Application of a radiotelemetric system to evaluate the performance of enteric coated and plain aspirin tablets

The bioavailability of enteric coated and plain aspirin tablets was studied in four beagle dogs. Blood sampling for enteric coated tablets was planned with the aid of a radiotelemetric system. The release of aspirin from its dosage form was detected by monitoring the change in intestinal pH. Aspirin and salicylic acid levels in plasma obtained from the enteric coated dosage form exhibited familiar concentration versus time absorption profiles. Variation in the plasma concentrations of these two compounds within each dog studied (four runs each) was relatively small when time zero was adjusted to the commencement of tablet dissolution. The plasma levels obtained from plain aspirin (three runs each), however, show atypical absorption. The estimated absolute bioavailability was 0.432 +/- 0.0213 and 0.527 +/- 0.0260 for enteric coated and plain aspirin, respectively. Other pharmacokinetic parameters for these two dosage forms such as the highest observed plasma concentration (Cmax) (10.9 +/- 0.535 microgram/mL versus 13.6 +/- 1.88 micrograms/mL) and the time to reach Cmax (tmax) (26.6 +/- 1.94 min versus 31.0 +/- 7.04 min) agree well. The mean values for gastric emptying time, in vivo coating dissolution time, and in vivo disintegration/dissolution time of the tablet core for enteric coated aspirin are 48.7 +/- 7.23 min, 44.3 +/- 3.80 min, and 34.7 +/- 2.04 min, respectively.     

Mycobacterium chelonae causing otitis media in an ear-nose-and-throat practice

Seventeen cases of otitis media caused by Mycobacterium chelonae were detected among patients seen at a single ear-nose-and-throat (ENT) office (Office A) in Louisiana between May 5 and September 15, 1987. All the patients had a tympanotomy tube or tubes in place or had one or more tympanic-membrane perforations, with chronic otorrhea that was unresponsive to standard therapy with antimicrobial agents. Middle-ear exploration in six patients revealed abundant granulation tissue; multiple granulomas and acid-fast bacilli were demonstrated on a section of tissue from one patient with a nonhealing mastoidectomy incision. Thirteen of the 14 ear isolates obtained from patients seen in Office A had the same unusual pattern of high-level resistance to aminoglycosides. M. chelonae and other nontuberculous mycobacteria were recovered from several sources of water in Office A, as well as in another ENT office (Office B) in a neighboring city that was visited by the index patient. Only one additional case was detected in Office B during the same period. Otologic instruments in Office A were cleaned in an ultrasonic bath with tap water and a liquid detergent; the contents of the bath were changed only once weekly. Instruments in Office B were placed in boiling water between patient examinations. This outbreak establishes M. chelonae as an agent of otitis media and underscores the need for high-level disinfection or sterilization of ENT instruments between examinations to prevent the transmission of this organism to patients in the office setting.     

Are outbreaks and sporadic respiratory infections byMycoplasma pneumoniae due to two distinct subtypes?

Thirty-seven clinical isolates ofMycoplasma pneumoniae, cultured from patients' respiratory material between 1986 and 1994, were typed by immunological methods and by polymerase chain reaction (PCR). For immunological typing two monoclonal antibodies (mAb) were used that recognized the P1 adhesion ofMycoplasma pneumoniae strain FH but differed in their ability to inhibit the adherence ofMycoplasma pneumoniae to erythrocytes. The mAb P1.58, which was not able to inhibit adherence, showed reactions with all patients' isolates in immunoblots, whereas the adherence-inhibiting mAb P1.62 reacted with only seven patients' isolates. Due to variations within the P1adhesin genome ofMycoplasma pneumoniae group 1 (Mycoplasma pneumoniae type strain M129) and group 2 (Mycoplasma pneumoniae type strain FH), two primer sets were designed. According to the size of the PCR-amplification products, all clinical isolates that showed no mAb P1.62 reactivity belonged toMycoplasma pneumoniae group 1, whereas mAb P1.62-positive-reacting mycoplasma isolates were characterized as group 2 strains. During an outbreak ofMycoplasma pneumoniae diseases in 1992, all 19 clinical isolates showed no cross-reactivity in immunoblots with the mAb P1.62 and were typed by PCR asMycoplasma pneumoniae group 1 strains. Furthermore, 206Mycoplasma pneumoniae complement fixation test — positive patient sera (titer>140) from the study period were tested for adherence-inhibiting antibodies towards both type strains. Thirty-two sera showed adherence-inhibiting antibodies towards group 1 and 22 towards group 2 mycoplasmas. In only seven sera were adherence-inhibiting antibodies directed to bothMycoplasma pneumoniae groups. The serological data of the outbreak in 1992 revealed that patients withMycoplasma pneumoniae group 1 infections developed adherence-inhibiting antibodies more frequently than did patients infected with group 2, which might have implications for the pathogenesis ofMycoplasma pneumoniae diseases and subsequent infections.     

Evaluation of the Washington State National Pharmaceutical Stockpile dispensing exercise, part II--dispensary site worker findings.

On January 24, 2002, the Washington State Department of Health, in collaboration with local and federal agencies, conducted an exercise of the Centers for Disease Control and Prevention's National Pharmaceutical Stockpile dispensing portion of the Washington State plan. This exercise included predrill planning, training, and the orchestration of services of more than 40 dispensary site workers. These workers provided education and post-exposure prophylaxis for over 230 patient volunteers in the aftermath of a simulated exposure to B. anthracis. This article discusses findings of a postdrill questionnaire completed by 90% of these dispensary site workers who provided triage, education, dispensary, security and other services during this exercise. In general, this dispensing drill promoted confidence in the worker participants and provided an opportunity for these participants to coordinate their activities. This mock bioterrorist preparedness exercise allowed worker participants and observers to review and evaluate the Washington State plan for dispensing the National Pharmaceutical Stockpile. This article is apparently the first published account of dispensary site workers' subjective impressions and quantitative analysis of their postdrill opinions following a simulated bioterrorist post-exposure chemoprophylaxis dispensing exercise.     

Identification of HLA-DRB1*1501-restricted T-cell epitopes from prostate-specific antigen.

The development of immunotherapy for prostate cancer based on the induction of autoimmunity to prostate tissue is very attractive because prostate is not a vital organ beyond the reproductive years. CD4 T cells play an important role in the development of antitumor immune responses, yet the identification of naturally processed MHC Class II-restricted epitopes derived from prostate differentiation antigens has not been described. To facilitate the search for prostate-specific antigen (PSA)-derived MHC class II-restricted peptides, we immunized mice transgenic for HLA-DRB1*1501 with human PSA and showed a robust dose-dependent immune response to the antigen. Screening a library of overlapping 20-mer peptides that span the entire PSA sequence identified two 20-mer peptides, PSA(171-190) and PSA(221-240), which were responsible for this reactivity. Immunization of DR2b transgenic mice with these peptides induced specific responses to the peptide and whole PSA. Identified peptides were used to stimulate CD4 T cells from HLA-DRB1*1501+ patients with a rare condition, granulomatous prostatitis, and who seem to have a preexisting immune response directed against the prostate gland. We previously showed a linkage of granulomatous prostatitis to HLA-DRB1*1501, suggesting that this disease may have an autoimmune etiology. Peptide-specific CD4 T-cell lines were generated from the peripheral blood of these patients as well as one patient with prostate cancer. These lines also recognized whole, processed PSA in the context of HLA-DRB1*1501. This study will be instrumental in understanding the interaction between circulating self-reactive T cells, organ-specific autoimmunity, and antitumor immune response. The use of these peptides for the immunotherapy of prostate cancer is under investigation.     

Dynamic knee valgus in competitive alpine skiers: Observation from youth to elite and influence of biological maturation

Numerous studies investigated the association between dynamic knee valgus and injury risk in post-pubertal and elite athletes; however, normative reference scores for competitive alpine skiers and observations on the development process throughout and beyond athletes' growth spurt are lacking. Thus, the aim of this study was to describe the dynamic knee valgus of competitive alpine skiers during drop jump landings (DJ) and single-leg squats (SLS) with respect to sex, sportive level, and biological maturation. Thirty-seven elite and 104 youth competitive alpine skiers around the growth spurt (U15) were examined for their maximal medial knee displacement (MKD) during DJ and SLS by a marker-based 3D motion analysis evaluating dynamic knee valgus. Additionally, skiers' age, anthropometry and biological maturation were assessed. MKD of youth and elite alpine skiers during DJ was comparable and did not improve with increasing training age. Female U15 skiers (on average further matured) had significantly larger MKD values during DJ than male U15 skiers (less matured) (P < .01). Moreover, MKD during DJ was directly associated with the athlete's individual biological maturation status. MKD values obtained from DJ significantly differed from those obtained during SLS (P < .01). The gender-specific difference in MKD values during DJ and their relationship with maturity offset highlight the fundamental changes to the neuromuscular control system during the growth spurt. Thus, biological maturation needs to be considered as a confounding factor for knee valgus screening. Caution is required when evaluating MKD by using high- and low-dynamic tasks, as corresponding information can differ.     

Antigen affinity and antigen dose exert distinct influences on CD4 T-cell differentiation

Cumulative T-cell receptor signal strength and ensuing T-cell responses are affected by both antigen affinity and antigen dose. Here we examined the distinct contributions of these parameters to CD4 T-cell differentiation during infection. We found that high antigen affinity positively correlates with T helper (Th)1 differentiation at both high and low doses of antigen. In contrast, follicular helper T cell (T_FH) effectors are generated after priming with high, intermediate, and low affinity ligand. Unexpectedly, memory T cells generated after priming with very low affinity antigen remain impaired in their ability to generate secondary Th1 effectors, despite being recalled with high affinity antigen. These data challenge the view that only strongly stimulated CD4 T cells are capable of differentiating into the T_FH and memory T-cell compartments and reveal that differential strength of stimulation during primary T-cell activation imprints unique and long lasting T-cell differentiation programs.Following infection, T-cell receptor (TCR) interactions with foreign peptide/MHC (pMHC) drive the rapid clonal expansion and differentiation of T cells into distinct effector subsets specialized against different classes of microbes. An early bifurcation in CD4 T-cell responses results in the generation of T helper (Th)1 effectors, which regulate innate cell microbicidal function and follicular helper T (T_FH) cells, which migrate to B-cell follicles to regulate germinal center (GC) responses and antimicrobial antibody production (1). After pathogen is cleared, T cells undergo a contraction phase during which the majority of effectors die by apoptosis, leaving behind a population of long-lived memory cells to provide protection upon subsequent reinfection. The decision to differentiate into Th1 and T_FH lineages appears to occur very early in the immune response (2, 3). Initial T-cell priming by dendritic cells (DCs) is sufficient to induce fate-committed Th1 and T_FH cells as early as 3 d after infection, whereas maintenance and further expansion of the T_FH compartment depends on T-cell interactions with B cells (2). Similarly, memory T-cell differentiation occurs very early after infection and is critically dependent on B-cell interactions for optimal priming (4, 5). Importantly, CD4 T-cell differentiation is coupled to division, and unlike CD8 T-cell differentiation, requires constant antigen recognition (6, 7).Although the strength of TCR–pMHC interactions has been shown to directly modulate T-cell expansion and clonal dominance within the Th cell compartment (8, 9), how this influences CD4 T-cell fate is not well understood. Cumulative TCR signaling can be influenced by both antigen affinity and antigen dose (10). In terms of proliferation, higher antigen dose can compensate for lower antigen affinity to some extent, but several reports have shown independent effects on T-cell responses both in vitro and in vivo (10–12). These data indicate that antigen affinity and antigen dose may promote qualitatively distinct TCR signals. Recently, modulation of the overall TCR signal by varying either TCR affinity or antigen dose was shown to influence the pattern of effector T-cell differentiation, with higher affinity ligands or higher antigen dose promoting T_FH generation (13–15). However, another study examining high and low avidity CD4 T-cell responses during viral infection found significant differences in Th1 but not T_FH generation (16). Sustained TCR–pMHC interactions have also been shown to promote memory T-cell differentiation, which is associated with increased TCR avidity (17, 18). These studies, however, have focused on the development of the Th1 memory compartment, which is phenotypically and functionally distinct from the T_FH memory compartment (19, 20). Thus, although strong TCR signals resulting from high antigen affinity or high antigen dose can clearly affect the extent and quality of T-cell differentiation, whether or not T cells can discriminate these signals, and how this contributes to T-cell differentiation during infection, has not been determined.To address this question, we infected mice with varying concentrations of Listeria expressing either high or low affinity antigens for the TCR. By normalizing the degree of proliferation induced by high and low affinity antigens we were able to discern distinct influences of antigen affinity and antigen dose on Th cell differentiation. We observed a strong positive correlation between antigen affinity and Th1 differentiation that occurs early and is dose independent. Importantly, high antigen dose does not compensate for the low efficiency of Th1 differentiation induced by low affinity antigen. In contrast, early T_FH effector generation was observed after priming with high, intermediate, and low affinity antigen, but was not maintained at later time points under conditions of low antigen dose. In addition, we found that T cells activated by either high or low affinity antigen are equally capable of memory T-cell differentiation. Surprisingly, memory T cells generated by either low antigen affinity or low antigen dose maintained their biased effector lineages following recall activation with high affinity antigen. These data indicate that differential strength of stimulation during primary T-cell activation can imprint unique and long lasting T-cell differentiation programs.     

Detecting Selection in the HIV-1 Genome during Sexual Transmission Events

Little is known about whether and how variation in the HIV-1 genome affects its transmissibility. Assessing which genomic features of HIV-1 are under positive or negative selection during transmission is challenging, because very few virus particles are typically transmitted, and random genetic drift can dilute genetic signals in the recipient virus population. We analyzed 30 transmitter–recipient pairs from the Zurich Primary HIV Infection Study and the Swiss HIV Cohort Study using near full-length HIV-1 genomes. We developed a new statistical test to detect selection during transmission, called Selection Test in Transmission (SeTesT), based on comparing the transmitter and recipient virus population and accounting for the transmission bottleneck. We performed extensive simulations and found that sensitivity of detecting selection during transmission is limited by the strong population bottleneck of few transmitted virions. When pooling individual test results across patients, we found two candidate HIV-1 genomic features for affecting transmission, namely amino acid positions 3 and 18 of Vpu, which were significant before but not after correction for multiple testing. In summary, SeTesT provides a general framework for detecting selection based on genomic sequencing data of transmitted viruses. Our study shows that a higher number of transmitter–recipient pairs is required to improve sensitivity of detecting selection.     

A thirty-year review of maternal mortality in Oklahoma, 1950 through 1979

Oklahoma's Maternal Mortality Committee has been active since 1941. During the 30-year period 1950 through 1979, the committee reviewed in detail 75.9% of the pregnancy-related deaths that occurred in Oklahoma. The maternal mortality ratio in 1950 was 95.1/100,000 live births, and for 1979 it was 8.1/100,000 live births, a decrease of 91.5%. The risk of death from childbearing remained greater for black women than for American Indian or white women throughout the three decades. For American Indian women, the risk of death associated with pregnancy has decreased and is almost equal to the risk for white women. The Maternal Mortality Committee estimated that two thirds of Oklahoma's maternal deaths were preventable. The proportion of deaths judged preventable did not vary substantially during the study period. We conclude that maternal mortality in Oklahoma can be reduced to fewer than three deaths per 100,000 live births. Intensive monitoring and investigation of deaths and their causes by local maternal mortality committees continues to be an important mechanism for obtaining information to assist health workers in the prevention of deaths.