A disulfide-bound HIV-1 V3 loop sequence on the surface of human rhinovirus 14 induces neutralizing responses against HIV-1

An immunogenic sequence from the V3 loop of the MN isolate of human immunodeficiency virus type 1 (HIV-1), His-Ile-Gly-Pro-Gly-Arg-Ala-Phe, was transplanted onto a surface loop of the VP2 capsid protein of human rhinovirus 14. To optimize for virus viability and immunogenicity of the transplanted sequence, the HIV sequence was flanked by (1) a cysteine residue that could form a disulfide bond and (2) randomized amino acids (in either of two arrangements) to generate numerous presentations of the Cys-Cys loop. The location for engineering in VP2 was chosen by searching the geometries of disulfide-bound loops in known protein structures. A model for the structure of the transplanted V3 loop sequence was developed using molecular dynamics and energy minimization calculations. Proteolytic digestion with and without reducing agent demonstrated the presence of the disulfide bond in the chimeric virus examined. Monoclonal and polyclonal antibodies directed against the V3 region of the HIV-1MN strain potently neutralized two chimeric viruses. Guinea pig antisera against two chimeric viruses were able to neutralize HIV-1MN and HIV-1ALA-1 in cell culture. The ability of chimeric viruses to elicit antibodies capable of neutralizing the source of the transplanted sequence could be favorable for vaccine development.

The progression of Alzheimer's disease from limbic regions to the neocortex: clinical, radiological and pathological relationships

Alzheimer's disease (AD) is characterised by the gradual accumulation of neurofibrillary pathology in selected regions of the brain. Earlier studies indicate that the accumulation of neurofibrillary tangles is associated both with decline in patient's cognitive performance as well as with medial temporal lobe atrophy on CT scans. There are also indications that progression through the pathological stages of AD is associated with decline in cognitive functions. The results of this study indicate that progression of disease, especially beyond the boundaries of the limbic regions, is associated with marked decline in the cognitive performance of patients suffering from AD. However the clinical manifestations of early pathological stages are not so well defined. We also found that the atrophy of the medial temporal lobe on CT scans is related to the progression of pathology. Atrophy is most apparent when the disease reaches its isocortical stages and is not marked in the limbic stages of the disease. The additive effect of pathologies co-existing with AD is apparent in reduced cognitive scores, while the atrophy of limbic structures, as measured on CT scans, seems to be mainly attributable to AD-related pathology.

Relationship between clinical and radiological diagnostic criteria for Alzheimer's disease and the extent of neuropathology as reflected by 'stages': a prospective study

The distribution of pathology related to Alzheimer's disease (AD) is not uniform throughout the brain. Sites which have a predilection for the development of Alzheimer-type pathology are the limbic regions and neocortical association areas. The changes in these areas of the brain develop gradually, following a well-determined sequence that allows a pathological staging of the disease process. According to the staging hypothesis, the first pathological alterations develop in the transentorhinal and entorhinal regions. The neurofibrillary pathology then spreads into the hippocampus, but not until the final stages does it affect the neocortex. In this study we analyse the relationship between the pathological stages of AD, according ot the staging hypothesis, and the clinical diagnosis in a prospectively assessed patient group. Prediction of any given pathological stage from the clinical diagnosis was found to be poor. This may be partly due to the fact that additional pathologies can alter the clinical picture and severity of dementia in patients who are only in the initial stages of AD. Nevertheless, the NINCDS-ADRDA clinical criteria had a high sensitivity for detection of AD-related pathology: the 'probable AD' category included 22/38 (57.9%) of those in the late isocortical stage, while the 'possible AD' category included 19/23 (82.6%) of those in the limbic stage. Using proposed neuro-imaging protocols for improved identification of patients with AD-related pathology, we largely identified subjects in whom the extent of pathology had spread to the neocortex.

Ethanol exposure differentially alters central monoamine neurotransmission in alcohol-preferring versus -nonpreferring rats

Individual differences in ethanol preference may be linked to differences in the functional activity of forebrain monoamine systems or their sensitivity to modification by ethanol. To test this hypothesis, basal extracellular concentrations of dopamine (DA) and serotonin (5-HT) in the nucleus accumbens as well as the effects of repeated ethanol pretreatment on the basal release of these transmitters were examined in alcohol-preferring (P), alcohol-nonpreferring (NP), and genetically heterogeneous Wistar rats. All animals received i.p. injections of ethanol (1.0 g/kg) or saline for 5 consecutive days. Fifteen hours after the final pretreatment, basal extracellular concentrations and "in vivo extraction fraction" values for DA and 5-HT were determined by no-net-flux in vivo microdialysis. In ethanol-naive rats, significant line differences were observed with high basal 5-HT release in P rats, low 5-HT release in NP rats, and intermediate 5-HT levels in Wistar rats. No differences among groups were noted in basal DA release. Ethanol pretreatment decreased basal extracellular 5-HT levels in P rats whereas increasing 5-HT efflux was seen in the Wistar and NP lines. In addition, ethanol pretreatment increased extracellular DA concentrations in Wistar and P rats, but not in NP rats. The results confirm a relationship between the functional status of forebrain DA and 5-HT systems and ethanol preference or aversion. Moreover, the data suggest that ethanol exposure can alter basal DA and 5-HT in the nucleus accumbens and that vulnerability to ethanol-induced changes in monoamine neurotransmission may be a factor in genetically determined ethanol preference.

Percutaneous nephrolithotomy with renal angiomyolipomas: a rare challenge

Renal angiomyolipomas (AML) are vascular tumors associated with a risk of spontaneous bleeding. Renal trauma may also initiate such hemorrhage. We present a case in which we initially avoided direct puncture and the possible risk of bleeding through extensive renal AMLs and then subsequently performed a direct puncture through the tumors. A 21-year-old obese male patient with tuberous sclerosis and mental retardation presented to our institution with left renal colic and was found to have a staghorn calculus. A CT scan revealed extensive bilateral renal AMLs. The patient had previously undergone renal angioinfarction for an enlarging right-sided AML, and nuclear renography demonstrated 70% function from the left side. The patient had a nephrostomy access created on the morning of a scheduled percutaneous nephrolithotomy under three-dimensional CT guidance. There was no clinically significant bleeding. Intraoperatively, a second access site was required in order to render the patient stone free. This was done using standard biplanar fluoroscopic technique and traversed an AML. Both tracts were balloon dilated prior to placement of a 34F Amplatz sheath. Postoperatively, the patient had an uneventful recovery. A CT scan performed 1 day postoperatively revealed no retroperitoneal collection. This case demonstrates that renal access can be achieved with remarkable accuracy using 3D CT imaging. Furthermore, although this approach seems most prudent in the case of extensive renal AMLs, fluoroscopically guided renal access and dilation to 34F was not associated with bleeding in this patient.

Unsupervised classification of Space Acceleration Measurement System (SAMS) data using ART2-A

The Space Acceleration Measurement System (SAMS) has been developed by NASA to monitor the microgravity acceleration environment aboard the space shuttle. The amount of data collected by a SAMS unit during a shuttle mission is in the several gigabytes range. Adaptive Resonance Theory 2-A (ART2-A), an unsupervised neural network, has been used to cluster these data and to develop cause and effect relationships among disturbances and the acceleration environment. Using input patterns formed on the basis of power spectral densities (psd), data collected from two missions, STS-050 and STS-057, have been clustered.

Complete renal embolization as an alternative to nephrectomy

PURPOSE

Simple nephrectomy is technically demanding in patients with recurrent inflammation or bleeding. It is also unwise to subject patients in poor health to the rigors of an extensive operative procedure. We report our experience with complete renal embolization as a safe and reliable alternative to surgical nephrectomy.

MATERIALS AND METHODS

Eight patients underwent complete renal embolization as an alternative to nephrectomy. Patients were given antibiotics intravenously before and after embolization. Six patients with indwelling nephrostomy tubes received post-embolization instillation of 80 mg. gentamicin before tube removal. Narcotic analgesics were also given as needed for pain control. Post-embolization hospital course was noted.

RESULTS

The indications for embolization included hydronephrotic, poorly functioning kidneys with pain in 5 cases, and recurrent bleeding from angiomyolipoma, bleeding after percutaneous resection of renal pelvic transitional cell carcinoma with metastases and spontaneous renal bleeding after hemodialysis in 1 each. Embolization was successful in 4 men and 4 women with a mean age of 58.8 years. In 6 patients severe flank pain required narcotic analgesics. One patient complained of nausea, 6 had fever and 6 had leukocytosis. In 1 case thrombosis of a limb of an aortobifemoral bypass graft required thrombectomy. Median hospital stay was 2.5 days. At a mean followup of 30.6 months presenting symptoms had resolved in all cases without hypertension, renal failure or abscess.

CONCLUSIONS

Complete renal embolization is a viable alternative to nephrectomy in patients with poorly functioning kidneys who present with pain or bleeding and in those who are poor operative candidates. This procedure is safe, reliable and minimally invasive with few long-term sequelae, and it is well tolerated.

Aurothioglucose inhibits murine thioredoxin reductase activity in vivo

Gold (I)-containing compounds, including aurothioglucose (ATG), are potent in vitro inhibitors of several selenocysteine-containing enzymes. Gold compounds have also been shown to potentiate the virulence of several viruses in mice, including coxsackievirus, implicated as a possible infectious agent in Keshan disease. One possible mechanism by which gold compounds may be increasing the virulence of viral infections in mice is by acting as a selenium antagonist in vivo and inducing oxidative stress. To investigate the possible role of gold compounds in inducing oxidative stress in mice, we assessed the ability of ATG administered in vivo to inhibit the activity of the selenocysteine-containing enzymes thioredoxin reductase (TR) and glutathione peroxidase (GPX1). Doses as low as 0. 025 mg ATG/g body weight caused significant and prolonged inhibition of TR activity in all tissues examined. No such inhibition of GPX1 activity was seen, indicating differential in vivo sensitivity of the enzymes to inhibition by ATG. In liver and heart, some recovery of TR activity was observed after a 7-d period, but no recovery was observed in pancreas or kidney. Because TR is involved in several important cellular redox functions, its inhibition most likely will affect multiple cellular processes. These results indicate that in vivo administration of ATG results in significant and long-lasting inhibition of TR activity. Such inhibition of TR could lead to increased levels of oxidative stress in vivo, thereby increasing the virulence of several viruses including the coxsackievirus.

Self-organizing map (SOM) of space acceleration measurement system (SAMS) data

In this paper, space acceleration measurement system (SAMS) data have been classified using self-organizing map (SOM) networks without any supervision; i.e., no a priori knowledge is assumed regarding input patterns belonging to a certain class. Input patterns are created on the basis of power spectral densities of SAMS data. Results for SAMS data from STS-50 and STS-57 missions are presented. Following issues are discussed in details: impact of number of neurons, global ordering of SOM weight vectors, effectiveness of a SOM in data classification, and effects of shifting time windows in the generation of input patterns. The concept of 'cascade of SOM networks' is also developed and tested. It has been found that a SOM network can successfully classify SAMS data obtained during STS-50 and STS-57 missions.

Endopyelotomy failure is associated with reduced transforming growth factor-beta

PURPOSE

Approximately 15% of patients with ureteropelvic junction obstruction have endopyelotomy failure and require an additional surgical procedure to remove the obstruction. Transforming growth factor-beta (TGF-beta), a cytokine which stimulates mesenchymal cell proliferation and extracellular matrix deposition, increases in the renal pelvis in response to obstruction. However, TGF-beta also is implicated in smooth muscle regeneration and wound healing. To understand the pathophysiology of ureteropelvic junction obstruction and determine why endopyelotomy fails in some obstructed ureteropelvic junctions, TGF-beta expression in obstructed and normal ureteropelvic junction segments was compared.

MATERIALS AND METHODS

Immunohistochemical staining using a rabbit polyclonal anti-TGF-beta was performed on deparafinfized 4 microm. sections of paraffin blocked ureteropelvic junction segments. Human obstructed ureteropelvic junction segments were removed during primary pyeloplasties (11) and secondary pyeloplasties after endopyelotomy failure (11). Normal ureteropelvic junction segments were removed during nephrectomy for purposes unrelated to obstruction (11). Grading on a scale of 0 to 4 was performed by a physician blinded to the source of the specimen.

RESULTS

Mean TGF-beta expression plus or minus standard error of the mean was significantly increased (p <0.02) in obstructed ureteropelvic junctions from primary pyeloplasties (2.6+/-0.7) compared to normal ureteropelvic junctions (1.6+/-0.7), as expected. However, TGF-beta expression in the endopyelotomy failure group (1.8+/-0.6) was not significantly different from that in normal ureteropelvic junctions and was significantly lower (p <0.05) than that in obstructed ureteropelvic junctions from primary pyeloplasties.

CONCLUSIONS

Obstructed ureteropelvic junctions in cases of endopyelotomy failure have decreased expression of TGF-beta compared with other obstructed ureteropelvic junctions. These data suggest that an elevation of TGF-beta in obstructed ureteropelvic junctions may be necessary for successful tissue repair after endopyelotomy.

The cell division cycle and the pathophysiology of Alzheimer's disease

Evidence is growing of a role of apoptosis in neurodegenerative disorders including Alzheimer's disease. Recent research indicates that cell cycle disturbances may promote apoptosis in neurodegenerative diseases. In this commentary we will discuss the control of the cell cycle in mammalian cells in general and in the central nervous system in particular. We then summarize the evidence for cell cycle perturbations in Alzheimer's disease and discuss the possible significance these may have for the development of pathological changes in this disease. Our working hypothesis is that, contrary to previous belief, neurons in the adult human brain are capable of re-entering the cell division cycle. The progression of the cell cycle is normally arrested at an early stage and neurons are able to re-differentiate. However, in Alzheimer's disease the cell cycle is allowed to progress into the G2 phase. At this stage re-differentiation is not possible and the neurons will suffer one of two fates: either they will die via an apoptotic pathway or they may produce Alzheimer-type pathology.

Abnormal function of potassium channels in platelets of patients with Alzheimer's disease

BACKGROUND

Reports of abnormalities of potassium-channel function in various cultured cells of Alzheimer's disease patients led us to attempt to characterise the pharmacological characteristics of the abnormal channel.

METHODS

We studied platelets from 14 patients with Alzheimer-type dementia and 14 non-demented controls matched for age and sex. The effects of specific inhibitors of K+ channels on the efflux of rubidium-86 ions, a radioactive analogue of K+, from the platelets were measured.

FINDINGS

Normal platelets contain three types of K+ channel, sensitive to the inhibitory actions of apamin (small-conductance calcium-dependent potassium channels), charybdotoxin (of less specificity, but probably intermediate-conductance calcium-dependent K+ channels), and alpha-dendrotoxin (voltage-sensitive K+ channels). However, 8Rb+ efflux from the platelets of patients with Alzheimer-type dementia was not inhibited by either apamin or charybdotoxin. By contrast, inhibition by alpha-dendrotoxin did occur.

INTERPRETATION

Our results suggest that calcium-dependent K+ channels in platelets are selectively impaired in Alzheimer's disease. A similar abnormality in neurons could contribute to the pathophysiology of the disorder.

Folate, vitamin B12, and serum total homocysteine levels in confirmed Alzheimer disease

BACKGROUND

Recent studies suggest that vascular disease may contribute to the cause of Alzheimer disease (AD). Since elevated plasma total homocysteine (tHcy) level is a risk factor for vascular disease, it may also be relevant to AD.

OBJECTIVE

To examine the association of AD with blood levels of tHcy, and its biological determinants folate and vitamin B12.

DESIGN

Case-control study of 164 patients, aged 55 years or older, with a clinical diagnosis of dementia of Alzheimer type (DAT), including 76 patients with histologically confirmed AD and 108 control subjects.

SETTING

Referral population to a hospital clinic between July 1988 and April 1996.

MAIN OUTCOME MEASURES

Serum tHcy, folate, and vitamin B12 levels in patients and controls at entry; the odds ratio of DAT or confirmed AD with elevated tHcy or low vitamin levels; and the rate of disease progression in relation to tHcy levels at entry.

RESULTS

Serum tHcy levels were significantly higher and serum folate and vitamin B12 levels were lower in patients with DAT and patients with histologically confirmed AD than in controls. The odds ratio of confirmed AD associated with a tHcy level in the top third (> or = 14 micromol/L) compared with the bottom third (< or = 11 micromol/L) of the control distribution was 4.5 (95% confidence interval, 2.2-9.2), after adjustment for age, sex, social class, cigarette smoking, and apolipoprotein E epsilon4. The corresponding odds ratio for the lower third compared with the upper third of serum folate distribution was 3.3 (95% confidence interval, 1.8-6.3) and of vitamin B12 distribution was 4.3 (95% confidence interval, 2.1-8.8). The mean tHcy levels were unaltered by duration of symptoms before enrollment and were stable for several years afterward. In a 3-year follow-up of patients with DAT, radiological evidence of disease progression was greater among those with higher tHcy levels at entry.

CONCLUSIONS

Low blood levels of folate and vitamin B12, and elevated tHcy levels were associated with AD. The stability of tHcy levels over time and lack of relationship with duration of symptoms argue against these findings being a consequence of disease and warrant further studies to assess the clinical relevance of these associations for AD.

Estrous cycle effects on operant responding for ethanol in female rats

Human females have been reported to be uniquely sensitive to the deleterious effects of ethanol, thus it is important to study the characteristics of and mechanisms underlying alcohol consumption that may be specific to females. Models of ethanol self-administration in female rats that take into consideration the estrous cycle have the potential to provide important information concerning these characteristics and mechanisms. The purpose of this study was to explore the effect of the cycle on ethanol self-administration using a limited access operant paradigm. Female Wistar rats were trained to lever press for 10% ethanol versus water using a saccharin fading procedure. Responses were examined across the four phases of the estrous cycle. No effects of estrous cycle phase were observed when these rats were allowed to cycle freely. Subsequently, estrous phase effects were investigated in females whose cycles had been synchronized. Under this condition, an effect of estrous phase was present, with lower ethanol intake observed in estrus (and in some cases proestrus). Synchronized rats all showed at least one very clear 4-day estrous cycle, whereas free-running rats' cycles ranged from 3 to 5 days. Thus, it is more likely that synchronized rats were tested in the identical portion of each phase, when hormone levels were less variable. These results suggest that ethanol may be more reinforcing during diestrus than proestrus and estrus in female rats.

The in vitro bactericidal effect of microwave energy on bacteria that cause prostatitis

OBJECTIVES

We investigated the in vitro nonthermal effects of microwaves delivered from Prostatron 2.0 on Escherichia coli and Enterobacter cloacae.

METHODS

The fingers of powder-free, sterile gloves were ligated, and bacterial solutions were transferred into the remaining area of the glove. The gloves were then sealed using silk ligatures. One set of gloves was subjected to the microwave treatment while another set was placed in a temperature-matched waterbath to act as control samples. The gloves containing the treatment group were taped around the probe, at the site where microwave energy exits the probe. During the treatment period, the temperatures from the urethral probe and the rectal probe were carefully monitored.

RESULTS

The mean (+/-SD) energy delivered was 46.6 +/- 9.5 kJ (range 30.0 to 59.5) for the 10 trials on E. coli and colony counts in the experimental microwaved gloves decreased significantly compared with control samples (5.26 +/- 4.5 x 10(5) versus 10.16 +/- 9.3 x 10(5) CFU/mL, P = 0.02). For the experiments on E. cloacae the mean (+/-SD) energy applied was 38.5 +/- 12.5 kJ, and a significant decrease in colony counts of microwaved samples was also observed compared with controls (11.04 +/- 4.8 x 10(5) versus 20.08 +/- 10.1 x 10(5) CFU/mL, P = 0.004).

CONCLUSIONS

Microwave energy, delivered from Prostatron 2.0, independent of heat production has an in vitro bactericidal effect on laboratory-cultured E. coli and E. cloacae.

Endopyelotomy for horseshoe and ectopic kidneys

PURPOSE

We report our experience with endopyelotomy for horseshoe and ectopic kidneys in the largest series to date to our knowledge, and discuss the technical modifications adopted to perform successfully percutaneous antegrade endopyelotomy.

MATERIALS AND METHODS

From September 1987 to April 1996, 4 patients with horseshoe and 5 with ectopic kidney underwent percutaneous antegrade endopyelotomy for symptomatic ureteropelvic junction obstruction. The percutaneous puncture was made more posteromedial and the ureteropelvic junction was incised lateral. A retrograde percutaneous access tract was created under laparoscopic guidance in pelvic kidneys.

RESULTS

The operative procedure was performed uneventfully in all patients with no major bleeding, pleural effusion or visceral perforation. The stents were removed at 6 weeks, and an excretory urogram was performed at 2 weeks, 6 months and yearly thereafter. In 2 patients (22%) with severe hydronephrosis, poor renal function and a long ureteral stricture surgical treatment failed immediately. The remaining 7 patients (78%) had long lasting clinical and radiographic success with a mean followup of 62 months.

CONCLUSIONS

Percutaneous antegrade endopyelotomy, with a few technical modifications, is a safe and effective treatment for ureteropelvic junction obstruction associated with horseshoe and ectopic kidneys.

Comparison of pathological diagnostic criteria for Alzheimer disease

Because the clinical picture of Alzheimer disease (AD) is often difficult to discriminate from other dementing illnesses, the diagnosis of AD requires neuropathological confirmation. However, for the pathological diagnosis of AD, there are no unanimously accepted criteria. The three currently used sets of pathological criteria (Khachaturian: Khachaturian, Arch Neurol 1985;42:1097-105; Tiemy: Tierney et al., Can J Neurol Sci 1986; 13:424-6; CERAD: Mirra et al., Neurology 1991;41:479-86) for the disease differ from each other considerably. We applied these criteria to the first 43 consecutive subjects (37 demented) with no neuropathology other than AD-type pathology from autopsies after longitudinal prospective clinical study in the Oxford Project to Investigate Memory and Ageing (OPTIMA). The results show that the CERAD category of definite AD corresponds closely with the cases that fulfill Tierney A3 inclusion criteria for AD. The combined CERAD categories of possible, probable, and definite AD correspond closely to cases fulfilling Khachaturian criteria forAD. The influence of a clinical diagnosis of dementia when Khachaturian and CERAD criteria were applied was considerable because between 9.3% and 90.7% of patients would have been categorized differently depending on whether clinical dementia was present or absent.

Endopyelotomy after failed pyeloplasty: the long-term results

PURPOSE

Endopyelotomy has been proposed as a technique to treat ureteropelvic junction obstruction after failed open pyeloplasty. However, to our knowledge no long-term results of this treatment have been reported. We report the long-term followup of a cohort of patients in whom pyeloplasty failed and who subsequently were treated with endopyelotomy.

MATERIALS AND METHODS

From January 1985 to February 1996, 72 patients in whom open surgical pyeloplasty failed were treated with percutaneous endopyelotomy. Mean patient age was 35 years (range 5 to 82). The interval between pyeloplasty and subsequent failure ranged from 2 months to 30 years (mean 57 months). The major presenting symptoms were pain in 82% of cases, fever and urinary tract infections in 37.5%, stone formation in 25% and gross hematuria in 21%.

RESULTS

Antegrade endopyelotomy using a hooked knife was performed in all patients with no unusual difficulty and minimal complications. A total of 63 patients (87.5%) had long lasting clinical and radiographic treatment success after a mean followup of 88.5 months. Of the 9 endopyelotomy failures (12.5%) 7 (77.8%) were detected immediately after stent removal at 6 weeks, 1 (11.1%) at 6 months and 1 (11.1%) at 10 months postoperatively (mean failure interval 3.3 months). The failures were corrected with repeat endopyelotomy in 1 patient, pyeloplasty in 3, ileal interposition in 1 and nephrectomy in 4.

CONCLUSIONS

Endopyelotomy is the treatment of choice for recurrent ureteropelvic junction obstruction after failed pyeloplasty, with a high and sustained long-term success rate and no reported new failures after 1-year followup. Furthermore, endopyelotomy is technically easier with less morbidity than repeat open pyeloplasty.

Longitudinal study of inflammatory factors in serum, cerebrospinal fluid, and brain tissue in Alzheimer disease: interleukin-1beta, interleukin-6, interleukin-1 receptor antagonist, tumor necrosis factor-alpha, the soluble tumor necrosis factor receptors I and II, and alpha1-antichymotrypsin

There is evidence consistent with the hypothesis that inflammatory and immune mechanisms are involved in the pathogenesis of Alzheimer disease (AD). We have investigated whether the levels of inflammatory associated proteins in serum or lumbar cerebrospinal fluid (CSF) reflect the progressive cognitive decline and brain atrophy of AD-patients. Levels of interleukin-1beta(IL-1beta), IL-1 receptor antagonist (IL-1ra), interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-alpha), the soluble TNF receptors type I and II (sTNFR I and II), and the acute phase protein alpha1-antichymotrypsin (x1-ACT) were determined in paired serum and CSF samples taken yearly over a period of 2-5 years from pathologically confirmed AD patients (n = 8) and normal controls or non-AD subjects with other CNS pathology (n = 9). No significant differences were found between AD subjects and controls in the mean levels of the above mediators. There was also no correlation in either subject group between the levels of these inflammatory mediators in serum or CSF, and the change in cognitive status or the progression of the atrophy of the medial temporal lobe measured by X-ray computed tomography (CT). The concentrations of IL-1beta, IL-6, and TNF-alpha were determined in brain tissue specimens of five to nine different brain regions in six of the AD patients and four of the non-AD subjects. The levels of IL-1beta and IL-6 in the various brain regions were not significantly different in the AD and the non-AD group. However, in AD patients the level of TNF-alpha was significantly lower in the frontal cortex (32%, p = 0.024), the superior temporal gyrus (57%, p = 0.021), and the entorhinal cortex (49%, p = 0.009) compared with non-AD subjects. Low levels of TNF-alpha in the brain areas that showed neuropathology in AD may indicate a dysregulation of the inflammatory process in AD. Despite this finding, this study does not support the use of measurements of any of the inflammatory mediators investigated here as a diagnostic parameter for AD, due the large overlap in the levels of these factors between AD patients and other subjects, and the poor relation to clinical signs of AD.

Endopyelotomy for horseshoe and ectopic kidneys

PURPOSE

We report our experience with endopyelotomy for horseshoe and ectopic kidneys in the largest series to date to our knowledge, and discuss the technical modifications adopted to perform successfully percutaneous antegrade endopyelotomy.

MATERIALS AND METHODS

From September 1987 to April 1996, 4 patients with horseshoe and 5 with ectopic kidney underwent percutaneous antegrade endopyelotomy for symptomatic ureteropelvic junction obstruction. The percutaneous puncture was made more posteromedial and the ureteropelvic junction was incised lateral. A retrograde percutaneous access tract was created under laparoscopic guidance in pelvic kidneys.

RESULTS

The operative procedure was performed uneventfully in all patients with no major bleeding, pleural effusion or visceral perforation. The stents were removed at 6 weeks, and an excretory urogram was performed at 2 weeks, 6 months and yearly thereafter. In 2 patients (22%) with severe hydronephrosis, poor renal function and a long ureteral stricture surgical treatment failed immediately. The remaining 7 patients (78%) had long lasting clinical and radiographic success with a mean followup of 62 months.

CONCLUSIONS

Percutaneous antegrade endopyelotomy, with a few technical modifications, is a safe and effective treatment for ureteropelvic junction obstruction associated with horseshoe and ectopic kidneys.

Necrosis of the urethra and tissue sloughing: a delayed complication after transurethral microwave thermotherapy

Transurethral microwave thermotherapy is a minimally invasive treatment for benign prostatic hyperplasia designed to destroy hyperplastic tissue without damaging the urethra. We present an unexpected complication of prostatic urethral necrosis and tissue sloughing after thermotherapy and discuss its possible cause.

The fit woman of the 21st century: making lifelong exercise the norm

My great-grandmother worked the fields, helped out in the family corn-broom factory, and raised nine children who played as a team in neighborhood baseball games. Along the way she undoubtedly met the surgeon general's recommendations for fitness, with ample weight-bearing exercise and strength training to boot.

Percutaneous removal of stone from caliceal diverticulum in patient with nephroptosis

A novel method is introduced for percutaneous stone extraction from a lower pole caliceal diverticulum in a patient with nephroptosis, also known as a floating kidney. The patient was fully recovered and asymptomatic at 2 months postoperatively with her kidney fixed in the flank position.

Accuracy of clinical operational diagnostic criteria for Alzheimer's disease in relation to different pathological diagnostic protocols

In this study we analysed the accuracy of two sets of clinical diagnostic criteria, the NINCDS/ADRDA and DSM-III-R, in relation to the currently used pathological diagnostic criteria for Alzheimer's disease (AD), the Khachaturian criteria, the Tierney A3 criteria and the CERAD protocol. The sensitivity of the individual clinical diagnostic criteria, NINCDS/ADRDA and DSM-III-R, is poor (34-58%) irrespective of the pathological diagnostic criteria applied for the definite diagnosis of AD. The combination of the NINCDS/ ADRDA 'possible' and 'probable dementia of the Alzheimer type' (DAT) categories has a high sensitivity (91-98%). However the combination resulted in very poor specificity (40-61 %). Thus, none of the clinical diagnostic criteria is satisfactory. We found similar results when we analysed the predictive value of these clinical diagnostic criteria. The positive predictive value of NINCDS 'probable DAT' category and that of the DAT diagnosis by DSM-III-R is very high (89-100%). This makes the use of these categories suitable for research purposes. However, the negative predictive value of both diagnoses is poor (33-63%), making these criteria unsuitable for diagnostic purposes in clinical practice.

A prospective endoscopic study of scalloped folds and grooves in the mucosa of the duodenum as signs of villous atrophy

BACKGROUND

Scalloping of the valvulae conniventes visible at endoscopy may predict the presence of villous atrophy. This prospective study was designed to discover how commonly duodenal mucosal scallops and grooves occurred and to delineate their relationship to villous atrophy.

METHODS

All patients undergoing upper gastrointestinal endoscopy by a single observer over 5 years were included. After inspection of the duodenal mucosa, biopsy samples were taken from those in whom the mucosa was abnormal (n = 26) and from those in whom it was not, but where biopsy was indicated (n = 100).

RESULTS

None of the 100 endoscopically normal controls had subtotal villous atrophy: 94 had normal histology, 2 had non-atrophic change, and 4 had partial villous atrophy; 14 of the 26 individuals (54%) with abnormal duodena had subtotal villous atrophy, 7 having both scallops and grooves. Four had scallops alone, and three had grooves only. All patients with both scallops and grooves had subtotal villous atrophy (100%), the positive predictive value of which was 36% for scallops alone and 38% for grooves alone.

CONCLUSIONS

Scallops and grooves together indicate that subtotal villous atrophy is very likely histologically, even when that diagnosis has not been suspected. A normal duodenum excludes it.

Transurethral microwave thermotherapy for management of benign prostatic hyperplasia: a single-institution experience

OBJECTIVES

This is the first and largest single institution retrospective study in the United States to examine the effects of transurethral microwave thermotherapy (TUMT) for the treatment of benign prostatic hyperplasia (BPH).

METHODS

From September 1996 to June 1997, 78 men with moderate to severe symptomatic BPH were treated with the Prostatron at our institution. Patient age ranged from 52 to 85 years. Prostate volume ranged from 23 to 110 cc, and mean total energy applied during the treatment was 156.17 kJ. Patients were re-evaluated at 3 months and were asked to answer a questionnaire regarding their opinion about the treatment.

RESULTS

At 3 months there was a significant decrease in mean symptom score from 19.6 to 11.2 (P <0.0001). Mean peak flow rate increased from 8.5 to 12.8 mLs (P <0.0001). Mean postvoid residual urine decreased from 56.8 to 22.0 mL (P <0.0001). We did not observe any severe complications. Unlike prior studies, we removed the Foley catheter, and patients performed clean intermittent catheterization (CIC) when necessary. There was no significant differences in subjective and objective parameters between these patients and those who did not need CIC. Patient opinion about the treatment was not affected by CIC. About two thirds (67.2%) of the patients in the study group were satisfied with the results of treatment, and 60.3% would undergo the same procedure again.

CONCLUSIONS

TUMT of the prostate is an effective, safe, and acceptable form of treatment for patients with BPH. Longer follow-up is needed to examine the durability of TUMT treatment.

Levels and proteolytic processing of chromogranin A and B and secretogranin II in cerebrospinal fluid in neurological diseases

Human cerebrospinal fluid (CSF) contains chromogranin A and B and secretogranin II which represent peptides secreted from neuronal large dense core vesicles. Within these vesicles these precursor peptides are at least partly processed to smaller peptides. We analysed the CSF levels of chromogranins/secretogranin by radioimmunoassay using specific antisera. The degree of their processing was characterized by molecular sieve column chromatography followed by radioimmunoassay. As previously shown secretogranin II is fully processed to smaller peptides including the peptide secretoneurin, whereas processing of chromogranin A was more limited. For chromogranin B we found in this study a high degree of processing comparable to that of secretogranin II. An analysis of CSF from patients with multiple sclerosis, essential tremor, Alzheimer and Parkinson disease, did not reveal any differences in proteolytic processing of chromogranins/secretogranin when compared to control CSF. We conclude that in the four diseases investigated there is no change in the proteolytic processing of the chromogranins/secretogranin within the large dense core vesicles. The absolute levels of chromogranins/secretogranin varied in CSF collected in different hospitals, however their relative ratios were remarkable constant. We suggest to use this ratio as a parameter to standardise CSF levels of other peptides, e.g. neuropeptides. In Parkinson patients the chromogranin A/secretogranin II ratio was significantly increased whereas in Alzheimer patients and those with essential tremor and multiple sclerosis no change of the ratios was observed. Apparently there are only limited changes in the biosynthesis, processing, secretion and CSF clearance of these peptides in pathological conditions.

Age differences in context integration in memory

This research examined the role of contextual integration in memories of younger and older adults. In 2 experiments, recall of a target picture to a context picture cue was better when sentences were generated that integrated the picture pair and when the picture pairs were already related to each other. Age differences were smallest when sentences were generated for semantically related pairs. Older adults generated the same type sentences as younger adults, although they generated fewer integrations for unrelated pairs. In a 3rd experiment, younger adults could not differentiate between younger- and older-generated sentences from Experiment 1, and the sentences did not differentially affect recall performance. The results are discussed in terms of age differences in self-initiated processing when using context.

Evaluation of problem solving and communication skills of persons with schizophrenia

Although much research has shown positive outcomes of teaching problem solving and communication skills to persons with schizophrenia, the amount of research on the assessment of these two sets of skills has been modest. The current study demonstrates an effective model for their assessment and includes a previously neglected procedure to determine if subjects attended to the skill prompts. It replicates and expands prior findings on problem solving and communication skills. Results indicated that persons with schizophrenia were generally deficit in problem solving skills. Persons without schizophrenia seemed to use more behavioral information when deciding if a problem existed and they were better able to differentiate between appropriate and inappropriate solutions to problems. Persons with schizophrenia were found to be deficit in communication skills that facilitate interaction and showed a style that subordinated their wants to those of others.

Crossing vessels. Endourologic implications

The controversy regarding the functional significance of vessels crossing at the ureteropelvic junction is not a new one, though this debate has been resurrected in recent years because of application of endourologic techniques to manage ureteropelvic junction (UPJ) obstruction. The principle limitation of endoscopic treatment of UPJ obstruction is the inferior success rate compared to open dismembered pyeloplasty. The influence crossing vessels may have in affecting both the success rates and complications of endoscopic treatment of UPJ obstruction has yet to be resolved. Crossing vessels may be important for two reasons: (1) they are a potential source of hemorrhage following endoscopic incision, and (2) they may play an etiologic role in UPJ obstruction and therefore may be a reason for failure of endoscopic techniques. This article reviews some of the historical aspects of crossing vessels and explores recent studies that are starting to shed some light on this controversial topic.

Use of YB(66) as monochromator crystals for soft-energy EXAFS

YB(66)(400) crystals present a new advance in monochromator crystals suitable for use at energies below 2 keV. In this paper a comparison of their performance with that provided by the more usual beryl and quartz crystals, which cover the same energy range, is presented. In general, the YB(66) crystals are much superior; however, they do exhibit a pair of large 'crystal glitch'-type features in the 1380-1440 eV region. These fall in the Mg K-EXAFS region and so can present a serious problem in studies of this edge for a wide range of materials. An important class of materials so afflicted are magnesium-substituted aluminophosphate molecular sieves (zeolites), which are used in many applications, in particular as solid acid catalysts for conversion of methanol to hydrocarbon.

Lymphoceles after laparoscopic pelvic node dissection

OBJECTIVE

Lymphocele formation has been infrequently reported as a complication of laparoscopic pelvic lymph node dissection (LPLND). We determined the incidence of clinical and subclinical lymphocele formation in patients undergoing transperitoneal LPLND.

METHODS

Charts and radiological records of 111 patients undergoing transperitoneal LPLND at this institution between January 1991 and December 1995 were reviewed to determine the incidence of lymphocele formation.

RESULTS

Of 111 patients undergoing LPLND, 12.6% had positive lymph nodes and received hormonal therapy. Radical retropubic (12) or perineal (28) prostatectomy was performed either simultaneously or within 2 weeks in 41% of the node-negative patients. Radiation therapy was the treatment modality in the remaining node negative patients (N = 57). Twenty-three patients undergoing radiation therapy had preplanning pelvic computed tomography (CT) scans 2 to 16 weeks (mean 8.2 weeks) after LPLND. These were reviewed by a single radiologist to determine the presence of subclinical lymphoceles. Seven patients (30.4%) had lymphoceles of varying sizes (3 large and 4 small). Although most were identified on CT scans 4 weeks after the procedure, two were identified on scans 12 and 16 weeks after the procedure (mean 6.5 weeks). None of these patients developed symptoms referable to or had treatment for the lymphocele during a 2 to 37 month follow-up (mean 20 months). Only two patients (3.5%) undergoing LPLND as an isolated procedure had clinical evidence of lymphocele formation, both of which were subsequently confirmed with CT scans (1 large, 1 small). One was treated with CT-guided drainage and sclerosis and the other resolved spontaneously.

CONCLUSION

The clinical incidence of lymphocele formation following LPLND remains relatively low. Only a portion of these patients requires intervention. Subclinical lymphoceles, as detected on follow-up CT scans, occur with a much greater frequency. These seldom become symptomatic requiring treatment. Rather, they appear to resolve spontaneously. Nevertheless, clinical suspicion should remain high in order to detect and properly treat symptomatic lymphoceles when they occur.

Development of X-ray photoemission electron microscopy (X-PEEM) at the SRS

The use of synchrotron radiation sources for X-ray spectroscopy is a well known and developed field. The majority of applications, however, have been limited to studies of materials containing only a single phase of the element of interest. Owing to limited availability of suitable instrumentation, the study of materials comprising intergrowths of different phases has presented difficulties in analysis. The majority of natural materials, including mineralogical samples, fall into this category. However, by applying the technique of photoemission electron microscopy (PEEM) to view the X-ray stimulated photoemission generated at an absorption edge, micro-area-selectable spectroscopy becomes possible. An instrument for X-ray PEEM (X-PEEM) is being developed at the Daresbury SRS and this paper shows how it can be used to obtain characteristic L-edge XANES spectra from finely intergrown iron oxide minerals.

An electrostrictive drive for fine pitch control in double-crystal monochromators

Precise control of the pitch angle of the crystals in a double-crystal monochromator is essential to preserve their accurate alignment while the instrument is scanned. Computer-controlled piezoceramic electrostrictive actuators have recently been installed to the top crystal in two monochromators at the Daresbury SRS to facilitate this. This complements the coarser control provided by the existing stepper motor to give an accurate positioning of the crystal alignment over the full rocking-curve width of the crystals. To maintain accurate alignment during a scan, a number of servo feedback options have been devised. In this paper an analysis of the performance of these drives is presented and their utility in a variety of different experimental techniques is discussed.

Can a hydrophilic guidewire be resterilized?

The Glidewire (Microvasive, Natick, MA) or Terumo wire (Terumo, Japan) is constructed with a hydrophilic polymer surface that enables easier passage through narrowed lumens in the urinary tract. This study examined the effects of gas sterilization on Glidewire surface structure, slipperiness, and ability to support bacterial growth. Light microscopy at 100x and 400x and scanning electron microscopy at 100 to 1300x were used to compare the surface tips of five new 0.038-inch Glidewires with those resterilized one or three times. The tips were immersed in water prior to standard gas sterilization for operating room equipment. Subjective evaluation of slipperiness involved asking 10 blinded urologists to assess the nature of new and resterilized wires by feel. Support of bacterial growth was assessed by comparing cultures performed on new wires (control) with those of wires incubated with Bacillus stearothermophilus. Microscopy, reviewed by a pathologist, revealed no perceivable surface differences after one and three gas sterilizations. Eight of the urologists noted similar or improved slipperiness of resterilized wires compared with new wires. Bacterial cultures of intentionally infected wire segments showed no growth after standard gas sterilization in all cases. In this study, gas sterilization did not adversely affect the lubricious nature or the surface coating of the hydrophilic coating of Glidewires. Also, gas resterilization was bactericidal to new and used wires that had been infected with a heat-tolerant organism.

Age differences in context integration in memory

This research examined the role of contextual integration in memories of younger and older adults. In 2 experiments, recall of a target picture to a context picture cue was better when sentences were generated that integrated the picture pair and when the picture pairs were already related to each other. Age differences were smallest when sentences were generated for semantically related pairs. Older adults generated the same type sentences as younger adults, although they generated fewer integrations for unrelated pairs. In a 3rd experiment, younger adults could not differentiate between younger- and older-generated sentences from Experiment 1, and the sentences did not differentially affect recall performance. The results are discussed in terms of age differences in self-initiated processing when using context.

Human rhinovirus type 14:human immunodeficiency virus type 1 (HIV-1) V3 loop chimeras from a combinatorial library induce potent neutralizing antibody responses against HIV-1

In an effort to develop a useful AIDS vaccine or vaccine component, we have generated a combinatorial library of chimeric viruses in which the sequence IGPGRAFYTTKN from the V3 loop of the MN strain of human immunodeficiency virus type 1 (HIV-1) is displayed in many conformations on the surface of human rhinovirus 14 (HRV14). The V3 loop sequence was inserted into a naturally immunogenic site of the cold-causing HRV14, bridged by linkers consisting of zero to three randomized amino acids on each side. The library of chimeric viruses obtained was subjected to a variety of immunoselection schemes to isolate viruses that provided the most useful presentations of the V3 loop sequence for potential use in a vaccine against HIV. The utility of the presentations was assessed by measures of antigenicity and immunogenicity. Most of the immunoselected chimeras examined were potently neutralized by each of the four different monoclonal anti-V3 loop antibodies tested. Seven of eight chimeric viruses were able to elicit neutralizing antibody responses in guinea pigs against the MN and ALA-1 strains of HIV-1. Three of the chimeras elicited HIV neutralization titers that exceeded those of all but a small number of previously described HIV immunogens. These results indicate that HRV14:HIV-1 chimeras may serve as useful immunogens for stimulating immunity against HIV-1. This method can be used to flexibly reconstruct varied immunogens on the surface of a safe and immunogenic vaccine vehicle.

Flank drainage-irrigation system for use after percutaneous renal surgery

A common problem after percutaneous renal surgery is leakage around the nephrostomy tube. The authors describe a method for fixing a nephrostomy tube in an ostomy bag while permitting access for irrigation or radiographic studies.

Techniques for stenting the normal and obstructed ureter

Ureteral obstruction is a common cause of urologic morbidity requiring quick and effective treatment, as prolonged obstruction can cause pain, infection, and eventual loss of renal function. Few would argue that initial drainage or bypassing of the obstruction is favorable initial management; however, urologists are often-times faced with technically difficult cases not responsive to the standard operative maneuvers. Recognizing the diversity of pathology and the potentially complicating issues, urologists should have in their armamentarium a systematic approach or algorithm for dealing with these common dilemmas, as well as an understanding of various tricks of the trade. This knowledge will prevent heightened anxiety at the time of surgery and will ensure the availability of the proper operative equipment. This article outlines an approach and discusses the obstacles and options in stenting the obstructed ureter.

Serum ferritin: it may guide the diagnosis of the anaemic patient

Crohn's disease is often complicated by anaemia. Assessment of iron deficiency may be hampered by modification of the serum ferritin concentration because of the associated acute phase response when disease is active. However a ferritin value of < 5 micrograms/L is indicative of iron deficiency, which is rarely found in Crohns disease.

Novel hemostatic nephrostomy tube

Significant hemorrhage from the access site is an infrequent complication of percutaneous renal surgery. We developed a novel nephrostomy tube that combines the benefits of the re-entry Malecot design with those of the Kaye tamponade catheter. The new nephrostomy tube was successful in preventing significant bleeding in high-risk patients who had this tube placed after percutaneous nephrostolithomy. All of the patients tolerated the tube without complications. Preliminary results show that this tube is easy to insert, well tolerated by patients, and effective in preventing and stopping bleeding from a percutaneous access site and that it maintains ureteral access.

Interrelations of age, self-reported health, speed, and memory

Contributions of self-reported health to adult age differences in perceptual speed and memory were assessed for 301 adults ages 20-90. Participants were asked 4 health status questions, given 3 perceptual speed tests, 2 working memory tests, and 2 memory tests. Self-reported health was found to predict speed better than it predicted memory. Covariance structural equation modeling was used to assess the relations among age, self-reported health, perceptual speed, working memory, and memory. The results support the hypothesis that any effects of self-reported health on age differences in memory are mediated by perceptual speed.

Synergy between the genes for butyrylcholinesterase K variant and apolipoprotein E4 in late-onset confirmed Alzheimer's disease

The allelic frequency of the gene for the K variant of butyrylcholinesterase (BCHE-K) was 0.17 in 74 subjects with late-onset (age > 65 years) histopathologically diagnosed Alzheimer's disease (AD), which was higher than the frequencies in 104 elderly control subjects (0.09), in 14 early-onset cases of confirmed AD (0.07) and in 29 confirmed cases of other dementia (0.10). The association of BCHE-K with late-onset AD was limited to carriers of the epsilon 4 allele of the apolipoprotein E gene (APOE), among whom the presence of BCHE-K gave an odds ratio of confirmed late-onset AD of 6.9 (95% C.I. 1.65-29) in subjects > 65 years and of 12.8 (1.9-86) in subjects > 75 years. In APOE epsilon 4 carriers over 75 years, only 1/22 controls, compared with 10/24 confirmed late-onset AD cases, had BCHE-K. We suggest that BCHE-K, or a nearby gene on chromosome 3, acts in synergy with APOE epsilon 4 as a susceptibility gene for late-onset AD.

Subclinical slipped capital femoral epiphysis. Relationship to osteoarthrosis of the hip

We examined the femora of 2665 adult human skeletons from an osteological collection to determine the prevalence of post-slip morphology termed femoral head-tilt deformity by Murray and pistol-grip deformity by Stulberg et al. The hypothesis was that primary osteoarthrosis of the hip is a secondary manifestation of a subclinical developmental disorder of the hip. The prevalence of post-slip morphology was 8 per cent (215 of 2665 skeletons). Severe osteoarthrosis was more prevalent in association with post-slip morphology (116 [38 per cent] of 306 hips) than in the matched controls (seventy-nine [26 per cent] of 306 hips) (p < 0.005). In the skeletons that had unilateral post-slip morphology, severe osteoarthrosis was more prevalent in the involved hips (thirty-one [37 per cent] of eighty-three) than in the contralateral, normal hips (eighteen [22 per cent] of eighty-three) (p < 0.05). Post-slip morphology, which was unrelated to age, was found to be a major risk factor for the development of high-grade osteoarthrosis. We noted evidence of high-grade osteoarthrosis in sixty-three (68 percent) of the ninety-three hips with minimum post-slip morphology in skeletons from individuals who had been fifty-six years old or more at the time of death compared with forty-five (48 percent) of the ninety-three control hips. This difference was significant (p < 0.025) [corrected]. The osteoarthrosis in the hips with post-slip morphology was distinctly characterized by anterior flattening of the acetabulum, cystic degeneration in the anterior metaphyseal-epiphyseal region, and progression to global osteoarthrosis of the hip.

Differential age-related processing limitations in recall and recognition tasks

The degree to which processing resources are responsible for age differences in performance on recall and recognition tasks was examined in this study. To examine this, a secondary task incorporating a memory component (digit preloads) was implemented during retrieval. Results revealed that older adults, relative to younger adults, exhibited greater decrements in secondary task performance as the difficulty of the secondary task increased. These age differences were greater in the recall task than in the recognition task. Hierarchical regression analyses indicated that speed accounted for the largest proportion of age-related variance in the recall task while both speed and working memory contributed to much of the secondary task variance. Results confirm the hypothesis that recall requires greater processing capacity than recognition and that older adults have greater processing-capacity limitations than younger adults.

Structure of poliovirus type 2 Lansing complexed with antiviral agent SCH48973: comparison of the structural and biological properties of three poliovirus serotypes

BACKGROUND

Polioviruses are human pathogens and the causative agents of poliomyelitis. Polioviruses are icosahedral single-stranded RNA viruses, which belong to the picornavirus family, and occur as three distinct serotypes. All three serotypes of poliovirus can infect primates, but only type 2 can infect mice. The crystal structures of a type 1 and a type 3 poliovirus are already known. Structural studies of poliovirus type 2 Lansing (PV2L) were initiated to try to enhance our understanding of the differences in host range specificity, antigenicity and receptor binding among the three serotypes of poliovirus.

RESULTS

The crystal structure of the mouse neurovirulent PV2L complexed with a potent antiviral agent, SCH48973, was determined at 2.9 A resolution. Structural differences among the three poliovirus serotypes occur primarily in the loop regions of the viral coat proteins (VPs), most notably in the loops of VP1 that cluster near the fivefold axes of the capsid, where the BC loop of PV2L is disordered. Unlike other known structures of enteroviruses, the entire polypeptide chain of PV2L VP4 is visible in the electron density and RNA bases are observed stacking with conserved aromatic residues (Tyr4020 and Phe4046) of VP4. The broad-spectrum antiviral agent SCH48973 is observed binding in a pocket within the beta-barrel of VP1, in approximately the same location that natural 'pocket factors' bind to polioviruses. SCH48973 forms predominantly hydrophobic interactions with the pocket residues.

CONCLUSIONS

Some of the conformational changes required for infectivity and involved in the control of capsid stability and neurovirulence in mice may occur in the vicinity of the fivefold axis of the poliovirus, where there are significant structural differences among the three poliovirus serotypes in the surface exposed loops of VP1 (BC, DE, and HI). A surface depression is located at the fivefold axis of PV2L that is not present in the other two poliovirus serotypes. The observed interaction of RNA with VP4 supports the observation that loss of VP4 ultimately leads to the loss of viral RNA. A model is proposed that suggests dual involvement of the virion fivefold and pseudo-threefold axes in receptor-mediated initiation of infection by picornaviruses.