Cognitive function in patients with peripheral artery disease: a prospective single-center cohort study

AIM

The aim of the present study was to examine the association between cardiovascular comorbidities and risk factors, and cognitive function in peripheral artery disease (PAD) patients, as well as to determine the influence of cognitive function on cardiovascular outcome in a two-year follow-up.

METHODS

The cognitive function of 104 PAD patients was assessed using the mini-mental test (MMSE). Ankle Brachial Index (ABI), Fontaine stage, PAD localization, cardiovascular risk factors and comorbidities were taken from the electronic patient charts. A multiple logistic regression model, which included myocardial infarction (MI), stroke/transient ischemic attack (TIA), diabetes mellitus (DM), coronary heart disease (CHD) and smoking was performed to compare patients with and without cognitive impairment. All study participants were followed for two years in order to evaluate their cardiovascular outcome, mortality and revascularisation rate.

RESULTS

There was no significant difference in mini-mental state between asymptomatic and symptomatic PAD patients. ABI and PAD localization was not related to cognitive function. However, pre-existing stroke, TIA, coronary artery disease (CAD) or DM were associated with a lower MMSE score. When MMSE was dichotomized in ≤27 and >27 points, the presence of CAD, history of cerebrovascular events and DM was associated with a MMSE ≤27 in multivariate analysis. There was no association between MMSE and cardiovascular event rate.

CONCLUSION

PAD patients with CAD, stroke, TIA or DM have worse cognitive function than those without these factors. There was no evidence that cognitve function influenced cardiovascular outcome.

Condom-use skills checklist: a proxy for assessing condom-use knowledge and skills when direct observation is not possible

Because of the continued importance of correct condom-use in controlling the HIV epidemic and the limited availability of tools for assessing correct condom-use, methods for assessing condom-application skills, especially when direct observation is not feasible, are needed. Accordingly, in the context of a high-risk population (The Bahamas) for HIV, a 17-item scale--the Condom-use Skills Checklist (CUSC)--was developed for use among young adolescents and adults. The rationale and approach to developing the scale and some measures of internal consistency, construct validity, and criterion-related validity have been described. It is concluded that the scale offers a reasonable alternative to direct observation among older subjects and that further development may make it more useful among pre-adolescents.

Assessment of nine candidate DTP-vaccines with reduced amount of antigen and/or without adjuvant as a fourth (booster-) dose in the second year of life

BACKGROUND

The incidence of local reactions to diphtheria-, tetanus and acellular pertussis (DTaP-) vaccines in infants and toddlers increases with each subsequent dose, and entire thigh swellings (ETS) have been reported. Lowering the amount of antigen or of adjuvant may decrease the reactogenicity of DTaP while maintaining a protective immune response.

OBJECTIVES

Following priming with three doses of a DTaP vaccine during infancy, the safety, reactogenicity and immunogenicity of nine different candidate DTaP-vaccines with reduced amounts of antigen and/or adjuvant given as fourth (booster) dose were evaluated.

METHODS

Study participants were healthy infants aged 15-27 months at the time of booster vaccination. Each participant had received three doses of a DTaP vaccine (Infanrixtrade mark, GlaxoSmithKline, Rixensart, Belgium; "reference DTaP") at age 3, 4, and 5 months as part of a previous clinical trial. More than 20,000 children were eligible for participation in the current study protocol at the time. In a first phase at a University hospital-based vaccination study center, nine sequential cohorts of 63-119 study subjects received one of nine different candidate vaccines. Patients and study personal were blinded with regard to which vaccine was currently in use. Reactogenicity was solicited from parents using diary cards. Blood was drawn prior to and 4 weeks after vaccination and immediately centrifuged. The serum was stored at -20 degrees C until serology was performed by ELISA tests. As soon as the first candidate vaccine with adequate reactogenicity and immunogenicity profile was identified in the first study phase, a second study phase was initiated in parallel, to evaluate the safety and reactogenicity of the respective candidate vaccine in private practices in large cohorts (1613-2095 study subjects per group).

RESULTS

In the first study phase, DTaP with no aluminum induced the highest frequency of ETS and fever. All other candidate vaccines caused lower rates of local and general reactions than the reference DTaP. As a general rule, vaccines with less antigen induced fewer reactions, although there was no strict dose-response effect and the difference, e.g. between a one-tenth and a one-fifth DTaP dose (DTaP 1/5; DTaP 1/10) was not clinically relevant. Separate injections of Td and aP caused fewer general reactions than the respective TdaP combination and local reactions were higher at the aP than at the Td injection site. Again, as a general rule, reduced amounts of antigen induced lower antibody concentrations, although all vaccines induced "protective" anti-tetanus and anti-diphtheria antibody responses. A total of 92-100% of children showed seroresponses to pertussis antigens even when vaccinated with reduced amounts of the respective pertussis antigen. Elimination of aluminum from DTaP vaccine induced higher anti-tetanus-antibody concentrations and so did a reduction of the amount of diphtheria antigen. Additional examples for antigen interaction were increased antibody concentrations, observed with injection of Td and aP into different limbs. In the second study phase, all three vaccines evaluated (one with a reduced amount of diphtheria antigen, TdaP; one with reduced amounts of all antigens, tdap; and one with a fifth dose of the reference vaccine (DTaP 1/5)) were safe and had an acceptable reactogenicity profile in a total of 4871 study subjects.

CONCLUSIONS

Local reactions due to DTaP booster doses in the second year of life can be reduced by reducing the amount of antigen in the respective vaccine while an adequate immunogenicity is maintained. Aluminum-free vaccines induced ETS and fever most commonly. Any changes in vaccine composition should lead to a full evaluation of the new product.

Evaluation of molecular methods to determine enterotoxigenic status and molecular genotype of bovine, ovine, human and food isolates of Staphylococcus aureus

This study evaluated the use of PFGE and single enzyme AFLP techniques for the determination of the genetic relationships between Staphyloccocus aureus isolates from human, bovine, ovine and food related sources and reports the prevalence of 'classic' (sea to see) and 'new' (seg, seh, sei, sej, sem, sen and seo) staphylococcal enterotoxin (se) genes in 92 S. aureus strains. A sub-set of the se genotyping results was confirmed by ELISA and the presence of SE toxin determined in isolates from different sources. A 100% correlation was observed, between detection of enterotoxin genes sea-see and expression of corresponding enterotoxin proteins in vitro. The se genotyping data generated from 90 of the S. aureus isolates showed that many of the S. aureus strains producing identical se genotypes correlated with both AFLP and PFGE pattern types. However, single enzyme AFLP technique did not possess the discriminatory power of the PFGE method, but similar clonal relationships were observed by both techniques in many of the isolates tested. Results reported here include the first comprehensive study using a single enzyme AFLP technique to investigate the genetic background of S. aureus isolates from a wide distribution including animal, human and food related sources.

Adverse effect of rifampin on quinine efficacy in uncomplicated falciparum malaria

The effects of adding rifampin to quinine were assessed in adults with uncomplicated falciparum malaria. Patients were randomized to receive oral quinine either alone (n = 30) or in combination with rifampin (n = 29). Although parasite clearance times were shorter in the quinine-rifampin-treated patients (mean +/- standard deviation, 70 +/- 21 versus 82 +/- 18 h; P = 0.023), recrudescence rates were five times higher (n = 15 of 23; 65%) than those obtained with quinine alone (n = 3 of 25; 12%), P < 0.001. Patients receiving rifampin had significantly greater conversion of quinine to 3-hydroxyquinine and consequently considerably lower concentrations of quinine in their plasma after the second day of treatment (median area under the plasma drug concentration-time curve from day zero to day 7 = 11.7 versus 47.5 micro g/ml. day, P < 0.001). Rifampin significantly increases the metabolic clearance of quinine and thereby reduces cure rates. Rifampin should not be combined with quinine for the treatment of malaria, and the doses of quinine should probably be increased in patients who are already receiving rifampin treatment.

Short term evaluation of a rural immunization program in Nigeria

BACKGROUND

Immunization remains the primary strategy in both the control and prevention of common childhood diseases, particularly in the developing world. Immunization and preprimary health care services were commenced in a rural community in Nigeria in 1998, when vaccine coverage for all Expanded Program on Immunization (EPI) diseases (tuberculosis, polio, diphtheria, pertussis, tetanus, measles, and hepatitis B) was considerably low with only 43% of children fully immunized.

METHODS

Children aged 0-2 years and living in a rural community were recruited into the study. Data on vaccination history was collected by both vaccination card and maternal history. Three hundred and twenty-seven children were recruited into the study. Study participants were vaccinated for EPI diseases. Hepatitis-B vaccine was administered at birth, and a combined diphtheria and tetanus toxoids, and pertussis whole cell vaccine (DTP) plus hepatitis-B vaccine was administered in a single injection after six weeks.

RESULTS AND CONCLUSIONS

Two years after the program was started, immunization coverage rates were 94% for BCG, 88% for DTP (third dose), and 82% for measles. All antigens showed significant improvements from baseline values (p < 0.0001). Eighty four percent of children were fully immunized against all six diseases, compared with 43% at the commencement (p < 0.0001). Hepatitis-B coverage (three doses) was 58%. The vaccination program has significantly improved vaccination coverage and could be a model for under served, non-industrialized communities.

Therapeutic responses to antibacterial drugs in vivax malaria

Some antibacterial drugs have antimalarial activity that can be exploited for the prevention or treatment of malaria. Monotherapy with tetracycline, doxycycline, clindamycin or azithromycin was assessed in 1995-98 in 92 adult patients in Thailand with Plasmodium vivax malaria. All patients recovered following treatment and the early therapeutic responses were similar among the 4 groups. The overall median fever clearance time was 57 h and the mean (SD) overall time to parasite clearance was 134 (48) h. Of 66 patients who completed a 28-day follow-up, reappearances of vivax infection occurred in 27 patients (41%) from all groups; delayed appearances of falciparum malaria occurred in 6 patients (9%), only from the azithromycin group. The overall mean (SD) time to reappearance of P. vivax was 23 (5) days and time taken for detection of falciparum malaria was 13 (4) days after starting treatment for vivax malaria. The 28-day cumulative cure rates of clindamycin (n = 12), tetracycline (n = 18) and doxycycline (n = 18) groups were similar (P > or = 0.14) and all were significantly higher compared to the azithromycin group (n = 18; P < or = 0.04). The intervals until vivax reappearance were also significantly shorter in the azithromycin group [mean (SD) = 21 (6) vs 25 (3) days, P < 0.05] suggesting that some of these were recrudescences. The apparent success rate (no subsequent appearances of either vivax or falciparum infection) was significantly lower for the azithromycin group (11%) compared to the other groups (34-78%; P < 0.01). In current antibacterial treatment regimens, short-course azithromycin has inferior antimalarial activity compared to clindamycin or the tetracyclines.

Haemophilus influenzae type b disease: impact and effectiveness of diphtheria-tetanus toxoids-acellular pertussis (-inactivated poliovirus)/H. influenzae type b combination vaccines

BACKGROUND

Since 1996 in Germany primary infant immunization against Haemophilus influenzae has been most commonly given in the form of diphtheria-tetanus toxoids-acellular pertussis/H. influenzae type b (DTaP/Hib) or diphtheria-tetanus toxoids-acellular pertussis (-inactivated poliovirus)/H. influenzae type b (DTaP-IPV/Hib) combination vaccines. These combination vaccines elicit lower anti-Hib antibody concentrations than the equivalent Hib conjugate administered as a separate injection, but the clinical relevance of this phenomenon is unknown.

METHODS AND FINDINGS

To assess the impact of DTaP/Hib combination vaccines on the incidence of invasive Hib disease in Germany, two independent surveillance systems, one hospital- and one laboratory-based, were used during 1998 and 1999 for detection of cases. Vaccination histories of all cases detected were obtained by telephone contact with parents or health care providers. During the 2-year study period invasive H. influenzae disease in the <5-year age group continued to fall, with a mean annual incidence of 1.01/100 000 children. National vaccination coverage rates revealed that only 70% of children given DTaP/Hib or DTaP-IPV/Hib received the recommended three doses in their first year of life, but the overall effectiveness of these vaccines was high at 97.5% (95% confidence interval, 96.3 to 98.4) for those who had received at least one dose. In subjects who received the full 3-dose schedule, effectiveness was 98.8% (95% confidence interval, 98.2 to 99.3).

CONCLUSION

Although it is well-documented that DTaP/Hib vaccines elicit lower anti-Hib titers than separate vaccines, such combinations are effective in reducing the incidence of invasive H. influenzae type b disease.

Therapeutic responses to quinine and clindamycin in multidrug-resistant falciparum malaria

Therapeutic responses to clindamycin in combination with quinine were assessed in adult Thai patients with uncomplicated multidrug-resistant Plasmodium falciparum malaria. In total 204 patients were randomized to receive a 7-day oral treatment regimen of quinine (Q(7)) either alone (n = 68), in combination with clindamycin (Q(7)C(7); n = 68), or in combination with tetracycline (Q(7)T(7); n = 68). All patients had uncomplicated recoveries with no serious adverse effects. Fever clearance times for both of the two combination regimens (median of 47 h and range of 8 to 120 h for Q(7)C(7) and median of 36 h and range of 8 to 117 h for Q(7)T(7)) were significantly shorter than that for the Q(7)-only regimen (median, 56; range, 4 to 152 h) (P = 0.002). Parasite clearance times (overall mean +/- standard deviation, 78 +/- 23 h) were not significantly different between the three treatment groups (P = 0. 98). The cure rates assessed at 28 days of follow-up were 100% for Q(7)C(7) and 98% for Q(7)T(7), whereas the cure rate was 87% for the Q(7)-only regimen (P < or = 0.04). Clindamycin in combination with quinine is a safe and effective treatment for multidrug-resistant P. falciparum malaria. This combination may be of particular value in children and pregnant women, in whom tetracyclines are contraindicated.

Role of respiratory function in exercise limitation in chronic heart failure

OBJECTIVE

To test the hypothesis that respiratory function contributes to limit maximal exercise performance in patients with chronic heart failure by using the technique of dead space loading during exercise.

DESIGN

Blinded subjects underwent two maximal incremental exercise tests in random order on an upright bicycle ergometer: one with and one without added dead space.

SETTING

: Tertiary-care university teaching hospital.

SUBJECTS

Seven patients with stable chronic heart failure (mean +/- SEM left ventricular ejection fraction, 27 +/- 3%).

RESULTS

Subjects were able to significantly increase their peak minute ventilation during exercise with added dead space when compared with control exercise (57.4 +/- 5.9 vs 50.0 +/- 5.6 L/min; p < 0.05). Peak oxygen uptake, workload, heart rate, and exercise duration were not significantly different between the added dead space and control tests. Breathing pattern was significantly deeper and slower at matched levels of ventilation during exercise with added dead space.

CONCLUSION

Because patients with chronic heart failure had significant ventilatory reserve at the end of exercise and were able to further increase their maximal minute ventilation, we conclude that respiratory function does not contribute to limitation of exercise in patients with chronic heart failure.

Therapeutic responses to different antimalarial drugs in vivax malaria

The therapeutic responses to the eight most widely used antimalarial drugs were assessed in 207 adult patients with Plasmodium vivax malaria. This parasite does not cause marked sequestration, so parasite clearance can be used as a direct measure of antimalarial activity. The activities of these drugs in descending order were artesunate, artemether, chloroquine, mefloquine, quinine, halofantrine, primaquine, and pyrimethamine-sulfadoxine (PS). Therapeutic responses to PS were poor; parasitemias did not clear in 5 of the 12 PS-treated patients, whereas all the other patients made an initial recovery. Of 166 patients monitored for > or =28 days, 35% had reappearance of vivax malaria 11 to 65 days later and 7% developed falciparum malaria 5 to 21 days after the start of treatment. There were no significant differences in the times taken for vivax malaria reappearance among the different groups except for those given mefloquine and chloroquine, in which all vivax malaria reappearances developed >28 days after treatment, suggesting suppression of the first relapse by these slowly eliminated drugs. There was no evidence of chloroquine resistance. The antimalarial drugs vary considerably in their intrinsic activities and stage specificities of action.

[Hepatitis A and hepatitis B seroprevalence in 4 centers in Brazil]

The prevalence of antibodies to hepatitis A and B virus was assessed in 3,653 subjects across four regions of Brazil. The anti-HAV and anti-HBc seroprevalence were 64.7% and 7.9%, respectively. The highest anti-HAV (92.8%) and anti-HBc (21.4%) rates were seen in the Northern region. In other regions, anti-HAV seroprevalence over 90% was only reached in the more elderly, indicating an intermediate endemicity and a significantly higher anti-HAV prevalence was seen in the low socioeconomic group between 1-30 years. With respect to anti-HBc seroprevalence an increase was seen in adolescents and there was a significantly higher anti-HBc prevalence in the lower socioeconomic group between 1-20 years. A 3.1% anti-HBc prevalence was seen in one-year-old infants, suggesting a vertical transmission. The major findings of this study indicate that the pre-adolescent and adolescent population in some Brazilian cities are at greatest risk from both hepatitis A and B infection, but for different reasons.

[Soroepidemiology of Varicella in Brazil - results of a prospective cross-sectional study]

OJECTIVES: Varicella has more serious consequences in adolescents and adults. Recent reports from Europe and Asia show an increasing number of adolescents and young adults being seronegative. As there is only limited data on varicella zoster virus (VZV) seroprevalence in Brazil and to facilitate the strategy for varicella vaccination we conducted a VZV seroprevalence study in Brazil. METHODS: This population-based, cross sectional seroepidemiology study was performed in 4 different regions of Brazil. The studied population was stratified according to gender, age and socioeconomic status. VZV IgG antibodies were analyzed by ELISA. RESULTS: 3,879 subjects aged 1-40 years were included into the study. The overall anti-VZV seropositivity rate across all age groups and centers in Brazil was 85.4%. There was a strong age relationship. Especially in the South East and South seroprevalence was low in the age group 1-5 years (44.5% and 57.8%, respectively) while in the North the rate was 88.9%. Overall, Varicella infection was independent of the socioeconomic level, but in the youngest age groups (1-10 years) seroprevalence rates were significantly lower in the high/medium socioeconomic class for most regions. Clinical history of chickenpox correlates well with anti- VZV seropositivity with a predictive value of 95.1% CONCLUSIONS: In preadolescence a substantial proportion of the Brazilian population is susceptible to Varicella infection, and a considerable part of the adolescents and young adults remain VZVseronegative and are thus also at risk.

Reactogenicity and immunogenicity of a new live attenuated combined measles, mumps and rubella vaccine in healthy children

OBJECTIVE

To compare the reactogenicity and immunogenicity of a novel live attenuated measles-mumps-rubella vaccine, SB MMR (Priorix; SmithKline Beecham Biologicals), with a widely used MMR vaccine, Merck MMR (M-M-R II; Merck & Co. Inc).

METHODS

A total of 4702 healthy children, ages 9 to 24 months, were enrolled in 8 single blind, randomized, controlled trials. Reactogenicity (local and general solicited symptoms and all unsolicited symptoms) was assessed for up to 42 days postvaccination. Immunogenicity [seroconversion rates and geometric mean titers (GMT)] was assessed at 42 or 60 days postvaccination in 1912 subjects in 7 studies. In two studies the persistence of the antibodies at Month 12 postvaccination was assessed in 201 subjects.

RESULTS

Local symptoms (pain on or immediately after injection; pain, redness and swelling within 4 days of injection) were reported less frequently after SB MMR than Merck MMR (P < 0.0001). General symptoms and all other events were similar between the two groups. Fever >39.5 degrees C was reported after 9.5 and 11.9% of the SB MMR and Merck MMR doses, respectively. At Days 42 to 60 postvaccination seroconversion rates for antimeasles antibodies were higher with SB MMR than with Merck MMR (98.7% vs. 96.9%, P < 0.031) but similar in both groups for anti-mumps and anti-rubella antibodies, GMTs being approximately 10% higher (P < 0.05) with Merck MMR than with SB MMR. At the Month 12 assessment the seropositivity rates and GMTs were similar in both groups.

CONCLUSION

When administered as primary vaccination in children in the second year of life, the new SB MMR vaccine has been shown to be superior to a comparator vaccine in terms of local reactogenicity, with equivalent immunogenicity.

Increased protected sex and abstinence among Namibian youth following a HIV risk-reduction intervention: a randomized, longitudinal study

OBJECTIVE

To evaluate an HIV risk-reduction intervention among Namibian adolescents.

METHODS

A randomized trial of a 14-session face-to-face intervention emphasizing abstinence and safer sexual practices conducted among 515 youths (median age 17 years and median grade 11) attending 10 secondary schools located in two districts in Namibia. Youths were randomly assigned to the intervention or control condition at the level of the individual. HIV risk behaviours, intentions and perceptions were assessed at baseline, immediately post-intervention and at 6 and 12 months post-intervention.

RESULTS

Among all 515 youths who enrolled in the programme, rates of either abstinence or sex with a condom were not different between control and intervention youths at baseline or in the follow-up period. However, analyses conducted among the subset of youths who were sexually inexperienced at baseline (n = 255) revealed that a higher percentage of intervention youths (17%) than control youths (9%, P<0.05) remained sexually inexperienced one year later. Moreover, in the immediate post-intervention period, among baseline virgins who subsequently initiated sex, intervention youths were more likely than control youths to use a condom (18 versus 10%, P<0.05). Additional HIV-related risk behaviours (failure to discuss previous HIV risk exposure with one's sexual partner and alcohol use), intentions to use condoms, and perceptions of the ability to use condoms were positively affected by the intervention.

CONCLUSIONS

There is evidence that the 'My Future is My Choice' (MFMC) intervention is reducing HIV risk behaviours among sexually inexperienced participants aged 15-18. Related risk behaviours and perceptions are also positively impacted by the intervention.

Comparative study of reactogenicity and immunogenicity of new and established measles, mumps and rubella vaccines in healthy children

Concerns about the association of aseptic meningitis with measles-mumps-rubella (MMR) vaccines containing the Urabe Am 9 strain and the increasing worldwide demand for MMR vaccines, prompted the development of a new mumps vaccine strain (RIT 4385) by SmithKline Beecham Biologicals (SB) as part of a trivalent live attenuated MMR vaccine. The present study assessed the immunogenicity and reactogenicity of two lots of 'Priorix' with a widely used and established vaccine M-M-R II (Merck & Co. Inc.) as comparator vaccine. 255 healthy children, 12 to 24 months of age, were enrolled in a single-blind study and randomly allocated to receive a single dose of one of two lots of "Priorix" or M-M-R II vaccine. Vaccinees were followed up for six weeks post-vaccination for solicited and unsolicited symptoms. Immunogenicity was determined in pre- and 60 days post-vaccination sera using commercial immunoassays for measles, mumps and rubella antibodies. There were no significant differences in immune responses between groups for any of the three vaccine components. In initially seronegative subjects, the respective post-vaccination seroconversion rates for 'Priorix' lots 1 and 2, and M-M-R II were 100, 100 and 97.6% for measles antibodies, 91.7, 95.1 and 94% for mumps antibodies and 100, 100 and 100% for rubella antibodies, respectively. GMTs for the three groups were 3,076, 3,641 and 3,173 mIU/ml for measles antibodies, 934, 900 and 1,043 U/ml for mumps antibodies, and 86.4, 87.5 and 97.1 IU/ml for rubella antibodies, respectively. The incidence of local symptoms was significantly lower for both 'Priorix' lots (17.6 and 15.3% for lots 1 and 2, respectively) than for M-M-R II (37.6%). Fever > or = 38.1 degrees C during the six-week observation period occurred in approximately 25% of all subjects in all groups with no differences between the groups. No parotid/salivary gland swelling or signs of suspected meningism were reported, and there were no serious adverse events related to vaccination. The new MMR vaccine 'Priorix' containing the new RIT 4385 mumps strain was safe and had a significantly improved local tolerability profile over the comparator vaccine, M-M-R II, while eliciting an at least equivalent immune response.

The influence of major histocompatibility complex class II genes and T-cell Vbeta repertoire on response to immunization with HBsAg

Nonresponsiveness to HBsAg vaccination is observed in 5-10% of vaccine recipients and is possibly caused by a defect in the T helper cell compartment. The immune response to HBsAg is influenced by genes of the major histocompatibility complex. We have investigated MHC class I and class II antigens in 53 adult responders and 73 nonresponders. Results obtained in this first study were tested in a second study with 56 responders and 62 nonresponders from an infant vaccination trial. In addition, the peripheral Vbeta-chain T-cell receptor repertoire was investigated using monoclonal antibodies and flow-cytometry in 26 adult responders and 38 nonresponders. As previously reported, nonresponsiveness to HBsAg vaccination was associated with DRB1*3 and DRB1*7. In addition, DRB1*13 was significantly increased among vaccine responders (35.2% vs 5.4%;p < 0.0001) suggesting an immune response promoting effect for this allele whereas the closely related allele DRB1*14 was associated with nonresponse in the infant study. There was no evidence for a hole in the T cell receptor Vbeta repertoire. In conclusion, in agreement with results obtained in mice there appears to be a hierarchy of DRB1* genes in the HBsAg immune response. The possible differential association of DRB1*13 and DRB1*14 may allow the identification of differences between responsiveness and nonresponsiveness to a few amino acid differences in the beta1-domain of the class II heterodimer.

Immunogenicity and reactogenicity of a Haemophilus influenzae type b tetanus conjugate vaccine when administered separately or mixed with concomitant diphtheria-tetanus-toxoid and acellular pertussis vaccine for primary and for booster immunizations

With an increasing number of new vaccines available for routine childhood immunization, combination vaccines are needed in order to maintain or achieve a high compliance with recommended immunization programmes. In a prospective, randomized, comparative, multi-centre study, 822 healthy infants were enrolled to receive three doses of either a candidate or a commercially available Haemophilus influenzae type b (Hib) vaccine concomitantly with diphtheria-, tetanus- acellular pertussis (DTaP) vaccine. Study subjects were randomly allocated to one of the following groups: (1) separate, or (2) mixed injection of DTaP and candidate Hib vaccine, or (3) separate injection of DTaP and commercial Hib vaccine. One year later the first 189 study subjects received either separate or mixed injections of the same Hib and DTaP vaccines as booster doses. Evaluation of reactogenicity was based on diary cards completed by parents. Immunogenicity was documented by measuring IgG antibody concentrations in serum samples taken before and 4 weeks after primary and booster vaccination. No serious adverse events occurred and most local and systemic reactions were mild to moderate. Booster doses were more reactogenic than primary doses with all groups. Antibody concentrations against pertussis antigens were similar to those seen with DTaP alone. All but one subject had protective antibody concentrations against diphtheria and tetanus. Primary immune response to the Hib vaccine was significantly lower in the group receiving the mixed Hib-DTaP vaccine, however, > or = 95% of vaccinees had anti-Hib antibody concentrations > or = 0.15 microg/ml and there was a marked booster response (> 100-fold) in all groups.

CONCLUSIONS

Mixing DTaP and Hib vaccines for primary immunization caused a decrease in anti-Hib antibody response, although after primary immunization as after booster doses, all subjects showed antibody concentrations considered to be protective for invasive Hib disease. Mixing of the vaccines did not result in increased reactogenicity.

Safety and immunogenicity of hepatitis A vaccine in patients with chronic liver disease

Acute hepatitis A superimposed on chronic liver disease (CLD) has been associated with severe or fulminant hepatitis. An open, multicenter study was performed to compare the safety and immunogenicity of an inactivated hepatitis A vaccine in patients with CLD with that in healthy subjects. A secondary objective was to compare the safety of the hepatitis A vaccine with that of a commercial hepatitis B vaccine in subjects with chronic hepatitis C. A total of 475 subjects over the age of 18 years were enrolled into 1 of 5 groups according to history, serological data, and previous diagnosis. Patients in groups 1 (healthy adults), 2 (chronic hepatitis B), 3 (chronic hepatitis C), and 5 (other CLD not caused by viral hepatitis) were vaccinated with two doses of inactivated hepatitis A vaccine, 6 months apart. Patients in group 4 (chronic hepatitis C) received 3 doses of a recombinant hepatitis B vaccine, according to a 0-, 1-, and 6-month schedule. Local injection-site symptoms were the most common reactions reported following vaccination in all groups (35.5% of all doses), with the hepatitis B vaccine eliciting fewer injection-site symptoms than the hepatitis A vaccine (19.8% compared with 37.5%). Although a higher percentage of healthy subjects (93%) seroconverted after a single dose of the hepatitis A vaccine than did subjects with chronic hepatitis C (73.7%) or CLD of nonviral etiologies (83.1%), more than 94% of all vaccinees were seropositive for anti-HAV after the complete vaccination course. At each time point, a lower geometric mean concentration of anti-HAV was observed for each group of CLD patients compared with the healthy control subjects. In conclusion, hepatitis A vaccine was well tolerated and induced a satisfactory immune response in patients with chronic hepatitis B, chronic hepatitis C, and miscellaneous CLD.

Feasibility study of a combined diphtheria-tetanus-acellular pertussis-hepatitis B (DTPa-HBV) vaccine, and comparison of clinical reactions and immune responses with diphtheria-tetanus-acellular pertussis (DTPa) and hepatitis B vaccines applied as mixed or injected into separate limbs

The feasibility of a combined diphtheria-tetanus-acellular pertussis-hepatitis B (DTPa-HBV) vaccine was assessed and a comparison made of immunogenicity and reactogenicity to DTPa and HBV vaccines mixed in one syringe and to concomitant but separate injections as a primary vaccination course in three groups of infants at 3, 4.5 and 6 months of age. All subjects attained protective levels of anti-HBs antibodies 1 month after the primary course with higher geometric mean titres (GMTs) in the combined or mixed vaccinations. GMTs for pertussis toxin (PT), filamentous haemagglutinin (FHA) and pertactin (PRN) were as good or better in the groups administered the combined formulation and the extemporaneously mixed vaccines than the separate administration. No serious adverse event related to the vaccination was reported in this study. Neither the combined formulation of DTPa and HBV vaccines nor the extemporaneous mixture increased the incidence or severity of adverse reactions compared with the separate administration of DTPa. This study shows the feasibility of a combined DTPa-HBV vaccine and the data support, in the interim, the mixing of DTPa and HBV vaccines which are tested in clinical trials for infant immunization.

Immune Response to Hepatitis A Vaccine Combined or Given Simultaneously with Typhoid Fever Vaccine

Background: Because both hepatitis A and typhoid vaccination are frequently indicated in the same traveler, a prospective, randomized controlled study was performed to evaluate the feasibility of simultaneous administration of hepatitis A and typhoid fever vaccines in adult volunteers. Methods: Two groups of 25 subjects received either separate injections of hepatitis A (Havrixtrade mark, SmithKline Beecham Biologicals) and typhoid fever (Typhim Vitrade mark, Pasteur-Mérieux) vaccines in opposite arms, or a syringe-mixed combination of both vaccines as a single injection. A booster dose of Havrix was given at 6 months. Results: The immune response to hepatitis A tended to be higher in the mixed-injection group, but this difference was significant (p=.048) only following the booster dose. Adverse reactions were generally mild with no differences between the two groups. Conclusion: A combined formulated vaccine against both typhoid fever and hepatitis A is feasible and offers more convenience without added adverse reactions to travelers who have appropriate indications for both vaccines.

Safety and efficacy of acellular pertussis vaccines: the Mainz study and other recent studies

Following concerns about the safety and reactogenicity profile of diphtheria, tetanus and whole cell pertussis vaccines (DTwP), new and less reactogenic alternatives were developed over the last two decades. The new diphtheria, tetanus and acellular pertussis vaccines (DTaP) no longer consist of the whole bacterial cell but of either extracts or of a few highly purified components. While it soon became clear that DTaP vaccines are significantly less reactogenic than DTwP vaccines, their efficacy was disputed and remained unproven. First studies and epidemiological data from Japan suggested vaccine efficacy rates (VE) of about 80%; however, the first blinded clinical trial from Sweden documented a much lower VE. Worldwide, seven large DTaP efficacy trials have recently been completed. Our own efforts included a large safety trial with 22505 vaccinees and, nested in this setting, a prospective household contact study. Typical WHO-defined pertussis developed in 7 of 112 DTaP vaccinated children following household exposure as compared to 96 cases in 173 children not vaccinated against pertussis. Thus, vaccine efficacy was calculated to be 88.7% (95% CI 76.6 to 94.6). The median duration of spasmodic cough in the few children vaccinated with DTaP who did start coughing was 17 days as compared to 35 days in unvaccinated children. No waning of protection was observed. None of the confounding variables analyzed influenced study results in favour of DTaP. Following administration of more than 67000 DTaP doses, 153 serious adverse events were reported. Eight events were considered possibly related and five were considered related to the study vaccine. According to additional study results from the other trials it can be concluded that DTaP vaccines, like DTwP vaccines, are safe and effective. The choice between DTwP and DTaP should be based on acceptance of the reactogenicity profile, coverage rates achieved, costs and other factors in each individual country.

Reactogenicity and immunogenicity of a booster dose of a combined diphtheria, tetanus, and tricomponent acellular pertussis vaccine at fourteen to twenty-eight months of age

OBJECTIVES

The primary objective was to assess the nature and incidence of adverse events after a fourth dose of a tricomponent acellular pertussis-diphtheriatetanus vaccine given in the second year of life after primary vaccination with the same vaccine at 3, 4, and 5 months of age. A secondary objective was to analyze the immunogeniecity of the booster vaccination.

DESIGN

Of the 5361 children enrolled (aged 14 to 28 months), adverse reactions were specifically solicited from the first 1863 enrollees for the first 4 days after vaccination and then were unsolicited for the remainder of the 4 weeks of follow-up (group 1). In the next 3498 subjects, safety and reactogenicify were entirely unsolicited for this 4-week period (group 2). Immunogenicity was analyzed by means of prebooster and postbooster serum antibody titers for all vaccine components in a random subgroup of 197 children from group 1.

RESULTS

Soliciting symptoms elicited reports of at least one symptom in 1314 of 1809 children in group 1 (72.6%), including 993 (54.9%) with local and 885 (48.9%) with general symptoms during the first 4 days after vaccination. When symptoms were gathered in an unsolicited fashion, only 580 of 3498 children in group 2 (16.6%) had a reported symptom during this time, consisting of 344 (9.8%) local and 319 (9.1%) general symptoms, respectively. An unsolicited symptom, areactive edematous swelling of the whole thigh, occurred in 62 children (1.1%), with 45 and 17 reports in groups 1 and 2, respectively. The vast majority of all reported symptoms were mild to moderate, and all children recovered without sequelae. Fourteen serious adverse events were reported, but none was considered to be related to the vaccination. Immunogenicity analysis showed a vaccine response to pertussis toxin in 99.5% of subjects, to filamentous hemagglutinin in 98.5%, and to pertactin (69 kd outer membrane protein) in 99%. All subjects had postvaccination antibody titers of 0.1 IU/ml or greater against diphtheria and tetanus toxoids.

[New developments in diagnosis and therapy of primary non-Hodgkin's lymphoma of the central nervous system]

Primary central nervous system lymphomas (PCNSLs) are increasing in frequency both in immunocompetent and immunodeficient individuals. The majority of PCNSLs are high grade B cell lymphomas. In AIDS patients most tumors contain EBV genome. PCNSLs usually present as intracerebral, often deep-seated lesions half of which are multilocular. Less frequent are diffuse periventricular, exclusively leptomeningeal, ocular or spinal spread. On imaging PCNSLs show as contrast-enhancing lesions with relatively little perifocal edema. CSF protein is usually elevated. Malignant cells are present in 20-30% of cases. Demonstration of a monoclonal B cell population by immunocytology or FACS analysis may also be diagnostic. Once PCNSL is suspected extensive systemic evaluation is not useful. Instead, (stereotactic) biopsy of brain lesion(s) should be performed. Prior to biopsy, corticosteroids should be withheld as they may obscure diagnosis. Symptomatic edema or increased intracranial pressure should therefore initially be treated with osmotherapeutics. All immunodeficient patients should receive empiric anti-toxoplasmosis therapy for about 14 days prior to biopsy. AIDS patients with PCNSL survive 3 to 5 months (median) after whole brain irradiation and usually do not benefit from chemotherapy. Immunocompetent patients have a median survival of 12 to 18 months after whole brain irradiation alone, but a median survival of 33 to 43 months after combined radiochemotherapy using cytostatic drugs which penetrate the blood-brain barrier. Based on these encouraging results current concepts aim to intensify chemotherapy and to reduce or delay radiotherapy in the treatment of immunocompetent patients.

Potential of the monoglyceride and triglyceride of DL-3-hydroxybutyrate for parenteral nutrition: synthesis and preliminary biological testing in the rat

Esters of short-chain organic acids have shown some promise as potential nutrients for parenteral feeding. Most glycerols are water insoluble but those of the ketone bodies have some water solubility. Of interest is that the triacylglycerol of 3-hydroxybutyrate has water solubility while the triacylglycerol of acetoacetate does not. The mono- and triacylglycerol of DL-3-hydroxybutrate were synthesized and tested for toxicity and nutritional value as parenteral nutrients. Both compounds have an estimated energy density of 19.7 kJ/g (4.7 kcal/g) and are water soluble. The compounds were infused into rats for 7 d at a rate to provide 113 kJ/d and were accompanied by a low-energy oral diet. Control, pair-fed rats were infused with isocaloric glucose or 0.9% saline. Nitrogen intake, output, and balance, body weight changes, and liver size were compared. The two glycerols of 3-hydroxybutyrate supported similar nitrogen retention, body weight changes, and liver size as found in the pair-fed control animals infused with glucose. Rats infused with saline retained less nitrogen, had decreased body weight, and had smaller livers. The data demonstrated that the glycerols of DL-3-hydroxybutyrate are not toxic, provide metabolic energy when infused intravenously, and could be used as nutrients for parenteral feeding.

Booster immunization of low- and non-responders after a standard three dose hepatitis B vaccine schedule--results of a post-marketing surveillance

Seventy-nine low-responders and 83 non-responders after a previous three-dose hepatitis B (HB) vaccine course at 0.1, and 6 months were enrolled to receive additional 20 micrograms recombinant HB vaccine doses every 2 months until all had anti-HBs levels > or = 100 mIU ml-1. After the first booster, 65.4% had anti-HBs levels > or = 100 mIU ml-1, 17.9% were low-responders (10-99 mIU ml-1), and 16.7% remained non-responders (< 10 mIU ml-1). All complying non-responders developed anti-HBs levels > or = 100 mIU ml-1 after the third booster at the latest, whereas all low-responders reached this level after the second booster. Although body mass index affected the response to the first hepatitis B booster, when full compliance to regular revaccination was ensured, all non- and low-responders eventually reached sufficient anti-HBs levels.

Cell-mediated immunity after pertussis vaccination and after natural infection

The aim of this study was the investigation of the specific cell-mediated (CMI) responses induced by DTaP and to compare these data to immunity after natural infection. The ability of peripheral blood T-lymphocytes to respond to the pertussis related antigens pertussis-toxin (PT), filamentous haemagglutinin (FHA), and Pertactin (PRN) was investigated in 40 children before vaccination and at different times after vaccination with DTaP (Infanrix) by measurement of antigen-specific proliferation, lymphocyte phenotype, cytokine production and expression of activation markers (CD25, HLADR). Similar investigations were performed in children 4-6 weeks after recovery from natural pertussis. DTaP created a specific T-cell-response to PT, FHA and PRN that increased continually, depending on the progress of the vaccination schedule. In contrast to waning antibody titres, CMI was stable even between the post-basic vaccination and the pre-booster period. The magnitude of CMI after DTaP equalled those after natural infection. Measurement of cytokine-pattern showed induction of IFN-tau-producing T-helper-1-cells with lower stimulation of IL 10-producing T-helper-2-cells for DTaP and natural infection. Our data indicate that DTaP-vaccination induces a potent immune response to PT, FHA, and PRN at least equivalent to CMI after natural infection. The finding of a preferential T-helper-1-induction after DTaP and natural infection suggests a role of IFN gamma-activated macrophages in the protective response against B. pertussis-induced disease.

Evidence for induction of polysaccharide specific B-cell-memory in the 1st year of life: plain Haemophilus influenzae type b-PRP (Hib) boosters children primed with a tetanus-conjugate Hib-DTPa-HBV combined vaccine

The lack of an adequate immune response to the major polysaccharide of the Haemophilus influenzae type b (Hib) capsule (polyribosyl ribitol phosphate) (PRP) in very young infants (< 18 months) can be overcome by conjugating PRP to a T-cell dependent carrier protein. We studied whether administration of a tetanus-PRP conjugate vaccine reconstituted with a diphtheria-tetanus-acellular pertussis-hepatitis B (DTPa-HBV) vaccine as a three dose primary course at 3, 4 and 5 months of age induced PRP-specific immunological memory, by examining the anti-PRP response to a dose of unconjugated PRP given with the DTPa-HBV booster approximately 1 year later. The unconjugated PRP elicited protective anti-PRP antibody levels (> or = 0.15 microgram/ml) in all but 3 of the 369 vaccinees, including 13 infants who failed to demonstrate a measurable immune response after the primary course. In a sub-cohort of 54 subjects all had anti-PRP levels > or = 0.5 microgram/ml within 7-14 days of the booster showing a rapid anamnestic type response. Both primary and booster responses were predominantly IgGl indicating a T-cell dependent response. The DTPa-HBV components elicited protective anti-diphtheria, anti-tetanus and anti-HBs antibody levels in > or = 98.5% of vaccinees, and immune responses to each of the acellular pertussis vaccine components in 92.3%-97.3% of subjects.

CONCLUSION

The tetanus-PRP conjugate vaccine not only elicited a good primary humoral response, but also induced immunological memory so that the infants were able to mount a large and rapid immune response to subsequent exposure to plain PRP, indicating that protection against circulating wild-type Hib had been generated. Successful induction of immunological memory occurred even when there was no measurable humoral anti-PRP response to the primary course. Tetanus-PRP conjugate vaccine can be used in combination with DTPa-HBV vaccine, when administered separately or as a single injection in the same syringe, in primary immunisation schedules at 3, 4 and 5 months of age.

Clinical experience of a tricomponent acellular pertussis vaccine combined with diphtheria and tetanus toxoids for primary vaccination in 22,505 infants

OBJECTIVES

To assess the safety and tolerability of 12 lots of SmithKline Beecham Biologicals' diphtheria-tetanus-tricomponent acellular pertussis vaccine (DTaP) in a large cohort of 22,000 vaccinees, with detailed analyses of reactivity, immunogenicity, and immune response to pertussis toxin in subsets.

METHODS

In a prospective, double-blind, multicenter trial in Germany, 22,505 healthy infants received three vaccinations of DTaP at age 3, 4, and 5 months. Serious adverse events were followed for 1 month after each vaccination, and neurologic events for 1 year or longer. Serum IgG antibodies were assayed before vaccination and 1 month after vaccination.

RESULTS

After 67,000 doses, 153 serious adverse events (0.23%) were reported, 8 considered possibly related, and 5 related to vaccination, including 1 hypotonic-hyporesponsive episode. Incidence rates of sudden infant death syndrome (7; 0.01%) or acute neurologic events (20; 0.030%) were no higher than expected and not considered to be related to vaccination. Redness and swelling of 20 mm or greater occurred after 44 (0.6%) and 40 (0.6%) of the 7270 doses, respectively, and high fever (> 39.5 degrees C) in 6 (0.08%) subjects within 48 hours of vaccination. In the immunogenicity analysis of 580 infants, 98% responded to pertussis toxin, 96% to filamentous hemagglutinin, and 98% to pertactin. In an additional 5712 infants, the response rate to pertussis toxin was 99%.

CONCLUSIONS

In a large cohort of 22,505 infants vaccinated, SmithKline Beecham Biologicals' tricomponent DTaP vaccine was shown to be safe, well-tolerated, and immunogenic for all component antigens.

Acellular pertussis vaccines: the rationale for an efficacy trial in Germany

After concern about the safety of diphtheria-tetanus toxoid-whole cell pertussis vaccines (DTPw), the recommendation to vaccinate children with DTPw was withdrawn in 1974 in the former West Germany. This led pertussis cases to increase to an estimated 100,000 annually. Despite renewal of the vaccination recommendation in 1991, vaccine use remained low. The German health care structure assures regular contact between most children and pediatricians. This enabled the conduct of a large efficacy trial with a diphtheria-tetanus toxoid-acellular pertussis (DTPa) vaccine. Because a placebo-controlled trial was not ethically possible, a prospective household contact study with a blinded clinical follow-up was done. Possible study participants were screened by their pediatrician, who also initiated diagnostic procedures. Clinical follow-up was done by another locally based but independent and blinded physician. Vaccine efficacy was calculated to be 89% (95% confidence interval, 76.6%-94.6%). None of the identified confounding factors biased results in favor of the DTPa vaccine.

Immunogenicity of a recombinant hepatitis B vaccine in adults

OBJECTIVES

To evaluate the immunogenicity and reactogenicity of a recombinant hepatitis B vaccine in health care staff under routine use and unselected conditions and to investigate factors that influence the response to vaccination.

METHODS

This prospective postmarketing surveillance study was performed in unselected health care staff and their relatives (age range, 12-60 years) at 58 hospitals. Overall, 880 subjects were administered a 20-microgram dose of a vaccine at 0, 1, and 6 months according to the prescribing information and under routine hospital practice, and they were tested for antibody to hepatitis B surface antigen after the third dose at the hospitals routine laboratory. The principal outcome measures were antibody to hepatitis B surface antigen titers that were expressed as the seroprotection rate (SPR) (SPR [given as a percentage], > or = 10 mlU/ mL), spontaneously reported adverse events, and geometric mean titers (in milli-international units per milliliter).

RESULTS

The compliance to the 3-dose schedule under routine hospital practice was 98.1%. The immune response was good in all age groups, and the overall SPR was 97.8% at 1 month after the third dose in field conditions with unselected health care workers. The SPR in vaccinees (age range, 40-59 years) was close to 95%. Age (P < .001), smoking (> or = 10 cigarettes per day) (P < .001), Broca index (> 110%) (P < .001), antibody to hepatitis B surface antigen testing (> 8 weeks after the last dose) (P = .03), chronic underlying disease (P = .04), and male gender (P = .04) were factors associated with lower geometric mean titers in routine vaccine use. No serious adverse events were reported.

CONCLUSION

The large immune response that was elicited by this hepatitis B vaccine in adults under daily routine field conditions reflected reality, with a high SPR also found in elderly and other persons with risk factors associated with a lower immune response.

Pertussis-specific cell-mediated immunity in infants after vaccination with a tricomponent acellular pertussis vaccine

The aim of this study was to investigate pertussis-specific cell-mediated immunity in infants vaccinated with a tricomponent acellular vaccine. Infants were investigated during a primary vaccination schedule from the third month of life to the sixth month as well as before and after a booster at 15 to 24 months. This is the first report of specific cell-mediated immune responses to pertussis-related antigens in infants below the age of 12 months. Our data show that the vaccine induces T-cell responses specific for the vaccine components, detoxified pertussis toxin, filamentous hemagglutinin, and pertactin, that increase progressively over the course of the vaccination schedule. In contrast to declining antibody titers, cell-mediated immune responses are stable over the postprimary to prebooster period. Vaccination results in a progressive increase in the number of T cells that express activation marker CD45RO preferentially on CD4-positive T cells after stimulation with pertussis antigens. Measurements of cytokine secretion profiles demonstrated a preferential induction of interleukin 2- and gamma interferon-producing T-helper 1 cells and only low production of interleukin 10. The observed persistence of the specific cell-mediated immunity may have a bearing on the protective mechanisms induced by pertussis vaccination. Cell-mediated immunity requires further study, particularly to improve our understanding of the persistence of protection afforded by vaccination up to the administration of booster doses.

Immunogenicity and reactogenicity of a combined hepatitis A/B candidate vaccine: first results

We evaluated immunogenicity and reactogenicity of an inactivated, combined hepatitis A/B candidate vaccine in 50 seronegative volunteers. Each volunteer received a total of three doses of vaccine (720 EIU HAV and 20 micrograms HBs antigen) according to a 0, 1 and 6 month vaccination schedule. One month after the first injection, the seroconversion rate was 90% (45/50) for anti-HAV and 28% (14/50) for anti-HBs, respectively. After the booster dose, at month 7, the seroconversion rate was as high as 100% (49/49) for anti-HAV and 94% (46/49) for anti-HBs. The geometric mean titres increased with each dose of vaccine administered. Mild, and mostly local side effects were reported in 54% of the volunteers after the first injection and in less than 10% after the third injection. Our results show that this inactivated, candidate hepatitis A/B vaccine is highly immunogenic and well-tolerated.

Therapeutic effects of chloroquine in combination with quinine in uncomplicated falciparum malaria

The efficacy and toxicity of oral quinine combined with oral chloroquine were studied in 50 Thai men with uncomplicated falciparum malaria. All were treated for 7 days with quinine sulphate (10 mg salt/kg every 8 h). Twenty-five of the patients, selected at random, were also given oral tetracycline (4 mg/kg four times daily) over the same period and the remainder were given chloroquine (25 mg base/kg over the first 3 days). There were no serious adverse effects. Overall fever-clearance times (FCT) and parasite-clearance times (PCT) in the chloroquine and tetracycline groups were not significantly different, with mean (S.D.) values of 51 (33) and 41 (27) h for FCT and 80 (25) and 83 (21) h for PCT, respectively. Most of the patients (18 in each group) were followed for > or = 2 months. Recrudescence rates (R1) were significantly higher in the chloroquine group than in the tetracycline group (39% v. 6%; P = 0.02), all recrudescences occurring within 4 weeks (18-25 days) of starting treatment. Subsequent parasitaemia with Plasmodium vivax, however, occurred less frequently in the chloroquine group (11%) than in the tetracycline group (33%) (P = 0.11) and took longer to develop in the chloroquine group [51 or 59 days compared with a mean (S.D.) value of 29 (10) days in the tetracycline group; P = 0.01]. Within the chloroquine group, FCT and PCT were both shorter in those with cure than in those with R1 resistance, with mean (S.D.) values of 41 (25) and 70 (33) h for FCT (P = 0.09) and 72 (20) and 100 (18) h for PCT (P = 0.01), respectively. Chloroquine does not potentiate the clinical response to quinine against resistant strains of uncomplicated falciparum malaria, nor does it convey any useful antipyretic effect.

Immunogenicity of an inactivated hepatitis A vaccine administered according to two different schedules and the interference of other "travellers" vaccines with the immune response

A total of 2036 persons consulting vaccination centers in Germany were vaccinated with an inactivated hepatitis A vaccine (containing 720 ELISA units of antigen) either according to the standard schedule (two vaccinations given 4 weeks apart) or to an abbreviated schedule (two vaccinations given 2 weeks apart) in a controlled clinical study. The abbreviated schedule induced a similar rate of seroconversion and geometric mean antibody titre as compared to the standard schedule. The incidence of reactions reported after vaccination was similar in both groups. When other "travellers" vaccines were given simultaneously neither the immunogenicity nor the reactogenicity of the hepatitis A vaccine were influenced. These findings have considerable practical importance in the prevention of hepatitis A in travellers.

Efficacy of acellular pertussis vaccine in early childhood after household exposure

OBJECTIVE

To evaluate the efficacy of a three-dose primary vaccination with a diphtheria-tetanus tricomponent acellular pertussis vaccine against "typical" pertussis, defined as a spasmodic cough of 21 days or longer with confirmation of Bordetella pertussis infection by culture or serology.

DESIGN

Passive monitoring for suspected first household (index) cases of typical pertussis in six areas in Germany comprising 22,505 children vaccinated with study vaccine at 3, 4, and 5 months of age. Blinded, prospective follow-up of household contacts of index cases for incidence and progression of pertussis.

SETTING

Six areas in Germany with a high incidence of pertussis.

SUBJECTS

Four hundred fifty-three households with index cases comprising 360 evaluable contacts eligible for analysis of vaccine efficacy.

MAIN OUTCOME MEASURE

Vaccine efficacy from attack rates of pertussis in household contacts classified by vaccination status.

RESULTS

Of the 173 nonvaccinated household contacts, 96 developed typical pertussis, compared with seven of 112 contacts vaccinated with acellular pertussis vaccine. Vaccine efficacy was consequently calculated to be 88.7% (95% confidence interval, 76.6% to 94.6%). Protection did not wane until at least the time recommended for booster vaccination. None of the analyzed potential confounding factors--age, socioeconomic status, erythromycin treatment, household composition, center effect, and selection bias--influenced study results in favor of the vaccine.

CONCLUSIONS

Under conditions of intense household exposure, primary vaccination with acellular vaccine protected against pertussis until at least the time recommended for booster vaccination. The vaccine can be expected to be equally or more effective in settings with lower infectious pressure.

Accelerated Schedule for Hepatitis B Immunization

Background: A considerable number of people remain unprotected against hepatitis B. These people may require immunization at short notice before being exposed to situations or locations where a risk of infection is present. Currently, full active immunization against hepatitis B, when administered according to recommended schedules, takes 2-6 months. This open, randomized multicentric study evaluated the reactogenicity and immunogenicity of a recombinant hepatitis B vaccine in adults when it was administered according to three different rapid vaccination schedules. Methods: Five hundred and twenty four healthy adults (aged 18-59 years) were randomly divided into three groups. Hepatitis B vaccine was given intramuscularly in the deltoid muscle at months 0, 1, and 2 (group A); weeks 0, 14, and 28 (group B); and weeks 0, 7, and 21 (group C). Symptoms were recorded by the subjects on individual diary cards. AntiHBs were measured using radioimmunoassay (Ausab-Abbott); a seroprotective titer was defined as 10 IU/L. Results: At day 28, no significant difference in seroprotection rates (SPRs) i.e., seroconversion >= 10 IU/L,was observed, between groups B (55.6%) and C (65.2%), but both these groups had significantly greater SPRs than group A (15.0%). Although not significant (p=.07), groups B and C also had higher SPRs than group A (78.5% and 76.4% versus 65%) at day 56. One month after completing the three dose schedules, the SPRs were as follows: 89.0% (group A); 78.5% (group B); and 76.4% (group C), increasing to > 94% at month 7 to 8 in all three groups. The SPRs at month 13 were 95.8%, 98.9%, and 98.6%, respectively. Among the three groups, no significant differences were observed from month 2 onwards in either SPRs or geometric mean titers. In groups A, B, and C, 3.7%, 5.0%, and 7.1% of the vaccine injections were associated with local symptoms. Also 8.3%, 6.2%, and 6.3% of subjects exhibited general symptoms following each vaccine dose; all symptoms were transient and resolved spontaneously. Conclusions: This recombinant hepatitis B vaccine administered at weeks 0, 7, 21, or at weeks 0, 14, 28, rapidly elicits high rates of seroprotection, which persist at least until month 12.

[Immunogenicity and tolerance of a combined hepatitis A/B vaccine. Preliminary results with a candidate vaccine]

AIM OF STUDY

Active immunization against hepatitis A having been undertaken in Germany since January 1993, a multicentre study was conducted to test, for the first time, immunogenicity of and tolerance to a candidate vaccine against hepatitis A and B.

SUBJECTS AND METHODS

50 healthy volunteers aged 18-40 years, negative for antibodies against hepatitis A (HAV) and B (HBs), received three intramuscular injections of the candidate vaccine (720 EIU of strain HM 175 and 20 micrograms recombinant HBsAg) in a total volume of 1 ml, on day 1 and then, one month and 6 months later.

RESULTS

Four weeks after the first injection the seroprotection rate (percentage of subjects with protective antibody titres) was 90% for HAV and 28% for HBs. The second injection produced seroconversion rates of 98% and 50%, respectively, and after the third one of 100% and 98%. All reported side effects were minor, of short duration and decreased after each injection. After the first injection, effects at the site of injection occurred in 50% of subjects, decreasing to 6% after the third one. The only systemic side effect, headache, occurred in only 4% of subjects and only after the first injection.

CONCLUSION

The test vaccine against hepatitis A and B proved to be highly immunogenic, safe and well tolerated.

Immunogenicity and safety of an inactivated hepatitis A vaccine in anti-HIV positive and negative homosexual men

The immunogenicity, reactogenicity, and safety of an inactivated hepatitis A vaccine were assessed in anti-HIV positive homosexual men. Fourteen anti-HIV positive (group 1) and 20 anti-HIV negative (group 2) men received vaccine (containing 720 ELISA units of hepatitis A antigen per dose) intramuscularly at 0, 1, and 6 months. Twelve unvaccinated anti-HIV positive men (group 3) were included as controls to evaluate disease progression. Seroconversion (anti-hepatitis V virus (HAV) > or = 20 mlU/ml) was higher in group 2 than group 1 at months 2 (100% vs. 73%) and 7 (100% vs. 77%). Group 2 had higher antibody titres than group 1 at months 1 (201 vs. 92 mlU/ml) and 7 (1,687 vs. 636 mlU/ml). The decline in CD4+ cells between months 0 and 7 was similar in groups 1 and 3 (6.4% vs. 16.2%), showing no evidence for harmful effect of the vaccine on the course of HIV infection. This hepatitis A vaccine appears safe, well tolerated, but less immunogenic in HIV positive homosexual men.

Clinical experience with an inactivated hepatitis A vaccine

Clinical trials of an inactivated hepatitis A vaccine have encompassed 104 studies completed by December 1993 in 27 countries. Studies involved 50,677 subjects and administration of > 120,000 vaccine doses. Results show that the vaccine is safe, clinically well-tolerated, and highly immunogenic in all age groups. A seroconversion rate of 100% is achieved 1 month after primary vaccination. Vaccine-induced antibody titers persist after a primary vaccination course for > or = 1 year with a single dose of 1440 ELISA units (EL.U.) in adults and after two doses of 360 EL.U. in children. A booster dose 6-12 months after the first vaccine dose induces very high antibody titers, which according to a mathematical model, are expected to protect against hepatitis A for > 20 years. The vaccine is equally immunogenic when administered simultaneously with other traveler vaccines, therefore enabling flexible and convenient vaccination against hepatitis A.

Effects of antithrombin III and antivenom on procoagulant activity of Russell's viper venom in a whole blood model

The procoagulant activities of Russell's viper venom were assessed in an in vitro whole blood model. Sequential samplings showed that the generation of fibrinopeptide A (FPA), a marker of thrombin activity, and platelet factor 4 (PF4), a marker of platelet activity, exhibited bi-phasic kinetics with an initial slow phase followed by a rapid phase of secretion. In the presence of Russell's viper venom, the generation of both FPA and PF4 was accelerated with the bi-phasic kinetics of PF4 being maintained while that of FPA completely disappeared. Administration of either antivenom (1,600 ng) or 10 IU antithrombin III (AT-III) had no antagonistic effect against the venom but combination of both resulted in a significant prolongation of both FPA and PF4 release (p < 0.05). High dose AT-III (20 IU) resulted in normalization of both FPA and PF4 kinetics and serial levels of both parameters were lower than those treated with the combined regimen, although these were not statistically significant. Unlike the untreated venom activated whole blood, there was no clot formation following treatment with either the combined regimen or high dose AT-III. The results of this study suggested that the effect of Russell's viper venom on the clotting cascade is more potent and direct than that on platelet activity. There were complementary effects between antivenom and AT-III is controlling of both FPA and PF4 release induced by the venom. Furthermore, in this in vitro experiment, AT-III alone when administered in a sufficient dose, abolished the procoagulant effects of Russell's viper venom.

Therapeutic effects of antivenom supplemented by antithrombin III in rats experimentally envenomated with Russell's viper (Daboia russelli siamensis) venom

The effects of equine antivenom and antithrombin III (AT-III) on the coagulopathy induced by Russell's viper venom (RVV, Daboia russelli siamensis) were investigated in the rat. After taking blood samples from the femoral vein for determination of simple blood clotting time and AT-III activity, all anaesthetized rats received an intramuscular injection of venom (2 micrograms/g). Treatment (antivenom or AT-III or both) was given intravenously through another femoral vein 30 min after venom injection. All untreated rats (n = 7) developed AT-III depletion (< 70%) [mean (S.D.)] 70 (36) min, and incoagulable blood 85 (53) min after venom injection. Supplementation with AT-III (either 0.25 U/g or 0.5 U/g) had no effect on the RVV induced coagulopathy (n = 20). Treatment with antivenom alone (10 micrograms/g) reduced the incidence of abnormal clotting significantly (8/15, 53%) (P = 0.03). When antivenom was given in combination with AT-III (0.5 U/g), abnormal clotting was prevented in all but one animal (1/15, 7%) (P = 0.007). AT-III activity declined progressively in all rats which developed non-clotting blood. These results suggest that coagulopathy in Russell's viper envenoming is associated with activation of coagulation and consumption of AT-III. Antivenom can prevent coagulopathy, but its neutralizing activity is augmented significantly by AT-III supplementation.