Cloning of Dirac fermions in graphene superlattices

Superlattices have attracted great interest because their use may make it possible to modify the spectra of two-dimensional electron systems and, ultimately, create materials with tailored electronic properties. In previous studies (see, for example, refs 1-8), it proved difficult to realize superlattices with short periodicities and weak disorder, and most of their observed features could be explained in terms of cyclotron orbits commensurate with the superlattice. Evidence for the formation of superlattice minibands (forming a fractal spectrum known as Hofstadter's butterfly) has been limited to the observation of new low-field oscillations and an internal structure within Landau levels. Here we report transport properties of graphene placed on a boron nitride substrate and accurately aligned along its crystallographic directions. The substrate's moiré potential acts as a superlattice and leads to profound changes in the graphene's electronic spectrum. Second-generation Dirac points appear as pronounced peaks in resistivity, accompanied by reversal of the Hall effect. The latter indicates that the effective sign of the charge carriers changes within graphene's conduction and valence bands. Strong magnetic fields lead to Zak-type cloning of the third generation of Dirac points, which are observed as numerous neutrality points in fields where a unit fraction of the flux quantum pierces the superlattice unit cell. Graphene superlattices such as this one provide a way of studying the rich physics expected in incommensurable quantum systems and illustrate the possibility of controllably modifying the electronic spectra of two-dimensional atomic crystals by varying their crystallographic alignment within van der Waals heterostuctures.

Anti-infective and osteointegration properties of silicon nitride, poly(ether ether ketone), and titanium implants

Silicon nitride (Si(3)N(4)) is an industrial ceramic used in spinal fusion and maxillofacial reconstruction. Maximizing bone formation and minimizing bacterial infection are desirable attributes in orthopedic implants designed to adhere to living bone. This study has compared these attributes of Si(3)N(4) implants with implants made from two other orthopedic biomaterials, i.e. poly(ether ether ketone) (PEEK) and titanium (Ti). Dense implants made of Si(3)N(4), PEEK, or Ti were surgically implanted into matching rat calvarial defects. Bacterial infection was induced with an injection of 1×10(4)Staphylococcus epidermidis. Control animals received saline only. On 3, 7, and 14days, and 3months post-surgery four rats per time period and material were killed, and calvariae were examined to quantify new bone formation and the presence or absence of bacteria. Quantitative evaluation of osteointegration to adjacent bone was done by measuring the resistance to implant push-out (n=8 rats each for Ti and PEEK, and n=16 rats for Si(3)N(4)). Three months after surgery in the absence of bacterial injection new bone formation around Si(3)N(4) was ∼69%, compared with 24% and 36% for PEEK and Ti, respectively. In the presence of bacteria new bone formation for Si(3)N(4), Ti, and PEEK was 41%, 26%, and 21%, respectively. Live bacteria were identified around PEEK (88%) and Ti (21%) implants, whereas none were present adjacent to Si(3)N(4). Push-out strength testing demonstrated statistically superior bone growth onto Si(3)N(4) compared with Ti and PEEK. Si(3)N(4) bioceramic implants demonstrated superior new bone formation and resistance to bacterial infection compared with Ti and PEEK.

Evaluation of the subaxial injury classification system

Study design:

Retrospective clinical study of patients treated for subaxial cervical spine trauma (SCST) at a tertiary medical center.

Purpose:

Evaluate the validity of the Subaxial Injury Classification (SLIC) system in surgical versus non-surgical decision making for SCST.

Inclusion criteria:

Age >12 years, presence of SCST with complete clinical and radiological (CT and MRI) data.

Exclusion criteria:

Patients with incomplete radiographic or clinical data, pathological fractures, isolated upper cervical trauma (occiput to C2), isolated transverse process or spinous process fractures, chronic or age indeterminate fractures, isolate MRI findings, and severe systemic trauma with death prior to either surgical or non-surgical treatment.

Results:

Fourteen patients were treated non-surgically (C), whereas 24 were treated surgically (S). In the C group, the SLIC score ranged from 0 to 5 points (standard deviation [SD] = 1.20 points; mean 1.07; median 1). Just 1 patient had an SLIC score greater than 2 (7.1% of the patients). In the S group, the SLIC score ranged from 1 to 10 points (standard deviation [SD] = 2.03 points; mean 5.6; median 6). Just 2 patients had an SLIC score smaller than 4 (both with 1 point each, 8.3% of the total group). All the other 22 (accounting for 91.6%) patients had an SLIC of 4 or more points.

Conclusions:

Our study suggests that the SLIC classification looks to be a promising system to aid spinal surgeons in the decision-making process of subaxial cervical trauma, but a large prospective cohort study is required.

Ultrasensitive measurement of hotspot mutations in tumor DNA in blood using error-suppressed multiplexed deep sequencing

Detection of cell-free tumor DNA in the blood has offered promise as a cancer biomarker, but practical clinical implementations have been impeded by the lack of a sensitive and accurate method for quantitation that is also simple, inexpensive, and readily scalable. Here we present an approach that uses next-generation sequencing to quantify the small fraction of DNA molecules that contain tumor-specific mutations within a background of normal DNA in plasma. Using layers of sequence redundancy designed to distinguish true mutations from sequencer misreads and PCR misincorporations, we achieved a detection sensitivity of approximately 1 variant in 5,000 molecules. In addition, the attachment of modular barcode tags to the DNA fragments to be sequenced facilitated the simultaneous analysis of more than 100 patient samples. As proof-of-principle, we showed the successful use of this method to follow treatment-associated changes in circulating tumor DNA levels in patients with non-small cell lung cancer. Our findings suggest that the deep sequencing approach described here may be applied to the development of a practical diagnostic test that measures tumor-derived DNA levels in blood.

Diffusion-weighted imaging in characterization of cystic pancreatic lesions

AIM

To evaluate whether apparent diffusion coefficient (ADC) measurements from diffusion-weighted imaging (DWI) can characterize or predict the malignant potential of cystic pancreatic lesions.

MATERIALS AND METHODS

Retrospective review of the magnetic resonance imaging (MRI) database over a 2-year period revealed 136 patients with cystic pancreatic lesions. Patients with DWI studies and histological confirmation of cystic mass were included. In patients with known pancreatitis, lesions with amylase content of >1000 IU/l that resolved on subsequent scans were included as pseudocysts. ADC of cystic lesions was measured by two independent reviewers. These values were then compared to categorize these lesions as benign or malignant using conventional MRI sequences.

RESULTS

Seventy lesions were analysed: adenocarcinoma (n=4), intraductal papillary mucinous neoplasm (IPMN; n=28), mucinous cystic neoplasm (MCN; n=9), serous cystadenoma (n=16), and pseudocysts (n=13). There was no difference between ADC values of malignant and non-malignant lesions (p=0.06), between mucinous and serous tumours (p=0.12), or between IPMN and MCN (p=0.42). ADC values for low-grade IPMN were significantly higher than those for high-grade or invasive IPMN (p=0.03).

CONCLUSION

ADC values may be helpful in deciding the malignant potential of IPMN. However, they are not useful in differentiating malignant from benign lesions or for characterizing cystic pancreatic lesions.

When is it reasonable to split pediatric en bloc kidneys for transplantation into two adults?

BACKGROUND

Traditionally, kidneys from donors ≥60 years old and pediatric kidneys are considered marginal organs for transplantation. Pediatric donor kidneys are underutilized for transplantation into adult recipients due to concern for poor outcomes.

METHODS

Using data from the Organ Procurement and Transplant Network, we analyzed patterns of pediatric kidney use (single vs en bloc) in the United States from 1987 to 2007. Using the Cox proportional hazards model, graft outcomes of pediatric donor kidneys transplanted as single vs en bloc grafts from different donor weight groups were compared with renal transplantation from donors ≥60 years old in an attempt to define a pediatric donor weight at which kidneys can be justifiably split to expand the donor pool.

RESULTS

Compared with older donor kidneys, graft failure risk of pediatric single kidneys was consistently lower when the donor weight exceeded 10 kg. On the other hand, graft survival benefit for pediatric en bloc kidneys was evident starting at donor weight ≤10 kg in comparison to older donor kidneys. Pediatric en bloc kidneys performed consistently better than pediatric single kidneys for all donor weight groups.

CONCLUSIONS

Splitting of pediatric donor en bloc kidneys for transplantation into 2 adults when the donor weight exceeds 10 kg was associated with acceptable graft outcomes. This practice, along with increased use of small pediatric donor kidneys, may help to alleviate the waiting list burden in renal transplantation.

Quantification of diffusivities of the human cervical spinal cord using a 2D single-shot interleaved multisection inner volume diffusion-weighted echo-planar imaging technique

BACKGROUND AND PURPOSE

DTI is a highly sensitive technique, which can detect pathology not otherwise noted with conventional imaging methods. This paper provides the atlas of reliable normative in vivo DTI parameters in the cervical spinal cord and its potential applications toward quantifying pathology.

MATERIALS AND METHODS

In our study, we created a reference of normal diffusivities of the cervical spinal cord by using a 2D ss-IMIV-DWEPI technique from 14 healthy volunteers and compared parameters with those in 8 patients with CSM. The 2D ss-IMIV-DWEPI technique was applied in each subject to acquire diffusion-weighted images. FA, lambda( parallel), and lambda( perpendicular) were calculated. A reference of normal DTI indices from 12 regions of interest was created and compared with DTI indices of 8 patients.

RESULTS

A map of reference diffusivity values was obtained from healthy controls. We found statistically significant differences in diffusivities between healthy volunteers and patients with CSM with different severities of disease, by using FA, lambda( parallel), and lambda( perpendicular) values.

CONCLUSIONS

DTI using 2D ss-IMIV-DWPEI is sensitive to spinal cord pathology. This technique can be used to detect and quantify the degree of pathology within the cervical spinal cord from multiple disease states.

Intensive glucose control and macrovascular outcomes in type 2 diabetes

AIMS/HYPOTHESIS

Improved glucose control in type 2 diabetes is known to reduce the risk of microvascular events. There is, however, continuing uncertainty about its impact on macrovascular disease. The aim of these analyses was to generate more precise estimates of the effects of more-intensive, compared with less-intensive, glucose control on the risk of major cardiovascular events amongst patients with type 2 diabetes.

METHODS

A prospectively planned group-level meta-analysis in which characteristics of trials to be included, outcomes of interest, analyses and subgroup definitions were all pre-specified.

RESULTS

A total of 27,049 participants and 2,370 major vascular events contributed to the meta-analyses. Allocation to more-intensive, compared with less-intensive, glucose control reduced the risk of major cardiovascular events by 9% (HR 0.91, 95% CI 0.84-0.99), primarily because of a 15% reduced risk of myocardial infarction (HR 0.85, 95% CI 0.76-0.94). Mortality was not decreased, with non-significant HRs of 1.04 for all-cause mortality (95% CI 0.90-1.20) and 1.10 for cardiovascular death (95% CI 0.84-1.42). Intensively treated participants had significantly more major hypoglycaemic events (HR 2.48, 95% CI 1.91-3.21). Exploratory subgroup analyses suggested the possibility of a differential effect for major cardiovascular events in participants with and without macrovascular disease (HR 1.00, 95% CI 0.89-1.13, vs HR 0.84, 95% CI 0.74-0.94, respectively; interaction p = 0.04).

CONCLUSIONS/INTERPRETATION

Targeting more-intensive glucose lowering modestly reduced major macrovascular events and increased major hypoglycaemia over 4.4 years in persons with type 2 diabetes. The analyses suggest that glucose-lowering regimens should be tailored to the individual.

Adding a dopamine agonist to preexisting levodopa therapy vs. levodopa therapy alone in advanced Parkinson's disease: a meta analysis

BACKGROUND

To perform a meta analysis of randomised placebo-controlled trials evaluating the use of dopamine agonist (DA) or placebo to preexisting levodopa therapy for the treatment of advanced Parkinson's disease (PD). We focused on clinically important efficacy [Unified Parkinson's Disease Rating Scale (UPDRS) activities of daily living (ADL) and motor scores as well as change in 'off' time and levodopa dose] and safety outcomes (withdrawal because of adverse drug events (ADEs), dyskinesias, hallucinations and mortality).

METHODS

A systematic literature search was performed between January 1990 and July 2007. The primary outcome measures assessed were the reduction in scores of Unified Parkinson's Disease Rating Scale (UPDRS) activities of daily living (ADL) and motor scores as well as reduction in 'off' time and reductions in levodopa dose from baseline. Safety end-points were also evaluated.

RESULTS

A total of 15 trials (n = 4380 subjects) were included in the meta analysis. Adjunctive DA use resulted in greater improvement as measured by the UPDRS ADL [weighted mean difference (WMD) -2.20, 95% confidence interval (CI) -2.64 to -1.76; p < 0.0001] and motor score reduction (WMD -5.56, 95% CI -6.82 to -4.31; p < 0.0001) as well as reduction in 'off' time measured in hours/day (WMD -1.20, 95% CI -1.78 to -0.62; p < 0.0001) and reduction in levodopa dose (WMD -128.5 mg, 95% CI -175.0 to -82.1; p < 0.0001) vs. placebo. Incidence of dyskinesia and hallucinations was higher with DAs [odds ratio (OR) 3.27, 95% CI 2.65-4.03; p < 0.0001] and (OR 3.34, 95% CI 2.44-4.58; p < 0.0001). Non-ergot DAs were qualitatively better, although both ergot and non-ergot DAs showed statistically significant improvements in all UPDRS scores.

CONCLUSION

Adjunctive DA use to levodopa is superior to levodopa alone in reducing PD symptoms in patients not controlled with monotherapy. DAs seem especially useful amongst PD patients with wearing-off phenomenon from levodopa therapy, but can cause some adverse events.

The body constitution of patients and intubation scales as predictors of difficult intubation considered in relation to the experience of the intubator

The aims of the study were to identify factors that may result in difficulties in intubation, and to compare the results obtained when an experienced and when a less experienced anaesthesiologist was involved. The 96 patients included in the study were evaluated for difficult intubation according to the following scales: Mallampati, upper lip bite test (ULBT) and Patil. The mobility of the cervical segments of the vertebral column, the distance between the jugular notch of the sternum and the chin and the anatomical constitution of the body were other factors that were taken into consideration. Statistical analysis was performed in order to identify factors that may result in difficulties in intubation for an experienced and for a less experienced anaesthesiologist.

High prevalence of chronic kidney disease in Thailand

We describe the prevalence of stage III and IV chronic kidney disease in Thailand from a representative sample of individuals aged 35 years and above using a stratified, multistage, cluster-sampling method. Population estimates were calculated by applying sampling weights from the 2000 Thai census. Glomerular filtration rates were estimated from serum creatinine using the Cockroft-Gault and the simplified Modification of Diet in Renal Disease (MDRD) formulae. The prevalence of stage III disease among individuals aged 35 years and above was estimated to be about 20% using the Cockroft-Gault formula and about 13% from the MDRD formula. Stage IV disease was present in about 0.9 and 0.6% of this population using the respective formulae. The highest prevalence rates were observed in less well-developed rural areas and the lowest in developed urban areas. The prevalence of chronic kidney disease was significantly higher than that reported in individuals over 40 years old from the United States for both stage III and IV disease and higher than the reported incidence in Taiwan and Australia. This high prevalence of chronic kidney disease in Thailand has obvious implications for the health of its citizens and for the allocation of health-care resources.

PSA failure following definitive treatment of prostate cancer having biopsy Gleason score 7 with tertiary grade 5

CONTEXT

In 2005, the International Society of Urologic Pathology consensus conference recommended that men with biopsy Gleason score 3 + 4 or 4 + 3 prostate cancer and tertiary pattern 5 should have their cancer classified as Gleason score 8 or 9, respectively. Yet, the management of men with Gleason score 7 vs 8 or 9 prostate cancer differs.

OBJECTIVE

To compare the prognostic significance of Gleason score 7 with tertiary grade 5 vs other Gleason scores with respect to time to prostate-specific antigen (PSA) failure in men with prostate cancer.

DESIGN, SETTING, AND PATIENTS

From 1989 to 2005, 2370 men with clinical tumor category 1c to 3b, node-negative, and nonmetastatic prostate cancer underwent definitive therapy with surgery or radiation therapy with or without hormonal therapy. A pathologist with expertise in genitourinary cancers assigned Gleason scores to the prostate needle biopsy specimens. Cox regression was used to assess whether a significant association existed between the presence of tertiary grade 5 in men with Gleason score 7 disease and time to recurrence compared with men with Gleason score 7 without tertiary grade 5, Gleason score 5 to 6, or 8 to 10 disease, adjusting for known prognostic factors and treatment.

MAIN OUTCOME MEASURE

Time to PSA failure.

RESULTS

Men with Gleason score 7 and tertiary grade 5 disease had a significantly shorter time to PSA failure than men with 7 without tertiary grade 5 (median time, 5.0 vs 6.7 years, respectively; adjusted hazard ratio (HR), 0.56; 95% confidence interval [CI], 0.32-0.97; P = .04) or score of 6 or less (median time, 15.4 years; adjusted HR, 0.24; 95% CI, 0.13-0.43; P < .001). However, a significant difference was not observed when these men were compared with men with Gleason score 8 to 10 disease (median time, 5.1 years; adjusted HR, 0.96; 95% CI, 0.54-1.71; P = .90).

CONCLUSION

In this study population, men with prostate cancer having biopsy Gleason score 7 and tertiary grade 5 had a higher risk of PSA-failure when compared with men with Gleason score 7 without tertiary grade 5 and had a comparable risk with men with Gleason score 8 to 10.

Family and personal history in colorectal cancer patients: what are we missing?

OBJECTIVE

Family and personal history of colorectal cancer and associated tumours are crucial in identifying families with hereditary nonpolyposis colorectal cancer (HNPCC). The aim of this study was to determine the adequacy of these aspects of history-taking in the management of colorectal cancer patients.

PATIENTS AND METHODS

Colorectal cancer patients attending outpatient follow-up were interviewed to obtain a detailed family and personal history of cancers. The medical notes were then reviewed to identify whether these had been documented previously.

RESULTS

One hundred and one patients took part. In seven, no family history had been recorded; none of these actually had a significant pedigree. In 88, the family history was not significant, a finding correctly documented in the records. Three had a high-risk family history and another three had a personal history of other possible HNPCC-related cancers. In each of these patients, the relevant findings had been documented, but no further action had been taken.

CONCLUSIONS

Family history was taken in the majority of patients, but in the only three with a pedigree indicative of HNPCC, its significance was not appreciated. The potential relevance of multiple HNPCC-related cancers in the same individual was also overlooked. Improved education and referral pathways are needed to ensure that families with HNPCC have access to appropriate surveillance and genetic testing.

Estimation of the delivered patient dose in lung IMRT treatment based on deformable registration of 4D-CT data and Monte Carlo simulations

The purpose of this study is to accurately estimate the difference between the planned and the delivered dose due to respiratory motion and free breathing helical CT artefacts for lung IMRT treatments, and to estimate the impact of this difference on clinical outcome. Six patients with representative tumour motion, size and position were selected for this retrospective study. For each patient, we had acquired both a free breathing helical CT and a ten-phase 4D-CT scan. A commercial treatment planning system was used to create four IMRT plans for each patient. The first two plans were based on the GTV as contoured on the free breathing helical CT set, with a GTV to PTV expansion of 1.5 cm and 2.0 cm, respectively. The third plan was based on the ITV, a composite volume formed by the union of the CTV volumes contoured on free breathing helical CT, end-of-inhale (EOI) and end-of-exhale (EOE) 4D-CT. The fourth plan was based on GTV contoured on the EOE 4D-CT. The prescribed dose was 60 Gy for all four plans. Fluence maps and beam setup parameters of the IMRT plans were used by the Monte Carlo dose calculation engine MCSIM for absolute dose calculation on both the free breathing CT and 4D-CT data. CT deformable registration between the breathing phases was performed to estimate the motion trajectory for both the tumour and healthy tissue. Then, a composite dose distribution over the whole breathing cycle was calculated as a final estimate of the delivered dose. EUD values were computed on the basis of the composite dose for all four plans. For the patient with the largest motion effect, the difference in the EUD of CTV between the planed and the delivered doses was 33, 11, 1 and 0 Gy for the first, second, third and fourth plan, respectively. The number of breathing phases required for accurate dose prediction was also investigated. With the advent of 4D-CT, deformable registration and Monte Carlo simulations, it is feasible to perform an accurate calculation of the delivered dose, and compare our delivered dose with doses estimated using prior techniques.

The splicing of U12-type introns can be a rate-limiting step in gene expression

Some protein-coding genes in metazoan genomes contain a minor class of introns that are excised by a distinct, low-abundance spliceosome. We have developed a quantitative RT-PCR assay that allows comparison of the relative rates of intron removal from the transcripts present in a pre-mRNA population. We show that the U12-type introns are more slowly spliced than the major-class (U2-type) introns from three endogenous pre-mRNAs in human tissue culture cells. In Drosophila melanogaster S2 cells, using minigene constructs designed to produce nearly identical mRNAs, we observe increased expression of fluorescent protein and mature mRNA upon mutation of a U12-type to a U2-type intron. These results provide evidence that the level of gene expression in vivo is lowered by the presence of a U12-type intron and implicate the U12-type spliceosome as a target in the post-transcriptional regulation of gene expression.

A cellular automaton model of early tumor growth and invasion

A hybrid cellular automaton model is described and used to simulate early tumor growth and examine the roles of host tissue vascular density and tumor metabolism in the ability of a small number of monoclonal transformed cells to develop into an invasive tumor. The model incorporates normal cells, tumor cells, necrotic or empty space, and a random network of native microvessels as components of a cellular automaton state vector. Diffusion of glucose and H(+)ions (the latter largely resulting from the tumor's excessive reliance on anaerobic metabolism) to and from the microvessels, and their utilization or production by cells, is modeled through the solution of differential equations. In this way, the cells and microvessels affect the extracellular concentrations of glucose and H(+)which, in turn, affect the evolution of the automaton. Simulations of the model demonstrate that: (i) high tumor H(+)ion production is favorable for tumor growth and invasion; however for every H(+)ion production rate, there exists a range of optimal microvessel densities (leading to a local pH favorable to tumor but not to normal cells) for which growth and invasion is most effective, (ii) at vascular densities below this range, both tumor and normal cells die due to excessively low pH, (iii) for vascular densities above the optimal range the microvessel network is highly efficient at removing acid and therefore the tumor cells lose their advantage over normal cells gained by high local H(+)concentration. While significant spatial gradients of glucose formed, no regions of detrimentally poor glucose perfusion (for either cell type) were observed, regardless of microvessel density. Depending on metabolic phenotype, a variety of tumor morphologies similar to those clinically observed were realized in the simulations. Lastly, a sharp transition (analogous to that of the adenoma-carcinoma sequence) between states of initial tumor confinement and efficient invasiveness was observed when H(+)production reached a critical value.

Capsaicin vanilloid receptor-1 mediates substance P release in experimental pancreatitis

We examined whether the capsaicin vanilloid receptor-1 (VR1) mediates substance P (SP) release from primary sensory neurons in experimental pancreatitis. Pancreatitis was achieved by 12 hourly injections of caerulein (50 microg/kg ip) in mice. One group received capsazepine (100 micromol/kg sc), a competitive VR1 antagonist, at 4-h intervals. Neurokinin-1 receptor (NK1R) internalization in acinar cells, used as an index of endogenous SP release, was assessed by immunocytochemical quantification of NK1R endocytosis. The severity of pancreatitis was assessed by measurements of serum amylase, pancreatic myeloperoxidase (MPO) activity, and histological grading. Caerulein administration caused significant elevations in serum amylase and pancreatic MPO activity, produced histological evidence of pancreatitis, and caused a dramatic increase in NK1R endocytosis. Capsazepine treatment significantly reduced the level of NK1R endocytosis, and this was associated with similar reductions in pancreatic MPO activity and histological severity of pancreatitis. These results demonstrate that repeated caerulein stimulation causes experimental pancreatitis that is mediated in part by stimulation of VR1 on primary sensory neurons, resulting in endogenous SP release.

Pulmonary stenosis and severe biventricular dysfunction: improvement following percutaneous valvuloplasty

A 15-year-old boy with severe pulmonary stenosis associated with severe right and left ventricular systolic dysfunction is reported. After successful percutaneous pulmonary valvuloplasty, there was an initial and early improvement in right ventricular (RV) function, followed by a delayed and more gradual improvement in left ventricular (LV) function. At long-term follow up, both RV and LV systolic functions were nearly normalized. Several mechanisms may be implicated, including ventricular interdependence, geometric factors, altered compliance and intrinsic alteration in the LV muscle. A delayed, but sustained, improvement in LV systolic function following relief of RV pressure overload suggests that the latter mechanism must have played an important role in the genesis of the LV dysfunction. Pulmonary stenosis associated with severe biventricular dysfunction may be treated primarily by percutaneous pulmonary balloon valvuloplasty with near-total recovery of the ventricular function.

Prevalence of sinonasal symptoms in patients with HIV infection

Infection with the human immunodeficiency virus (HIV) is increasing in prevalence, and disease patterns are changing as patient survival lengthens. The purpose of this cross-sectional epidemiological study was to assess the prevalence and severity of self-reported symptoms of otolaryngologic disease in a group of patients attending a general HIV outpatient clinic (n = 203), and to compare the prevalence of self-reported symptoms with a sample of patients without HIV infection (n = 100). Of the HIV-infected patients, 65% of patients had AIDS, 35% were HIV-positive, and the median CD4 count was 135. Although only 11% of patients had seen an otolaryngologist in the prior 6 months, the majority of patients (66%) reported the presence of sinonasal disease during that time. Allergic rhinitis (80%) and sinusitis (54%) were the most commonly reported sinonasal symptoms, and 44% regularly used nasal or sinus medications. Sinonasal disease severity was significantly higher than the self-reported severity of mouth/throat disease (p = 0.01), ear disease (p = 0.03), and neck/salivary disease (p = 0.01). Although patients' self-reported overall health status was associated (p = 0.02) with CD4 count, the severity of sinonasal symptoms was not associated (p = 0.93) with CD4 count. Similarly, sinonasal symptom severity did not differ between HIV-positive and AIDS patients (p = 0.45). In other words, sinonasal disease severity did not improve as general health status improved.

Fluorescence-imaged microdeformation of the outer hair cell lateral wall

Outer hair cell (OHC) electromotility appears to be central to mammalian hearing and originates within its lateral wall. The OHC lateral wall is a unique trilaminate structure consisting of the plasma membrane (PM), the cortical lattice (CL), and the subsurface cisternae (SSC). We selectively labeled and imaged the lateral wall components in the isolated guinea pig OHC under confocal microscopy. The PM was labeled with a voltage-sensitive dye, di-8-ANEPPS; the SSC was labeled with the sphingomyelin precursor, NBD-C6-ceramide; and F-actin in the CL was labeled with conjugates of phalloidin. Interactions among the three layers were evaluated with the micropipette aspiration technique. The PM was tethered to the CL and SSC until, at a critical deformation pressure, the PM separated, allowing visualization of the extracisternal space, and ultimately formed a vesicle. After detaching, the stiffness parameter of the PM was 22% of that of the intact lateral wall. We conclude that the lateral wall PM is more compliant than the CL/SSC complex. The data clarify the structural basis for electromotile force coupling in the OHC lateral wall.

Renal transplantation following immunoadsorption in highly sensitized recipients

Five highly sensitized patients, with panel reactivity greater than 80% for 1.75-5 years, were treated by extracorporeal staphylococcal protein-A immunoadsorption, prednisolone, and cyclophosphamide. The five patients underwent treatment of 18-40 (mean 31) liters of plasma, respectively in 4-7 (mean 5.6) sessions. This reduced the titer of cytotoxic antibodies to sensitizing antigens to < 1/8 in all cases and abolished reactivity to crossreacting antigens. Two patients required retreatment following resynthesis of cytotoxic antibodies. All five patients have been transplanted, and four of these now have stable serum creatinines of 168 mumol/L at 34 months, 208 mumol/L at 29 months, 96 mumol/L at 5 months, and 125 mumol/L at 3 months posttransplantation. One patient had primary graft dysfunction due to acute tubular necrosis; the kidney was removed after eight weeks and showed cortical necrosis without evidence of acute rejection.