Epitope-specific humoral immunity to Plasmodium vivax Duffy binding protein

Erythrocyte invasion by Plasmodium vivax is completely dependent on binding to the Duffy blood group antigen by the parasite Duffy binding protein (DBP). The receptor-binding domain of this protein lies within a cysteine-rich region referred to as region II (DBPII). To examine whether antibody responses to DBP correlate with age-acquired immunity to P. vivax, antibodies to recombinant DBP (rDBP) were measured in 551 individuals residing in a village endemic for P. vivax in Papua New Guinea, and linear epitopes mapped in the critical binding region of DBPII. Antibody levels to rDBP(II) increased with age. Four dominant linear epitopes were identified, and the number of linear epitopes recognized by semi-immune individuals increased with age, suggesting greater recognition with repeated infection. Some individuals had antibodies to rDBP(II) but not to the linear epitopes, indicating the presence of conformational epitopes. This occurred in younger individuals or subjects acutely infected for the first time with P. vivax, indicating that repeated infection is required for recognition of linear epitopes. All four dominant B-cell epitopes contained polymorphic residues, three of which showed variant-specific serologic responses in over 10% of subjects examined. In conclusion, these results demonstrate age-dependent and variant-specific antibody responses to DBPII and implicate this molecule in partial acquired immunity to P. vivax in populations in endemic areas.     

The effect on grades of the timing and site of third-year internal medicine clerkships

Two important factors affecting the performances of third-year medical students on their basic internal medicine clerkships were investigated: (1) the effect on their grades of when in the academic year they took the internal medicine clerkship, and (2) the effect on their grades of the site of the clerkship. During the academic years 1983-84, 1984-85, and 1985-86, the Department of Internal Medicine of the University of Illinois College of Medicine at Chicago conducted 12-week junior clerkships at six hospital sites. The study analyzed the 535 students' subjective grades, clerkship examination scores, final grades, and National Board of Medical Examiners Part I (NBME-I) scores. Although students' performances as characterized by subjective evaluations did not improve as the academic year progressed, mean scores on clerkship examinations improved steadily during the same period. The site of the clerkship, whether a community-affiliated hospital or a medical center hospital, affected neither subjective nor objective grades.     

Clearance of Theiler's virus infection depends on the ability to generate a CD8+ T cell response against a single immunodominant viral peptide

Theiler's murine encephalomyelitis virus (TMEV) induces a chronic demyelinating disease in the central nervous system of susceptible mice. Resistance to persistent TMEV infection maps to he D locus of the major histocompatibility complex suggesting a prominent role of antiviral CTL in the protective immune response. Introduction of the D(b) gene into the FVB strain confers resistance to this otherwise susceptible mouse line. Infection of the FVB/D(b) mouse with TMEV provides a model where antiviral resistance is determined by a response elicited by a single class I molecule. Resistant mice of the H-2(b) haplotype mount a vigorous H-2D(b)-restricted immunodominant response to the VP2 capsid protein. To investigate the extent of the contribution of the immunodominant T cell population in resistance to TMEV, FVB/D(b) mice were depleted of VP2-specific CD8(+) T cells by peptide treatment prior to virus infection. Peptide-treated mice were not able to clear the virus and developed extensive demyelination. These findings demonstrate that the D(b)-restricted CD8(+) T cells specific for a single viral peptide can confer resistance to TMEV infection. Our ability to manipulate this cellular response provides a model for investigating the mechanisms mediating protection against virus infection by CD8(+) T cells.     

HIV-1 seroconversion during pregnancy resulting in vertical transmission.

The uptake of antenatal HIV testing in England and Scotland improved from 33% in 1998 to 92% in 2004 after implementing an opt-out policy. However, there is the potential for missing HIV seroconversion during pregnancy unless a further test is carried out between antenatal booking, which mostly occurs between 12-14 weeks, and delivery. We report a 32-year old Caucasian woman who developed a primary symptomatic HIV infection late in pregnancy. Unfortunately, despite antiretroviral treatment, caesarean section and formula feeding to reduce the risk of mother to child transmission (MCT), the baby was found to be infected by 12 weeks of age. Despite a 95% uptake rate at King's College Hospital, another HIV seroconversion during late pregnancy was detected after the partner was admitted with AIDS defining diagnoses. In the absence of national data on HIV seroconversion rates in pregnancy, further maternal HIV testing later in pregnancy, especially for women at-risk in an ethnically diverse area such as London, should be considered.     

Risk factors,clinical course and outcomes of pregnancy-related group A streptococcal infections: retrospective 13-year cohort study

Objectives

To investigate the incidence, risk factors, clinical course and outcomes of pregnancy-related group A streptococcus (GAS) infection.

Differences in professional activities, perceptions of professional problems, and practice patterns between men and women graduates of Jefferson Medical College

Differences between men and women graduates of one medical school in practice patterns, professional activities, and problems were investigated. A questionnaire was mailed in 1986 to 600 physicians, randomly selected from 1,102 who had graduated from Jefferson Medical College of Thomas Jefferson University between 1977 and 1981. Four hundred fifty (364 men and 86 women) responded (75%). The women were less likely than the men to be employed full-time; however, proportionately more women than men held full-time academic appointments, treated patients from low-income families, and served in underserved areas in inner cities. The women reported working fewer hours per week and having fewer patients than did the men. The women published scientific articles as often as did the men but were less likely to serve on professional committees, receive professional awards, or develop medical procedures. The women were less concerned about the oversupply of physicians and malpractice litigation. Implications of the findings for health manpower planning and practice pattern expectations are discussed.     

The Recuperative Effects of REM Sleep and Stage 4 Sleep on Human Performance After Complete Sleep Loss: Experiment 1

Twelve young (17–21 yrs) male Navy recruits volunteered for a sleep loss study. After 4 baseline days, the Ss were completely deprived of sleep for 2 days and nights. Next followed an experimental phase of 2 days and nights after which all Ss received 2 nights of uninterrupted sleep. During the experimental phase, the 4 Ss in the REM-deprived group were aroused whenever they showed signs of REM sleep. The 4 Ss of the stage 4-deprived group were aroused whenever they showed signs of entering stage 4 sleep, and the 4 Ss of the Control group had uninterrupted sleep. All tests (speed and accuracy of addition, speed and accuracy of self-paced vigilance, errors of omission in experimenter paced vigilance, immediate recall of word lists, and mood) showed significant impairment after the first night of complete sleep loss. But during the experimental (sleep-stage-deprivation) and recovery phases, all three groups showed equal rates of recovery. Depriving the S of stage REM or stage 4 during recovery sleep does not affect the recuperation rate. Frequent arousals (50–100 per night) also do not impair recovery. The amount of sleep is probably more important than the kind of sleep.