Excluding familial hypocalciuric hypercalcaemia before surgery for primary hyperparathyroidism - a practical evaluation of urinary calcium using a retrospective cohort design

INTRODUCTION

Familial hypocalciuric hypercalcaemia (FHH) and primary hyperparathyroidism (PHPT) are both associated with raised serum calcium and parathyroid hormone (PTH) levels; the former should be excluded in patients undergoing surgery for the latter. Twenty-four-hour urinary calcium collections (24UCA) can be performed to quantify total calcium excreted; however, results of this method do not take into account factors such as kidney function. Current guidelines suggest measuring urine calcium to creatinine clearance ratio (CCCR) as the initial step. The aim of this study was to evaluate the use of CCCR and 24UCA in a cohort design, to reliably exclude FHH patients before surgery for PHPT.

METHODS

A retrospective cohort study of all patients having urine calcium investigations in a single centre, over a 2-year period was performed. Relevant biochemical data and recorded diagnoses were collected.

RESULTS

In total, 296 urine calcium measurements were included from 199 patients. Ten (5%) had genetically confirmed or suspected FHH, 171 (85.9%) had surgically proven or suspected PHPT and the remainder had other diagnoses. At a CCCR cut-off of ≤0.020, positive and negative predictive values (PPV and NPV) were 2.33% and 100%, respectively. At a cut-off of ≤0.015, NPV was maintained at 100% and PPV increased to 3.28%. Low 24UCA measurements (<2.5mmol/L/24h) generated a NPV for FHH of 95.2%.

CONCLUSION

A CCCR measurement below 0.020 should raise the possibility of FHH and genetic screening should be considered. 24UCA had a lower predictive power to exclude FHH (NPV), and measurements should be interpreted in the context of renal function.

Spontaneous thyroid abscesses without underlying malignancy: a differential diagnosis for recent onset or rapidly growing thyroid masses

Thyroid abscess is a rare cause of neck swelling in patients. The rich iodine environment, good vasculature and protective capsule make bacterial growth suboptimal. We present two cases of thyroid abscess without underlying thyroid cancer in immunocompromised patients presenting to a thyroid unit. The demographics, clinical details, investigation, management and outcomes of two patients with thyroid abscess were reviewed. Two octogenarian women were referred with neck lumps originating in the thyroid gland. Ultrasound demonstrated fluid collection in the thyroid, aspiration of which demonstrated Escherichia coli. The patients had underlying diabetes mellitus and raised inflammatory markers at presentation. Both were treated with antibiotics and follow-up demonstrated complete resolution of infection with no underlying thyroid neoplasm. Thyroid abscesses are an important differential diagnosis in rapidly growing thyroid masses due to the potential for rapid deterioration, especially in patients with conditions or medications causing immunosuppression. Urgent admission should be considered to facilitate prompt intervention and rapid recovery.

Protocol for an open-label, single-arm trial of HIV pre-exposure prophylaxis (PrEP) among people at high risk of HIV infection: the NSW Demonstration Project PRELUDE

INTRODUCTION

Despite a number of HIV prevention strategies, the number of new HIV infections remains high. In Australia, over three-quarters of new HIV diagnoses are in gay and bisexual men (GBM). Pre-exposure prophylaxis (PrEP) has been shown to be effective at preventing new HIV infections in several randomised trials. The PRELUDE study aims to evaluate the implementation of PrEP in healthcare settings in New South Wales (NSW), Australia, among a sample of high-risk adults.

METHODS AND ANALYSIS

PRELUDE is an ongoing open-label, single-arm demonstration project, conducted in public and private clinics across NSW, Australia. Enrolment began in November 2014. The study is designed for 300 high-risk participants-mainly GBM and heterosexual women. Participants receive daily oral PrEP, composed of emtricitabine (FTC) and tenofovir disoproxil fumarate (TDF), for up to 2.5 years. Quarterly study visits include testing for HIV and sexually transmitted infections (STIs), assessment of ongoing eligibility and side effects, and self-reported adherence. Following each study visit, online behavioural surveys are administered to collect information on medication adherence, risk behaviours and attitudes. Blood samples will be collected in a subset of patients 1, 6 and 12 months after PrEP initiation to measure FTC/TDF concentrations. Analyses using longitudinal regression models will focus on feasibility, adherence, safety, tolerability and effects of PrEP on behaviour. This study will inform PrEP policy and guide the implementation of PrEP in Australia in people at high risk of HIV.

ETHICS AND DISSEMINATION

The study will be conducted in accordance with the Declaration of Helsinki. All patients will provide written informed consent prior to participation in the study. Publications relating to each of the primary end points will be gradually released after 12 months of follow-up is complete.

TRIAL REGISTRATION NUMBER

NCT02206555; Pre-results.

Financial stress is associated with reduced treatment adherence in HIV-infected adults in a resource-rich setting

OBJECTIVES

Financial stress has been identified as a barrier to antiretroviral adherence, but only in resource- limited settings. Almost half of HIV-infected Australian adults earn no regular income and, despite highly subsidised antiretroviral therapy and universal health care, 3% of HIV-infected Australians cease antiretroviral therapy each year. We studied the relationship between financial stress and treatment adherence in a resource-rich setting.

METHODS

Out-patients attending the HIV clinic at St Vincent's Hospital between November 2010 and May 2011 were invited to complete an anonymous survey including questions relating to costs and adherence.

RESULTS

Of 335 HIV-infected patients (95.8% male; mean age 52 years; hepatitis coinfection 9.2%), 65 patients (19.6%) stated that it was difficult or very difficult to meet pharmacy dispensing costs, 49 (14.6%) reported that they had delayed purchasing medication because of pharmacy costs, and 30 (9.0%) reported that they had ceased medication because of pharmacy costs. Of the 65 patients with difficulties meeting pharmacy costs, 19 (29.2%) had ceased medication vs. 11 (4.1%) of the remaining 270 patients (P < 0.0001). In addition, 19 patients (5.7%) also stated that it was difficult or very difficult to meet travel costs to the clinic. Treatment cessation and interruption were both independently associated with difficulty meeting both pharmacy and clinic travel costs. Only 4.9% had been asked if they were having difficulty paying for medication.

CONCLUSIONS

These are the first data to show that pharmacy dispensing and clinic travel costs may affect treatment adherence in a resource-rich setting. Patients should be asked if financial stress is limiting their treatment adherence.

Principles of antidote pharmacology: an update on prophylaxis, post-exposure treatment recommendations and research initiatives for biological agents

The use of biological agents has generally been confined to military-led conflicts. However, there has been an increase in non-state-based terrorism, including the use of asymmetric warfare, such as biological agents in the past few decades. Thus, it is becoming increasingly important to consider strategies for preventing and preparing for attacks by insurgents, such as the development of pre- and post-exposure medical countermeasures. There are a wide range of prophylactics and treatments being investigated to combat the effects of biological agents. These include antibiotics (for both conventional and unconventional use), antibodies, anti-virals, immunomodulators, nucleic acids (analogues, antisense, ribozymes and DNAzymes), bacteriophage therapy and micro-encapsulation. While vaccines are commercially available for the prevention of anthrax, cholera, plague, Q fever and smallpox, there are no licensed vaccines available for use in the case of botulinum toxins, viral encephalitis, melioidosis or ricin. Antibiotics are still recommended as the mainstay treatment following exposure to anthrax, plague, Q fever and melioidosis. Anti-toxin therapy and anti-virals may be used in the case of botulinum toxins or smallpox respectively. However, supportive care is the only, or mainstay, post-exposure treatment for cholera, viral encephalitis and ricin - a recommendation that has not changed in decades. Indeed, with the difficulty that antibiotic resistance poses, the development and further evaluation of techniques and atypical pharmaceuticals are fundamental to the development of prophylaxis and post-exposure treatment options. The aim of this review is to present an update on prophylaxis and post-exposure treatment recommendations and research initiatives for biological agents in the open literature from 2007 to 2009.

Transmission of triple-class, drug-resistant HIV-1 in Australia

We report the first two cases of transmitted triple-class, drug-resistant HIV-1 in Australia. Baseline testing of a newly diagnosed man showed four reverse transcriptase resistance mutations (affecting two drug classes) and six protease resistance mutations. A source patient was identified, and a likely second case newly infected 1 year later, suggesting sequential transmission. This raises therapeutic implications for the individual patients, as well as public health concerns.

Is screening for sexually transmitted infections in men who have sex with men who receive non-occupational HIV post-exposure prophylaxis worthwhile?

BACKGROUND/AIMS

Non-occupational HIV post-exposure prophylaxis (NPEP) is routinely prescribed after high risk sexual exposure. This provides an opportunity to screen and treat individuals at risk of concurrent sexually transmitted infections (STI). The aim of this study was to assess the efficacy of an STI screening programme in individuals receiving NPEP.

METHODS

STI screens were offered to all individuals receiving NPEP from March 2001 to May 2004. Screen results were compared to type of sexual exposure and baseline patient characteristics.

RESULTS

A total of 253 subjects were screened, representing 85% of the target population. All were men who have sex with men (MSM). Common exposure risks were receptive anal intercourse (RAI) in 61% and insertive anal intercourse (IAI) in 33%. 32 (13%) individuals had one or more STI. The most common STIs were rectal infections with Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) in 11 (4.5%) and six (2.5%) individuals, respectively. Subjects with rectal CT were significantly more likely to be co-infected with rectal NG (p<0.001). There was no association between the presence of a rectal STI and age or exposure risk. Only six (19%) individuals with an STI were symptomatic at screening.

CONCLUSION

In this cohort of MSM receiving NPEP, high rates of concomitant STIs are observed highlighting the importance of STI screening in this setting.

The use of a triple nucleoside-nucleotide regimen for nonoccupational HIV post-exposure prophylaxis

OBJECTIVES

Nonoccupational post-exposure prophylaxis (NPEP) for HIV is recommended after high-risk sexual exposure. Because of the high incidence of intolerable side effects observed with protease inhibitor- and zidovudine-based NPEP regimens, our unit changed standard NPEP treatment to 28 days of tenofovir-lamivudine-stavudine (TDF-3TC-d4T). The aim of this study was to compare side effects and numbers of individuals completing NPEP before and after this change.

METHODS

Parameters were compared amongst individuals commencing the following NPEP regimens: zidovudine-lamivudine (ZDV-3TC), zidovudine-lamivudine-nelfinavir (ZDV-3TC-NFV) and TDF-3TC-d4T.

RESULTS

A total of 385 individuals received ZDV-3TC (n = 36), ZDV-3TC-NFV (n = 225) or TDF-3TC-d4T (n = 137) as NPEP for the first time between June 1999 and November 2003. Noncompletion rates were 25%, 32% and 15%, respectively (P = 0.001), with odds ratios for noncompletion being 2.0 [95% confidence interval (CI) 0.8-4.8] and 2.7 (95% CI 1.6-4.8) in the first two groups compared with the TDF-3TC-d4T group (P = 0.008). Adverse events were less common in the TDF-3TC-d4T group, with significantly lower rates of nausea and headache, but significantly higher rates of peripheral neuropathy and asymptomatic raised transaminases. There was no HIV seroconversion in any group.

CONCLUSIONS

TDF-3TC-d4T is significantly better tolerated than ZDV-3TC or ZDV-3TC-NFV as NPEP and results in greater numbers of individuals completing 28 days of treatment.

Analysis of expressed sequence tag loci on wheat chromosome group 4

A total of 1918 loci, detected by the hybridization of 938 expressed sequence tag unigenes (ESTs) from 26 Triticeae cDNA libraries, were mapped to wheat (Triticum aestivum L.) homoeologous group 4 chromosomes using a set of deletion, ditelosomic, and nulli-tetrasomic lines. The 1918 EST loci were not distributed uniformly among the three group 4 chromosomes; 41, 28, and 31% mapped to chromosomes 4A, 4B, and 4D, respectively. This pattern is in contrast to the cumulative results of EST mapping in all homoeologous groups, as reported elsewhere, that found the highest proportion of loci mapped to the B genome. Sixty-five percent of these 1918 loci mapped to the long arms of homoeologous group 4 chromosomes, while 35% mapped to the short arms. The distal regions of chromosome arms showed higher numbers of loci than the proximal regions, with the exception of 4DL. This study confirmed the complex structure of chromosome 4A that contains two reciprocal translocations and two inversions, previously identified. An additional inversion in the centromeric region of 4A was revealed. A consensus map for homoeologous group 4 was developed from 119 ESTs unique to group 4. Forty-nine percent of these ESTs were found to be homoeologous to sequences on rice chromosome 3, 12% had matches with sequences on other rice chromosomes, and 39% had no matches with rice sequences at all. Limited homology (only 26 of the 119 consensus ESTs) was found between wheat ESTs on homoeologous group 4 and the Arabidopsis genome. Forty-two percent of the homoeologous group 4 ESTs could be classified into functional categories on the basis of blastX searches against all protein databases.

The effect of production variables in monolog and dialog on comprehension by novel listeners

Prior research has identified a number of dimensions along which speakers modify referring expressions. The present study aimed to determine and describe the actual relationship existing between these production characteristics and corresponding measures of listener comprehension. Spoken descriptions were elicited from eight speakers during monolog and dialog conditions of the tangram task. In a subsequent listening experiment, 163 new subjects listened to the referring expressions from the speech corpus, and were asked to select, from an array of tangram figures, the one that was being described in the referring expression. Results revealed that the production variables most commonly documented by previous researchers collectively contributed to listener comprehension to a surprisingly small, but consistently significant, degree. Furthermore, the communicative context in which referring expressions were produced did not substantially influence their overall comprehensibility; instead, communicative context, as well as the individual characteristics of the speaker who produced the referring expression, appeared to affect which variables listeners found most useful when inferring what the speaker meant.

HIV-1-associated central nervous system dysfunction

Despite more than 15 years of extensive investigative efforts, a complete understanding of the neurological consequences of HIV-1 CNS infection remains elusive. Although the resources of numerous investigators have been focused on studies of HIV-1-associated CNS disease, the complex nature of the disease processes that underlie the clinical, pathological, and cellular manifestations of HIV-1 CNS infection have required a larger volume of studies than was initially envisioned. Several major areas remain as the focus of current research efforts. One of the more pressing issues facing researchers and clinicians alike is the search for correlates to the development of HIV-1-associated CNS neuropathology and the onset of HIVD. Although numerous parameters have been studied, none have been shown to be absolute predictors or markers of HIV-1-related CNS dysfunction. The identification of solid correlates of HIVD is an important goal that would permit clinical identification of individuals at risk for developing potentially crippling, life-threatening CNS abnormalities and would facilitate early treatment of nascent neurological problems. A more complete comprehension of the cellular foundations of CNS dysfunction and HIVD is also a fundamental part of strategies designed to treat or prevent HIV-1-associated CNS disease. Future investigations will strive to expand the body of knowledge concerning the complex interactions between infected and uninfected neuroglial cells and the roles of numerous cytokines, chemokines, and other soluble agents that are deregulated during HIV-1 CNS infection. In particular, a thorough understanding of the mechanisms of neurotoxicity may facilitate the development of new therapies that alleviate or eliminate the clinical consequences of CNS infection. Finally, investigators will continue to study HIVD within the context of single and combination drug therapies used in the treatment of HIV-1 infection and AIDS. As newer and more effective systemic treatments for HIV-1 infection and AIDS are introduced, the effects of these treatments on the onset, incidence, and severity of HIVD will also require intensive study. The impact of drug therapies on the ability of the CNS to act as an HIV-1 reservoir will also need to be addressed. Introduction of each new drug or drug combination will necessitate studies of drug penetration into the CNS and efficacy against the development of CNS abnormalities. Furthermore, as more effective treatments prolong the lifespan of individuals infected with HIV-1, the impact of extended survival on the occurrence and severity of HIVD will also require further investigations. The quest for answers to these and other questions will be complicated by the diversity of experimental systems used to study different aspects of HIV-1 CNS infection and HIVD. Each system has its own unique strengths and weaknesses. Clinical observations provide a continuous spectrum of symptomatic findings but reveal little about the underlying mechanisms of disease. In vivo imaging techniques, such as CT and MRI, also provide a continuum of observations, but the images are limited in their resolution. Neuropathological examinations of postmortem HIV-1-infected brains offer gross, cellular, and molecular views (including phenotypic and genotypic analyses of CNS viral isolates) of the diseased brain, but only provide a snapshot of the end-stage neurologic dysfunction. Studies that rely on animal surrogates for HIV-1, including SIV, simian-HIV (SHIV), feline immunodeficiency virus (FIV), visna virus, and HIV-1 SCID-hu models, permit experimental protocols that cannot be carried out in humans, but are limited by the fidelity with which each virus and animal model emulates the conditions and events observed in the human host. Finally, in vitro techniques, which include the use of primary cells and cell lines, adult or fetal human cell cultures, and BBB barrier model systems, are also convenient means by which aspe

A second outbreak of hepatitis C virus infection from anti-D immunoglobulin in Ireland

OBJECTIVE

To investigate the infectivity for hepatitis C virus (HCV) of intravenous anti-D immunoglobulin batches manufactured in Ireland between 1991 and 1994.

METHODS

Women who had received anti-D manufactured between 1991 and 1994 were screened for serological markers of HCV infection and for the presence of HCV RNA by RT-PCR amplification and virus genotyping.

RESULTS

44 women exposed to anti-D manufactured between 1991 and 1994 were polymerase chain reaction positive for HCV RNA, 19 of whom were infected with genotype 3a virus shown by phylogenetic analysis of the NS5B gene to be closely related to that from the single implicated donor.

CONCLUSIONS

Anti-D manufactured in 1991-1994 transmitted infection of HCV genotype 3a. The prevalence of HCV-specific antibody in anti-D recipients was relatively low (0.59%), consistent with the low level of virus RNA in these anti-D batches.

Does botulinum toxin injection make esophagomyotomy a more difficult operation?

BACKGROUND

Some patients with achalasia treated by botulinum toxin injection still require an esophagomyotomy. In this study, we analyzed the impact of botulinum toxin injection on the technical aspects and outcome of esophagomyotomy.

METHODS

We studied 57 patients, with a mean age of 46 years (range, 12-97) who were treated between January 1995 and March 1998 by esophagomyotomy performed via minimally invasive techniques by one team. Operative reports, videotapes, and clinical outcome were analyzed to define the technical difficulties, perforations, and outcome.

RESULTS

Fifteen of the 57 patients had received one or more injections of botulinum toxin (botox group) preoperatively. Difficulties in dissection of the submucosal plane were encountered in eight of the 15 cases (53.3%), and a mucosal laceration (perforation) occurred in two cases (13.3%). Forty-two of the 57 patients had not received any injections (non-botox group). In three patients (7%), difficulties in identifying or following the submucosal plane were encountered, although 29 patients had one or more previous dilations, and perforation occurred in one case (2.4%). All mucosal injuries were repaired laparoscopically, and the patients recovered without obvious sequelae. Dysphagia improved significantly after the operation in both groups (botox group, from preoperative score of 3. 8 to a postoperative score of 0.7; non-botox, from a score of 3.4 preoperatively to 0.5 postoperatively). Regurgitation also improved in both groups (botox, 2.7 preoperatively, 0.92 postoperatively; non-botox group, 2.0 preoperatively, 0.56 postoperatively).

CONCLUSIONS

Injection of botulinum toxin significantly increases the technical difficulties and thus the potential risk of esophagomyotomy. The immediate results were equally good for both groups in our series, but the long-term sequelae of repeated injections are unknown. Laparoscopic Heller myotomy is a safe and effective procedure even after unsuccessful treatment with botulinum toxin.

Estimation of the retinal nerve fibre layer thickness in the papillomacular area of long standing stage IV macular holes

AIM

To compare the thickness of the retinal nerve fibre layer (RNFL) in the papillomacular area of patients with long standing stage IV macular holes with age matched controls, using a scanning laser polarimeter.

METHODS

The nerve fibre analyser (NFA) was used to measure the mean thickness of the RNFL around the optic nerve head, the thickness values of temporal and nasal 45 degrees sectors and the integral values in 10 patients with macular holes and in 10 age matched controls.

RESULTS

The mean RNFL thickness around the optic nerve head was 79.71 (SD 15.06) microm in the macular hole group and 75.1 (10.8) microm in the control group (p = 0.44). The mean thickness in the temporal sector was 63.69 (12.08) microm in the macular hole group and 58.65 (8.9) microm in the control group (p = 0.3). The mean ratio between the temporal and nasal sector thickness values was 0.8441 in the macular hole group and 0.7819 in the controls (p = 0.42).

CONCLUSIONS

There was no significant difference in the thickness of the RNFL in the papillomacular area in the two groups. This suggests that there may be no changes in the thickness of the RNFL in patients with long standing macular holes.

Correlation of histological findings with gadolinium enhanced MRI scans during healing of a PHEMA orbital implant in rabbits

BACKGROUND/AIMS

To investigate a poly(2-hydroxyethyl methacrylate) (PHEMA) orbital implant with a spongy anterior hemisphere and a smooth gel posterior hemisphere, by histology correlated with magnetic resonance images.

METHODS

Following enucleation, eight rabbits received PHEMA implants to which the muscles were directly sutured, and underwent gadolinium enhanced magnetic resonance imaging (MRI) from 3 to 52 weeks. After the rabbits were killed, the implants were removed, cut in a plane corresponding to the scan, and processed for light and electron microscopy.

RESULTS

All eight rabbits retained their implant to the end of the study period without complications. The scans demonstrated muscle attachment to the anterior half of the implant, and enhancement was seen on injection of gadolinium chelate. Histology confirmed muscle attachment, and cellular and vascular ingrowth. Over time, a transformation from reactive inflammatory to relatively non-vascular scar tissue was seen within the implant. Calcium deposits in one implant were detected by imaging and histology.

CONCLUSION

The implants are readily visualised on MRI. Muscle attachment and fibrovascular ingrowth into the anterior hemisphere are seen, while encapsulation of the posterior hemisphere is minimal. Histological findings confirm the progress of the healing response, with initial inflammation and marked vascularisation, developing later into quiescent scar tissue predominantly of fibroblasts.

Variation of hepatitis C virus following serial transmission: multiple mechanisms of diversification of the hypervariable region and evidence for convergent genome evolution

We have studied the evolution of hepatitis C virus (HCV) from a common source following serial transmission from contaminated batches of anti-D immunoglobulin. Six secondary recipients were each infected with virus from identifiable primary recipients of HCV-contaminated anti-D immunoglobulin. Phylogenetic analysis of virus E1/E2 gene sequences [including the hypervariable region (HVR)] and part of NS5B confirmed their common origin, but failed to reproduce the known epidemiological relationships between pairs of viruses, probably because of the frequent occurrence of convergent substitutions at both synonymous and nonsynonymous sites. There was no evidence that the rate at which the HCV genome evolves is affected by transmission events. Three different mechanisms appear to have been involved in generating variation of the hypervariable region; nucleotide substitution, insertion/deletion of nucleotide triplets at the E1/E2 boundary and insertion of a duplicated segment replacing almost the entire HVR. These observations have important implications for the phylogenetic analysis of HCV sequences from epidemiologically linked isolates.

Is the single use of intraoperative 5-fluorouracil in filtering surgery for high-risk cases enough?

PURPOSE

To study the efficacy of the adjunctive use of a single intraoperative application of 5-fluorouracil (5FU) in eyes with poor prognoses for a successful outcome with a trabeculectomy.

METHOD

Twenty-four patients (25 eyes) with a mean age of 63.7 +/- 14.7 years (range 27-86 years) and a history of one or more risk factors (age < 50 years, more than 3 years on topical medication, a previous failed filter, previous cataract surgery, uveitis, neovascular glaucoma) underwent trabeculectomy with the intraoperative application of 5FU on a sponge (25 mg/ml) for 5 min. The average follow-up was 10.1 +/- 5.5 months.

RESULTS

The mean pre-operative intraocular pressure (IOP) was 24.7 +/- 6.2 mmHg and the mean post-operative IOP was 13.9 +/- 3.5 mmHg. Success, defined as an IOP within desired target levels for a particular eye, in the presence of a functioning filter, without supplementary medical therapy, was achieved in 56.5% of cases.

CONCLUSIONS

Our results of successful filters in this group of patients with moderate- to high-risk characteristics approach similar figures quoted for trabeculectomies without the adjunctive use of intraoperative 5FU in eyes with poor prognoses with a similar length of follow-up. Though the numbers are small there is a trend that indicates that the intraoperative application of a single dose of 5FU alone may not be sufficient in eyes with moderate- to high-risk characteristics of failure of a trabeculectomy.

Long-term evolution of the hypervariable region of hepatitis C virus in a common-source-infected cohort

The long-term evolution of the hepatitis C virus hypervariable region (HVR) and flanking regions of the E1 and E2 envelope proteins have been studied in a cohort of women infected from a common source of anti-D immunoglobulin. Whereas virus sequences in the infectious source were relatively homogeneous, distinct HVR variants were observed in each anti-D recipient, indicating that this region can evolve in multiple directions from the same point. Where HVR variants with dissimilar sequences were present in a single individual, the frequency of synonymous substitution in the flanking regions suggested that the lineages diverged more than a decade previously. Even where a single major HVR variant was present in an infected individual, this lineage was usually several years old. Multiple lineages can therefore coexist during long periods of chronic infection without replacement. The characteristics of amino acid substitution in the HVR were not consistent with the random accumulation of mutations and imply that amino acid replacement in the HVR was strongly constrained. Another variable region of E2 centered on codon 60 shows similar constraints, while HVR2 was relatively unconstrained. Several of these features are difficult to explain if a neutralizing immune response against the HVR is the only selective force operating on E2. The impact of PCR artifacts such as nucleotide misincorporation and the shuffling of dissimilar templates is discussed.

An upstream stimulatory factor (USF) binding motif is critical for rat preprotachykinin-A promoter activity in PC12 cells

We demonstrate the presence of a functional E box motif in the proximal rat preprotachykinin-A (rPPT) promoter. This element (spanning nucleotides -67 to -47) exhibits the sequence 5'-CACGTG-3' which is recognized and bound by the basic helix-loop-helix family of regulatory proteins. We also show that at least one of the factors bound to this rPPT promoter element in both HeLa and PC12 nuclear extract is the ubiquitously expressed transcription factor, the upstream stimulatory factor (USF). Mutation of this element by insertion of a 10 bp linker into the E box motif, in an rPPT promoter fragment spanning -865 to +92, destroys the ability of this promoter fragment to support reporter gene expression in a PC12 cell model of rPPT promoter activity. The data indicate that this rPPT E box element is likely to function as an important cis-regulatory domain in the rPPT promoter.

Multiple protein complexes, including AP2 and Sp1, interact with a specific site within the rat preprotachykinin-A promoter

We demonstrate that there is a unique AP2 binding site in the rat preprotachykinin-A promoter (rPPT) spanning -865 to -47. AP2 is a transcription factor whose expression in sensory neurons has been correlated with rPPT expression in these cells. This binding site is adjacent to an element we previously identified as binding a single stranded DNA binding protein which was also present in sensory neurons. These two complexes encompass a region which we had proposed might form a stem-loop structure, allowing binding of the single stranded DNA binding protein to the DNA. Here using electrophoretic mobility shift analysis we demonstrate that the DNA region corresponding to the putative stem-loop structure is bound by a variety of transcription factors, including in addition to AP2 the ubiquitous Sp1. DNase 1 footprint analysis demonstrates that binding to this domain by the proteins recognising the double-stranded form of the cis acting element is mutually exclusive. A promoter fragment containing this domain demonstrated a DNase 1 footprint over the 5' region of the stem-loop structure. Competition of the binding for this element by an oligonucleotide corresponding to the stem-loop structure removed the 5' footprint and exposed a new footprint over the 3' region of the stem-loop structure and extending for several base pairs. This change in protection observed with DNase 1 digestion also correlated with changes of the DNase 1 pattern at specific locations 3' of the proposed stem-loop structure. These changes correlated with two DNA sequences which were homologous to one another and to a region within the proposed stem-loop structure. Our results indicate that AP2 could regulate rPPT gene expression by a variety of mechanisms.

Transcriptional control of neuropeptide gene expression in sensory neurons, using the preprotachykinin-A gene as a model

Control of neuropeptide gene expression in sensory neurons is determined in part by a variety of tissue-specific, developmental, and stimulus-induced transcription factors that interact with the promoters of these genes. We have analysed the regulation of the rat preprotachykinin-A (rPPT) gene, which is expressed in a subset of dorsal root ganglia neurons. A region of the promoter encompassing approximately 1300 base pairs spanning the transcriptional start site has been analysed in detail both by functional analysis of promoter activity in clonal cell lines and dorsal root ganglia neurons grown in culture and by in vitro characterisation of transcription factor interaction with this region. Interestingly our analysis indicates an important role in rPPT gene expression for the E box transcription factor family. This class of transcription factor has been demonstrated to be a major determinant of calcitonin gene related peptide (CGRP) expression, which is also expressed in dorsal root ganglia neurons often under similar conditions as rPPT. In addition, multiple regulatory domains have been identified in the rPPT promoter, which act as activators in a variety of cell types. These elements are silenced in the context of the rPPT promoter in many non-neuronal cells. Therefore, tissue-specific expression of reporter genes directed by the rPPT promoter in transient transfection is determined in part by a variety of silencer elements, which act to repress the function of several domains that act as constitutive enhancers of expression in a wide range of cells. Removal or modulation of silencer elements in the rPPT promoter allows activity in a wider variety of cell types. We postulate that control of rPPT gene expression is the results of dynamic interplay of both positive and negative regulatory elements, a phenomenon observed in several other neuronal-specific genes, including that encoding CGRP.

The use of dynamic ultrasound B-scan to detect retinal tears in spontaneous vitreous haemorrhage

The use of dynamic ultrasound B-scan to detect retinal tears in spontaneous vitreous haemorrhage is described. A 6-month prospective study was undertaken of non-diabetic patients who presented with spontaneous vitreous haemorrhage, in whom the fundus could not be visualised and in whom a rhegmatogenous aetiology was suspected. Patients were followed up at least weekly with repeat B-scans until adequate fundus visualisation was possible. Eight patients in total were included in the study; of these, 4 were thought to have retinal tear at initial ultrasound examination and this was confirmed later when the haemorrhage cleared. A scanning protocol is suggested.

Cell-specific activation of the glial-specific JC virus early promoter by large T antigen

JC virus causes the human demyelinating disease progressive multifocal leukoencephalopathy by selective infection of glial cells. This cell specificity results from glial-specific expression of viral early genes (large and small T antigens). Analysis of transcriptional regulation by the MH1 JC virus early promoter demonstrates that glial specificity is directed by the basal promoter. Because T antigen regulates the basal region of several viral and cellular promoters, we investigated whether it controls the JC virus basal promoter in a glial-specific manner. A JC virus T antigen expression plasmid generated a 95-kDa protein which exhibited nuclear localization and physical association with p53. T antigen repressed the JC virus and SV40 early promoters 4- to 5-fold in glioma cells. Conversely, T antigen induced 100- to 200-fold activation of the JC virus early promoter in nonglial cells, whereas the SV40 promoter was repressed. Activation required the JC virus TATA box sequence and a pentanucleotide repeat immediately upstream of the TATA box, but was independent of the upstream enhancer region. These data demonstrate that the JC virus basal promoter is responsible for glial-specific gene expression and suggest a mechanism for this regulation.

Three immediate early gene response elements in the proximal preprotachykinin-A promoter in two functionally distinct domains

The preprotachykinin-A promoter contains two blocks of DNA sequence, with a high degree of homology to one another, both containing activator protein 1/cAMP response element-like elements which constitute cis-acting regulatory domains. These two domains are differentially regulated in HeLa cells and primary cultures of dorsal root ganglion neurons when they are placed in the context of a reporter gene driven by the c-fos minimum promoter. One of the domains, corresponding to a region of the preprotachykinin promoter spanning nucleotides -345 to -308, contains two activator protein 1 elements adjacent to an E-box binding protein consensus sequence. Both of the activator protein 1 elements can bind a complex containing c-fos/c-fos related antigen proteins and the adjacent E-box element is specifically recognized by proteins present in HeLa nuclear extract. This domain requires the synergistic action of both activator protein 1 elements to drive expression of the reporter gene in both HeLa and dorsal root ganglion cells. The second or proximal domain spans nucleotides -198 to -155 and contains a previously characterized activator protein 1/cAMP response element/ATF enhancer element which, in contrast to the activator protein 1 elements in the distal domain, functions in both HeLa and dorsal root ganglion cells as one copy. This domain is differentially regulated in HeLa and dorsal root ganglia. The previously characterized enhancer activity is repressed in the context of the extended cis-acting domain in HeLa cells but remains active in dorsal root ganglion, although no further enhancement of activity supported by the single enhancer is observed when in the context of the extended sequence. This proximal domain, in addition to binding the enhancer complex, can be bound by at least two other complexes, one of which binds to an E-box consensus sequence. As the elements corresponding to the E-box consensus in both domains cross-compete for binding of specific complex(es) it would appear that repression of the activity of the proximal domain is correlated with a specific protein complex binding adjacent to the characterized enhancer in the region spanning nucleotides -198 to -155. The preprotachykinin-A proximal promoter is therefore bound by multiple activator protein I complexes, which in the context of the cis-acting domains in which they are present can be differentially regulated. In the proximal domain their function may also be regulated in a tissue-specific manner by other proteins which bind to adjacent regulatory elements.

Characterisation of a functional E box motif in the proximal rat preprotachykinin-A promoter

Three E box motifs, which are upstream of the major transcriptional start site, have previously been characterised in the rat preprotachykinin-A (rPPT) promoter. Only one of these, in the proximal promoter spanning nucleotides -67 to -47, has been demonstrated to support reporter gene expression in clonal cell lines under basal growth conditions. Here we demonstrate that the reporter gene expression can be further induced by the action of phorbol 12-myristate 13-acetate (TPA) and nerve growth factor (NGF), respectively, in both HeLa and the neuronally derived PC12 cells. This response is due to the E box motif and not an overlapping consensus sequence for a putative AP1 element, a class of element previously demonstrated to respond to both TPA and NGF in these cell lines. Finally, we demonstrate that this E box motif can support similar levels of reporter gene expression in primary cultures of dorsal root ganglion neurons as observed in clonal cell lines, demonstrating that E box binding complexes can (1) function as a transcriptional regulator in dorsal root ganglion neurons and (2) bind to and therefore presumably regulate rPPT promoter activity.

Repression of preprotachykinin-A promoter activity is mediated by a proximal promoter element

The rat preprotachykinin-A promoter, which is able to direct reporter gene expression in adult dorsal root ganglia neurons grown in culture, has no detectable activity in HeLa and PC12 cells. DNAase 1 footprinting and electrophoretic mobility shift analyses with HeLa nuclear extract indicated the presence of a protein complex binding to a region of the rat preprotachykinn-A gene promoter between the TATA box and the major transcriptional start site. We demonstrate that the sequence of the preprotachykinin-A promoter spanning nucleotides -47 to +92 functions to repress reporter gene expression in HeLa and PC12 cells but not in adult rat dorsal root ganglia grown in culture, and that this repression is correlated with a protein(s) binding to the element between the TATA box and major transcription initiation site. These results indicate that the tissue-specific expression of the preprotachykinin-A gene could require the interaction of both positive and negative regulatory DNA elements.

The rat preprotachykinin-A promoter is regulated in PC12 cells by the synergistic action of multiple stimuli

We demonstrate in PC12 cells that although nerve growth factor, forskolin or potassium-evoked depolarisation independently induced minimal or no expression from the rat preprotachykinin-A gene (rPPT) promoter linked to a reporter gene, exposure of the cells to various combinations of these stimuli specifically activated the rPPT promoter in transient transfection assays.

An activator element within the preprotachykinin-A promoter

The rat Preprotachykinin-A promoter (PPT) directs high levels of expression in dorsal root ganglia (DRG) neurons in culture either endogenously or when linked to a receptor construct. It is not active in any of the established tissue culture cell lines which we have analyzed. To search for transcriptional regulators within this promoter we have started to dissect the promoter into individual elements to determine their function. A DNA element which had previously been suggested to regulate transcription from DNA sequence analysis of the rat PPT promoter occurs at position -200 relative to the major start of transcription within the PPT promoter. The equivalent element from the bovine PPT promoter had previously been proposed to be a cAMP responsive element (CRE). The sequence of this enhancer has similarities with both the AP1 and CRE DNA consensus sequences. We have demonstrated that one copy of this rat PPT element linked to a heterologous basal promoter will enhance transcription in HeLa and PC12 cell lines as well as adult rat DRG neurons grown in culture. It is also demonstrated that the rat PPT element will bind proteins in HeLa nuclear extract distinct from those binding to the well-characterized Gibbon Ape Leukemia Virus (GALV) AP1 or somatostatin CRE sites by gel retardation analysis. This PPT element, when cloned in a heterologous reporter construct, although showing properties of both AP1 and CRE elements, was functionally distinguished from both the somatostatin CRE element and the GALV AP1 enhancer when these elements were tested in the same reporter construct. This PPT element has a constitutive level of activity in adult rat DRG neurons, which is fivefold higher than that driven by the reporter construct promoter. It is also significantly different from the same reporter construct linked to the somatostatin CRE and analyzed in DRG neurons.