Design, synthesis and biological evaluation of 5$\sp\prime$-mononucleotide prodrugs: Strategies to introduce nucleotides into cells

The neutral bis ((pivaloyloxy)methyl) (PIV$\sb2\rbrack$ derivatives of FdUMP, ddUMP, and AZTMP were synthesized as potential membrane-permeable prodrugs of FdUMP, ddUMP, and AZTMP. These compounds were designed to enter cells by passive diffusion and revert to the parent nucleotides after removal of the PIV groups by hydrolytic enzymes. These prodrugs were prepared by condensation of FUdR, ddU, and AZT with PIV$\sb2$ phosphate in the presence of triphenylphosphine and diethyl azodicarboxylate (the Mitsunobo reagent). PIV$\sb2$-FdUMP, PIV$\sb2$-ddUMP, and PIV$\sb2$-AZTMP were stable in the pH range 1.0-4.0 (t$\sb{1/2} = {>}$100 h). They were also fairly stable at pH 7.4 (t$\sb{1/2} = {>}$40 h). In 0.05 M NaOH solution, however, they were rapidly degraded (t$\sb{1/2} < 2$ min). In the presence hog liver carboxylate esterase, they were converted quantitatively to the corresponding phosphodiesters, PIV$\sb1$-FdUMP, PIV$\sb1$-ddUMP, and PIV$\sb1$-AZTMP; after 24 h incubation, only trace amounts of FdUMP, ddUMP, and AZTMP (1-5%) were observed indicating that the PIV$\sb1$ compounds were poor substrates for the enzyme. In human plasma, the PIV$\sb2$ compounds were rapidly degraded with half-lives of less than 5 min. The rate of degradation of the PIV$\sb2$ compounds in the presence of phosphodiesterase I was the same as that in buffer controls, indicating that they were not substrates for this enzyme. In the presence of phosphodiesterase I, PIV$\sb1$-FdUMP, PIV$\sb1$-ddUMP, and PIV$\sb1$-AZTMP were converted quantitatively to FdUMP, ddUMP, and AZTMP.^ PIV$\sb2$-ddUMP and PIV$\sb2$-AZTMP were effective at controlling HIV type 1 infection in MT-4 and CEM tk$\sp-$ cells in culture. Mechanistic studies demonstrated that PIV$\sb2$-ddUMP and PIV$\sb2$-AZTMP were taken up by the cells and converted to ddUTP and AZTTP, both potent inhibitors of HIV reverse transcriptase. However, a potential shortcoming of PIV$\sb2$-ddUMP and PIV$\sb2$-AZTMP as clinical therapeutic agents is that they are rapidly degraded (t$\sb{1/2}$ = approx. 4 minutes) in human plasma by carboxylate esterases. To circumvent this limitation, chemically-labile nucleotide prodrugs and liposome-encapsulated nucleotide prodrugs were investigated. In the former approach, the protective groups bis(N, N-(dimethyl)carbamoyloxymethyl) (DM$\sb2$) and bis (N-(piperidino)carbamoyloxymethyl) (DP$\sb2$) were used to synthesize DM$\sb2$-ddUMP and DP$\sb2$-ddUMP, respectively. In aqueous buffers (pH range 1.0-9.0) these compounds were degraded with half-lives of 3 to 4 h. They had similar half-lives in human plasma demonstrating that they were resistant to esterase-mediated cleavage. However, neither compound gave rise to significant concentrations of ddUMP in CEM or CEM tk$\sp-$ cells. In the liposome-encapsulated nucleotide prodrug approach, three different liposomal formulations of PIV$\sb2$-ddUMP (L-PIV$\sb2$-ddUMP) were investigated. The half-lifes of these L-PIV$\sb2$-ddUMP preparations in human plasma were 2 h compared with 4 min for the free drug. The preparations were more effective at controlling HIV-1 infection than free PIV$\sb2$-ddUMP in human T cells in culture. Collectively, these data indicate that PIV$\sb2$-FdUMP, PIV$\sb2$-ddUMP, and PIV$\sb2$-AZTMP are effective membrane-permeable prodrugs of FdUMP, ddUMP, and AZTMP. ^

SYNTHESIS AND BIOLOGICAL EVALUATION OF ANTITUMOR ALDOPHOSPHAMIDE ACETALS

Although the major metabolic pathways of cyclophosphamide are well established, the mechanism of antitumor drug selectivity is highly controversial. However, it is widely accepted that aldophosphamide, one of the primary metabolites, plays a crucial role in drug selectivity. In an attempt to gain a better understanding of the mechanism of selectivity of cyclophosphamide, a series of aldophosphamide analogs have been synthesized.^ The new analogs, unlike aldophosphamide, are relatively stable in neutral solution; however, they are converted rapidly to aldehydo intermediates in the presence of carboxylate esterase. Due to structural differences, these analogs may be classified into three different groups, arbitrarily designated as A, B, C, depending upon the facility with which the intermediate aldehydes form 4-hydroxy cyclic tautomers. The half-life of the aldehydo/4-hydroxy cyclic tautomeric mixture is longer for bis(acetoxy)aldophosphamide acetal I (a representative of group A), shorter for the n-ethyl analog III (B), and shortest for the N,N-dimethyl analog IV (C). The ratio of aldophosphamide: 4-hydroxycyclophosphamide at pseudoequilibrium is 1: 4 for compound I, 1: 2 for compound III and 0: 1 for compound IV. The therapeutic efficacy of these compounds are group A $>$ group B $>$ group C. It is apparent that the equilibrium position between the aldehydo and 4-hydroxy cyclic tautomers, which determines their stability, is a crucial determinant of both the cytotoxicity and antitumor selectivity. These findings, taken in conjunction with the aldehyde dehydrogenase selectivity hypothesis, may provide an explanation for the unique antitumor activity of cyclophosphamide. ^

Environmental and behavioral risk factors for moderate or severe rotavirus diarrhea in children less than 24 months

On a global basis rotaviruses are the most important agents involved in childhood diarrhea. In developing countries they account for 6% of all diarrheas and 20% of all diarrhea related deaths of children under 5 years of age, with over 1 billion episodes and over 4 million deaths annually. Given the disease burden, there is a need for better understanding the risk factors involved in rotavirus disease, to identify areas of intervention. In order to provide this information, two areas were developed: a review of the literature, examining the causal evidence for rotavirus diarrhea and a case comparison study. The case comparison study analyzed two areas: identifying climate factors and, identifying environmental and behavioral risk factors. The literature review showed that few analytical studies have identified specific risk factors such as home environment, and a winter seasonal trend for temperate areas, but in key areas evidence is contradictory. The case comparison study for climate factors demonstrated that seasonality occurs in a tropical country like Venezuela and that a complex interplay between weather conditions contribute to the seasonal pattern. A positive association between rain fall (OR 4.1); dew point (OR 2.3) and temperature differential during the day (OR 1.4) and, an inverse association with temperature (OR 0.5) and relative humidity (OR 0.8) was found. This information is useful in understanding the seasonal pattern of rotavirus and for planning health care needs. The second analysis demonstrated that environmental variables such as crowding (OR 14.3), contact with someone with an infectious disease (OR 4.9) and animal ownership (OR 2.3) were important. Restricting the analysis to animal owners demonstrated that living In a rural settling (OR 13.8), defecating in inappropriate places (OR 7.2), crowding(4.2) and indoor animals (4.0) are of importance. Behavioral variables identified were: lack of breast feeding (OR 4.0) and visiting when someone was sick (OR 3.4). Biological and demographic variables of importance were: age, with a dose response relationship; undernurishment (OR 11.3) and household per capita monthly income less than US $ 16.30 (OR 8.5). Using a diarrhea compeer group we found that, although some of the previous variables were of importance, no major differences were found. These findings are important in identifying paths for prevention and further research. ^

Development and formative evaluation of an obesity prevention intervention for the pediatric primary care setting: Helping HAND (Healthy Activity and Nutrition Directions)

As the obesity epidemic continues to increase, the pediatric primary care office setting remains a relatively unexplored arena to offer obesity prevention interventions for children. The increased risk for adult obesity among 10 to 14 year-old children who are overweight, suggests obesity prevention programs should be introduced just before this age or early in this age period. Research is also accumulating on the importance of targeting parents along with children, since parents are in charge of the home environment for children. Therefore, the aim of this project was to develop an obesity prevention program called Helping HAND (Healthy Activity and Nutrition Directions) based on Social Cognitive Theory and authoritative parenting techniques for the pediatric primary care setting and conduct one-on-one interviews with parents as the initial formative evaluation of the intervention material for the obesity prevention intervention. A secondary aim of the project was to determine the feasibility of identifying appropriate subjects for the intervention, and conducting qualitative evaluations of the materials through recruitment through pediatric primary care settings. ^

The Skip To Breakfast project: Development, implementation, and feasibility evaluation of an intervention to increase healthful breakfast consumption among fifth grade students and their families

Children and adults frequently skip breakfast and rates are currently increasing. In addition, the food choices made for breakfast are not always healthy ones. Breakfast skipping, in conjunction with unhealthy breakfast choices, leads to impaired cognitive functioning, poor nutrient intake, and overweight. In response to these public health issues, Skip To Breakfast, a behaviorally based school and family program, was created to increase consistent and healthful breakfast consumption among ethnically diverse fifth grade students and their families, using Intervention Mapping™. Four classroom lessons and four parent newsletters were used to deliver the intervention. For this project, a healthy, "3 Star Breakfast" was promoted, and included a serving each of dairy product, whole grain, and fruit, each with an emphasis on being low in fat and sugar. The goal of this project was to evaluate the feasibility and acceptability of the intervention. A pilot-test of the intervention was conducted in one classroom, in a school in Houston, during the Fall 2007 semester. A qualitative evaluation of the intervention was conducted, which included focus groups with students, phone interviews of parents, process evaluation data from the classroom teacher, and direct observation. Sixteen students and six parents participated in the study. Data were recorded and themes were identified. Initial results showed there is a need for such programs. Based on the initial feedback, edits were made to the intervention and program. Results showed high acceptability among the teacher, students, and parents. It became apparent that students were not reliably getting the parent newsletters to their parents to read, so a change to the protocol was made, in which students will receive incentives for having parents read newsletters and return signed forms, to increase parent participation. Other changes included small modifications to the curriculum, such as, clarifying instructions, changing in-class assignments to homework assignments, and including background reading materials for the teacher. The main trial is planned to be carried out in Spring 2008, in two elementary schools, utilizing four, fifth grade classes from each, with one school acting as the control and one as the intervention school. Results from this study can be used as an adjunct to the Coordinated Approach To Child Health (CATCH) program. ^

Process and outcome evaluation of the hepatitis B perinatal vaccination program in Houston, Texas, 1991--1993

A retrospective cohort study was designed to evaluate the compliance of vaccination dose schedules and vaccination effectiveness at 12 months of age among a total of 226 high-risk infants born to HBsAg-positive pregnant women who participated in the HBV Perinatal Vaccination Program in Houston, Texas, 1991-1993.^ The seroprevalence of HBsAg-positivity was 0.5% among pregnant women who attended prenatal clinics in Houston, Texas, 1991-1993. The Asian women had the highest seroprevalence rate (5.9%), followed by black (1.9%), white (0.7%), and Hispanic women (0.3%). The seroprevalence of HBsAg increased with age (p =.02); the highest seroprevalence rate found among the $>$40 group (5.4%), followed by the 20-40 age group, and the $<$20 age. A steady increase was observed in the number of infants, from 45 in 1991, to 103 in 1993. The majority of these infants were black (58.0%), followed by Hispanic (28.8%), Asian (8.4%), and white infants (4.0%). Significant increases were observed from 1991 to 1993 in the number of infants who initiated vaccination (86.7% to 98.1%, p =.02) and in those infants who were post-tested at 12 months of age (24.4% to 44.7%, p =.04). During the same period an increase was also observed in the number of infants who completed the vaccination dose schedules (62.2% to 72.8%, p =.37). The compliance rates were not statistically significant regarding gender, race or ethnicity, health service area, medical referral source, and residential geographic areas. About 56.0% of the reasons cited for non-compliance among the 144 infants who neither completed the vaccination dose schedules nor received the 12-month post-test were "moved," and "no response/not at home." A total of 82 infants completed the vaccination dose schedules and were post-tested at 12 months of age for anti-HBs-positivity, and 96.3% of these infants seroconverted. A race-specific statistically significant seroconversion difference was found among infants who received all vaccination doses and were post-tested at 12 months of age (100% for the black and the white, 96.3% for the Hispanic, and 80.0% for the Asians infants, p =.05).^ From a public health perspective, the HBV Perinatal Vaccination Program improved during its first three years (1991-1993). It was effective in preventing perinatal HBV infection in almost 97.0% of infants who were vaccinated and post-tested. To increase the efficiency and efficacy of the program, the following recommendations are proposed: (1) Increase the vaccination compliance rate by educating and improving the tracking, communication and coordination channels with those individuals involved in the process and by increasing staff resources. (2) Reduce the post-test vaccination non-compliance by post-testing infants simultaneously with third vaccination dose at 6 months of age, and only post-test those infants who are anti-HBs-negative at 9-12 months of age. (Abstract shortened by UMI.) ^

A STUDY OF THE RELATIONSHIP BETWEEN SELF-ASSESSMENT AND CLINICAL EVALUATION OF HEARING STATUS

The relationship was explored between a subjective measure of hearing status, derived from a functional self-assessment expressed in terms of ability to hear and understand spoken words, and a comparable objective measure of hearing status, obtained from a speech reception test. The Augmentation Survey of the Health and Nutrition Examination Survey of the National Center for Health Statistics provided the necessary data for a sample of 3059 adults. Using chi-square tests for the subsample with the highest level of objectively assessed hearing status, favorable subjective assessments were found to be significantly associated with higher income, lower age group, higher level of educational attainment, greater psychological adjustment, fewer symptoms of depression, and higher self-ratings of overall health. In a linear regression with self-assessment of hearing status as the dependent variable, less than one-quarter of the variation could be explained by objective status and the six explanatory variables.^

THE ALCOHOL TREATMENT PROFILE SYSTEM: ITS DEVELOPMENT AND AN EVALUATION OF ITS CAPABILITIES

The development of the Alcohol Treatment Profile System (ATPS) was described and an evaluation of its perceived value by various States was undertaken, The ATPS is a treatment needs assessment tool based on the unification of several large national epidemiologic and treatment data sets. It was developed by the National Institute on Alcohol Abuse and Alcoholism (NIAAA) and responsibility for its creation was given to the NIAAA's Alcohol Epidemiologic Data System (AEDS). The ATPS merges county-level measures of alcohol problem prevalence (the specially constructed AEDS Alcohol Problem Indicators), indicating "need" for treatment, and treatment utilization measures (the National Drug and Alcohol Treatment Utilization Survey), indicating treatment "demand." The capabilities of the ATPS in the unique planning and policy-making settings of several States were evaluated.^