6-min periods in which the respiratory rate was controlled in a predetermined but erratic fashion. Pharmacological autonomic blockade with atropine, propranolol, and both, in combination with changes in posture, was used to characterize the sympathetic and vagal contributions to these relationships, as well as to dissect the direct mechanical links between respiration and arterial pressure from the effects of the RSA on arterial pressure. We found that 1) the pure sympathetic (standing + atropine) HR response is characterized by markedly reduced magnitude at frequencies greater than 0.1 Hz and a phase delay, whereas pure vagal (supine + propranolol) modulation of HR is characterized by higher magnitude at all frequencies and no phase delay; 2) both the mechanical links between respiration and arterial pressure and the RSA contribute significantly to the effects of respiration on arterial pressure; 3) the RSA contribution to arterial pressure fluctuations is significant for vagal but not for sympathetic modulation of HR; 4) the mechanical effects of respiration on arterial pressure are related to the negative rate of change of instantaneous lung volume; 5) the mechanical effects have a higher magnitude during systole than during diastole; and 6) the mechanical effects are larger in teh standing than the supine position. Most of these findings can be explained by a simple model of circulatory control based on previously published experimental transfer functions from our laboratory.

Adult↗
PubMed1990

Immunization of six-month-old infants with different doses of Edmonston-Zagreb and Schwarz measles vaccines.

Because measles causes an estimated 2 million deaths per year among children in developing countries, including a substantial proportion of infants less than nine months old--the age at which vaccination is recommended--there has been interest in using different strains of vaccine and higher doses to achieve immunization of younger infants. We conducted a randomized trial of three different doses of Edmonston-Zagreb and of Schwarz measles vaccines in infants to evaluate the effect of the strain and dose of vaccine on the serologic response and acute adverse reactions to vaccination. Six-month-old infants received a standard, medium, or high dose of one of the vaccines, and nine-month-old infants received a standard dose. Antibody levels were measured before and after vaccination, by means of a plaque-reduction neutralization assay, in 1061 six-month-olds and 299 nine-month-olds. Edmonston-Zagreb vaccine produced higher rates of seroconversion and seropositivity than comparable doses of Schwarz vaccine. Among the six-month-old infants, the seroconversion rate 18 weeks after vaccination with the standard dose of Edmonston-Zagreb vaccine was 92 percent, that with the medium dose was 96 to 97 percent, and that with the high dose was 98 percent; the rates for the corresponding doses of Schwarz vaccine were 66 percent, 76 percent, and 91 percent, respectively. Higher seroconversion rates were observed with an increase in the dose of either Edmonston-Zagreb (P less than 0.01) or Schwarz (P less than 0.001) vaccine. The seroconversion rates produced by high and medium doses of Edmonston-Zagreb vaccine in six-month-olds were equal to or significantly higher than the rate produced by a standard dose of Schwarz vaccine in nine-month-olds (87 percent). Clinical adverse reactions were not associated with the strain or dose of a vaccine. We conclude that Edmonston-Zagreb vaccine is more immunogenic than Schwarz vaccine in infants and can induce effective immunization against measles at six months of age.

Age Factors↗
PubMed1990

Evidence from carbon isotope measurements for diverse origins of sedimentary hydrocarbons.

The organic matter found in sedimentary rocks must derive from many sources; not only from ancient primary producers but also from consumers and secondary producers. In all of these organisms, isotope effects can affect the abundance and distribution of 13C in metabolites. Here, by using an improved form of a previously described technique in which the effluent of a gas chromatograph is continuously analysed isotopically, we report evidence of the diverse origins of sedimentary organic matter. The record of 13C abundances in sedimentary carbonate and total organic carbon can be interpreted in terms of variations in the global carbon cycle. Our results demonstrate, however, that isotope variations within sedimentary organic mixtures substantially exceed those observed between samples of total organic carbon. Resolution of isotope variations at the molecular level offers a new and convenient means of refining views both of localized palaeoenvironments and of control mechanisms within the global carbon cycle.

Archaea↗
PubMed1990

The humoral immune response to type 1 oral poliovirus vaccine in children previously immunized with enhanced potency inactivated poliovirus vaccine or live oral poliovirus vaccine.

Sixty-one children who had previously received three doses of enhanced potency inactivated poliovirus vaccine (epIPV) at 2, 4, and 18 months of age and 56 children who had previously received oral poliovirus vaccine (OPV) according to the same schedule were challenged with a single dose of monovalent, type 1 oral poliovirus vaccine (OPV1) between 19 and 52 months of age. Before the OPV1 challenge, the previously epIPV-immunized recipients had a geometric mean poliovirus type 1 microneutralization antibody titer (geometric mean titer [GMT]) of 11.1 IU, which was significantly higher than the prechallenge GMT of 2.2 IU among the children who had previously received OPV. Three weeks after the OPV1 challenge, the GMTs for the epIPV-immunized recipients and the OPV-immunized recipients were 35.3 IU and 5.1 IU, respectively. For the epIPV-immunized recipients, both the prechallenge GMT and the postchallenge GMT were dependent on the D antigen content of the vaccine that they had previously received. A fourfold or greater rise in poliovirus type 1 antibody occurred after the OPV1 challenge in 50.9% of the epIPV-immunized children and in 28.6% of the OPV-immunized children; this difference was statistically significant. For both groups, antibody boosts were inversely correlated with the pre-challenge serum antibody titer. However, the epIPV-immunized children consistently were more likely to boost than the OPV-immunized children at equivalent levels of prechallenge antibody. This experience indicated that OPV1 administration effectively raises the level of serum antibody in children previously immunized with three doses of epIPV, especially in children with lower levels of preexisting antibody. This booster response was superior to the booster response of children who received three doses of OPV.

Antibodies, Viral↗
PubMed1990

Measles antibody: reevaluation of protective titers.

A school blood drive before a measles outbreak permitted correlation of preexposure measles antibody titers with clinical protection using the plaque reduction neutralization (PRN) test and an EIA. Of 9 donors with detectable preexposure PRN titer less than or equal to 120, 8 met the clinical criteria for measles (7 seroconfirmed) compared with none of 71 with preexposure PRN titers greater than 120 (P less than .0001). Seven of 11 donors with preexposure PRN titers of 216-874 had a greater than or equal to 4-fold rise in antibody titer (mean, 43-fold) compared with none of 7 with a preexposure PRN titer greater than or equal to 1052 (P less than .02). Of 37 noncases with preexposure PRN titer less than 1052, 26 (70%) reported one or more symptoms compared with 11 (31%) of 35 donors with preexposure PRN titers greater than or equal to 1052 (P less than .002). By EIA, no case had detectable preexposure antibody; the preexposure geometric mean titer of asymptomatic donors (220) was not significantly higher than that of symptomatic donors who did not meet the clinical criteria for measles (153) (P = .10). The study suggests that PRN titers less than or equal to 120 were not protective against measles disease and illness without rash due to measles may occur in persons with PRN titers above this level.

Adult↗