Effect of faecal consistency on virological diagnosis.

A study was set up to investigate the effect of consistency of routine faecal specimens on the diagnostic yield by electron microscopy (EM) and virus isolation. A total of 3078 specimens were characterized as solid, semisolid, or liquid. Of 2568 specimens processed by EM a virus was demonstrated in 8.6% of liquid, 19.9% of semisolid and 25.2% of solid specimens (Chi-squared for linear trend, P value <0.0001). This observation was valid for both adenovirus (2.4%, 5.0% and 6.6%) and rotavirus (5.2%, 13.6% and 16.6%). Virus isolation was positive in 3.6% of liquid, 17.4% of semisolid and 18.1% of solid specimens. (Chi-squared for linear trend, P value <0.0001). We suggest that solid faecal specimens at the end of an episode of diarrhoea will have a higher diagnostic yield than liquid specimens at the peak of symptoms. Our findings repudiate the commonly held dogma that viruses of gastroenteritis are more likely to be found in liquid than in solid faecal specimens. This finding has important implications for those establishing diagnostic algorithms for the investigation of viral gastroenteritis.

Intermolecular interactions involved in solute retention on carbon media in reversed-phase high-performance liquid chromatography.

Carbon adsorbents for RPLC separations are greatly underutilized due to the poor chromatographic properties of the earliest commercially available materials and our limited understanding of solute interactions with the solid surface. Previously, we reported on the properties of a carbon surface prepared by vapor deposition on porous zirconia microspheres. The resulting material is a new type of carbon sorbent with considerably improved chromatographic properties. Here we present a fundamental study of the intermolecular interactions influencing solute retention on these novel carbon phases under RPLC conditions. Retention on seven unique carbon phases has been correlated with solute descriptors of dispersion, dipolarity/polarizability, and hydrogen bond basicity through the use of linear solvation energy relationships (LSERs). In stark contrast, conventional bonded phases do not show the large contribution from dipolarity/ polarizability, that is observed on these types of carbon. The presence of this interaction indicates a distinct difference between carbon and conventional bonded RPLC phases. Other results suggest that solvent sorption plays a significant role in controlling solute retention on carbon. In addition, we investigated the temperature dependence of retention on carbon and found typical RPLC-like behavior.

Diastereomeric selectivity of carbon-coated zirconia reversed-phase liquid chromatographic media.

The determination of enantiomeric excess, that is, the relative amount of any pair of optical antipodes, constitutes a integral part of the work of analytical and synthetic chemists involved in natural products research or pharmaceutical development. Mosher's reagent [alpha-methoxy-alpha-(trifluoromethyl)phenylacetyl chloride] has evolved into a major tool for the determination of absolute configuration by NMR. We report here on the separation of diastereomers formed by derivatizing enantiomers with Mosher's reagent. We have shown that reversed-phase liquid-solid adsorption chromatography on carbon surfaces frequently gives considerably superior resolution of diastereomeric pairs than does RPLC on conventional bonded phases. The improved resolution results from the very high sensitivity of solid carbon surfaces to the geometric organization of the solute rather than from differences in column efficiency. We compare the separation of pharmaceutically and biologically important stereoisomeric mixtures, including (+/-)-warfarin and (+/-)-amino acid esters, on both conventional bonded phases and carbon surfaces prepared by chemical vapor deposition of organic compounds on porous zirconia microparticles.

Prevention of perinatal transmission of hepatitis B virus (HBV): a comparison of two prophylactic schedules.

Perinatal transmission of hepatitis B virus (HBV) from HBsAg carrier mothers who were HBeAg+, antiHBe+, or negative for both HBe markers, was interrupted using either 4 doses of vaccine, or one dose of hepatitis B immunoglobulin (HBIG) at birth, combined with 4 doses of vaccine. In those infants who received HBIG at birth, the antiHBs titre was significantly higher at 1 and 2 months old, but at 6, 9, and 18 months old, there was no significant difference. Among the infants of carrier mothers who did not display HBeAg (i.e., were antiHBe+, or negative for both HBe markers), a transient subclinical infection would have been expected in around 10% had there been no intervention. No evidence of such infection was detected, and no difference in outcome was found between the two treatment groups. Amongst infants born to HBeAg+ carrier mothers, infection occurred in 1 out of 8 who had received HBIG and vaccine, and in 3 of 8 who had received vaccine only. The difference in outcome was not statistically significant, but the numbers analysed were small. The infections which occurred in spite of prophylaxis may be attributable to in utero infection, poor response to vaccine by the infant, or to the mother having a particularly high HBV-DNA level. HBIG given at birth to infants of HBeAg+ carrier mothers may enhance the protection of infants who are destined to be poor responders to vaccine.

Selective C7 complement deficiency causing recurrent meningococcal infection.

We report on two sisters both with complete absence of the 7th component of complement. This congenital immunodeficiency disorder is associated with recurrent bacterial infection, especially that due to Neisseria species. These cases illustrate many of the well-recognised features of this disorder, but in one patient the illness was complicated by infective endocarditis due to N. meningitidis, a feature not previously reported.

Children with gastroesophageal reflux with or without partial thoracic stomach (hiatal hernia) have normal gastric emptying.

Gastric emptying was measured using a modification of the double-sampling dye dilution technique in 16 children with gastroesophageal reflux and partial thoracic stomach (hiatal hernia), 13 with reflux per se, and 12 controls with nonspecific vomiting. No differences could be demonstrated between the rate of emptying in these groups. Our study failed to provide a rational explanation for the copious projectile vomiting that is a frequent manifestation of these disorders.

Trimethoprim in enteric fever.

Seventy-one patients suffering from typhoid or paratyphoid fever were treated with trimethoprim. Sixty-three were cured. Only three patients continued to excrete Salmonella typhi in stools at the time of discharge from hospital. Trimethoprim alone is a suitable agent for the treatment of enteric fever.

Parents' understanding of coeliac disease and diet.

Parents of 50 children with coeliac disease were questioned about their knowledge of the disorder and the child's dietary compliance. Twenty of 50 parents admitted that compliance was less than strict. This correlated with poor knowledge of the disease which in turn was related to the family's social status. Membership of the Coeliac Society (23 of 50) correlated with both parental understanding and dietary compliance. Greater emphasis on dietary compliance and education of parents and patients is required.