Heavy ion beam measurement of the hydration of cementitious materials.

The setting and development of strength of Portland cement concrete depends upon the reaction of water with various phases in the Portland cement. Nuclear resonance reaction analysis (NRRA) involving the (1)H((15)N,alpha,gamma)(12)C reaction has been applied to measure the hydrogen depth profile in the few 100 nm thick surface layer that controls the early stage of the reaction. Specific topics that have been investigated include the reactivity of individual cementitious phases and the effects of accelerators and retarders.

Human immunodeficiency virus type 1 (HIV-1) gp120-specific antibodies in neonates receiving an HIV-1 recombinant gp120 vaccine.

Infants born to human immunodeficiency virus type 1 (HIV-1)-infected mothers were immunized at birth and at ages 4, 12, and 20 weeks with low-, medium-, or high-dose recombinant gp120 vaccine with MF59 adjuvant (HIV-1(SF-2); n=52) or with MF59 alone as a placebo (n=9). An accelerated schedule (birth and ages 2, 8, and 20 weeks) was used for an additional 10 infants receiving the defined optimal dose and for 3 infants receiving placebo. At 24 weeks, anti-gp120 ELISA titers were greater for vaccine-immunized than for placebo-immunized infants on both schedules, and 87% of vaccinees had a vaccine-induced antibody response. At 12 weeks, antibody titers of infants on the accelerated vaccine schedule exceeded those of infants receiving placebo (4949 vs. 551; P=.01), and 63% of the vaccinees met the response criteria. Thus, an accelerated schedule of gp120 vaccinations generated an antibody response to HIV-1 envelope distinct from transplacental maternal antibody by age 12 weeks. These results provide support for further studies of vaccine strategies to prevent mother-to-infant HIV-1 transmission.

Infectivity enhancement by human immunodeficiency virus type 1 Nef is independent of its association with a cellular serine/threonine kinase.

Nef proteins from human immunodeficiency virus type 1 isolate SF2 (HIV-1SF2) and simian immunodeficiency virus isolate mac239 (SIVmac239) have been found to associate with a cellular serine/threonine kinase designated NAK. We have recently shown that the association of Nef with NAK is isolate dependent. To identify the structural basis for Nef-kinase association, several chimeric molecules were constructed between SF2 Nef (binding NAK) and 233 Nef (a primary isolate not binding NAK) and stably expressed in HuT-78 human T cells via retrovirus-mediated gene transfer. The Nef 233/SF2/SF2 chimera in which the N-terminal 37 amino acids of SF2 Nef were replaced by those of 233 Nef showed the same ability as SF2 Nef to bind NAK. The Nef 233/SF2/233 chimera in which the N-terminal 37 amino acids and the C-terminal 72 amino acids of SF2 Nef were replaced by corresponding sequences from 233 Nef completely lost the ability to associate with the kinase activity. Furthermore, replacement of the C-terminal 72 amino acids of 233 Nef with the equivalent SF2 sequence (chimera 233/233/SF2) fully restored kinase association to 233 Nef. These results suggest that (i) the core of Nef is not sufficient for NAK binding, (ii) the C terminus of SF2 Nef contains structural determinants important for association with NAK, and (iii) the failure of 233 Nef to bind NAK is due to a defect in its C terminus. Taking advantage of the C terminus of 233 Nef being nonfunctional and using an infectious clone of HIV-1SF2, we show that association with NAK is not required for Nef-mediated infectivity enhancement. While the strong and reproducible association of some Nef isolates with NAK has been clearly established, the role of NAK in Nef function remains to be fully elucidated.

Enteric pathogens associated with gastrointestinal dysfunction in children with HIV infection.

Infants and young children with HIV infection commonly suffer from gastrointestinal manifestations of their disease. Many HIV infected children have evidence of persistent diarrhoea, malabsorption, malnutrition or growth failure. The aetiology and pathogenesis of gastrointestinal dysfunction in HIV infected children have not been well defined. We performed immunocytochemical analyses on intestinal tissue from 19 HIV-infected children with gastrointestinal dysfunction or growth failure. None of these 19 children had microbial pathogens identified in faecal samples using standard microbiological methods. Intestinal tissues were obtained from the children by biopsy and were examined for antigens from Pneumocystis carinii, cytomegalovirus (CMV) and herpes simplex virus (HSV) using the avidin-biotin-complex immunohistochemical technique and monoclonal or monospecific antibodies. We detected at least one of these pathogens in samples from eight (42%) of 19 HIV infected children. P. carinii was the most prevalent pathogen, found in five of the eight HIV infected children. All of the children with intestinal pneumocystis infection were receiving prophylaxis directed at the prevention of pulmonary disease with this organism and none of them were undergoing active pulmonary infection. We also identified CMV antigens in intestinal tissues from four children and HSV antigens in intestinal tissues from one child. Two children were infected with more than one pathogen. On the other hand, none of these pathogens were found in the tissues obtained from 10 HIV-uninfected patients who had intestinal tissues obtained for chronic non-infectious diarrheal and inflammatory diseases (P < 0.01, Fisher's exact test). Our findings indicate that some children with HIV infection and gastrointestinal dysfunction may be infected with opportunistic pathogens despite negative analyses employing standard microbiological methods. Our study also indicates that HIV infected children can undergo intestinal infection with P. carinii despite the administration of standard immunoprophylactic regimens directed at the prevention of infection with this organism.

Convergent evolution within the V3 loop domain of human immunodeficiency virus type 1 in association with disease progression.

Phylogenetic analysis was used to study in vivo genetic variation of the V3 region of human immunodeficiency virus type 1 in relation to disease progression in six infants with vertically acquired human immunodeficiency virus type 1 infection. Nucleotide sequences from each infant formed a monophyletic group with similar average branch lengths separating the sets of sequences. In contrast to the star-shaped phylogeny characteristic of interinfant viral evolution, the shape of the phylogeny formed by sequences from the infants who developed AIDS tended to be linear. A computer program, DISTRATE, was written to analyze changes in DNA distance values over time. For the six infants, the rate of divergence from the initial variant was inversely correlated with CD4 cell counts averaged over the first 11 to 15 months of life (r = -0.87, P = 0.024). To uncover evolutionary relationships that might be dictated by protein structure and function, tree-building methods were applied to inferred amino acid sequences. Trees constructed from the full-length protein fragment (92 amino acids) showed that viruses from each infant formed a monophyletic group. Unexpectedly, V3 loop protein sequences (35 amino acids) that were found at later time points from the two infants who developed AIDS clustered together. Furthermore, these sequences uniquely shared amino acids that have been shown to confer a T-cell line tropic phenotype. The evolutionary pattern suggests that viruses from these infants with AIDS acquired similar and possibly more virulent phenotypes.

Longitudinal assessment of growth in children born to mothers with human immunodeficiency virus infection.

OBJECTIVES: To describe and to evaluate the longitudinal growth of children born to mothers with human immunodeficiency virus (HIV) infection. DESIGN: Measurements of weight, length (measured in infants in a recumbent position) and height (measured in older children in an upright position), and head circumference were documented and evaluated longitudinally using generalized estimating equations in a group of children born to HIV-infected mothers. Children infected with HIV were compared with uninfected children and with National Center for Health Statistics standards. SETTING: Primary care clinic in an urban hospital devoted to the medical care of children born to HIV-infected mothers. PATIENTS: One hundred nine children born to HIV-infected mothers, 59 HIV-infected and 50 uninfected, between birth and 70 months of age. RESULTS: The mean birth weights of both groups were below the 50th percentile. While the mean weight-for-age curve of uninfected children attained the 50th percentile by age 24 months, the mean birth weight-for-age curve of HIV-infected children remained below the 50th percentile. Weight gain became significantly different between the two groups by age 36 months. The mean birth length-for-age curves of HIV-infected and uninfected children was also below the 50th percentile. The mean height-for-age curve of uninfected children attained the 50th percentile by age 40 months, while that of HIV-infected children remained well below the 50th percentile. Linear growth between HIV-infected and uninfected children diverged earlier than weight, becoming significantly different by age 15 months. CONCLUSIONS: Although children born to HIV-infected mothers are born with weight and length below the 50th percentile, uninfected children catch up, while HIV-infected children remain below the 50th percentile and experience an earlier and more pronounced decrease in linear growth (height-for-age) than in weight-for-age.

Human immunodeficiency virus-specific IgA in infants born to human immunodeficiency virus-seropositive women.

OBJECTIVE: To determine the sensitivity and specificity of human immunodeficiency virus (HIV)-specific IgA for vertically transmitted HIV infection, particularly during the first month of life. DESIGN/SETTING/PATIENTS: Prospective cohort study of 140 infants born to HIV-seropositive women in a large urban teaching hospital and of 248 older infants and children referred for diagnosis and treatment of HIV infection. MAIN OUTCOME MEASURES: The HIV-specific IgA immunoblot results were compared with the infection status of patients as determined by Centers for Disease Control and Prevention (Atlanta, Ga) criteria or by sequential early diagnostic assays for HIV. Sensitivity, specificity, and predictive values were calculated for each age range. RESULTS: Among infants studied from birth, the rate of vertical transmission of HIV was 21.6% (25/116). The sensitivity of HIV-specific IgA for the first month of life was 8.0% (2/25), and the specificity was 90.1% (82/91). Sensitivity increased progressively during the first year of life, and the negative predictive value was 94.6% by 6 to 8 months of age. The positive predictive value of this assay was 18.2% for neonates but was 96% to 100% after the first month of life. CONCLUSIONS: False-positive test results for HIV-specific IgA occurred with diminishing frequency during the first 4 weeks of life, and the frequency of detectable HIV-specific IgA was similar among the HIV-infected and uninfected groups at this age. Beyond 1 month of age, detection of HIV-specific IgA is highly specific and is a useful serum-based assay for early diagnosis of HIV infection. These results suggest that maternal-fetal transfusion is common and support the hypothesis that the majority of maternal-fetal transmission of HIV occurs around the time of parturition.

A controlled trial of intravenous immune globulin for the prevention of serious bacterial infections in children receiving zidovudine for advanced human immunodeficiency virus infection. Pediatric AIDS Clinical Trials Group.

BACKGROUND: Serious bacterial infections are common in children infected with the human immunodeficiency virus (HIV). Studies performed before zidovudine became standard therapy found that intravenous immune globulin decreases the number of serious bacterial infections in these children. We designed a multicenter study to evaluate the efficacy of intravenous immune globulin in children with advanced HIV infection who were receiving zidovudine. METHODS: In a double-blind trial 255 children between 3 months and 12 years of age who had the acquired immunodeficiency syndrome (AIDS) or AIDS-related complex were randomly assigned to receive either intravenous immune globulin (400 mg per kilogram of body weight) (n = 129) or placebo (0.1 percent albumin) (n = 126) every 28 days. All children received 180 mg of zidovudine per square meter of body-surface area orally four times daily. Treatment assignment was stratified according to whether the patients had a history of one or more serious bacterial infections, had previously been treated with zidovudine, or were currently receiving prophylaxis with trimethoprim-sulfamethoxazole. The median length of follow-up was 30.6 months. RESULTS: The estimated two-year rates of serious bacterial infections with confirmed pathogens were 16.9 percent for the immune globulin group and 24.3 percent for the placebo group (relative risk, 0.60; 95 percent confidence interval, 0.35 to 1.04; P = 0.07). The treatment effect was seen primarily among the 174 children who were not receiving trimethoprim-sulfamethoxazole prophylaxis at entry; the estimated two-year rates of infection were 11.3 percent for the immune globulin group and 26.8 percent for the placebo group (relative risk, 0.45; 95 percent confidence interval, 0.22 to 0.91; P = 0.03). For the 81 children who were receiving trimethoprim-sulfamethoxazole prophylaxis initially, the rates were 27.7 percent in the immune globulin group and 17.7 percent in the placebo group (relative risk, 1.26; 95 percent confidence interval, 0.44 to 3.66; P = 0.67). The two-year survival was similar in the two groups: 79.2 percent among immune globulin recipients and 75.4 percent among placebo recipients (P = 0.41). CONCLUSIONS: In children with advanced HIV disease who are receiving zidovudine, intravenous immune globulin decreases the risk of serious bacterial infections. However, this benefit is apparent only in children who are not receiving trimethoprim-sulfamethoxazole as prophylaxis.

Effect of enteral tube feeding on growth of children with symptomatic human immunodeficiency virus infection.

Malnutrition and growth failure are frequent clinical consequences of human immunodeficiency virus (HIV) infection in children. Tube feeding is a means by which to increase the enteral intake of nutrients. We examined the effect of tube feeding in 18 children, median age 6 months (range, 3-159). Tube feedings were initiated due to growth failure in all, which was also associated with dysfunctional swallowing or aspiration in seven children and gastroesophageal reflux in two. Tube feedings were infused via nasogastric tube (n = 4) or gastrostomy tube (n = 14) and were continued for a median of 8.5 months (range, 2-24). Stoma complications developed in three children with gastrostomy tubes; these were the only tube-related side effect. Tube feedings were discontinued due to noncompliance (n = 3), gastrostomy leakage (n = 2), intolerance (n = 2), and death (n = 3). Anthropometric changes were evaluated comparing mean standard deviation scores (Z) before and after tube feeding. Tube feeding resulted in significantly increased weight for age (Z, -2.13 +/- 0.7 vs. -1.46 +/- 1.4; p = 0.04), weight for height (Z, -1.07 +/- 1.0 vs. -0.13 +/- 1.0; p = 0.004), and arm fat area (Z, -1.75 +/- 1.3 vs. -0.62 +/- 1.2; p = 0.01). However, tube feeding did not result in significant changes in height for age (Z, -1.93 +/- 0.8 vs. -1.74 +/- 1.6) or arm muscle area (Z, -1.24 +/- 0.9 vs. -0.57 +/- 1.2). Tube feedings effectively increased the weight of HIV-infected children in this study, but they were not sufficient to correct linear growth deficits.

Acid dissociation of immune complexes improves diagnostic utility of p24 antigen detection in perinatally acquired human immunodeficiency virus infection.

Since acid treatment of serum is known to disrupt immune complexes, the diagnostic utility of the p24 antigen assay was examined after acid treatment of 345 serum samples from 158 children born to women infected with human immunodeficiency virus (HIV). Although the p24 antigen assay after acid treatment was negative in 9 HIV-1-infected children < 1 week old, antigen was detectable at high levels in all 30 samples obtained from infected children 1-9 months old. Overall, antigen was positive in 145 (sensitivity 89.5%) of 162 samples from 47 HIV-1-infected children > or = 1 month old. In contrast, the sensitivity of the p24 antigen assay without acid dissociation was only 18% (P < .001). Among the 76 uninfected children, 132 (specificity 99.2%) of 133 specimens were p24 antigen-negative after acid dissociation. These results demonstrate that acid treatment of serum markedly improves the sensitivity and predictive value of the p24 antigen assay for diagnosis of perinatally acquired HIV-1 infection in children 1 month of age or older.

Phase I-II study of piperazinedione in adults with solid tumors and acute leukemia.

Piperazinedione was administered to 79 patients with solid tumors on an intermittent schedule with single doses of 1.5-36 mg/m2. Courses were usually repeated at 4-week intervals. Twenty-five patients with leukemia were treated at doses of 18-36 mg/m2 (occasionally for 2 successive days) every 1-4 weeks. Of 48 evaluable patients with malignant melanoma, three (6%) achieved partial remission and nine (20%) had stable disease. Eight of 17 (47%) patients with adenocarcinomas and one of two (50%) patients with lymphomas also had stable disease. Six of 14 (43%) patients with acute myelogenous leukemia showed hematologic improvement, as did one of 11 (9%) patients with blast cell crisis of chronic myelogenous leukemia. The principal toxic effect was myelosuppression, which occurred in 69% of the patients with solid tumors. Profound bone marrow aplasia occurred in 19% of the patients, resulting in six deaths (8%). Risk factors for marrow aplasia included extensive prior therapy, prior nitrosoureas, cumulative toxicity from piperazinedione, and abnormal liver function tests. The recommended doses for further studies are 9 mg/m2 for patients with risk factors for marrow aplasia, 12 mg/m2 for patients with prior therapy, 15 mg/m2 for previously untreated patients, and 24-36 mg/m2 for patients with acute leukemia.