A chemical and ecological assessment into elemental loading from ford crossings in Ashdown Forest, Sussex, United Kingdom

Numerous studies have identified the issue of road surface runoff as a source of contamination into waterways but the impact of vehicular wash-off is less well understood. A ford crossing provides a pathway for vehicle-derived contaminants emanating from both road surface runoff and vehicular wash-off into a river system. Twyford Lane Ford (Ford 1) and Birchgrove Lane Ford (Ford 2), located ca. 600 m apart on a tributary of the River Ouse in Sussex (UK), were the focus of this study. A combination of biomonitoring (assessment of benthic macroinvertebrates) and chemical assessments of water and sediments has been undertaken to determine any detrimental impacts, such as a lack in biodiversity, resulting from the ford crossings. Sediment concentrations of chromium (Cr³⁺), lead (Pb) and zinc (Zn) were generally elevated at Ford 1, attenuating at sampling points between the fords to then peak at Ford 2. However, sediment particle size was seen to have an influence on elemental concentrations. In general, an increase in elemental concentrations was associated with a higher percentage of fine-grained sediments (≤63 μm). Elevated concentrations of Zn and magnesium (Mg) were identified within water samples taken during a precipitation event following a prolonged dry period. The biomonitoring results found reduced BMWP (Biological Monitoring Working Party) scores at positions close to the ford crossings, and where the stream was in proximity to the roadside. Sensitive Ephemeroptera were largely absent at sampling points closest to the fords, which is likely to be associated with elevated Zn. The results suggest that careful consideration should be applied when selecting crossing points over sensitive waters.

P1415Wide antral circumferential pulmonary vein isolation ablation using a novel balloon cryoablation catheter

Background

Pulmonary vein isolation using cryotherapy is an established treatment for the management of patients with paroxysmal atrial fibrillation. Ablation using the commercially available balloon cryocatheter has been shown to create wide antral pulmonary vein isolation. A novel balloon cryocatheter (BCC) has been designed to maintain uniform pressure and size during ablation, potentially improving contact with the antral anatomy. The extent of ablation created using the novel BCC has not previously been established.

Purpose

To determine the anatomical extent of pulmonary vein isolation using electroanatomical mapping when performing catheter ablation for paroxysmal atrial fibrillation using the novel BCC.

Methods

Nine consecutive patients underwent pre-procedure computed tomography angiography of the left atrium to quantify the chamber dimensions. An electroanatomical map was created using the cryoablation system mapping catheter and a high definition mapping system. A bipolar voltage map was obtained following ablation to determine the extent of pulmonary vein isolation ablation. A volumetric technique was used to quantify the extent of vein and posterior wall electrical isolation in addition to traditional techniques for proving entrance and exit block.

Results

All patients had paroxysmal atrial fibrillation, mean age 56 years, 7 (78%) male. Electrical isolation was achieved for 100% of the pulmonary veins; mean total procedure time was 109 min (+/- 26 SD), and fluoroscopy time 14.9 min (+/- 2.4 SD). The median treatment applications per vein was one (range one - four), and median treatment duration 180 sec (range 180 -240). Left atrial volume 32 mL/m2 (+/- 7 SD), and mean left atrial posterior wall area 22 cm2 (+/- 4 SD). Data was available for quantitative assessment of the extent of ablation for eight patients. No lesions (0 of 32) were ostial in nature. The antral surface area of ablation was not statistically different between the left and right sided pulmonary veins (p 0.63), which were 5.9 (1.6 SD) and 5.4 (2.1 SD) cm2 respectively. In total 50% of the posterior left atrial wall was ablated. 

Conclusion

Pulmonary vein isolation using a novel BCC provides a wide and antral lesion set. There is significant debulking of the posterior wall of the left atrium.

Abstract Figure.

Polarization Transfer in Wide-Angle Compton Scattering and Single-Pion Photoproduction from the Proton

Wide-angle exclusive Compton scattering and single-pion photoproduction from the proton have been investigated via measurement of the polarization transfer from a circularly polarized photon beam to the recoil proton. The wide-angle Compton scattering polarization transfer was analyzed at an incident photon energy of 3.7 GeV at a proton scattering angle of θ_{cm}^{p}=70°. The longitudinal transfer K_{LL}, measured to be 0.645±0.059±0.048, where the first error is statistical and the second is systematic, has the same sign as predicted for the reaction mechanism in which the photon interacts with a single quark carrying the spin of the proton. However, the observed value is ~3 times larger than predicted by the generalized-parton-distribution-based calculations, which indicates a significant unknown contribution to the scattering amplitude.

New precision measurements of the 235U(n,γ) cross section

The neutron capture cross section of (235)U was measured for the neutron incident energy region between 4 eV and 1 MeV at the DANCE facility at the Los Alamos Neutron Science Center with an unprecedented accuracy of 2-3% at 1 keV. The new methodology combined three independent measurements. In the main experiment, a thick actinide sample was used to determine neutron capture and neutron-induced fission rates simultaneously. In the second measurement, a fission tagging detector was used with a thin actinide sample and detailed characteristics of the prompt-fission gamma rays were obtained. In the third measurement, the neutron scattering background was characterized using a sample of (208)Pb. The relative capture cross section was obtained from the experiment with the thick (235)U sample using a ratio method after the subtraction of the fission and neutron scattering backgrounds. Our result indicates errors that are as large as 30% in the 0.5-2.5 keV region, in the current knowledge of neutron capture as embodied in major nuclear data evaluations. Future modifications of these databases using the improved precision data given herein will have significant impacts in neutronics calculations for a variety of nuclear technologies.

Autosomal dominant subcortical gliosis presenting as frontotemporal dementia

OBJECTIVE

To describe a multigenerational kindred with a frontotemporal dementia clinical syndrome (FTDS), extensive subcortical gliosis pathology, and autosomal dominant genetics.

METHODS

Clinical, imaging, and pathologic evaluations of multiple family members.

RESULTS

Symptom onset commonly occurred in the fifth or sixth decade, although some kindred members did not develop obvious symptoms until their eighth decade. White matter changes were prominent on both MRI and CT imaging. Results from six brain autopsy evaluations showed consistent but varying degrees of pathology that, while unique, share some histologic similarities with leukodystrophies. These brains were notably devoid of both tau- and ubiquitin-containing inclusions.

CONCLUSIONS

Subcortical gliosis in this kindred arises from mutation of a novel gene or else represents a unique frontotemporal dementia clinical syndrome variant caused by mutation of an already known gene. Clinical relevance and research implications are discussed.

Alternative mating tactics in the New Zealand fur seal (Arctocephalus forsteri): when non-territorial males are successful too

In polygynous mammals, the status of many males does not allow them to have a high social rank and theory predicts selection for alternative mating tactics. Alternative tactics were suggested to explain discrepancies between mating and paternity successes in several pinniped species. However, information on alternative tactics in fur seals is limited. Here, we focus on the polygynous New Zealand fur seal, Arctocephalus forsteri, predicting that competition for females is likely to cause a diversification of male mating tactics and that non-territorial tactics can yield reproductive success. We describe the behaviour of 38 males in a medium to large colony. Paternity success was assessed using CERVUS and PASOS, from a pool of 82 pups sampled at the study site and at neighbouring breeding areas. To see whether size is correlated with mating tactic, the length of 17 males was estimated using photogrammetry. Cluster analysis identified three male behavioural profiles: one corresponding to large territorial males and two illustrating alternative tactics employed by smaller non-territorial males. Of the 13 pups born at the study site that were assigned a father, eight were sired by three territorial males and five were sired by non-territorial males. Our study highlights that holding a territory is not a necessary condition for reproductive success in all otariids.

Outcome in cardiac recipients of donor hearts with increased left ventricular wall thickness

The ongoing shortage of donors for cardiac transplantation has led to a trend toward acceptance of donor hearts with some structural abnormalities including left ventricular hypertrophy. To evaluate the outcome in recipients of donor hearts with increased left ventricular wall thickness (LVWT), we retrospectively analyzed data for 157 cardiac donors and respective recipients from January 2001 to December 2004. There were 47 recipients of donor heart with increased LVWT >or=1.2 cm, which constituted the study group and 110 recipients of a donor heart with normal LVWT < 1.2 cm that formed the control group. At 3 +/- 1.5 years, recipient survival was lower (50% vs. 82%, p = 0.0053) and incidence of allograft vasculopathy was higher (50% vs. 22%, p = 0.05) in recipients of donor heart with LVWT > 1.4 cm as compared to LVWT <or= 1.4 cm. By Cox regression, donor LVWT > 1.4 cm (p = 0.003), recipient preoperative ventricular assist device (VAD) support (p = 0.04) and bypass time > 150 min (p = 0.05) were predictors of reduced survival. Our results suggest careful consideration of donor hearts with echocardiographic evidence of increased LVWT in the absence of hypovolemia, because they may be associated with poorer outcomes; such hearts should potentially be reserved only for the most desperately ill recipients.

The selective neurotoxicity produced by 3-chloropropanediol in the rat is not a result of energy deprivation

The biochemical mechanism of toxicity of the experimental astrocyte neurotoxicant and food contaminant S-3-chloro-1,2-propanediol (3-CPD) has been proposed to be via inhibition of glyceraldehyde-3-phosphate dehydrogenase (GAPDH). We have confirmed this action in liver, which shows inhibition to 6.0+/-0.7% control at the neuropathic dose of 140 mg/kg. However, GAPDH activity in brain only fell to a minimum of 54+/-24% control, and the concentrations of lactate and pyruvate (the downstream products of GAPDH), showed no pre-neuropathic decreases in 3-CPD susceptible brain tissue. There was no inhibition of GAPDH activity in primary astrocyte cultures at sub-cytotoxic exposures. We therefore sought alternative mechanisms to explain its toxicity to astrocytes. We were able to show that 3-CPD is a substrate for glutathione-S-transferase and also that, after bioactivation by alcohol dehydrogenase, it generates an irreversible inhibitor of glutathione reductase. In addition, incubation of brain slices from the 3-CPD-vulnerable inferior colliculus produces a depletion of glutathione and an inhibition of glutathione-S-transferase that is not seen in equivalent slices taken from the 3-CPD-resistant occipital neocortex. A smaller but significant and similarly regionally selective decrease in glutathione content is also seen in vivo. We conclude that 3-CPD does not produce its astrocytic toxicity via energy deprivation, and suggest that selective bioactivation and consequent disruption of redox state is a more likely mechanism.

Intraspinal synovial cysts: A retrospective study

BACKGROUND

We report the clinical presentation, radiographic studies, intraoperative findings, histopathological analysis, and post-treatment outcome in 26 patients diagnosed with spinal synovial cysts (SSCs).

AIMS

To describe the clinical presentation, radiographic studies, operative findings, and postoperative follow-up in 26 patients with SSCs.

SETTINGS AND DESIGN

The study was retrospective in design, involving chart review. Individual patient data was tabulated and patterns were recognized.

MATERIALS AND METHODS

The charts for 26 patients who underwent surgical extirpation of SSC between April 1993 and October 2002 were retrospectively reviewed. Specifically, initial clinical presentation, pertinent radiographs (X-rays, magnetic resonance imaging, computed tomography), intraoperative findings, histopathology, and postoperative follow-up were noted.

STATISTICAL ANALYSIS USED

Patient data was tabulated and analyzed for patterns in demographics, symptoms and histopathology.

RESULTS

SSCs were more common in females than males (17:9 ratio). Presenting symptoms were back pain with radiculopathy in 13 (50%), radicular pain in the absence of back pain in 10 (38%), and back pain without radicular pain in three (11%). In addition, 17 patients (65%) had sensory deficit, and 9 (35%) had motor deficit. Most SSCs occurred at the lumbar (19/26) or lumbosacral (5/26) regions, with only 2 (2/26) in the thoracic region. One patient had bilateral SSC at the L4-5 level. Intraoperatively, each cyst was located adjacent to a degenerated facet joint. These lesions could grossly be identified intraoperatively and histopathological confirmation was achieved in all the cases.

CONCLUSIONS

SSCs are important lesions to consider in the differential diagnosis of lumbar epidural masses and surgical resection leads to significant improvement in the majority of cases.

Human neuroepithelial cells express NMDA receptors

L-glutamate, an excitatory neurotransmitter, binds to both ionotropic and metabotropic glutamate receptors. In certain parts of the brain the BBB contains two normally impermeable barriers: 1) cerebral endothelial barrier and 2) cerebral epithelial barrier. Human cerebral endothelial cells express NMDA receptors; however, to date, human cerebral epithelial cells (neuroepithelial cells) have not been shown to express NMDA receptor message or protein. In this study, human hypothalamic sections were examined for NMDA receptors (NMDAR) expression via immunohistochemistry and murine neuroepithelial cell line (V1) were examined for NMDAR via RT-PCR and Western analysis. We found that human cerebral epithelium express protein and cultured mouse neuroepithelial cells express both mRNA and protein for the NMDA receptor. These findings may have important consequences for neuroepithelial responses during excitotoxicity and in disease.

Membrane cross-talk in the early distal tubule segment of frog kidney: role of calcium stores and chloride

The activities of transport mechanisms in epithelial cells are generally coordinated in order to minimise disturbances in cellular ion content and volume. Furosemide, a potent inhibitor of transport in the renal diluting segment, up-regulates apical K+ channel activity following the release of calcium from intracellular stores. The signal pathway between furosemide application and this calcium release is not known. Single early distal tubule segments from frog kidney were permeabilised with saponin in order to monitor calcium levels within cytoplasmic stores using the calcium-sensitive dye, mag-fura. The uptake (or release) of calcium to (or from) stores was initiated by adding agents to the bath solution, which is in direct contact with the intracellular organelles. ATP promoted calcium uptake into stores, whereas ATP removal led to a slower, spontaneous calcium release. Following loading, calcium stores could be rapidly depleted by inositol 1,4,5-trisphosphate (IP3), but not ryanodine. Calcium release was evident upon lowering the "intracellular" chloride concentration from 12 to 4 mM, equivalent to the fall in chloride induced by furosemide in intact cells. These results suggest that intracellular chloride may function as a second messenger, mediating cross-talk between the apical membrane and intracellular calcium stores.

The ultrastructural and immunohistochemical heterogeneity of CD-30-positive neoplasms: so-called anaplastic large cell Ki-1 lymphomas

Anaplastic large cell lymphoma (ALCL), also referred to as Ki-1 lymphomas, was first recognized as an entity with characteristic light microscopic appearance in 1985. This tumor is composed of variably cohesive cells, often with large, markedly atypical, and multinucleated cellular forms. The recognition of ALCL resulted from the development of a monoclonal antibody in Kiel, Germany, named Ki-1, which was initially believed to be a putative marker for Reed-Sternberg cells. This antibody was later found to be specific against the epitope CD-30. Attempts to create strict criteria to preserve this neoplasm as a specific entity have undergone evolution. However, it is now clear that included in this group are a variety of pleomorphic neoplasms with CD-30 immunoreactivity. Some of these neoplasms are nonlymphoid and show marked heterogeneity in their immunohistochemical and ultrastructural profiles. This article aims to highlight the ultrastructural spectrum of neoplasms exhibiting CD-30 positivity that are within the spectrum of ALCL. It remains to be determined if there are subgroups of these CD-30-positive neoplasms that can be segregated on the basis of ultrastructural and immunohistochemical criteria with corresponding clinical correlates that may impact on their management, treatment, and prognosis. We review here the heterogeneity of CD-30-positive neoplasms (so-called anaplastic large cell Ki-1 lymphomas).

Outpatient cervical ripening with intravaginal misoprostol

OBJECTIVE

To determine if outpatient cervical ripening using misoprostol can initiate labor within 48 hours of medication administration and to determine if time from medication administration to time of delivery is decreased using outpatient cervical ripening.

METHODS

Uncomplicated singleton, vertex pregnancies at 41 weeks' gestation or later with Bishop score of 4 or less were eligible for enrollment. Other inclusion criteria included intact membranes, less than eight uterine contractions per hour, a reactive nonstress test, and amniotic fluid index (AFI) over 5 cm. After randomization, 25 micro(cg) of misoprostol or placebo was placed within the posterior vaginal fornix. Patients were continuously monitored for 4 hours, then discharged if not in active labor. Patients returned in 24 hours for a repeat administration of the respective medication. Patients not delivered within 48 hours were admitted for inpatient induction of labor. Statistical analysis was performed with the Fisher, Student t, chi(2), and Mann-Whitney U tests, with P <.05 considered statistically significant.

RESULTS

Among the 60 patients enrolled, 27 (45%) received misoprostol and 33 (55%) received placebo. The majority (24 of 27, 88.9%) of study group patients entered active labor within 48 hours after dosing, compared with 16.7% (five of 33) of placebo group patients (P <.001). The time from initial dose to delivery was significantly shorter in the misoprostol group (36.9 +/- 3.8 compared with 61.3 +/- 3.8 hours, P <.001).

CONCLUSION

Intravaginal misoprostol is effective for outpatient cervical ripening. No adverse effects were encountered, although further study is required to determine the safety of this treatment regimen.

Lack of definitive severe mitochondrial signs and symptoms among deceased HIV-uninfected and HIV-indeterminate children < or = 5 years of age, Pediatric Spectrum of HIV Disease project (PSD), USA

BACKGROUND

In response to recent reports of mitochondrial dysfunction in HIV-uninfected infants exposed to antiretroviral (ARV) prophylaxis, the Perinatal Safety Review Working Group reviewed deaths in five large HIV-exposed perinatal cohorts in the United States to determine if similar cases of severe mitochondrial toxicity could be detected. We describe the results of this review for the PSD cohort.

METHODS

Hospitalization, clinic and death records for deceased HIV-uninfected and HIV-indeterminate children who were less than 5 years of age were reviewed. Standard definitions were used to classify HIV infection status and the likelihood that signs and symptoms were related to mitochondrial dysfunction. Children were classified as having signs and symptoms that were considered (1) unrelated, (2) unlikely, (3) consistent with, or (4) likely related to mitochondrial disease. SIDS deaths were put into a separate category.

RESULTS

8,465 of 13,125 HIV-exposed children were either HIV-uninfected or HIV-indeterminate. Among the 84 deaths in the subgroup of 8,465 children, 9 were considered in Class 2 (unlikely), 4 were considered in Class 3 (consistent with), and none were considered in Class 4 (likely). 97% of those children who received ARV prophylaxis received zidovudine alone. None of the HIV-uninfected deaths were classified in 2, 3, or 4; and only one of these was exposed to ARV prophylaxis. Among the 3 HIV-indeterminate children who were classified in 3 (consistent with), 2 had no or unknown ARV exposure before 1994 when use of ZDV prophylaxis became the standard of care. Both HIV-uninfected and HIV-indeterminate children with ARV exposure or unknown exposure had lower mortality rates than children without ARV exposure.

CONCLUSION

Monoprophylaxis with ZDV was not associated with higher death rates in the cohort of 8,465 children or with any findings likely consistent with mitochondrial dysfunction among the 85 deaths. Ongoing monitoring of drug safety in large multi-site prospective cohort studies of HIV-exposed children is essential in the era of highly active antiretroviral therapy.

Rationale, design, and methods for a Coreg (carvedilol) Heart Failure Registry (COHERE). COHERE Participant Physicians

BACKGROUND

The success of beta-blocking agents in clinical trials of heart failure (HF) has led to a widespread call for their increased use, which assumes these agents will perform as well in the usual care setting. Given the traditional contraindication of the use of beta-blocking agents in HF, and their perception as difficult to use in HF, observing how they perform in the usual care setting could be critical in accelerating their widespread application. Carvedilol is the only beta-blocking agent currently approved in the United States for use in HF.

METHODS

The Coreg (brand of carvedilol; SmithKline Beecham Pharmaceuticals, Philadelphia, PA) Heart Failure Registry (COHERE) is intended to collect data on outcomes and other clinical variables in a typical HF population and to observe experience with carvedilol in the hands of community practitioners. COHERE does not include any specific patient selection or exclusion criteria. The decision to use carvedilol is entirely at the discretion of the participant physician, based on evidence of HF as judged by assessments the practitioner usually uses. All patients will be followed for 1 year, with information on outcomes and other clinical variables collected and analyzed at baseline, the end of titration, and at 6 and 12 months after reaching the maximum tolerated dose. About 600 participant physicians selected to be as representative as possible of the community practice setting will enroll approximately 6,000 patients.

CONCLUSIONS

COHERE will be the first and largest prospective observational experience with a new treatment, ie, carvedilol, in patients with HF managed in the usual care setting and should provide valuable information about this new treatment in this environment compared with the more rigid clinical trials setting.

Undifferentiated sex cord/stromal testis tumor

Completely undifferentiated sex cord/stromal tumors of the testis are rare after puberty. We describe such a tumor in an 18-year-old man presenting with a right testis mass.

Glioblastoma multiforme in a case of acquired immunodeficiency syndrome: investigation a possible oncogenic influence of human immunodeficiency virus on glial cells. Case report and review of the literature

Malignant glioma is the most common primary brain neoplasm, but generally it is not included in the differential diagnosis of enhancing lesions of the central nervous system (CNS) in patients suffering from acquired immunodeficiency syndrome. We report a case of glioblastoma multiforme (GBM) in a 29-year-old man with human immunodeficiency virus (HIV). Primary CNS lymphoma was suspected, making a definitive histological diagnosis crucial. An initial stereotactic biopsy sample was insufficient to establish a diagnosis and a second biopsy of the lesion was obtained. The histopathological investigation confirmed GBM and adjuvant external radiation treatment was given to the patient, who survived for 4 months after the initial biopsy. A decline in the rate of Toxoplasma infection and the changing diseases observed in HIV infection indicate the importance of obtaining a biopsy in cases of CNS mass lesions.

Effect of high- versus low-dose angiotensin converting enzyme inhibition on cytokine levels in chronic heart failure

OBJECTIVES

We examined the effect of long-term treatment with two doses of the angiotensin converting enzyme (ACE) inhibitor enalapril on various immunological variables in patients with chronic congestive heart failure (CHF).

BACKGROUND

Immunological mediators are increasingly recognized to play a pathogenic role in the pathophysiology of CHF. Whether ACE inhibitor therapy modifies immunological variables has not previously been investigated.

METHODS

Seventy-five patients (mean age 52 +/- 11 years) with CHF were randomized between low-(5 m g daily) and high-dose (40 mg daily) enalapril in a double-blind trial. Circulating levels of immunological parameters (i.e., proinflammatory cytokines, chemokines and adhesion molecules) were measured at baseline, at 10 weeks and at the end of the study (34 weeks).

RESULTS

All immunological parameters, except soluble interleukin (IL)-6 receptor, were increased in CHF compared with 21 healthy controls. During the study immunoreactive IL-6 levels decreased (p < 0.05) and soluble IL-6 receptor increased (p < 0.05) during high-dose but not during low-dose enalapril therapy. Furthermore, IL-6 bioactivity decreased only during the high-dose (p < 0.001), resulting in a significant difference in change during treatment between the two dosage groups (p < 0.001). This decrease in IL-6 bioactivity was significantly associated with decreased interventricular septum thickness as assessed by echocardiography (r = 0.56, p = 0.013). No other variables changed during treatment.

CONCLUSIONS

In patients with severe CHF, high-dose enalapril therapy is associated with a significant decrease in IL-6 activity. However, despite treatment with a high-dose ACE inhibitor, a persistent immune activation exists in these patients which may be of importance for the progression of CHF.

Immunohistochemical localization of NMDA- and AMPA-type glutamate receptor subunits in the basal ganglia of red-eared turtles

Corticostriatal and thalamostriatal projection systems have been shown to utilize glutamate as a neurotransmitter in mammals and birds. Although corticostriatal and thalamostriatal projection systems have been demonstrated in turtles, it is uncertain whether they too use glutamate as their neurotransmitter. Immunohistochemical localization of glutamate and of NMDA- and AMPA-type ionotropic glutamate receptor subunits (NMDAR2A/B, GluR1, GluR2/3, and GluR4) were used to address this issue. Numerous medium-sized neurons that were rich in NMDAR2A/B and GluR2/3 were observed in the striatal part of the basal ganglia of red-eared turtles. Smaller numbers of medium-sized neurons and some large neurons rich in the GluR1 and GluR4 subunits were also observed in the striatum. The striatal neuropil was notably rich in GluR1, GluR2/3 and NMDAR2A/B subunits. The pallidal region was specifically rich in large neurons possessing GluR4 subunits. Consistent with the glutamate receptors on striatal and pallidal neurons, sources of input to the striatum and pallidum in turtle such as the dorsomedial and dorsolateral thalamic nuclei (which appear to correspond to intralaminar thalamic nuclei), telencephalic pallial cell groups, and the apparent subthalamic nucleus homologue were rich in glutamatergic neurons. The results show that the thalamostriatal, corticostriatal and subthalamo-pallidal projection systems of turtles are glutamatergic and that similar basal ganglia cell types in turtles and mammals have largely similar glutamate receptor characteristics.

The mode of delivery and the risk of vertical transmission of human immunodeficiency virus type 1--a meta-analysis of 15 prospective cohort studies

BACKGROUND

To evaluate the relation between elective cesarean section and vertical transmission of human immunodeficiency virus type 1 (HIV-1), we performed a meta-analysis using data on individual patients from 15 prospective cohort studies.

METHODS

North American and European studies of at least 100 mother-child pairs were included in the meta-analysis. Uniform definitions of modes of delivery were used. Elective cesarean sections were defined as those performed before onset of labor and rupture of membranes. Multivariate logistic-regression analysis was used to adjust for other factors known to be associated with vertical transmission.

RESULTS

The primary analysis included data on 8533 mother-child pairs. After adjustment for receipt of antiretroviral therapy, maternal stage of disease, and infant birth weight, the likelihood of vertical transmission of HIV-1 was decreased by approximately 50 percent with elective cesarean section, as compared with other modes of delivery (adjusted odds ratio, 0.43; 95 percent confidence interval, 0.33 to 0.56). The results were similar when the study population was limited to those with rupture of membranes shortly before delivery. The likelihood of transmission was reduced by approximately 87 percent with both elective cesarean section and receipt of antiretroviral therapy during the prenatal, intrapartum, and neonatal periods, as compared with other modes of delivery and the absence of therapy (adjusted odds ratio, 0.13; 95 percent confidence interval, 0.09 to 0.19). Among mother-child pairs receiving antiretroviral therapy during the prenatal, intrapartum, and neonatal periods, rates of vertical transmission were 2.0 percent among the 196 mothers who underwent elective cesarean section and 7.3 percent among the 1255 mothers with other modes of delivery.

CONCLUSIONS

The results of this meta-analysis suggest that elective cesarean section reduces the risk of transmission of HIV-1 from mother to child independently of the effects of treatment with zidovudine.

Lack of long-term effects of in utero exposure to zidovudine among uninfected children born to HIV-infected women. Pediatric AIDS Clinical Trials Group Protocol 219/076 Teams

CONTEXT

With the success of zidovudine chemoprophylaxis for prevention of perinatal transmission of the human immunodeficiency virus (HIV), an increasing number of HIV-exposed but uninfected children will have in utero exposure to zidovudine and other antiretroviral drugs.

OBJECTIVE

To evaluate the long-term effects of in utero exposure to zidovudine vs placebo among a randomized cohort of uninfected children.

DESIGN

Prospective cohort study based on data collected during Pediatric AIDS Clinical Trials Group Protocol 076, a perinatal zidovudine HIV prevention trial, and Protocol 219, a long-term observational protocol.

SETTING

Pediatric research clinics in the United States.

PATIENTS

Two hundred thirty-four uninfected children born to 230 HIV-infected women enrolled in Protocol 076 and followed up through February 28, 1997, in Protocol 219 (122 in the zidovudine group and 112 in the placebo group).

MAIN OUTCOME MEASURES

Physical growth measurements, immunologic parameters, cognitive/developmental function, occurrence of neoplasms, and mortality data assessed every 6 months for children younger than 24 months and yearly thereafter or as clinically indicated. Baseline echocardiogram and funduscopic evaluations were collected before 36 months of age.

RESULTS

Median age of children at time of last follow-up visit was 4.2 years (range, 3.2-5.6 years). There were no significant differences between children exposed to zidovudine and those who received placebo in terms of sequential data on lymphocyte subsets; weight, height, and head circumference z scores; and cognitive/developmental function. No deaths or malignancies occurred. Two children (both exposed to zidovudine) are being followed up for abnormal, unexplained ophthalmic findings. One child exposed to zidovudine had a mild cardiomyopathy on echocardiogram at the age of 48 months; the child is clinically asymptomatic.

CONCLUSIONS

No adverse effects were observed in HIV-uninfected children with in utero and neonatal exposure to zidovudine followed up for as long as 5.6 years. Continued prospective evaluations of children born to HIV-infected women who are exposed to antiretroviral or immunotherapeutic agents are critical to assess the long-term safety of interventions that prevent perinatal HIV transmission.

Responses of regular spiking and fast spiking cells in turtle visual cortex to light flashes

Sharp electrodes were used to record light-evoked postsynaptic potentials (PSPs) from neurons in turtle visual cortex in an in vitro preparation of the geniculocortical pathway. Neurons were placed into four groups based on the firing patterns produced by intracellular current injections: regular spiking (RS), fast spiking (FS), intrinsic bursting (IB), and chattering (CH) cells. RS cells have been shown to be pyramidal cells while FS cells are typically interneurons. Light stimuli were diffuse, 1-s flashes of 640-nm light with intensities (I) varying from 0 to 10(4) photons microm(-2) s(-1). The response (R) in each case was the maximal amplitude of the light-evoked depolarizing PSP. Cells of all four types showed sigmoidal intensity-response (IR) functions with a linear rising phase for stimuli above the intensity threshold followed by saturation at high light intensities. Responses at high intensities were variable and some cells showed indications of supersaturation. Light-evoked PSPs had longer latencies and times-to-peak response in RS cells than they did in FS cells. RS cells fired action potentials as much as 200 ms later than did FS cells. Since responses recorded in RS cells at light intensities just above threshold are unlikely to involve contributions from other pyramidal cells, these data indicate that the geniculocortical or feedforward pathway to pyramidal cells has a high gain. The fact that FS cells fire well before RS cells suggests that feedforward inhibition plays a role in controlling the gain of the geniculocortical pathway.

Neuropeptide Y receptor 1 (NPY-Y1) expression in human heart failure and heart transplantation

Neuropeptide Y (NPY) is a neurotransmitter released from cardiac sympathetic nerve terminals along with catecholamines. It influences vascular tone and cardiac function, probably through the receptor subtype Y1. The present study examined the expression of Y1 in patients with end-stage heart failure and in heart transplant recipients. Y1 mRNA was analyzed in right ventricular endomyocardial biopsies taken from 12 donor hearts prior to implantation (controls), 15 patients with end stage heart failure at time of transplantation, and 16 patients more than 1 year after transplantation. RT-PCR (reverse transcription polymerase chain reaction) was used to detect mRNA for the Y1 receptor, the beta1-adrenergic-receptor, and beta-actin. Y1 mRNA was present in biopsies of all donor hearts, but was observed significantly less frequently in the two patient groups; only 5 out of 15 (P < 0.01) heart failure and 9 out of 16 (P < 0.05) transplant recipients demonstrated visible PCR product. In contrast, mRNA for the beta1-adrenergic receptor and beta-actin were detected by RT-PCR in all samples. Our results provide the first evidence for altered regulation of the neuropeptide Y1 receptor in heart failure and transplant patients, and suggests that loss of signal transduction by this receptor may be adaptive in both groups.

Angiotensin II receptor subtype AT1 and AT2 expression after heart transplantation

OBJECTIVE

Cardiac hypertrophy appears early after heart transplantation, and may represent a myocardial response to injury. Recent evidence suggests that angiotensin II (Ang II) may promote growth through the AT1 and inhibit growth through the AT2 receptor subtypes. We therefore asked whether hypertrophy after heart transplantation is characterized by alterations in Ang II receptor gene expression.

METHODS

The expression of Ang II receptor subtypes. AT1 and AT2, was analyzed in right ventricular endomyocardial biopsies taken from 10 human donor hearts prior to implantation (controls) and from 17 heart transplant recipients, 11 studied during annual evaluation (> 1 year after transplantation) and 6 one week after transplantation. Competitive reverse transcription polymerase chain reaction (RT-PCR) was performed using synthetic RNA internal standards for both receptor subtypes.

RESULTS

AT1 and AT2 receptor mRNAs were detected in all samples. AT1 receptor mRNA decreased 4.5 fold (p < 0.01) and AT2 receptor mRNA 4.2 fold (p < 0.001) in transplant patients compared with controls. In the subgroup of patients examined one week after surgery AT1 was reduced relative to AT2 receptor mRNA, resulting in an altered ratio of AT1 to AT2 early after transplantation. There was no correlation between Ang II receptor levels and left ventricular wall thickness, and the decrease in receptor level did not correlate with any hemodynamic parameters, cyclosporine blood levels, or plasma renin, Ang II or pANP, except for a negative correlation between AT2 mRNA and plasma renin (r = -0.49, p = 0.05).

CONCLUSIONS

Contrary to our expectations, mRNA for both Ang II receptors was downregulated after heart transplantation. The cause of myocardial hypertrophy after heart transplantation is still unclear, but the hypertrophy does not appear to be driven by increased transcription of the AT1 receptor.

Serial exercise testing and prognosis in selected patients considered for cardiac transplantation

OBJECTIVES

This study sought to examine the predictive value of variables obtained from serial maximal exercise testing, echocardiography, and ejection fraction in patients referred as potential heart transplant candidates.

BACKGROUND

Variables such as peak VO2, left ventricular dimensions, ejection fraction, and hemodynamic measurements are known to predict prognosis in heart failure, but there are few data on the impact of serial measurements of these variables on subsequent mortality.

METHODS AND RESULTS

Two hundred sixty-three ambulatory patients with severe heart failure referred as potential candidates for heart transplantation who underwent two exercise tests (mean 7.8 months apart) after optimal medical treatment were identified. At the same two time points, echocardiography was performed in 106 (37%) and ejection fraction was measured in 84 (30%). During a mean follow-up period of 3.9+/-0.1 years, 70 (25%) died and 45 (19%) underwent heart transplantation. Exercise capacity, peak exercise heart rate, and peak exercise systolic blood pressure achieved were all significantly higher among survivors compared with nonsurvivors. Among the survivors a slight increase in peak VO2 and ejection fraction were observed, but there were no significant differences in the changes of any of the measured variables between survivors and nonsurvivors. There were no significant differences in survival between patients with increased versus those with decreased peak VO2, left ventricular dimensions, or ejection fraction.

CONCLUSION

Although peak VO2, left ventricular dimensions, and ejection fraction predict survival, changes in these parameters do not add any prognostic information in patients with severe heart failure who have been stabilized with optimal medical treatment. Routine use of these procedures therefore does not seem to be warranted and should be performed only in the context of a specific clinical situation. Serial measurements of these parameters do not appear to be useful in the risk stratification of patients referred for heart transplantation.

Ultrasound densitometric analysis of carotid plaque composition. Pathoanatomic correlation

BACKGROUND AND PURPOSE

The components of a carotid artery plaque might affect the risk of ipsilateral stroke. The accuracy of carotid duplex scan in assessing stroke risk reflects the experience of the scan reader. Thus, methods that can enhance ultrasonic evaluation of plaque morphology might allow a more objective means of determining carotid-mediated stroke risk.

METHODS

We performed densitometric analysis of B-mode images of carotid plaques in nine patients scheduled for carotid endarterectomy. All patients had preoperative duplex color imaging and cerebral arteriography. The surgical specimen was analyzed histologically to determine the plaque components (soft plaque/organized thrombus, intraplaque hemorrhage/lipid deposition, fibrosis, and calcification). The specimen findings were correlated with the densitometric measurements to determine whether the density analysis would allow a reliable determination of the plaque substratum.

RESULTS

With 1.0 as a reference point for the moving column of blood, the mean acoustic densities (+/-SD) were as follows: organized thrombus, 1.8 +/- 0.5; intraplaque hemorrhage/lipid deposition, 5.15 +/- 0.9; fibrosis, 9.51 +/- 2.9; and calcification, 15.5 +/- 8.6.

CONCLUSIONS

We conclude that densitometric evaluation allows differentiation of the various possible components of carotid plaque. The determination of plaque composition, based on density measurement, may provide information about its potential for thromboembolization.

Exercise capacity of heart transplant recipients: the importance of chronotropic incompetence

BACKGROUND

Maximal exercise capacity is limited in patients after heart transplantation. The extent to which chronotropic incompetence contributes to this intolerance has not been well defined.

METHODS

This prospective cross-sectional study examined the heart rate response to exercise and its relation to exercise capacity in 159 heart transplant recipients during progressive, symptom-limited, upright exercise. All prior exercise studies of heart transplant recipients that reported peak oxygen uptake and peak heart rate were also evaluated.

RESULTS

Peak oxygen uptake was closely correlated with peak heart rate (r = 0.39, p < 0.001) and maximum increase in heart rate (r = 0.49, p < 0.001) during exercise by our patients. Similar correlations were found in the published studies for peak oxygen uptake versus maximal heart rate (r = 0.54, p < 0.05) and peak oxygen uptake versus increase in heart rate (r = 0.63, p < 0.02). The current study showed that the increase in heart rate from rest to peak exercise was significantly higher and the decline in heart rate after exercise significantly faster for patients 2 or more years after transplantation than for patients less than 2 years after transplantation (46 +/- 2 versus 38 +/- 1.9 beats/min, p < 0.05); the decline in heart rate 4 minutes after exercise was 27 +/- 1.8 versus 16 +/- 1.8 beats/min, respectively ( p < 0.001).

CONCLUSION

The reduction in peak oxygen consumption, particularly during the first 2 years, appears to be related in part to chronotropic incompetence. Late after transplantation the heart rate response to exercise is greater and the decline in heart rate after exercise faster, suggesting possible autonomic reinnervation in some patients. Chronotropic incompetence may be an inadequate explanation of oxygen uptake impairment seen late after transplantation, when other factors such as myocardial dysfunction and intrinsic skeletal muscle abnormalities are of increasing importance.

Carbon Dioxide Gas Embolism in the Experimental Animal

Accidental vascular placement of Veress needle or cannula during laparoscopic insufflation with carbon dioxide gas (CO2) may cause a fatal gas embolism. Deliberate CO2 injection into the vena cava of dogs did not define a safe flow rate or pressure to prevent mortality. We studied incremental increase in pressure at the same maximum rate of gas flow (corresponding to 2.5 L/mm in a 70-kg man, the maximum flow rate possible with a Veress needle) to define the pressure at which pigs did not reversibly tolerate intravenous CO2 insufflation. The right iliac vein was cannulated and CO2 was insufflated at the maximum flow rate but at three pressures, 15, 20, and 25 mm Hg. During each cycle CO2 was insufflated until the elapse of 30 seconds or a change in end tidal CO2 by 50%. Five of the six animals tolerated intravenous CO2 at 15 mm Hg pressure. In one animal, during insufflation at 15 mm Hg the flow rate was accidentally set at twice the standard level, which resulted in immediate and fatal CO2 embolism. During insufflation at 20 mm Hg four pigs died, the last one during insufflation at 25 mm Hg. Transient insufflation of CO2 at low pressure (15 mm Hg) is well tolerated because pressure in the venous system may limit gas flow. However, a decrease in end tidal CO2 should alert the anesthesiologist to stop insufflation immediately. This will allow recovery. When insufflating pressures are in the middle (20 mm Hg) or high range (25 mm Hg), CO2 embolism can be fatal despite its early recognition.

Perceived self-control of seizures in young people with epilepsy

Evidence now suggests that some people can exert some degree of control over seizure initiation and inhibition. In order to explore this further, 79 young people with epilepsy, attending specialist residential schools, were interviewed regarding awareness of seizure precipitants; recognition of seizure warnings; attempts at seizure inhibition, and ways of self-inducing seizures. Questionnaires with the same content were completed by residential care staff. Results show that many subjects claimed to identify seizure precipitants (63.3%), experienced warnings (70.9%), and had developed means of trying to inhibit seizure occurrence (50.6%). However, in each instance, staff reports were much lower (56.9%, 47.2%, and 22.2%, respectively), and one-to-one concordance was poor. A larger than expected percentage of self-induction was reported for both subjects (8.9%) and staff (9.7%). The implication of these results for both the investigation and treatment of epilepsy are discussed further.