Provincial differences in infant deaths in South Africa – an effect of antiretroviral interventions?

Original article

Disseminated bacille Calmette-Guérin disease in HIV-infected South African infants

OBJECTIVE

To determine the population-based incidence of disseminated bacille Calmette-Guérin (BCG) disease in HIV-infected infants (aged <or= 1 year) in a setting with a high burden of tuberculosis and HIV infection coupled with a well-functioning programme for the prevention of HIV infection in infants.

METHODS

The numerator, or number of new cases of disseminated BCG disease, was derived from multicentre surveillance data collected prospectively on infants with a confirmed HIV infection during 2004-2006. The denominator, or total number of HIV-infected infants who were BCG-vaccinated, was derived from population-based estimates of the number of live infants and from reported maternal HIV infection prevalence, vertical HIV transmission rates and BCG vaccination rates.

FINDINGS

The estimated incidences of disseminated BCG disease per 100 000 BCG-vaccinated, HIV-infected infants were as follows: 778 (95% confidence interval, CI: 361-1319) in 2004 (vertical HIV transmission rate: 10.4%); 1300 (95% CI: 587-2290) in 2005 (transmission rate: 6.1%); and 1013 (95% CI: 377-1895) in 2006 (transmission rate: 5.4%). The pooled incidence over the study period was 992 (95% CI: 567-1495) per 100 000.

CONCLUSION

Multicentre surveillance data showed that the risk of disseminated BCG disease in HIV-infected infants is considerably higher than previously estimated, although likely to be under-estimated. There is an urgent need for data on the risk-benefit ratio of BCG vaccination in HIV-infected infants to inform decision-making in settings where HIV infection and tuberculosis burdens are high. Safe and effective tuberculosis prevention strategies are needed for HIV-infected infants.

High incidence of tuberculosis among HIV-infected infants: evidence from a South African population-based study highlights the need for improved tuberculosis control strategies

BACKGROUND

There are limited population-based estimates of tuberculosis incidence among human immunodeficiency virus (HIV)-infected and HIV-uninfected infants aged < or =12 months. We aimed to estimate the population-based incidence of culture-confirmed tuberculosis among HIV-infected and HIV-uninfected infants in the Western Cape Province, South Africa.

METHODS

The incidences of pulmonary, extrapulmonary, and disseminated tuberculosis were estimated over a 3-year period (2004-2006) with use of prospective representative hospital surveillance data of the annual number of culture-confirmed tuberculosis cases among infants. The total number of HIV-infected and HIV-uninfected infants was calculated using population-based estimates of the total number of live infants and the annual maternal HIV prevalence and vertical HIV transmission rates.

RESULTS

There were 245 infants with culture-confirmed tuberculosis. The overall incidences of tuberculosis were 1596 cases per 100,000 population among HIV-infected infants (95% confidence interval [CI], 1151-2132 cases per 100,000 population) and 65.9 cases per 100,000 population among HIV-uninfected infants (95% CI, 56-75 cases per 100,000 population). The relative risk of culture-confirmed tuberculosis among HIV-infected infants was 24.2 (95% CI, 17-34). The incidences of disseminated tuberculosis were 240.9 cases per 100,000 population (95% CI, 89-433 cases per 100,000 population) among HIV-infected infants and 14.1 cases per 100,000 population (95% CI, 10-18 cases per 100,000 population) among HIV-uninfected infants (relative risk, 17.1; 95% CI, 6-34).

CONCLUSIONS

This study indicates the magnitude of the tuberculosis disease burden among HIV-infected infants and provides population-based comparative incidence rates of tuberculosis among HIV-infected infants. This high risk of tuberculosis among HIV-infected infants is of great concern and may be attributable to an increased risk of tuberculosis exposure, increased immune-mediated tuberculosis susceptibility, and/or possible limited protective effect of bacille Calmette-Guérin vaccination. Improved tuberculosis control strategies, including maternal tuberculosis screening, contact tracing of tuberculosis-exposed infants coupled with preventive chemotherapy, and effective vaccine strategies, are needed for infants in settings where HIV infection and tuberculosis are highly endemic.

Night-time and daytime atypical manifestations of gastro-oesophageal reflux disease: frequency, severity and impact on health-related quality of life

BACKGROUND

Respondents with gastro-oesophageal reflux disease (GERD) report having a variety of atypical manifestations. The relationship between these manifestations and disease severity, night-time GERD and functioning has not been determined.

AIM

To determine if atypical manifestations are related to increased disease severity, night-time GERD and decreased functioning.

METHODS

A web survey among US adults was conducted, using a validated GERD screener. Frequency of night-time and daytime typical symptoms (acid regurgitation and heartburn) and atypical manifestations were assessed. Respondents were classified as night-time GERD or daytime GERD based on typical symptom frequency. Prevalence of frequent atypical manifestations (> or =2 days or nights/week) was assessed.

RESULTS

Gastro-oesophageal reflux disease cases had a higher prevalence of each atypical manifestation (P < 0.05 for all) compared with controls. Night-time GERD respondents had a higher prevalence of atypical manifestations compared with daytime GERD respondents (P < 0.05 for most manifestations) and the prevalence of atypical manifestations increased with GERD symptom severity (P < 0.05 for most). Those with atypical manifestations reported lower functioning scores (P < 0.05 for most).

CONCLUSIONS

Respondents with typical GERD symptoms commonly report atypical manifestations, especially those with night-time symptoms and those with greater underlying GERD severity. Respondents with GERD and atypical manifestations had more impaired functioning than those with typical symptoms only.

Stable inhibition of human thymidylate synthase expression following retroviral introduction of an siRNA gene

Thymidylate synthase (TS) is an essential enzyme that synthesizes thymidylic acid in the de novo biosynthetic pathway. Inhibiting TS enzyme activity with substrate or cofactor analogs leads to inhibition of DNA replication and cell death. For this reason, TS is an important target enzyme for cancer chemotherapeutic drugs. We describe an alternative approach to reducing cellular TS enzyme activity using short interfering RNA (siRNA) technology to lower TS mRNA levels. Plasmids that direct the synthesis of siRNAs that target nucleotides 898-916 and 965-983 (relative to the A of the translational start codon) of human TS mRNA were highly effective at reducing TS enzyme levels in transient transfection assays. Infection of HeLa cells with retroviruses that contain the effective siRNA genes led to a stable 80-95% reduction of TS enzyme and mRNA. A similar percent reduction in TS expression was observed in a cell line that overproduces TS enzyme 100-fold due to TS gene amplification. Cells that exhibited the greatest reduction in TS enzyme level grew poorly in medium that lacked thymidine. These observations suggest that siRNA approaches may provide an alternative therapeutic strategy to reduce TS enzyme levels.

Sentinel surveillance of sexually transmitted infections in South Africa: a review

OBJECTIVES

To review studies of sexually transmitted infection (STI) prevalence in South Africa between 1985 and 2003 in selected sentinel populations. To examine how STI prevalence varies between populations and to identify the limitations of the existing data.

METHODS

Studies of the prevalence of syphilis, chancroid, granuloma inguinale, lymphogranuloma venereum, gonorrhoea, chlamydia, trichomoniasis, bacterial vaginosis, candidiasis, and herpes simplex virus type 2 (HSV-2) were considered. Results were included if they related to women attending antenatal clinics or family planning clinics, commercial sex workers, individuals in the general population (household surveys), patients with STIs, patients with genital ulcer disease (GUD), or men with urethritis.

RESULTS

High STI prevalence rates have been measured, particularly in the case of HSV-2, trichomoniasis, bacterial vaginosis and candidiasis. The aetiological profile of GUD appears to be changing, with more GUD caused by HSV-2 and less caused by chancroid. The prevalence of gonorrhoea and syphilis is highest in "high risk" groups such as sex workers and attenders of STI clinics, but chlamydia and trichomoniasis prevalence levels are not significantly higher in these groups than in women attending antenatal clinics.

CONCLUSIONS

The prevalence of STIs in South Africa is high, although there is extensive variability between regions. There is a need for STI prevalence data that are more nationally representative and that can be used to monitor prevalence trends more reliably.

Review article: sleep and its relationship to gastro-oesophageal reflux

Gastro-oesophageal reflux disease (GERD) is among the most common gastrointestinal conditions in the USA. For most symptomatic patients, reflux events occur during both daytime and night-time hours. Whereas daytime reflux events tend to be frequent but brief, reflux events that occur during sleep are comparatively less frequent but significantly longer. Longer oesophageal acid-clearance and acid-mucosal contact times during sleep are at least partly due to several physiological changes associated with sleep, including dramatic declines in saliva production and frequency of swallowing, decreased conscious perception of heartburn and consequent arousal and clearance behaviours, and slower gastric emptying. Obstructive sleep apnea syndrome and obesity seem to predispose some patients to nocturnal GERD, and the presence of either of these conditions may help to identify patients with symptoms consistent with GERD. Recognition and treatment of night-time GERD are important because it can be associated with decreased quality of life (including sleep disruption) and increased risk of serious oesophageal and respiratory complications.

Regulation of ribosomal protein mRNA content and translation in growth-stimulated mouse fibroblasts

When resting (G0) mouse 3T6 fibroblasts are serum stimulated to reenter the cell cycle, the rates of synthesis of rRNA and ribosomal proteins increase, resulting in an increase in ribosome content beginning about 6 h after stimulation. In this study, we monitored the content, metabolism, and translation of ribosomal protein mRNA (rp mRNA) in resting, exponentially growing, and serum-stimulated 3T6 cells. Cloned cDNAs for seven rp mRNAs were used in DNA-excess filter hybridization studies to assay rp mRNA. We found that about 85% of rp mRNA is polyadenylated under all growth conditions. The rate of labeling of rp mRNA relative to total polyadenylated mRNA changed very little after stimulation. The half-life of rp mRNA was about 11 h in resting cells and about 8 h in exponentially growing cells, values which are similar to the half-lives of total mRNA in resting and growing cells (about 9 h). The content of rp mRNA relative to total mRNA was about the same in resting and growing 3T6 cells. Furthermore, the total amount of rp mRNA did not begin to increase until about 6 h after stimulation. Since an increase in rp mRNA content did not appear to be responsible for the increase in ribosomal protein synthesis, we determined the efficiency of translation of rp mRNA under different conditions. We found that about 85% of pulse-labeled rp mRNA was associated with polysomes in exponentially growing cells. In resting cells, however, only about half was associated with polysomes, and about 30% was found in the monosomal fraction. The distribution shifted to that found in growing cells within 3 h after serum stimulation. Similar results were obtained when cells were labeled for 10.5 h. About 70% of total polyadenylated mRNA was in the polysome fraction in all growth states regardless of labeling time, indicating that the shift in mRNA distribution was species specific. These results indicate that the content and metabolism of rp mRNA do not change significantly after growth stimulation. The rate of ribosomal protein synthesis appears to be controlled during the resting-growing transition by an alteration of the efficiency of translation of rp mRNA, possibly at the level of protein synthesis initiation.

Involvement of level I neck lymph nodes in advanced squamous carcinoma of the larynx

This study was performed to evaluate the incidence of metastasis at level I in patients with squamous laryngeal cancer. One hundred consecutive patients with squamous carcinoma of the larynx were submitted to surgical treatment including radical neck dissection. The tumor stage was T3 or T4, and the neck stage was N1-N2c. Lymph node metastases were pathologically confirmed in 80 patients. Metastases were concentrated within level II in 59% of cases, level III in 17% of cases, level IV in 11% of cases, and level V in 6% of cases. Only 2 patients (2%) had detectable tumors in the lymph nodes of the submandibular triangle (level IB). This study shows that patients with laryngeal cancer rarely present metastases at the submandibular triangle, even in advanced local disease with cervical metastasis staged as N1 to N2c. Therefore, dissection of the submandibular triangle is indicated only in the presence of clinical, radiographic, or cytologic evidence of metastatic disease at level I.

Training: putting the pieces together

What steps are needed to develop and successfully manage a comprehensive safety and health program for your institution? Don't overlook a long-term action plan and remember that safety is a shared responsibility, says the author.

The anticytomegaloviral activity of raltitrexed is abrogated in quiescent mouse fibroblasts that overexpress thymidylate synthase

Cytomegalovirus (CMV) replication in non-proliferating cells requires the coordinated expression of the host enzymes responsible for deoxyribonucleotide synthesis. Thymidylate synthase (TS) is an essential cellular enzyme that catalyzes de novo synthesis of thymidylic acid (dTMP). In this report we show that murine CMV (MCMV) replication and DNA synthesis are inhibited in quiescent 3T6 fibroblasts by raltitrexed, a quinazoline-based folate analog that specifically inhibits TS. This antiviral activity was abrogated in LU3-7 cells, a 3T6 derivative that overproduces TS by about 50-fold. These observations indicate that the anticytomegaloviral activity of raltitrexed is associated with TS inhibition and suggest that cellular TS activity is required for efficient CMV replication in quiescent cells.

Inhibition of the mammalian transcription factor LSF induces S-phase-dependent apoptosis by downregulating thymidylate synthase expression

The thymidylate synthase (TS) gene, which is induced at the G(1)-S transition in growth-stimulated cells, encodes an enzyme that is essential for DNA replication and cell survival. Here we demonstrate that LSF (LBP-1c, CP2) binds to sites within the TS promoter and intronic regions that are required for this induction. Mutation of the LSF binding sites inhibits G(1)-S induction of mRNA derived from a TS minigene. Furthermore, expression of dominant-negative LSF (LSFdn) prevents the increase in TS enzyme levels during G(1)-S, and induces apoptosis in growth- stimulated mouse and human cell lines. Such apoptosis can be prevented either by circumventing the TS requirement through addition of low concentrations of thymidine, or by coexpression of the TS gene driven by a heterologous promoter. Induction of apoptosis by LSFdn parallels the process known as thymineless death, which is induced by the TS inhibitor and chemotherapeutic drug 5-fluorodeoxyuridine. Thus, LSF is a novel regulatory factor that supports progression through S-phase by targeting a single gene that is critical for cell survival.

Progress and problems in achieving the United States national target for completion of antituberculosis treatment

SETTING

The target for antituberculosis treatment in the United States is for 90% of patients to complete therapy within 12 months.

OBJECTIVE

To assess progress in achieving the US national target for tuberculosis treatment.

DESIGN

A comparison of treatment outcome in two cohorts of patients with drug-susceptible tuberculosis in California-those reported in 1993-1994 (8488 patients) and 1995-1996 (7823 patients). Risk factors for delay in treatment completion (more than 12 months) were assessed.

RESULTS

The percentage of cases completing treatment within 12 months increased in the 1995-1996 cohort (to 68.2%), primarily due to concomitant reductions in delays in treatment completion (to 11.1%) and defaulting (to 2.4%). Disparities in timely treatment completion narrowed over time and in nearly all subpopulations, especially in groups with lowest treatment completion in the 1993-1994 cohort. Remaining risk factors for delay in treatment completion included AIDS and older ages. A substantial percentage of patients died or moved before treatment completion.

CONCLUSIONS

Despite recent improvements, completion of antituberculosis treatment in California has not reached the national target. Reaching this target will require further reductions in delays in treatment completion and deaths during treatment, and ensuring that patients who move eventually complete treatment.

Intramural tracking: a feature of esophageal intramural pseudodiverticulosis

OBJECTIVE

Our purpose was to determine the frequency of intramural tracking in patients with esophageal intramural pseudodiverticulosis and to characterize the morphologic features of this finding on barium studies.

MATERIALS AND METHODS

A review of radiology files at two institutions revealed 30 cases of esophageal intramural pseudodiverticulosis diagnosed at esophagography. In all cases, the radiographs were reviewed retrospectively to determine the frequency and morphologic features of intramural tracking in these patients. The number and distribution of pseudodiverticula and the presence or absence of strictures or esophagitis were also noted.

RESULTS

Fifteen (50%) of 30 patients with esophageal intramural pseudodiverticulosis had intramural tracking on esophagography. The tracks had an average length of 1.2 cm (length range, 0.3-7 cm) and an average width of 1.6 mm (width range, 1-4 mm). The pseudodiverticula were more numerous and had a more diffuse distribution in patients with tracking than in patients without tracking. Although patients with and without tracking had a similar frequency of strictures and esophagitis, patients with tracking were more likely to have strictures involving the upper or mid esophagus, whereas patients without tracking were more likely to have strictures in the distal esophagus. These findings indicate that intramural tracking is more likely to occur in patients with the diffuse form of esophageal intramural pseudodiverticulosis.

CONCLUSION

Intramural tracking was detected on esophagography in 50% of patients with esophageal intramural pseudodiverticulosis, so this type of tracking is a more common radiographic finding than has previously been recognized. Although intramural tracking has little or no known clinical significance, it is important to be aware of this finding so that it is not mistaken for a large flat ulcer in the esophagus or for an extramural collection associated with esophageal peridiverticulitis.

Transcriptional control elements of the rat thymidylate synthase promoter: evolutionary conservation of regulatory features

The sequence elements that are important for the transcription and regulation of the rat thymidylate synthase (TS) gene were analyzed. The rat TS promoter lacks a TATA box and directs transcriptional initiation at multiple sites between 60 and 20 nt upstream of the AUG translational start codon. Promoter deletion analyses showed that the region between -100 and -42 nt relative to the AUG codon was both necessary and sufficient for high level promoter activity and was designated the essential promoter region. The essential region also had bidirectional promoter activity. Site-directed mutagenesis revealed that four elements were especially important for promoter activity. These include Ets motifs at -85 and -50, an Sp1 motif at -80, and an LSF motif that overlapped the upstream Ets and Sp1 motifs. Inactivation of E2F motifs that are upstream and downstream of the essential promoter region had no measurable effect on promoter activity in transient transfection assays. The rat TS promoter region directed S-phase-specific expression of a stably transfected minigene if a spliceable intron was included in the transcribed region. When the intron was deleted or the E2F motifs were inactivated, expression of the minigene changed very little during the G1 to S transition.

Murine cytomegalovirus stimulates cellular thymidylate synthase gene expression in quiescent cells and requires the enzyme for replication

Herpesviruses accomplish DNA replication either by expressing their own deoxyribonucleotide biosynthetic genes or by stimulating the expression of the corresponding cellular genes. Cytomegalovirus (CMV) has adopted the latter strategy to allow efficient replication in quiescent cells. In the present report, we show that murine CMV (MCMV) infection of quiescent fibroblasts induces both mRNA and protein corresponding to the cellular thymidylate synthase (TS) gene, which encodes the enzyme that catalyzes the de novo synthesis of thymidylic acid. The increase in TS gene expression was due to an increase in gene transcription, since the activity of a reporter gene driven by the mouse TS promoter was induced following MCMV infection. Mutagenesis of the potential E2F-responsive element immediately upstream from the TS essential promoter region abolished the virus-mediated stimulation of the TS promoter, suggesting that the transactivating activity of MCMV infection was E2F dependent. Cotransfection experiments revealed that expression of the viral immediate-early 1 protein was sufficient to mediate the increase in TS promoter activity. Finally, MCMV replication and viral DNA synthesis were found to be inhibited by ZD1694, a quinazoline-based folate analog that inhibits TS activity. These results demonstrate that upregulation of cellular TS expression is required for efficient MCMV replication in quiescent cells.