Hib vaccination in infants born prematurely

Aims: To document the immunogenicity and persistence of antibody to polyribosyl-ribitol phosphate (PRP) as well as the clinical protection against invasive Haemophilus influenzae type b (Hib) disease in premature infants immunised at the routine schedule. Methods: Blood was obtained at 2, 5, 12, and 64 months of age from a cohort of prematurely born infants (≤32 weeks gestation). Anti-PRP antibody concentrations were compared with those of a control cohort of infants born at full term and vaccinated at the same schedule. Hib vaccine failures occurring between October 1992 and October 2000 were reported by paediatricians through an active, prospective, national survey in the UK and Republic of Ireland. The number of prematurely born children with vaccine failure was compared with the corresponding number born at term. Results: Twenty seven prematurely born infants were followed to 5 years of age. Compared with term infants they had a significantly lower geometric mean concentration of anti-PRP antibody and/or a significantly lower proportion above one or both of the conventional protective antibody concentrations (0.15 and 1.0 µg/ml) at all ages. A total of 165 cases of invasive Hib disease were identified over eight years of national surveillance. Eighteen were premature (<37 weeks); approximately 12 would be expected. The relative risk of UK premature infants developing disease compared with term infants was 1.5 (95% CI 0.9 to 2.6). Conclusions: Premature infants develop lower antibody concentrations than term infants following Hib conjugate vaccination. Premature infants may also have an increased risk of clinical vaccine failure, but interpretation is limited by the small number of premature infants developing invasive Hib disease over eight years of national surveillance. Overall, vaccination with Hib conjugate vaccines affords a high level of protection to premature babies.     

Clinical evaluation of the HemoSonic monitor in cardiac surgical patients in the ICU

The HemoSonic monitor (HemoSonic 100, Arrow International, Reading, PA, U.S.A.) is a minimally invasive device to determine cardiac output by means of M-mode and pulsed Doppler ultrasound. We evaluated the HemoSonic monitor by comparing its output to paired measurements obtained by the standard thermodilution technique in patients who had recently undergone cardiac surgery. Forty-seven paired measurements were carried out in 13 patients. The correlation between the two methods was very good with a correlation coefficient of 0.81. Comparison of the two techniques using the method described by Bland and Altman showed a mean of the differences of -0.23. The limits of agreement were -2.35 to 1.89. There was a reduced correlation between techniques at higher values of cardiac output. We concluded that the HemoSonic monitor has a place in intensive care monitoring, with good correlation with cardiac output measured by the thermodilution technique. It appears to be less suitable for use in patients with a high cardiac output state. The oesophageal probe is moderately difficult for patients to tolerate and is only appropriate for use in sedated patients. The accuracy of the device is somewhat operator-dependent.     

Preliminary experience with the Berger neurobiopsy device for ultrasound guided aspiration and biopsy of intracranial lesions

Our preliminary experience is presented in the use of the Berger neurobiopsy device for ultrasound localization and biopsy of intracranial lesions through a burr hole. The apparatus and technique are described, along with the results of its use in the first 49 patients. In these patients 43 tumours were biopsied, all except one successfully. Three abscesses were aspirated, two intraventricular shunt catheters were sited and in one patient the diagnosis of postradiation gliosis was confirmed and tumour excluded. The advantages and limitations of the technique are discussed. It is advocated as a simple and time-saving alternative to CT stereotactic biopsy in many cases.     

Selenium content of foods purchased or produced in Ohio

Approximately 450 samples of about 100 types of foods consumed by rural and urban Ohioans were analyzed for selenium. Meat, dairy products, eggs, and grain products produced in Ohio have considerably lower selenium content than corresponding products produced in high selenium areas, such as South Dakota. Retail Ohio foods with interregional distribution tended to be higher in selenium content than corresponding foods produced in Ohio. Best sources of selenium in Ohio foods commonly consumed were meat and pasta products. Poor sources of selenium were fruits, most vegetables, candies, sweeteners, and alcoholic and nonalcoholic beverages. Establishment of an accurate data base for selenium depends on knowledge of the interregional distribution of foods, the selenium content of foods at their production site, and the selenium content of foods with wide local distribution.     

Beta-Lactamase Effect on Ampicillin Treatment of Haemophilus influenzae B Bacteremia and Meningitis in Infant Rats

Intraperitoneal injections of 250 mg of ampicillin per kg every 6 h for 30 h sterilized the blood and cerebrospinal fluid of infant rats infected with either a beta-lactamase-containing strain of Haemophilus influenzae type b or a strain lacking the enzyme. However, a single injection of 100 mg/kg sterilized the blood and cerebrospinal fluid of significantly fewer of those rats infected with the beta-lactamase-producing strain. The results suggest that resistance of beta-lactamase-containing strains of H. influenzae in vivo may be inoculum dependent, as demonstrated previously in vitro. The infant rat model appears suited for the quantitative delineation of the effect of beta-lactamase on the treatment of H. influenzae bacteremia and meningitis with beta-lactamase antibiotics.     

Qualitative and quantitative assessment of meningococcal antigens to evaluate the potential strain coverage of protein-based vaccines

A unique multicomponent vaccine against serogroup B meningococci incorporates the novel genome-derived proteins fHbp, NHBA, and NadA that may vary in sequence and level of expression. Measuring the effectiveness of such vaccines, using the accepted correlate of protection against invasive meningococcal disease, could require performing the serum bactericidal assay (SBA) against many diverse strains for each geographic region. This approach is impractical, especially for infants, where serum volumes are very limited. To address this, we developed the meningococcal antigen typing system (MATS) by combining a unique vaccine antigen-specific ELISA, which detects qualitative and quantitative differences in antigens, with PorA genotyping information. The ELISA correlates with killing of strains by SBA and measures both immunologic cross-reactivity and quantity of the antigens NHBA, NadA, and fHbp. We found that strains exceeding a threshold value in the ELISA for any of the three vaccine antigens had ≥80% probability of being killed by immune serum in the SBA. Strains positive for two or more antigens had a 96% probability of being killed. Inclusion of multiple different antigens in the vaccine improves breadth of coverage and prevents loss of coverage if one antigen mutates or is lost. The finding that a simple and high-throughput assay correlates with bactericidal activity is a milestone in meningococcal vaccine development. This assay allows typing of large panels of strains and prediction of coverage of protein-based meningococcal vaccines. Similar assays may be used for protein-based vaccines against other bacteria.     

The molecular study of bacterial virulence: a review of current approaches,illustrated by the study of adhesion in uropathogenicEscherichia coli

Pathogenic bacteria coexist with their hosts in a relationship which most frequently allows persistence of the bacteria without causing disease. In a small proportion of colonised individuals the complex mutual interaction between microbe and host is upset, leading to disease in the host. The investigation of bacterial virulence determinants and their genetic control at the molecular level is an important facet of the development of strategies to combat disease. This review focuses on the investigation of a single pathogenic organism as a means of illustrating modern approaches to the investigation of bacterial virulence. The importance of uropathogenicEscherichia coli in causing acute and recurrent pyelonephritis with the consequent morbidity of chronic renal failure is well established. Pyelonephritis-associated (Pap) pili are likely to be critical virulence factors in uropathogenicE. coli. The evidence for their role in pathogenicity and the control of their expression at the molecular genetic level is discussed.     

Measurement of the T2 relaxation time of ethanol and cerebral metabolites, in vivo.

The SPACE volume selection technique was combined with a spin-echo sequence to measure the transverse relaxation time of the resonances of ethanol and cerebral metabolites in the dog brain, in vivo. The method was extended to measure brain metabolite T2 values in the rat using 1H NMR microspectroscopy. The T2 decays for the resonances of the metabolites N-acetylaspartate, creatine/phosphocreatine, and choline/phosphorylcholine were found to be biexponential with long T2 components of 490, 260, and 350 ms for the dog and 490, 220, and 355 ms for the rat brain, respectively. The existence of a second T2 component may originate from J-coupled nonresolved metabolite resonances. The relaxation decay for the ethanol triplet could be fitted to a single exponential giving a T2 relaxation time of 335 ms. However, given the large errors in the measurement of ethanol peak intensities at short echo times because of overlapping lipid signal and the effects of J-modulation, a biexponential decay with a long T2 component of 335 ms cannot be ruled out. Ambiguities regarding the reported partial detection of the 1H NMR signal of ethanol in the brain are discussed.     

In vivo volume-selective metabolite editing via correlated z-order

Volume-selected 1H NMR spectroscopy was combined with spectral editing to selectively detect brain metabolites. The SPACE localization sequence was used to create a voxel of zeta-magnetization which could then be edited for any scalar coupled metabolite by the use of selective excitation in the ECZOTIC sequence to generate longitudinal spin order. The sequence returns an edited signal with no intrinsic loss of magnetization. The method was applied to observe approximately 10 mM ethanol and 17 mM lactate in the brain of a dog.