Christina Chan

Use of a Live Attenuated Varicella Vaccine to Boost Varicella-Specific Immune Responses in Seropositive People 55 Years of Age and Older: Duration of Booster Effect

Varicella-zoster virus (VZV)-specific T cell immunity was measured in 130 persons > or = 55 years of age 6 years after they received a live attenuated VZV vaccine. Circulating T cells, which proliferated in vitro in response to VZV antigen, were enumerated (VZV responder cell frequency assay). Six years after the booster vaccination, the VZV-responding cell frequency (1/61,000 circulating cells) was still significantly (P < .05) improved over the baseline measurements (1/70,000) and appears to have diminished the expected decline in frequency as these vaccinees aged (to 1/86,000). Ten herpes-zoster--like clinical events were recorded. Although the frequency of these events, approximately 1/100 patient-years, is within the expected range of such events for this age cohort, the number of lesions was small, there was very little pain, and there was no postherpetic neuralgia. These results support the development of a vaccine to prevent or attenuate herpes zoster.

Fluid substitution: Estimating changes in VP without knowing VS

Two methods are presented for estimating the change of seismic P‐wave velocity that accompanies pore fluid changes in a rock in the common situation when S‐wave velocity is unknown. In contrast, Gassmann’s relation operates on the rock bulk modulus, which can only be calculated when both VP and VS are measured. The first method operates directly on the P‐wave modulus and is equivalent to replacing the bulk moduli of the rock and mineral in Gassmann’s relation with the corresponding P‐wave moduli. The second method uses a graphical construction to estimate the decomposition of the measured P‐wave modulus into bulk and shear moduli, which then allows the conventional Gassmann’s formula to be used. When applied to a large set of sandstone data, the predictions of both methods, computed with VP only, are within a few percent of the Gassmann’s relation, using both VP and VS.

Fluid substitution: Estimating changes in V{sub P} without knowing V{sub S}

Two methods are presented for estimating the change of seismic P‐wave velocity that accompanies pore fluid changes in a rock in the common situation when S‐wave velocity is unknown. In contrast, Gassmann’s relation operates on the rock bulk modulus, which can only be calculated when both VP and VS are measured. The first method operates directly on the P‐wave modulus and is equivalent to replacing the bulk moduli of the rock and mineral in Gassmann’s relation with the corresponding P‐wave moduli. The second method uses a graphical construction to estimate the decomposition of the measured P‐wave modulus into bulk and shear moduli, which then allows the conventional Gassmann’s formula to be used. When applied to a large set of sandstone data, the predictions of both methods, computed with VP only, are within a few percent of the Gassmann’s relation, using both VP and VS.

Shedding of Sabin Poliovirus Type 3 Containing the Nucleotide 472 Uracil-to-Cytosine Point Mutation after Administration of Oral Poliovirus Vaccine

A uracil-to-cytosine point mutation at nucleotide (nt) 472 of Sabin oral poliovirus vaccine (OPV) type 3 is found in conjunction with vaccine-associated paralytic poliomyelitis (VAPP). Direct RNA extraction and mutant analysis by polymerase chain reaction and restriction enzyme cleavage were used to identify this point mutation in clinical samples. A total of 238 stool samples were obtained from 28 healthy infants for 6 weeks after OPV vaccination. More than 25% of infants shed OPV3 in the week after vaccination, with a decrease on day 6. A second wave of OPV3 shedding occurred beginning the second week after vaccination and was maintained through the end of the study period. During the first week after vaccination, the proportion of nt 472 mutants in the shed OPV3 increased from undetectable to almost 100%. During the second shedding period, the proportion of nt 472 mutants remained close to 100%. These results suggest that selective mutation drives the VAPP-associated nt 472 point mutation for OPV3 in the human gastrointestinal tract.

Challenges in the practice of human milk nutrition in the neonatal intensive care unit.

The use of human milk for preterm infants has increased over the past decade reflecting an improved awareness of the benefits of human milk. Inherent in this paradigm shift is the recognition that human milk is a living tissue; full of immune cells, probiotics and hundreds of compounds that confer bioactivity and immune protective properties. Together these factors deliver a powerful effect in reducing clinical morbidities such as necrotizing enterocolitis and sepsis in the preterm infant. However, as breastfeeding is not possible for the very premature infant, human milk needs to be introduced in the neonatal intensive care unit through alternative means, resulting in significant handling and manipulation of maternal milk. This presents risks in quality control and provision of optimal nutrition delivery. Therefore, a comprehensive approach to standardizing preterm infant nutrition is essential to optimize the collection, storage, fortification and delivery of human milk to preterm neonates. In this paper we discuss the challenges presented by supporting human milk nutrition, and the rationale for the development of the Supporting Premature Infant Nutrition (SPIN) program at our institution.

Pooling Expressed Breastmilk to Provide a Consistent Feeding Composition for Premature Infants

OBJECTIVE We hypothesized that pooling a mothers expressed breastmilk for 24 hours compared with individual pump session collection of milk would provide a more consistent caloric product without increasing bacterial contamination. STUDY DESIGN We investigated 24-hour pooled breastmilk collection by enrolling 19 mothers who were expressing milk for their infants. Mothers followed a standardized milk collection protocol for 4 study days: daily milk was pooled in a sterile 1-L bottle on Day 1, and on Day 2 milk was aliquoted for each pump session into a sterile 120-mL container. The next week the order of collection was reversed. Milk samples were plated, incubated, and evaluated for bacteria colonization. Milk samples were analyzed for protein, fat, and carbohydrate content. RESULTS There was inherently less variability in the caloric and nutrient content of pooled milk compared with individual samples, in which caloric density varied by as much as 29%. Mothers milk had highly variable bacterial counts ranging from 0 to greater than 100,000 colonies/mL. High bacteria counts (>100,000 colonies/mL) occurred in 14.7% (31 of 211) of individual samples compared with 8.6% (three of 35) of pooled samples (p=0.39). CONCLUSIONS Twenty-four-hour pooling of human milk reduces nutrient and caloric variability without increasing bacterial counts.

Direct extraction of Sabin poliovirus genomes from human fecal samples using a guanidine thiocyanate extraction method

To permit rapid and efficient detection of Sabin poliovirus type 3 from human fecal samples, we developed a guanidine thiocyanate (GuSCN) extraction and reverse transcriptase polymerase chain reaction (RT-PCR) method. Using 10-fold serial dilutions from stock Sabin-Leon 12 a1b poliovirus type 3 at 10(7) TCID(50) per 0.1 ml, genome was detected to a dilution of 10(3) TCID(50) per 0.1 ml. A total of 40 archived fecal samples were examined using this GuSCN extraction method followed by RT-PCR. Fourteen of 20 poliovirus type 3 tissue culture-positive specimens (70%) and two of 20 tissue culture-negative specimens (10%) were detected by GuSCN extraction and RT-PCR. All positive and negative extraction and RT-PCR controls were identified accurately. This GuSCN extraction and RT-PCR technique is rapid, inexpensive, and can be readily adapted to identify genome sequences of other enterovirus types in large numbers of fecal samples. Moreover, the GuSCN technique extracts viral RNA directly from fecal samples, allowing observation of in vivo alterations of genome sequences. Further studies are underway to examine the development of revertant point mutations in the Sabin poliovirus type 3 genome following oral administration of trivalent Sabin Oral Poliovirus Vaccine to humans.

Human milk galectin-3 binding protein and breast-feeding-associated HIV transmission.

Analysis of milk from 247 HIV-infected Zambian mothers showed that galectin-3 binding protein concentrations were significantly higher among HIV-infected mothers who transmitted HIV through breast-feeding (6.51 ± 2.12 &mgr;g/mL) than among nontransmitters but were also correlated with higher milk and plasma HIV RNA copies/mL and lower CD4+ cell counts. The association between galectin-3 binding protein and postnatal transmission was attenuated after adjustment for milk and plasma HIV load and CD4+ cell counts. This suggests that although milk galectin-3 binding protein is a marker of advanced maternal disease, it does not independently modify transmission risk.

Galectin-3 binding protein in human preterm infant umbilical cord plasma

BACKGROUND Galectin-3 binding protein (Gal3BP) is a glycoprotein isolated in colostrum that may be an immunologically active component with effects on the neonatal immune system. This compound has been found in the blood of term newborn infants, but has not been studied in preterm infants. OBJECTIVE Compare umbilical cord plasma Gal3BP concentration between preterm and term infants. STUDY DESIGN Observational study of mother-infant pairs consented at UCSD Medical Center comparing umbilical cord plasma Gal3BP concentration in preterm and term infants. Umbilical cord plasma was collected at birth and stored at -80°C before Gal3BP analysis by ELISA. This study was powered to evaluate differences in preterm and term infant Gal3BP concentration. The secondary aim was to determine the effect of maternal and infant clinical factors on Gal3BP concentration. RESULTS A total of 64 preterm and 30 term umbilical cord plasma samples were analyzed. By univariate analysis, Gal3BP concentration was elevated in the setting of prematurity, maternal diabetes, antenatal steroid exposure, and increasing maternal parity (p <  0.05); and decreased in chorioamnionitis (p = 0.03). Using a multiple linear regression model prematurity, chorioamnionitis and maternal diabetes remained significant. CONCLUSIONS Umbilical cord plasma Gal3BP concentration is elevated in prematurity. This may reflect inflammatory states in infant and mother, but further study is warranted.