The developmental timing of spinal touch processing alterations predicts behavioral changes in genetic mouse models of autism spectrum disorders

Altered somatosensory reactivity is frequently observed among individuals with autism spectrum disorders (ASDs). Here, we report that although multiple mouse models of ASD exhibit aberrant somatosensory behaviors in adulthood, some models exhibit altered tactile reactivity as early as embryonic development, whereas in others, altered reactivity emerges later in life. Additionally, tactile overreactivity during neonatal development is associated with anxiety-like behaviors and social behavior deficits in adulthood, whereas tactile overreactivity that emerges later in life is not. The locus of circuit disruption dictates the timing of aberrant tactile behaviors, as altered feedback or presynaptic inhibition of peripheral mechanosensory neurons leads to abnormal tactile reactivity during neonatal development, whereas disruptions in feedforward inhibition in the spinal cord lead to touch reactivity alterations that manifest later in life. Thus, the developmental timing of aberrant touch processing can predict the manifestation of ASD-associated behaviors in mouse models, and differential timing of sensory disturbance onset may contribute to phenotypic diversity across individuals with ASD.

Cortical reactivations predict future sensory responses

Many theories of offline memory consolidation posit that the pattern of neurons activated during a salient sensory experience will be faithfully reactivated, thereby stabilizing the pattern1,2. However, sensory-evoked patterns are not stable but, instead, drift across repeated experiences3-6. Here, to investigate the relationship between reactivations and the drift of sensory representations, we imaged the calcium activity of thousands of excitatory neurons in the mouse lateral visual cortex. During the minute after a visual stimulus, we observed transient, stimulus-specific reactivations, often coupled with hippocampal sharp-wave ripples. Stimulus-specific reactivations were abolished by local cortical silencing during the preceding stimulus. Reactivations early in a session systematically differed from the pattern evoked by the previous stimulus-they were more similar to future stimulus response patterns, thereby predicting both within-day and across-day representational drift. In particular, neurons that participated proportionally more or less in early stimulus reactivations than in stimulus response patterns gradually increased or decreased their future stimulus responses, respectively. Indeed, we could accurately predict future changes in stimulus responses and the separation of responses to distinct stimuli using only the rate and content of reactivations. Thus, reactivations may contribute to a gradual drift and separation in sensory cortical response patterns, thereby enhancing sensory discrimination7.

Striatum supports fast learning but not memory recall

Animals learn to carry out motor actions in specific sensory contexts to achieve goals. The striatum has been implicated in producing sensory-motor associations, yet its contribution to memory formation or recall is not clear. To investigate the contribution of striatum to these processes, mice were taught to associate a cue, consisting of optogenetic activation of striatum-projecting neurons in visual cortex, with forelimb reaches to access food pellets. As necessary to direct learning, striatal neural activity encoded both the sensory context and outcome of reaching. With training, the rate of cued reaching increased, but brief optogenetic inhibition of striatal activity arrested learning and prevented trial-to-trial improvements in performance. However, the same manipulation did not affect performance improvements already consolidated into short- (within an hour) or long-term (across days) memories. Hence, striatal activity is necessary for trial-to-trial improvements in task performance, leading to plasticity in other brain areas that mediate memory recall.

Thyroid hormone rewires cortical circuits to coordinate body-wide metabolism and exploratory drive

Animals adapt to varying environmental conditions by modifying the function of their internal organs, including the brain. To be adaptive, alterations in behavior must be coordinated with the functional state of organs throughout the body. Here we find that thyroid hormone- a prominent regulator of metabolism in many peripheral organs- activates cell-type specific transcriptional programs in anterior regions of cortex of adult mice via direct activation of thyroid hormone receptors. These programs are enriched for axon-guidance genes in glutamatergic projection neurons, synaptic regulators across both astrocytes and neurons, and pro-myelination factors in oligodendrocytes, suggesting widespread remodeling of cortical circuits. Indeed, whole-cell electrophysiology recordings revealed that thyroid hormone induces local transcriptional programs that rewire cortical neural circuits via pre-synaptic mechanisms, resulting in increased excitatory drive with a concomitant sensitization of recruited inhibition. We find that thyroid hormone bidirectionally regulates innate exploratory behaviors and that the transcriptionally mediated circuit changes in anterior cortex causally promote exploratory decision-making. Thus, thyroid hormone acts directly on adult cerebral cortex to coordinate exploratory behaviors with whole-body metabolic state.

The developmental timing of spinal touch processing alterations and its relation to ASD-associated behaviors in mouse models

Altered somatosensory reactivity is frequently observed among individuals with autism spectrum disorders (ASDs). Here, we report that while multiple mouse models of ASD exhibit aberrant somatosensory behaviors in adulthood, some models exhibit altered tactile reactivity as early as embryonic development, while in others, altered reactivity emerges later in life. Additionally, tactile over-reactivity during neonatal development is associated with anxiety-like behaviors and social interaction deficits in adulthood, whereas tactile over-reactivity that emerges later in life is not. The locus of circuit disruption dictates the timing of aberrant tactile behaviors: altered feedback or presynaptic inhibition of peripheral mechanosensory neurons leads to abnormal tactile reactivity during neonatal development, while disruptions in feedforward inhibition in the spinal cord lead to touch reactivity alterations that manifest later in life. Thus, the developmental timing of aberrant touch processing can predict the manifestation of ASD-associated behaviors in mouse models, and differential timing of sensory disturbance onset may contribute to phenotypic diversity across individuals with ASD.

Impact of the COVID-19 pandemic on overall percutaneous coronary interventions from the France-PCI registry: Comparative analysis of the years 2019 and 2020

Introduction

In 2020, the coronavirus disease 2019 (COVID-19) pandemic disrupted the health system and a drop in percutaneous coronary interventions (PCI) was observed.

Objective

The objective of this study was to evaluate the impact of the COVID-19 pandemic on a full year of elective and urgent PCIs, from the national France-PCI registry.

Method

The primary endpoint was to compare the number of PCIs performed in 2019 (before the pandemic), and 2020 (during the pandemic).

Results

Between January 1, 2019 and December 31, 2020, in the 20 participating centers, 22,807 consecutive PCIs were included. The total number of PCIs was reduced by −11.5% between 2019 and 2020 (12,102 versus 10,705; P < 0.001), mainly due to a reduction in elective interventions (−21.9%; P < 0.001). There was a significant decrease in PCIs for stable angina (P < 0.001) and silent ischemia (P < 0.001). For urgent PCIs, the decrease was less, mainly driven by a non-ST+ acute coronary syndromes (ACS) reduction (−5.7%; P = 0.01), as well as a decrease of early ST-Elevation myocardial infarctions (STEMIs) < 24 Hours (−7.1%; P = 0.02). There was also a significant increase in the number of late STEMIs > 24H (+23.4%; P = 0.002). Following the decrease in ACS during the first lockdown from March to May 2020, there was an unexpected significant increase in urgent interventions (“rebound effect”) out of step with the rest of the year (P = 0.002) (Fig. 1A). Nevertheless, there was no increase in elective PCIs after the first lockdown in comparison with the rest of the year 2020 (P = 0.67) (Fig. 1B). In 2020, patients were significantly younger (P = 0.001), with less prior history of coronary artery disease (P = 0.001), and prasugrel was more often prescribed after PCIs (P = 0.001). In 2020, the radial approach was more often performed (P = 0.001), as well as an “Ad-hoc” PCI (P = 0.01), and the median fluoroscopy time was lengthened (P < 0.001). For STEMIs < 24H, there was more frequently anterior localizations (P = 0.03), and ground medical transport was the majority (P = 0.03). The time from onset of symptoms to first medical contact was significantly lengthened (P = 0.01), and a non-significant increase in total ischemic time (P = 0.08) was found. Finally, there was no significant increase in intra-hospital cardiovascular events during the pandemic in 2020.

Conclusion

We show an extraordinary reduction in elective and urgent PCIs, as well as a never described paradoxical increase in urgent PCIs after the first lockdown, during the COVID-19 pandemic.

[stent thrombosis : A won battle ? (data from the France PCI registry)]

GOAL

The aim of the study is to assess the incidence, risk factors and prognosis of definite stent thrombosis (ST) at 1 year in the France PCI multicenter prospective registry.

PATIENTS AND METHODS

Only patients who underwent coronary angioplasty with at least one stent implantation between 1^st January 2014 and 31 December 2019 were included. The population was separated into 2 groups: the "ST" group with stent thrombosis and the "control" group without stent thrombosis.

RESULTS

35,435 patients were included. 256 patients (0.72%) presented a ST at 1 year. The rate of ST decreased significantly in acute coronary syndrome (1.5% in 2014 vs. 0.73% in 2019; p = 0.05) but not in chronic coronary syndrome (0.46% in 2014 vs 0.40%; p = 0.98). The risk factors are young age (65.8 years vs 68.2; p = 0.002), clinical context (35.27% vs 16.68%; p = 0.0001), diabetes (35.2 % vs 26.4%; p = 0.002), renal failure (11.7% vs 8%; p = 0.009) and history of coronary angioplasty (28.63% vs 21.86%; p = 0.009) and peripheral arterial disease (14.5% vs 10.1%; p = 0.021), LV dysfunction (37% vs 27.5%; p = 0.003), mean length (39.6 mm vs 31, 7mm; p <0.0001) and the mean number of stents per procedure (1.9 vs 1.6; p <0.0001), a TIMI flow ≤1 pre procedure (21.5% vs 12.4%; p <0.0001) and an intrastent restenosis (11% vs 6%; p <0.0001). The 1-year mortality of the ST group was significantly higher than that of the control group (19.14% vs 5.82%; p <0.0001).

CONCLUSION

Since 2014, the incidence of ST at 1 year has been decreasing but remains stuck at a floor level of 0.54% in 2019. The battle for ST seems to have been partly won and its risk factors well identified, but its mortality is still high.

[COVID-19 and STEMI]

The COVID-19 pandemic had an unexpected impact on cardiovascular emergencies, particularly STEMI. The France PCI registry and other studies around the world have highlighted a significant decrease in myocardial infarctions arriving at hospital. This decrease is mainly related to patients' fear of coming to the hospital and being contaminated. Although the STEMI revascularisation time targets (<120min) are often difficult to achieve in normal times, they were almost impossible to achieve in periods of lockdown because of the many obstacles. Longer delays and longer total ischemic time have led to excess mortality, especially in the regions most affected by the epidemic. Recommendations for the management of STEMI during the COVID-19 period have thus been issued by the scientific societies. STEMI in patients with COVID-19 often have an uncommon clinical presentation, and the absence of coronary obstruction on angiography is frequent. Their prognosis is very poor. Only public information campaigns and an organisation adapted to the management of coronary emergencies during epidemics can try to limit their effects and avoid aggravating an already fragile health situation in the future.

Abnormal Striatal Development Underlies the Early Onset of Behavioral Deficits in Shank3B-/- Mice

The neural substrates and pathophysiological mechanisms underlying the onset of cognitive and motor deficits in autism spectrum disorders (ASDs) remain unclear. Mutations in ASD-associated SHANK3 in mice (Shank3B^−/−) result in the accelerated maturation of corticostriatal circuits during the second and third postnatal weeks. Here, we show that during this period, there is extensive remodeling of the striatal synaptic proteome and a developmental switch in glutamatergic synaptic plasticity induced by cortical hyperactivity in striatal spiny projection neurons (SPNs). Behavioral abnormalities in Shank3B^−/− mice emerge during this stage and are ameliorated by normalizing excitatory synapse connectivity in medial striatal regions by the downregulation of PKA activity. These results suggest that the abnormal postnatal development of striatal circuits is implicated in the onset of behavioral deficits in Shank3B^−/− mice and that modulation of postsynaptic PKA activity can be used to regulate corticostriatal drive in developing SPNs of mouse models of ASDs and other neurodevelopmental disorders.

Peixoto et al. show that the onset of behavioral deficits in Shank3B^−/− mice occurs during early postnatal development and that these can be ameliorated by reducing the glutamatergic synaptic drive in medial regions of the striatum by the downregulation of PKA activity.

P1739Does helicopter transport delay prehospital transfer for STEMI patients in rural areas? Findings from the CRAC France PCI registry

Background

Whether helicopter transportation for ST-Elevation Myocardial Infarction (STEMI) patients in France is the faster alternative is not known. Data from United States and Europe are controversial and studies have been limited to small series of patients

Purpose

The aim of this study was to analyse delays in emergency medical system (EMS) transfer of STEMI patients from home to the nearest percutaneous coronary intervention (PCI) centre (primary transfer) or from non-PCI centres to PCI centres (secondary transfer) according to transport modalityin a rural French region.

Methods and results

Data from the prospective multicentre CRAC France PCI registrywere analysed for 1911 STEMI patients: 410 transferred by helicopter (HEMS) and 1501 by ground transport (GEMS). The primary endpoint was the percentage of transfers with first medical contact (FMC) to primary PCI (PPCI) within the 90-min recommended in guidelines. The secondary endpoint was time FMC–PPCI. With HEMS,FMC-PPCI <90 min was less frequently achieved than with GEMS (9.8% vs 37.2%; odds ratio 5.49; 95% confidence interval [3.90; 7.73]; p<0.0001). Differences were greatest for transfers <50 km (13.7% vs 44.7%; p<0.0001) and for primary transfers (22.4% vs 49.6%; p<0.0001). Median time from FMC to PPCI and from symptom onset to PPCI (total ischemic time) were significantly higher in HEMS group than in GEMS group (respectively 137 min vs 103 min; p<0.0001 and 261min vs 195 min; p<0,0001). There was no significant difference in in-hospital mortality between the HEMS and GEMS groups (6.9% vs 6.6%; p=0.88).

STEMI patients FMC-PPCI < 90 min

Conclusion

Helicopter transport of STEMI patients was 5 times less effective than ground transport in maintaining the 90-min FMC-PPCI time recommended in guidelines, particularly for transfer distances <50 km.

Acknowledgement/Funding

Regional health agency of CVL, Medtronic, Boston Scientific, Abbot, Biosensor, Terumo, Biotronik, Lilly Daichii Sankyo, Hexacath and Braun.

[Left main PCI: Current treatment]

Percutaneous coronary intervention (PCI) of left main coronary artery has become a strong alternative to coronary artery bypass surgery in selected patients. The treatment decision must be validated by the Heart Team. Several PCI techniques of distal left main PCI have been described but the KISSS (Keep it simple, swift and safe) principle recommended by the European Bifurcation Club must be kept in mind. Provisional stenting is the first-line technique. A two-stent strategy may be needed in the presence of≥2.5mm side branch diameter and significant ostial stenosis as well as in presumably difficult rewiring. In all cases, POT (Proximal Optimisation Technique) is mandatory. Intracoronary imaging can be of great help in perfecting the result or even to improve outcomes.

[Non-ST elevation acute coronary syndrome: CRAC register experience]

PURPOSE

To compare the clinical, angiographic, therapeutic and prognostic characteristics of nonagenarians presenting with non-ST elevation acute coronary syndrome with those of patients under 90 years of age.

METHODS

We used the CRAC register database including 6 catheterization laboratories in the Center Val-de-Loire region. Only patients with positive-troponin non-ST elevation ACS included in the registry from 2014 to 2017 were selected for epidemiological and procedural data. Regarding antiplatelet therapy, hospital and one-year follow-up data, only patients in the 2014-2015 period were analyzed.

RESULTS

From January 1st, 2014 to December 31st, 2017, 5.964 patients with a positive-troponin non-ST ACS, including 133 nonagenarians (2.2%) were included in the CRAC registry. Arterial hypertension and the history of coronary angioplasty were more common among nonagenarians. They present more multivessel and left main disease. The use of the bare metal stent was predominant in 2014-2015 and then became marginal in 2016-2017. Clopidogrel was the most widely used anti platelet and more than one in two nonagenarians remain on dual therapy after 12 months. One-year stroke and hospital and one-year mortality were higher in this age group.

CONCLUSIONS

Nonagenarians with a positive-troponin non-ST elevation ACS have more severe coronary artery disease and a poorer prognosis than those younger than 90 years of age.

Recovery of Voice After Reconstruction of the Recurrent Laryngeal Nerve and Adjuvant Nimodipine

Background

Transection injury to the recurrent laryngeal nerve (RLN) has been associated with permanent vocal fold palsy, and treatment has been limited to voice therapy or local treatment of vocal folds. Microsurgical repair has been reported to induce a better function. The calcium channel antagonist nimodipine improves functional recovery after experimental nerve injury and also after cranial nerve injury in patients. This study aims to present voice outcome in patients who underwent repair of the RLN and received nimodipine during regeneration.

Methods

From 2002–2016, 19 patients were admitted to our center with complete unilateral injury to the RLN and underwent microsurgical repair of the RLN. After nerve repair, patients received nimodipine for 2–3 months. Laryngoscopy was performed repeatedly up to 14 months postoperatively. The Voice Handicap Index (VHI) was administered, and patients’ maximum phonation time (MPT) was recorded during the follow-up.

Results

All patients recovered well after surgery, and nimodipine was well tolerated with no dropouts. None of the patients suffered from atrophy of the vocal fold, and some patients even showed a small ab/adduction of the vocal fold on the repaired side with laryngoscopy. During long-term follow-up (>3 years), VHI and MPT normalized, indicating a nearly complete recovery from unilateral RLN injury.

Conclusions

In this cohort study, we report the results of the first 19 consecutive cases at our center subjected to reconstruction of the RLN and adjuvant nimodipine treatment. The outcome of the current strategy is encouraging and should be considered after iatrogenic RLN transection injuries.

A neural circuit for gamma-band coherence across the retinotopic map in mouse visual cortex

Cortical gamma oscillations have been implicated in a variety of cognitive, behavioral, and circuit-level phenomena. However, the circuit mechanisms of gamma-band generation and synchronization across cortical space remain uncertain. Using optogenetic patterned illumination in acute brain slices of mouse visual cortex, we define a circuit composed of layer 2/3 (L2/3) pyramidal cells and somatostatin (SOM) interneurons that phase-locks ensembles across the retinotopic map. The network oscillations generated here emerge from non-periodic stimuli, and are stimulus size-dependent, coherent across cortical space, narrow band (30 Hz), and depend on SOM neuron but not parvalbumin (PV) neuron activity; similar to visually induced gamma oscillations observed in vivo. Gamma oscillations generated in separate cortical locations exhibited high coherence as far apart as 850 μm, and lateral gamma entrainment depended on SOM neuron activity. These data identify a circuit that is sufficient to mediate long-range gamma-band coherence in the primary visual cortex.

[Stent thrombosis: what's up in 2017?]

Stent thrombosis (ST) is still a dreadful and threatening complication of percutaneous coronary intervention (PCI) with a high risk of morbi-mortality. Nevertheless, it becomes exceptional (0.6% at 1 year and 0.15%/year later) thanks to improvement of stents and use of new P2Y12 inhibitors. Endo-coronary imaging and especially Optical Coherence Tomography (OCT) change radically its understanding with revealing quiet systematic morphologic endoluminal abnormalities (97% of the cases). OCT becomes an essential tool in practice (ESC recommendation class IIa) and allows a therapeutic strategy optimization. Its prevention is based on mechanical causes correction and a personalized adaptation of anti-platelet treatment.

[Prevalence and factors related to therapeutic adherence among black African outpatients with stable coronary artery disease in a cardiology department of Dakar in Senegal]

INTRODUCTION

The management of coronary artery disease has made important progress. Adherence to therapeutic measures is a great challenge for improving the long-term prognosis. In this work, we evaluate factors related to therapeutic adherence in black African patients with stable coronary artery disease.

METHODOLOGY

We conducted a survey over three months (February-May 2008) in three cardiology departments in Dakar. We studied the regularity of drug intake, the adherence to the dietary advices and the appointments for consultation as well as the factors related to adherence. Good adherence was defined by a compliance rate greater or equal to 80% and a compliance rate less than 40% defined poor adherence.

RESULTS

We included 105 patients (61 men) with a mean age of 60.67±11.29 years. Good compliance was noted in 56.2% of cases for drug treatment, 42% for dietary advices and 65% for appointments for consultation. A history of acute coronary events (P=0.04), a good knowledge of the disease (P=0.03) and a healthcare (P=0.02) were the factors related to a good adherence to drug treatment, whereas ischemic cardiomyopathy was a factor for poor adherence (P=0.002). Knowledge of coronary disease was the only factor correlated with good adherence to lifestyle (P=0.014).

CONCLUSION

Therapeutic adherence remains unsatisfactory in Black African patients with stable coronary artery disease, hence the importance of patient education to reach a good adherence for therapeutic, because better adherence improves long-term prognosis of coronary artery disease.

[Pulmonary embolism mimicking acute anterior myocardial infarction: diagnostic trap]

Pulmonary embolism remains the major malingerer of acute chest disease. The clinical and electrocardiographic manifestations may deviate to a diagnosis of myocardial infarction. We report a case of bilateral pulmonary embolism in a patient of 50 years. The electrocardiogram showed ST elevation in anteroseptal and lateral leads. The diagnosis of acute myocardial infarction was selected and a fibrinolysis achieved. Getting out under beta-blocker therapy, antiplatelet, statin and angiotensin-converting enzyme inhibitors after 10 days hospitalization, the patient was readmitted one month later for a massive pulmonary embolism. Coronary angiography performed after the second hospitalization was normal.

Phase II study of temozolomide and celecoxib in the treatment of metastatic melanoma

18015

Background: There is increasing evidence that the expression of Cyclo-oxygenase 2 correlates with development and progression of malignant melanoma. Celecoxib (C) has demonstrated some kind of activity in monotherapy in melanoma. Temozolomide (T) has consistent activity in melanoma, either as monotherapy or in combination. We designed a phase II study to determine the efficacy and toxicity of the combination of Celecoxib and Temozolomide in advanced melanoma as first line of therapy Methods: From January 2004 to October 2005, 13 patients with metastatic melanoma were enrolled in the study. There were 4 males and 9 females. The median age was 59 years. Patients received Temozolomide 200/mg/mq day po for 5 days every 4 weeks and Celecoxib 400 mg BID for 10 days every 4 weeks. Results: Among 12 evaluable patients there were 4 partial responses (30.8%), no complete response or disease stabilization. Progression occurred in 8 patients (61.5%). The median TTP was 3.14 months and the median survival was 9.06 months. The median number of cycles was 2, only 2 patients completed four cycles of treatment. Most commonly seen toxicities were nausea/vomiting (46%), fatigue (93%), thrombocytopenia (15.3%), leukopenia (7.6%). Two patients discontinued the treatment due to grade 4 thrombocytopenia. Conclusions: The combination of Temozolomide and Celecoxib is safe, manageable and provides clinical benefit, but its activity is not superior to standard therapy.

No significant financial relationships to disclose.

Ki-67/MIB-1 as prognostic factor for locoregional recurrence after adjuvant radiation therapy in early breast cancer: A population-based study

20074

Background: Adjuvant radiotherapy (RT) has been shown to decrease the risk of locoregional recurrence (LRR) in women with infiltrating early breast cancer, with or without an associated systemic treatment. RT is more effective on high proliferating cells and we could evaluate the proliferative activity of any cancer through Ki-67/ MIB-1 antibodies. Adjuvant RT for breast cancer could show a greater efficacy to prevent LRR in the higher proliferating cancers. Methods: We conducted a retrospective analisys on all the 5004 cases of infiltrating early breast cancer diagnosed in the Province of Modena between 1989 and 2004 and registered in the Modena Cancer Registry. Beneath them we were able to find data about 1885 women who underwent adjuvant RT. We analyzed the data concerning this population on the basis of number of LRR and Ki-67 labeling index. Since the lack of a worldwide agreed Ki-67 cut off value representing an high proliferation rate of cell activity, we examinate our data in an univariate analisys establishing for the Ki-67 three different cut offs values ( 20%, 30% and 50%). Results: Between 1885 women who underwent RT, 91 ( 4.8%) had a LRR. Median follow-up was 6 years (range 1–15 years). Using a cut off for the Ki-67 of 20% to fix an high cell proliferation, 67 women had a Ki-67 < 20% and 24 ≥ 20%. The p-value was 0.176. Increasing the cut off to the 30%, 75 women had a Ki-67 < 30% and 16≥ 30%. The p-value was 0.048. Finally, considering the Ki-67 value to 50%, 87 women had a value < 50% and 4 ≥ 50%, with a p-value of 0.992. In our analisys, it doesn’t seem that an increasing Ki-67 value would be correlated with a higher LRR. We are considering in a further analisys the weight of the different sistemic therapies on our results. Conclusions: The Ki-67 expression doesn’t seem to be considered a statistically significant prognostic factor for LRR in early breast cancer after adjuvant RT.

No significant financial relationships to disclose.

Circadian variations of rectal cell proliferation in patients affected by advanced colorectal cancer

The circadian rhythm of the rectal cell proliferation was studied in five patients affected by advanced colon cancer. Biopsies were taken from apparently normal mucosa at 10 cm from the anal verge, every 6 h in a 24-h period. Fragments were incubated for 1 h in a culture medium containing bromodeoxyuridine (BrdUrd). As compared with the mean 24 h values, the percentage of BrdUrd-labelled cells in the crypts (Labelling Index, LI) was lower in the specimens collected at 10.00 PM (P = 0.02) The LI in such biopsies was also lower than the LI observed at the baseline time, 10.00 AM (P = 0.001) The results suggest that the rectal cell proliferation in patients with advanced colon cancer fluctuates during the day. The study of the rhythmicity of the intestinal cells may be useful to modulate the infusion of antiproliferative agents to prevent damage of the normal colorectal mucosa.

Cancer surveillance in ulcerative colitis: critical analysis of long-term prospective programme

BACKGROUND

Patients with longstanding ulcerative colitis are at increased risk of colorectal cancer. In the literature, no agreement has yet been reached regarding prevention strategies. Our report sums up a prospective study started in 1980.

METHODS

A total of 65 patients affected by ulcerative colitis for more than seven years were admitted to a regular colonoscopic and biopsy follow-up programme.

RESULTS

Some 20 years after the beginning of the study, 23 (35.3%) patients have been operated upon, 2 patients have died but not from cancer 29 (44.66%) patients have abandoned the programme. Only 11 (16.9%) patients have remained under colonoscopic surveillance.

CONCLUSION

These results cast some doubts on the significance of such a programme and on its long-term feasibility.

Normal-pressure hydrocephalus

This article presents a brief history of normal-pressure hydrocephalus, its clinical presentation, and different theories on its pathophysiology. The different diagnostic tests, differential diagnosis, and its treatment are presented.

Effect of radiographic contrast agents on leukocyte metabolic response

BACKGROUND

The use of radiographic contrast media in the setting of possible bowel ischemia and potential perforation is known to carry a risk of morbidity and mortality. However, studies of the effect of available contrast media on host immunological defense mechanisms are lacking. We have examined the effect of barium and of two water-soluble contrast agents of differing iodine concentration and osmolality, Conray 30 and Cysto Conray II, on leukocyte phagocytosis.

MATERIALS AND METHODS

Blood samples were incubated with the contrast media alone (termed the "resting state"), and in combination with a standard phagocytic challenge (Zymosan polysaccharide extract) and with Staphylococcus epidermidis, Streptococcus faecalis and Escherichia coli, to determine the effect of contrast media upon leukocyte phagocytic response. Incubation with saline was used as control. In the case of barium, the "resting state" and standard challenge experiments were repeated at nine dilutions, ranging from 1:1 to 1:1000. The leukocyte phagocytic response was measured in two ways: CO2 generation (an index of metabolic activity) and chemiluminescence (an index of generation of reactive oxygen species and bacterial killing).

RESULTS

Barium, at clinical dilutions, causes a significant increase of baseline "resting state" phagocytic activity, which in turn leads to significant blunting of subsequent response to phagocytic challenge and adversely affects the response to all bacteria tested. There is no baseline activation of leukocytes by the water-soluble media, although there was some inhibition (rather than activation) of leukocyte metabolic activity. The effect of the water-soluble media on bacteria was more complex (although inhibition is minor compared to barium).

CONCLUSIONS

Our data demonstrate that barium is a significant activator of phagocytic cells, which results in deactivation of phagocytic response when challenged; these data serve to explain the enhanced adverse effect of barium in cases of fecal peritonitis.

Physician understanding of patient resuscitation preferences: insights and clinical implications

OBJECTIVE

To describe physician understanding of patient preferences concerning cardiopulmonary resuscitation (CPR) and to assess the relationship of physician understanding of patient preferences with do not resuscitate (DNR) orders and in-hospital CPR.

DESIGN

We evaluated physician understanding of patient CPR preference and the association of patient characteristics and physician-patient communication with physician understanding of patient CPR preferences. Among patients preferring to forego CPR, we compared attempted resuscitations and time to receive a DNR order between patients whose preference was understood or misunderstood by their physician.

PATIENTS/SETTING

Seriously ill hospitalized adult patients were enrolled in the Study to Understand Prognoses and Preferences for the Outcomes of Treatments. GENERAL RESULTS: Physicians understood 86% of patient preferences for CPR, but only 46% of patient preferences to forego CPR. Younger patient age, higher physician-estimated quality of life, and higher physician prediction of 6-month survival were independently associated with both physician understanding when a patient preferred to receive CPR and physician misunderstanding when a patient preferred to forego CPR. Physicians who spoke with patients about resuscitation and had longer physician-patient relationships understood patients' preferences to forego CPR more often. Patients whose physicians understood their preference to forego CPR more often received DNR orders, received them earlier, and were significantly less likely to undergo resuscitation.

CONCLUSIONS

Physicians often misunderstand seriously ill, hospitalized patients' resuscitation preferences, especially preferences to forego CPR. Factors associated with misunderstanding suggest that physicians infer patients' preferences without asking the patient. Patients who prefer to forego CPR but whose wishes are not understood by their physician may receive unwanted treatment.

Intradialytic serial vascular access flow measurements

Hemodialysis vascular access failure represents a major source of morbidity and mortality in chronic hemodialysis (CHD) patients. Serial vascular access blood flow (VABF) measurements are being used as a screening method at an increasing rate. There are limited data on the changes in VABF throughout the hemodialysis session, which may potentially affect the validity of VABF measurement. This study is performed to evaluate the trend in VABF during a given hemodialysis session by serial VABF measurements, along with potential factors that may affect VABF. Thirty-two CHD patients had serial VABF measurements performed during a hemodialysis session. Each patient had three serial VABF measurements during a hemodiaysis treatment (within 30, 90, and 150 minutes from the start of hemodialysis). Mean arterial blood pressure (MAP), ultrafiltration rate, and patient symptoms were recorded simultaneously. The mean VABF was 1,344 +/- 486 mL/min within 30 minutes of hemodialysis and decreased to 1,308 +/- 532 and 1,250 +/- 552 mL/min after 90 and 150 minutes, respectively. This trend was statistically significant (P = 0.03). There was a strong correlation between VABF measurements and MAP, which was more pronounced after 90 minutes of initiation of hemodialysis (r = 0.68; P < 0.001). Using multivariate analysis, it can be predicted that after 90 minutes of hemodialysis, each 10% decrease in MAP would result in an expected decrease of 8% in VABF. There was no effect of type of vascular access, baseline VABF, or amount of ultrafiltration on VABF changes. In conclusion, VABF measurements can be performed up to 2 to 2(1/2) hours from the start of hemodialysis in the majority of patients. The major determinant of VABF changes is MAP. In a subset of patients with a decrease MAP greater than 15%, it is advisable to perform VABF measurement either at the first 90 minutes of hemodialysis or postpone it to another treatment session, when MAP is more stable.

The potential of intradialytic parenteral nutrition: A review

Malnutrition is common in chronic hemodialysis (CHD) patients and is strongly related to increased morbidity and mortality. Among the various approaches to treat malnutrition in this patient population, intradialytic parenteral nutrition (IDPN) is the treatment of choice for a small but important percentage of malnourished CHD patients. However, the new revised policies relating to IDPN reimbursement by Medicare in the US have made it very difficult to qualify patients for this potentially useful therapy. This restrictive policy was adopted mainly because there are no clear data that support IDPN use or efficacy. Studies to date in the literature do not provide clear documentation of the benefits of IDPN or their cost-effectiveness. The purpose of this review is to critically evaluate studies relating to the use of IDPN as a potential therapy to treat malnutrition in CHD patients and to discuss potential trials to prove its cost-effectiveness.

Increased susceptibility to erythrocyte C5b-9 deposition and complement-mediated lysis in chronic renal failure

BACKGROUND

Decreased red blood cell survival contributes to the anemia of chronic renal failure patients. Because patients on chronic dialysis therapy are frequently exposed to excessive complement activation, we investigated the susceptibility of this patient population to erythrocyte C5b-9 deposition, complement-mediated lysis, and ghost formation.

METHODS

We developed a flow cytometric assay using antibodies to both glycophorin and the C5b-9 complex to detect C5b-9 deposition on intact erythrocytes and erythrocyte ghosts. Serum C5b-9 levels and C5b-9 deposition on erythrocyte ghosts were measured by enzyme-linked immunosorbent assay.

RESULTS

A significant increase in C5b-9 deposition on intact erythrocytes was demonstrated in patients with advanced chronic renal failure (2.2 +/- 0.5%) and in patients on chronic maintenance hemodialysis (2.3 +/- 0.4%) compared with normal volunteers (0.9 +/- 0.1%, P = 0.005 vs. chronic renal failure, P < 0.001 vs. chronic hemodialysis patients). There was also a significantly higher percentage of C5b-9-positive erythrocyte ghosts in patients with advanced chronic renal failure (20.6 +/- 5%) and in chronic hemodialysis patients (15.5 +/- 3.1%) compared with normal controls (2.6 +/- 0.9%, P < or = 0.001 vs. advanced chronic renal failure and chronic hemodialysis patients). Treatment of erythrocyte preparations with cobra venom factor, which activates the complement cascade, resulted in dramatic increases in the percentages of C5b-9-positive erythrocyte ghosts in patients with chronic renal failure (49.9 +/- 6.9%) and in chronic hemodialysis patients (45.0 +/- 4.2%) compared with normal volunteers (22.3 +/- 2.7%, P < 0.001 vs. chronic renal failure and chronic hemodialysis patients). Erythrocyte membrane expression of the complement regulatory proteins CD59 and CD55 did not significantly differ between normal controls and hemodialysis patients. Plasma C5b-9 levels after cobra venom factor stimulation were higher in chronic renal failure patients (538 micrograms/ml) compared with normal controls (345 micrograms/ml, P < 0.001).

CONCLUSIONS

Patients with chronic renal failure and on hemodialysis therapy are susceptible to erythrocyte C5b-9 deposition with subsequent lysis and ghost formation. Susceptibility to complement-mediated erythrocyte injury may contribute to the anemia of chronic renal disease.

Hemodialysis access failure: a call to action

Recent evidence suggests that the cost as well as the morbidity associated with the maintenance of hemodialysis access is increasing rapidly; currently, the cost exceeds 1 billion dollars and access related hospitalization accounts for 25% of all hospital admissions in the U.S.A. This increase in cost and morbidity has been associated with several epidemiological trends that may contribute to access failure. These include late patient referral to nephrologists and surgeons, late planning of vascular access as well as a shift from A-V fistulaes to PTFE grafts and temporary catheters, which have a higher failure rate. The reasons for this shift in the types of access is multifactorial and is not explained by changes in the co-morbidities of patients presenting to dialysis. Surgical preference and training also appear to play an important role in the large regional variation and patency rate of these PTFE grafts. We propose a program for early placement of A-V fistulae, a continuous quality improvement, multidisciplinary program to monitor access outcome, the development of new biomaterials, and a research plan to investigate pharmacological intervention to reduce development of stenosis and clinical interventions to treat those that do develop, prior to thrombosis.

Results of linear accelerator-based radiosurgery for intracranial meningiomas

OBJECTIVE

We report the outcomes of patients treated with linear accelerator-based radiosurgery for intracranial meningiomas at our institution.

METHODS

We reviewed 127 patients with 155 meningiomas treated with stereotactic radiosurgery (SRS) at the study institutions between October 1988 and December 1995.

RESULTS

There were 86 female and 41 male patients (median age, 61.5 yr; range, 19.9-87.9 yr). The median follow-up period was 31 months (range, 1.2-79.8 mo). The median tumor volume was 4.1 cc (range, 0.16-51.2 cc), and the median marginal dose was 15 Gy (range, 9-20 Gy). The tumor locations were as follows: convexity, 31 tumors; parasagittal/falcine, 39 tumors; cranial base, 82 tumors; and ventricular/pineal, 3 tumors. There were 106 benign, 26 atypical, and 18 malignant meningiomas and 5 cases of meningiomatosis. SRS was performed on 48 lesions as the initial treatment and on 107 lesions as adjunct therapy. Freedom from progression was observed in 107 patients (84.3%) at a median time of 22.9 months (range, 1.2-79.8 mo). Twenty patients (15.7%) had disease progression (16 marginal [12.6%] and 4 local [3.1%]) at a median time of 19.6 months (range, 4.1-69.3 mo); the median time for freedom from progression for the benign, atypical, and malignant meningiomas was 20.9, 24.4, and 13.9 months, respectively. Actuarial tumor control for the patients with benign meningiomas was 100, 92.9, 89.3, 89.3, and 89.3% at 1, 2, 3, 4, and 5 years, respectively. Six patients (4.7%) had permanent complications attributable to SRS (median time, 10.3 mo; range, 4.3-18.0 mo); 13 patients died as a result of causes related to the meningiomas (median, 17.5 mo; range, 4.3-37.3 mo). The 1-, 2-, 3-, 4-, and 5-year survival probability for the entire group of patients was 90.3, 82.6, 73.6, 70.5, and 68.2%, respectively; for patients with benign meningiomas, excluding death resulting from intercurrent disease, the survival probability was 97.6, 94.8, 91.0, 91.0, and 91.0%, respectively. The 1-, 2-, 3-, and 4-year survival probability for the patients with atypical and malignant meningiomas was 91.7, 83.3, 83.3, and 83.3% and 92.3, 64.6, 43.1, and 21.5%, respectively.

CONCLUSION

Even though complications from SRS are expected more frequently with large tumors near critical structures, SRS is a safe and effective means of treating selected meningiomas.

A multicenter comparison of dialysis membranes in the treatment of acute renal failure requiring dialysis

The mortality of patients with acute renal failure (ARF) remains high, and in several large studies approaches 60%. This mortality is particularly high in patients with ARF who require dialysis and has not changed substantially over several years, despite the introduction of major advances in monitoring and treatment. Increasing prevalence of comorbidities has been suggested as the major factor in this persistently high mortality. This study investigates the potential role of the dialysis membrane on patient outcome in a prospective multicenter study of 153 patients with ARF requiring dialysis. The membrane assignment was made in alternating order and was limited to membranes with low complement activation (Biocompatible [BCM]) and cellulosic, high complement activation (Bioincompatible [BICM]). Both types of membranes were low-flux membranes. Patients were dialyzed with the assigned membrane until recovery, discharge from hospital, or death. The severity of illness of each patient was assessed using the APACHE II score at the time of initiation of dialysis. A logistic regression analysis was used to adjust for the APACHE II score. The results of the study showed a statistically significant difference in survival (57% in patients on BCM, 46% in patients on BICM; P = 0.03) and in recovery of renal function (64% in patients on BICM and 43% in patients on BICM; P = 0.001). These differences were particularly marked in the patients who were nonoliguric (>400 ml/d of urine output) at initiation of the study. In the subset of patients who were nonoliguric at the start of dialysis, a larger fraction (70%) became oliguric after initiating dialysis on a BICM membrane, in contrast to 44% who were initiated on a BCM membrane (P = 0.03). It is concluded that the biocompatibility of the dialysis membrane plays a role in the outcome of patients with ARF, particularly those who are nonoliguric at the time of initiation of dialysis.

Correlation between lumbo-ventricular perfusion and MRI-CSF flow studies in idiopathic normal pressure hydrocephalus

BACKGROUND

After the initial description of normal pressure hydrocephalus (NPH) and its clinical triad, there has been a continuous interest from clinicians and researchers to set different diagnostic criteria that would make the selection of candidates for shunt surgery easier and more precise.

METHODS

A preliminary group of 12 patients was given a diagnosis of idiopathic normal pressure hydrocephalus by clinical and radiologic criteria. Each patient underwent two different tests: a magnetic resonance imaging-cerebrospinal fluid (MRI-CSF) flow study and a lumbo-ventricular perfusion test. The purpose was to compare the correlation of the results obtained with these tests and the clinical results obtained after CSF diversion. Eleven patients were given shunts and one was managed with lumbar punctures.

RESULTS

One year after treatment, 10 of the 12 patients had improved with good results. The MRI-CSF flow studies were reliable in six patients; there were five false negatives and one false positive. The lumbo-ventricular perfusion test showed reliability in nine patients; there were two false negatives and one false positive. In only three patients were the results of both of these tests in accordance with the outcome.

CONCLUSIONS

Even though there are few patients in this study so far, the data suggests that at the present time the most predictive guides for the diagnosis of NPH and its outcome after shunting are the clinical criteria and the radiological findings in computed tomography (CT) and/or MRI rather than lumbo-ventricular perfusion and CSF flow studies.

Initial characterization of the dosimetry and radiology of a device for administering interstitial stereotactic radiosurgery

OBJECTIVE

We report the design and initial characterization of the dosimetry and radiobiology of a novel device for interstitial stereotactic radiosurgery.

INSTRUMENTATION

The device is lightweight, handheld, and battery-powered, and it emits x-ray radiation from the tip of a probe 3 mm in diameter by 10 cm in length.

METHODS

The dosimetry was characterized by two independent methods: thermoluminescent dosimeters and radiochromic film. The radiobiology was characterized by in vivo irradiation of rat liver, dog liver, and dog brain. The animals were killed at varying intervals of time, and histological examinations were performed. Heat transfer from the probe to dog brain was studied in vivo by placing thermocouple sensors around the probe tip before irradiating.

RESULTS

Both dosimetric methods showed a steep dose-distance fall-off relationship (proportional to the reciprocal of the cube of the distance from the probe tip). Rats and dogs that were killed weeks to months after liver irradiation tended to have sharply demarcated lesions. Liver enzyme levels, measured serially in the dogs, did not give evidence of chronic inflammation. Histological examination of the brains of dogs that were killed acutely after irradiation did not show evidence of inflammation, edema, or hemorrhage. The tissue temperature elevation 1 cm from the tip never exceeded 0.5 degree C, thereby excluding hyperthermia as a significant contributor to the formation of lesions.

CONCLUSIONS

Because this device requires relatively few supporting resources, has sharp dosimetric properties, and seems to be safe, it may be useful as a clinical tool for interstitial stereotactic radiosurgery.

Gangliogliomas in adults

BACKGROUND

Gangliogliomas are rare tumors occurring in both children and adults that are characterized by the presence of neoplastic cells resembling both neurons and glia.

METHODS

The authors reviewed 18 adults patients with intracranial gangliogliomas treated at the study institutions between October 1987 and November 1995.

RESULTS

The median age at diagnosis was 33.7 years, with a range of 21 to 55 years. Median follow-up was 37.7 months, with a range of 4 months to 13 years. Clinical manifestations among the patients included seizures (13), headache (2), ataxia (1), and hemiparesis and paresthesias (1 patient each). Tumors were located in the temporal lobe (6 patients), temporal lobe and thalamus (1 patient), frontal lobe (5 patients), cerebellum (4 patients), and insula or thalamus (1 patient each). Thirteen patients underwent gross total resection, 4 underwent incomplete resection, and 1 underwent only a stereotactic biopsy. Treatment modalities included surgery only, surgery plus radiation, and surgery plus radiation and chemotherapy. Median survival was 90.3 months, with a range of 14 months to 13 years. Three patients were dead at follow-up with a mean survival of 32.3 months. These patients showed anaplastic features in their pathology at initial surgery or surgery for recurrence.

CONCLUSIONS

In adults, gangliogliomas have a relatively favorable prognosis; however, the presence of anaplastic features predicts a worse outcome.

In vitro differentiation of isolated stem cells from the midgut of Manduca sexta larvae

Isolated spherical stem cells from midguts of pharate fourth-instar larvae of Manduca sexta proliferated in vitro in the presence of 1 ng ml-1 20-hydroxyecdysone and co-cultured fat body tissue or cell-free fat body extract from M. sexta, Lymantria dispar or Heliothis virescens. In this environment, the stem cells were able to undergo mitosis and increase in number. However, stem cells were only able to differentiate to mature goblet and columnar cells when cell-free conditioned medium, taken from midgut cell cultures containing mature cells as well as stem cells and differentiating forms, was introduced into the culture medium. The presence of early and mature goblet cells, lying randomly on their sides, suggested that cell polarity developed in vitro as an intrinsic property of individual cells rather than with reference to an external inductive material. The differentiation factor (or factors) from the conditioned medium appears to include a heat-stable, peptide-like molecule of 10 kDa or less.

Use of Medicare data to identify incident breast cancer cases

Surveillance, Epidemiology and End Results (SEER) data from the National Cancer Institute (NCI) provide reliable information about cancer incidence. However, because SEER data are geographically limited and have a 2-year time lag, we evaluated whether Medicare data could provide timely information on cancer incidence. Comparing Medicare women hospitalized for breast cancer with women reported to SEER, Medicare data had high specificity (96.6 percent), yet low sensitivity (59.4 percent). We conclude that Medicare hospitalization data can identify incident cases for cancers that usually require inpatient hospitalization. For cancers that often only receive outpatient treatment, such as breast cancer, additional Medicare data, such as physician bills, are needed to understand the entirety of treatment practices.

Intravenous immune globulin in the treatment of patients with systemic lupus erythematosus and end-stage renal disease

Intravenous immune globulin (IVIg) has been advocated as efficacious therapy for a variety of disorders including idiopathic thrombocytopenic purpura and Kawasaki disease. Several reports have also documented the effectiveness of IVIg in systemic lupus erythematosus (SLE). Two patients with symptomatic SLE and ESRD were treated with IVIg. Both patients tolerated IVIg administration well and demonstrated clinical and serologic improvement. Both individuals also experienced a transient decline in serum albumin concentration with IVIg treatment. The mechanisms by which IVIg might have effected improvement in these patients are varied and are likely related to the immunomodulatory actions of IVIg. The reversible change in albumin concentration seen in these individuals may be secondary to abrupt alterations in oncotic homeostasis. Despite this unusual effect, the documented improvement in these patients suggests that IVIg therapy may be of benefit in patients with active SLE and ESRD. Further studies are warranted to examine the mechanisms by which IVIg may exert its therapeutic effect.

Intravenous immune globulin in the treatment of patients with systemic lupus erythematosus and end-stage renal disease

Intravenous immune globulin (IVIg) has been advocated as efficacious therapy for a variety of disorders including idiopathic thrombocytopenic purpura and Kawasaki disease. Several reports have also documented the effectiveness of IVIg in systemic lupus erythematosus (SLE). Two patients with symptomatic SLE and ESRD were treated with IVIg. Both patients tolerated IVIg administration well and demonstrated clinical and serologic improvement. Both individuals also experienced a transient decline in serum albumin concentration with IVIg treatment. The mechanisms by which IVIg might have effected improvement in these patients are varied and are likely related to the immunomodulatory actions of IVIg. The reversible change in albumin concentration seen in these individuals may be secondary to abrupt alterations in oncotic homeostasis. Despite this unusual effect, the documented improvement in these patients suggests that IVIg therapy may be of benefit in patients with active SLE and ESRD. Further studies are warranted to examine the mechanisms by which IVIg may exert its therapeutic effect.

The use of the Codman-Medos Programmable Hakim valve in the management of patients with hydrocephalus: illustrative cases

Cerebrospinal fluid shunting is an important method of treating hydrocephalus. It sometimes has been difficult to achieve the optimum CSF pressure and ventricular size after shunt placement. Hydraulic and mechanical mismatching may occur, creating either overdrainage, as manifested by slit ventricle syndrome and/or subdural hygromas; or underdrainage, as manifested by a failure of the ventricles to change in size, with persistence of symptoms. A variable pressure valve (Codman-Medos Programmable Hakim valve system) has been developed to allow non-invasive increase or decrease in cerebrospinal fluid pressure in differentials of 10 mm of water within a range of 30-200 mm of water. This allows the neurosurgeon to adjust the pressure to the patient's particular clinical needs at any given moment. As part of a pilot study of the valve's safety, 13 patients in this center were treated with this programmable shunting system from October 1991 to January 1993. Twelve patients were over age 18 and one was younger than this. Six patients had previously been shunted with other valve systems, and the remaining seven had never been shunted before. The etiology of hydrocephalus included idiopathic normal pressure hydrocephalus (6 patients), aqueductal stenosis (3 patients), Chiari malformation (2 patients), meningitis (1 patient), and unknown etiology (1 patient). This paper describes the use of this valve in five illustrative cases; slit ventricle syndrome in an adult, chronic ventriculomegaly with aqueductal stenosis (2 cases), and idiopathic normal pressure hydrocephalus (2 cases). This programmable valve has been particularly useful in gradually decreasing ventricle size in idiopathic normal pressure hydrocephalus.(ABSTRACT TRUNCATED AT 250 WORDS)

Hemodialysis membrane biocompatibility in acute renal failure

Hemodialysis is a lifesaving procedure for patients with acute renal failure. Nevertheless, the institution of hemodialysis may result in a continued or accelerated decline in renal function. Loss of osmotic drive and hypotension may be partially responsible for this observation. However, multiple lines of evidence suggest that the nature of the hemodialysis membrane also influences renal function following acute renal failure. The cellulosic hemodialysis membrane activates humoral pathways and the cellular elements of blood. The inflammatory responses entrained from the activation result in hypersensitivity reactions attributable to anaphylatoxin generation, hypoxemia, increased susceptibility to infection, and catabolic events. In addition, recent studies indicate that the use of bioincompatible membranes delays recovery from acute renal failure. Increased numbers of neutrophils are found in the glomeruli following exposure to cellulosic membranes, suggesting that inflammatory events induced by complement activation may mediate continuing renal injury and prolonged recovery from acute renal failure. Membrane choice for patients with acute renal failure is emerging as an important therapeutic consideration, just as it is for those patients on long-term dialysis.