Creation of a versatile automated two-step purification system with increased throughput capacity for preclinical mAb material generation

The ever-increasing speed of biotherapeutic drug discovery has driven the development of automated and high throughput purification capabilities. Typically, purification systems require complex flow paths or third-party components that are not found on a standard fast protein liquid chromatography instrument (FPLC) (e.g., Cytiva's ÄKTA) to enable higher throughput. In early mAb discovery there is often a trade-off between throughput and scale where a high-throughput process requires miniaturized workflows necessitating a sacrifice in the amount of material generated. At the interface of discovery and development, flexible automated systems are required that can perform purifications in a high-throughput manner, while also generating sufficient quantities of preclinical material for biophysical, developability, and preclinical animal studies. In this study we highlight the engineering efforts to generate a highly versatile purification system capable of balancing the purification requirements between throughput, chromatographic versatility, and overall product yields. We incorporated a 150 mL Superloop into an ÄKTA FPLC system to expand our existing purification capabilities. This allowed us to perform a range of automated two-step tandem purifications including primary affinity captures (protein A (ProA)/immobilized metal affinity chromatography (IMAC)/antibody fragment (Fab)) followed by secondary polishing with either size exclusion (SEC) or cation exchange (CEX) chromatography. We also integrated a 96 deep-well plate fraction collector into the ÄKTA FPLC system with purified protein fractions being analyzed by a plate based high performance liquid chromatography instrument (HPLC). This streamlined automated purification workflow allowed us to process up to 14 samples within 24 hr, enabling purification of ∼1100 proteins, monoclonal antibodies (mAbs), and mAb related protein scaffolds during a 12-month period. We purified a broad range of cell culture supernatant volumes, between 0.1 - 2 L, with final purification yields up to 2 g. The implementation of this new automated, streamlined protein purification process greatly expanded our sample throughput and purification versatility while also enabling the accelerated production of greater quantities of biotherapeutic candidates for preclinical in vivo animal studies and developability assessment.

Impact of IgG subclass on monoclonal antibody developability

IgG-based monoclonal antibody therapeutics, which are mainly IgG1, IgG2, and IgG4 subclasses or related variants, have dominated the biotherapeutics field for decades. Multiple laboratories have reported that the IgG subclasses possess different molecular characteristics that can affect their developability. For example, IgG1, the most popular IgG subclass for therapeutics, is known to have a characteristic degradation pathway related to its hinge fragility. However, there remains a paucity of studies that systematically evaluate the IgG subclasses on manufacturability and long-term stability. We thus conducted a systematic study of 12 mAbs derived from three sets of unrelated variable regions, each cloned into IgG1, an IgG1 variant with diminished effector functions, IgG2, and a stabilized IgG4 variant with further reduced FcγR interaction, to evaluate the impact of IgG subclass on manufacturability and high concentration stability in a common formulation buffer matrix. Our evaluation included Chinese hamster ovary cell productivity, host cell protein removal efficiency, N-linked glycan structure at the conserved N297 Fc position, solution appearance at high concentration, and aggregate growth, fragmentation, charge variant profile change, and post-translational modification upon thermal stress conditions or long-term storage at refrigerated temperature. Our results elucidated molecular attributes that are common to all IgG subclasses, as well as those that are unique to certain Fc domains, providing new insight into the effects of IgG subclass on antibody manufacturability and stability. These learnings can be used to enable a balanced decision on IgG subclass selection for therapeutic antibodies and aid in acceleration of their product development process.

Impact of IgG subclass on molecular properties of monoclonal antibodies

Immunoglobulin G-based monoclonal antibodies (mAbs) have become a dominant class of biotherapeutics in recent decades. Approved antibodies are mainly of the subclasses IgG1, IgG2, and IgG4, as well as their derivatives. Over the decades, the selection of IgG subclass has frequently been based on the needs of Fc gamma receptor engagement and effector functions for the desired mechanism of action, while the effect on drug product developability has been less thoroughly characterized. One of the major reasons is the lack of systematic understanding of the impact of IgG subclass on the molecular properties. Several efforts have been made recently to compare molecular property differences among these IgG subclasses, but the conclusions from these studies are sometimes obscured by the interference from variable regions. To further establish mechanistic understandings, we conducted a systematic study by grafting three independent variable regions onto human IgG1, an IgG1 variant, IgG2, and an IgG4 variant constant domains and evaluating the impact of subclass and variable regions on their molecular properties. Structural and computational analysis revealed specific molecular features that potentially account for the differential behavior of the IgG subclasses observed experimentally. Our data indicate that IgG subclass plays a significant role on molecular properties, either through direct effects or via the interplay with the variable region, the IgG1 mAbs tend to have higher solubility than either IgG2 or IgG4 mAbs in a common pH 6 buffer matrix, and solution behavior relies heavily on the charge status of the antibody at the desirable pH.

0319 Sleep Architecture and Neurocognitive and Behavioral Functioning in Youth from the General Population

Introduction

The transition from childhood to adolescence is critical for the onset of psychopathology and reflects significant changes in the sleeping brain. Sleep deprivation studies have shown that rapid eye movement (REM) and non-rapid eye movement (NREM) sleep are differentially involved in specific cognitive functions. The aim of this study was to examine the association of sleep architecture with neurobehavioral outcomes in a population-based sample.

Methods

We studied 700 children (5-12y, 47.1% female, 23.7% minority) and 421 adolescents (12-23y, 46.1% female, 21.8% minority) from the Penn State Child Cohort. All subjects underwent a 9-hour polysomnography and a 4-hour neurobehavioral evaluation. Neurocognitive outcomes included the Stroop test, digit span backwards (DSB), and coding to measure high- and low-order cognitive functions. Behavioral outcomes included the Child/Adult Behavior Checklist to measure internalizing symptoms and externalizing behaviors. Correlation analysis examined the cross-sectional association between sleep architecture and neurocognitive and behavioral outcomes.

Results

In childhood, %REM sleep was negatively associated with DSB scores (r=-0.088, p=0.027), particularly in males (r=-0.167, p=0.002). Furthermore, %NREM sleep was positively associated with DSB scores in males (r=0.126, p=0.021). In adolescent females, %NREM and %REM sleep were positively (r=0.146, p=0.044) and negatively (r=-0.158, p=0.029) associated with DSB scores, respectively. In adolescence, %NREM sleep was negatively associated with internalizing symptoms (r=-0.109, p=0.026).

Conclusion

Male children and female adolescents who spent a higher proportion of the night in NREM sleep had better working memory performance. Adolescent females who spent a lower proportion of the night in NREM sleep had greater internalizing symptoms. This study suggests a role for sleep architecture in neurobehavioral deficits in youth. Future studies are necessary to determine the contributions of low- and high-frequency sleep EEG dynamics to these clinical outcomes.

Support

National Institutes of Health (R01MH118308, R01HL97165, R01HL63772, UL1TR000127)

Left ventricular isovolumic velocity and duration variables calculated from colour-coded myocardial velocity images in normal individuals

AIMS

To describe the normal myocardial velocity profile during the isovolumic contraction and relaxation period at four different locations within left ventricular base and to establish normal age and gender related isovolumic time and velocity values.

METHODS AND RESULTS

In 49 healthy individuals (26 women/23 men) in age groups 21-49 and 50-76 years, tissue velocity profiles and 2D-data were acquired at high temporal resolution (90-147 frames/s) for a subsequent off-line analysis using software enabling retrieval of myocardial Doppler velocity and 2D/anatomical M-mode information from different cardiac locations during the same cardiac cycle. The obtained velocity curves during the isovolumic contraction and relaxation period were usually biphasic and displayed clear regional differences in their respective positive and negative maximal velocities. Besides some gender related differences, mainly in the duration of the positive and negative velocity wave components during the isovolumic contraction period, a clear age-dependent increase in the duration of the isovolumic relaxation phase and its negative and positive velocity components was observed.

CONCLUSION

Modern tissue Doppler imaging supplemented by anatomical M-mode images of the mitral and aortic valve movements allows a proper analysis of the rapid isovolumic myocardial movements. The presented normal isovolumic time and velocity values may prove useful for studies of myocardial function.

Effect of tissue Doppler on the accuracy of novice and expert interpreters of dobutamine echocardiography

The subjective interpretation of dobutamine echocardiography (DBE) makes the accuracy of this technique dependent on the experience of the observer, and also poses problems of concordance between observers. Myocardial tissue Doppler velocity (MDV) may offer a quantitative technique for identification of coronary artery disease, but it is unclear whether this parameter could improve the results of less expert readers and in segments with low interobserver concordance. The aim of this study was to find whether MDV improved the accuracy of wall motion scoring in novice readers, experienced echocardiographers, and experts in stress echocardiography, and to identify the optimal means of integrating these tissue Doppler data in 77 patients who underwent DBE and angiography. New or worsening abnormalities were identified as ischemia and abnormalities seen at rest as scarring. Segmental MDV was measured independently and previously derived cutoffs were applied to categorize segments as normal or abnormal. Five strategies were used to combine MDV and wall motion score, and the results of each reader using each strategy were compared with quantitative coronary angiography. The accuracy of wall motion scoring by novice (68 +/- 3%) and experienced echocardiographers (71 +/- 3%) was less than experts in stress echocardiography (88 +/- 3%, p <0.001). Various strategies for integration with MDV significantly improved the accuracy of wall motion scoring by novices from 75 +/- 2% to 77 +/- 5% (p <0.01). Among the experienced group, accuracy improved from 74 +/- 2% to 77 +/- 5% (p <0.05), but in the experts, no improvement was seen from their baseline accuracy. Integration with MDV also improved discordance related to the basal segments. Thus, use of MDV in all segments or MDV in all segments with wall motion scoring in the apex offers an improvement in sensitivity and accuracy with minimal compromise in specificity.

Assessment of regional long-axis function during dobutamine echocardiography

Echocardiographic analysis of regional left ventricular function is based upon the assessment of radial motion. Long-axis motion is an important contributor to overall function, but has been difficult to evaluate clinically until the recent development of tissue Doppler techniques. We sought to compare the standard visual assessment of radial motion with quantitative tissue Doppler measurement of peak systolic velocity, timing and strain rate (SRI) in 104 patients with known or suspected coronary artery disease undergoing dobutamine stress echocardiography (DbE). A standard DbE protocol was used with colour tissue Doppler images acquired in digital ciné-loop format. Peak systolic velocity (PSV), time to peak velocity (TPV) and SRI were assessed off-line by an independent operator. Wall motion was assessed by an experienced reader. Mean PSV, TPV and SRI values were compared with wall motion and the presence of coronary artery disease by angiography. A further analysis included assessing the extent of jeopardized myocardium by comparing average values of PSV, TPV and SRI against the previously validated angiographic score. Segments identified as having normal and abnormal radial wall motion showed significant differences in mean PSV (7.9 +/- 3.8 and 5.9 +/- 3.3 cm/s respectively; P < 0.001), TPV (84 +/- 40 and 95 +/- 48 ms respectively; P = 0.005) and SRI (-1.45 +/- 0.5 and -1.1 +/- 0.9 s(-1) respectively; P < 0.001). The presence of a stenosed subtending coronary artery was also associated with significant differences from normally perfused segments for mean PSV (8.1+/-3.4 compared with 5.7+/-3.7 cm/s; P < 0.001), TPV (78 +/- 50 compared with 92 +/- 45 ms; P < 0.001) and SRI (-1.35 +/- 0.5 compared with -1.20 +/- 0.4 s(-1); P = 0.05). PSV, TPV and SRI also varied significantly according to the extent of jeopardized myocardium within a vascular territory. These results suggest that peak systolic velocity, timing of contraction and SRI reflect the underlying physiological characteristics of the regional myocardium during DbE, and may potentially allow objective analysis of wall motion.

Application of tissue Doppler to interpretation of dobutamine echocardiography and comparison with quantitative coronary angiography

The main limitation of dobutamine echocardiography (DE) is its subjective interpretation. We sought to reduce the need for expert interpretation by developing a quantitative approach to DE using myocardial Doppler velocity (MDV) in 242 patients undergoing DE. In 128 patients with a normal dobutamine echocardiogram, the normal range was designed to give a specificity of 80%. The accuracy of this range was investigated in 114 consecutive patients who underwent coronary angiography within 2 months of DE. A standard dobutamine echocardiographic protocol was used, with MDV gathered from color tissue Doppler at rest and peak stress. Wall motion at these stages was scored by experienced observers using a 16-segment model and MDV was measured off-line. Sensitivity and specificity of wall motion scoring and MDV were obtained by comparison with angiographic evidence of disease, defined as stenosis > 50% of the coronary artery diameter. The normal range in tethered segments (septum, anteroseptum, and inferior) was > or = 7 cm/s in the basal segments and > or = 5 cm/s in the midsegments. In the free wall (anterior, lateral, and posterior), the cutoff was > or = 6 cm/s in the base and > or = 4 cm/s in the midventricle. Of 114 patients undergoing angiography, 84 (75%) had significant stenoses, and the sensitivity of wall motion scoring and MDV were 88% and 83%, respectively, with specificities of 81% and 72% (p = NS). The accuracy was similar overall (86% vs 80%), as well as in each vascular territory. These data suggest that a fully quantitative interpretation of DE using site-specific normal ranges of tissue Doppler, which account for regional variations of base-apex function, is feasible and equivalent in accuracy to expert wall motion scoring.

Anatomical M-mode: A novel technique for the quantitative evaluation of regional wall motion analysis during dobutamine echocardiography

Recognition of abnormal wall motion during dobutamine echocardiography requires an expert observer. Anatomical M-mode echocardiography may offer a novel quantitative approach to interpretation, amenable to less expert readers. We studied the application of this new modality to 124 patients (80 with known coronary anatomy and 44 patients at low probability of coronary disease) who underwent dobutamine echocardiography, using a standard protocol. Wall motion was interpreted by an experienced reader, using digitally stored 2-dimensional echocardiographic images at rest and peak stress. Percentage of systolic thickening was measured offline using anatomical M-mode echocardiography in the basal and mid segments at rest and peak dose, and compared with wall motion scores and coronary angiography. Of 729 segments, wall motion was identified as normal in 449, ischemic or viable in 171 and showed resting WM abnormalities only in 109 segments. After exclusion of the apex, anatomical M-mode measurements were feasible in 729 of 960 possible basal- and mid-zone segments (76%). Measurement of systolic thickening at peak dose was reproducible within (r2 = 0.83) and between observers (r2 = 0.93). Systolic thickening was significantly greater in segments with normal wall motion (37 +/- 2%) compared with ischemic or viable segments (30 +/- 2%, p < 0.001), and scar segments (23 +/- 3%, p < 0.001). There was an increment of thickening from rest to stress in normal and viable segments, no change in scar, and a decrement in ischemic segments. Significant coronary artery disease (defined by stenoses >70% diameter) was present in 59 patients. Systolic thickening showed significant variation between segments interpreted by wall motion scoring and angiography as true and false positive and true and false negative (p < 0.05). Measurement of systolic thickening using anatomical M-mode echocardiography offers an objective method to quantify systolic thickening at dobutamine echocardiography but has limited clinical feasibility.

Screening for coronary artery disease

Unidentified coronary artery disease remains a significant cause of premature death and morbidity during the prime of life. The availability of effective interventions for the management of ischemia has provoked new interest in screening for this condition in asymptomatic patients, in the hope of reducing the burden of this condition. Although widespread use of stress testing is ineffective, the use of imaging techniques may offer better accuracy for detection of ischemia. Other tests that identify evidence of atheroma in the peripheral or coronary circulation may be useful to identify patients at risk.

Knowledge in health visiting practice

Health visiting is a practical discipline, hence knowledge in health visiting practice cannot be thought of as inert, that is merely as items of information merely; rather, it must be thought of in terms of a dynamic interplay among the individuality of the knower (the practitioner), the sources whereby knowledge may be acquired, and the contexts in which it must be applied. This discussion is an exploration of that interplay. Thus, in the discussion, the distinctive demands on the practitioner (and the kinds of personal qualities these entail) in acquiring and applying knowledge are highlighted, as are the sources of knowledge and the constraints of context. Three sources of knowledge are noted: authority, personal experience, and intuition. Context is conceived both in terms of the macro, sociopolitical, level and in terms of the micro level, i.e. the individual homes and interpersonal relationships in and through which health visiting is typically practised. Conclusions are drawn relating to the education of health visitors. The discussion draws on a distinction between three kinds of knowledge: factual or propositional knowledge, knowledge by acquaintance, and practical knowledge, or know-how.

Respecting and breaking confidences: conceptual, ethical and educational issues

Issues of confidentiality are an integral part of professional nursing practice, hence reflection on these issues is an integral part of nurse education. 'Respecting and breaking confidences: conceptual, ethical and educational issues' argues that reflection must take account of at least two conceptual issues, namely, what is confidential information? and what constitutes a breach of confidentiality? An answer to these questions is logically presupposed by the ethical questions considered, i.e. what should clients be told about the parameters of confidentiality at the first point of contact? and what would justify a breach of confidence? The discussion is anchored in a critique of the Advisory Paper (1987) on confidentiality, published by the United Kingdom Central Council for Nursing, Midwifery and Health Visiting. It concludes by drawing out some implications for nurse education.

Controversial issues: a case for neutrality?

Controversial issues are defined, in this discussion, as those in relation to which contrary views can be held without those views being contrary to reason. Such issues arise in the range of courses constituting nurse education, especially, but not exclusively, where ethical questions are discussed. The nurse educator may, therefore, have to decide whether or not to say what she thinks, in particular she may have to decide whether or not to assert her own view as correct. Where professional beliefs and values are involved, to assert a view as correct may seem to be required. Might this, though, detract from the aim of developing students' capacity for autonomous reflection? The discussion assesses whether neutrality, in the sense either of not stating one's view or not asserting it as correct, is desirable, by examining arguments both for and against, and highlights ways in which a neutral stance both is, and is not, an option.

Serious hemorrhage complicating diagnostic abdominal paracentesis

We describe two patients awaiting orthoptic liver transplantation in whom diagnostic paracentesis for the diagnosis of spontaneous bacterial peritonitis led to major hemorrhage. Accordingly, we advise caution in patients such as ours, particularly if the prothrombin time or partial thromboplastin time is more than twice the control value.

The limits of confidentiality

Two conditions are commonly taken to constitute an obligation of confidentiality: information is entrusted by one person to another; and there is an express understanding that this will not be divulged. This conception of confidentiality, however, does not match much of the practice of health care. Health care practitioners would, for example, hold themselves to be under an obligation of confidentiality in situations where neither of these conditions obtain. The discussion proposes, therefore, two additional grounds for confidentiality. This is in order to clarify, in general terms, the scope of this obligation (i.e. to clarify at what point confidentiality can be said to have been broken). The 'limits of confidentiality', it is argued, are set by the wishes of the client or, where these are not known, by reference to those whose right and need to know relate to the care of the client. Anonymous references to the client outside this limit may not be breaches of confidence; whether they are or not depends, it is suggested, on if such reference is responsible.

Using clients

An important part of the student nurse's training involves reflection on practice, as expressed in written assignments and seminar discussions. In this, students make use of material drawn from their work with clients. A key ethical question is, therefore: should clients' permission be sought by students for this use of case material in coursework assignments. This article examines in some detail the arguments both for and against seeking clients' permission and concludes that, in view of the principle of respect for autonomy, there is a moral obligation to gain consent. It is argued, however, that there may be legitimate exceptions to this.

Recovery of chorda tympani nerve function following injury

The chorda tympani (CT) nerve carries taste information from the anterior tongue to the brain stem. Injury to the chorda tympani may result in loss or distortion of taste information. This study examined changes occurring in the hamster peripheral taste system during recovery from injury. The hamster chorda tympani nerve was crushed in the middle ear and the animals were allowed to survive from 2 to 16 weeks. At 2 weeks, CT fibers had degenerated distal to the crush site. Up to 16 weeks after crush, there were 67% fewer myelinated fibers in regenerated nerves than in controls. The mean area of the Ca(2+)-ATPase-stained core of the fungiform taste buds was significantly smaller than in controls 2 weeks after injury, but recovered to control values by 4 weeks. Electrophysiological responses to taste stimuli were recorded from the chorda tympani distal to the injury. No responses were seen after 2 weeks; weak and unstable responses were seen after 3 weeks. By 4-8 weeks, relative responses to taste stimuli were similar to control responses, but the variability of the responses to sucrose was significantly greater than that in controls. The frequency of responses to the water rinse following taste stimuli, particularly sucrose, was also greater in the regenerated nerves. The abnormal electrophysiological responses to sucrose may be the result of the differential rate of return of fiber types and/or the transduction mechanisms. In some ways, recovery of the peripheral gustatory system after damage to the chorda tympani nerve recapitulates the later stages of taste bud development.

Improved pediatric patient flow in a general emergency department by altering triage criteria

OBJECTIVE

To evaluate the effect of altering pediatric triage criteria on ED triage scoring and patient flow.

METHODS

A prospective observational study of a pediatric triage modification was performed. Data for all pediatric patients presenting to an urban general ED during a six-month study period were collected. After the first three months, pediatric triage criteria were altered by elevating the acuity of several historical items and specifically listing abnormal signs and symptoms. Outcome measures included triage score assignment, criteria making the patient emergent, proportion of emergent or urgent triage assignments, and times to examination, disposition, and admission.

RESULTS

Altering pediatric triage criteria resulted in a significant (p < 0.05) increase in the number of patients triaged as emergent (2% vs 15%) or urgent (48% vs 55%). In addition, for emergent and urgent patients there was a significant decrease (p < 0.05) in the mean times to ED examination (50 vs 44 min), floor admission (355 vs 245 min), and intensive care unit admission (221 vs 132 min). The triage changes that had a significant impact on these results were a history of color change, decreased activity, and prematurity with complications.

CONCLUSIONS

A significant improvement in pediatric patient flow occurred after posting age-specific abnormal signs and symptoms as well as elevating triage acuity for specific historical clues.

DNA typing of grapevines: a universal methodology and database for describing cultivars and evaluating genetic relatedness

With established ampelographic techniques for grapevine identification it is often difficult to achieve a satisfactory, objective result. We have developed a DNA typing system using sequence-tagged microsatellite site markers as a means of differentiating cultivars of grapevine. A semi-automated analysis procedure was linked to an electronic database and found to be an objective and reliable system for cultivar identification using this simple marker type. The accumulated DNA typing data from over eighty cultivars demonstrated that cultivars that are difficult to differentiate phenotypically using ampelographic techniques can be distinguished by DNA typing. Parentage analysis uncovered errors in parent assignment or cultivar identification in specific cases. The electronic database has a conservative format to take into account the occurrence of null alleles and the possibility of missed alleles. Computer-assisted comparisons of cultivars in the database can be performed and various approaches for estimating the match probability that two unrelated cultivars have the same genotype simply due to chance are discussed. We suggest that further development of the database through international co-operation using standardised sequence-tagged site markers offers the possibility of achieving a universal grapevine identification system.

Repetitive DNA of grapevine: classes present and sequences suitable for cultivar identification

Repetitive DNA sequences present in the grapevine genome were investigated as probes for distinguishing species and cultivars. Microsatellite sequences, minisatellite sequences, tandemly arrayed genes and highly repetitive grapevine sequences were studied. The relative abundance of microsatellite and minisatellite DNA in the genome varied with the repeat sequence and determined their usefulness in detecting RFLPs. Cloned Vitis ribosomal repeat units were characterised and showed length heterogeneity (9.14-12.15 kb) between and within species. A highly repetitive DNA sequence isolated from V. vinifera was found to be specific only to those species classified as Euvitis. DNA polymorphisms were found between Vitis species and between cultivars of V. vinifera with all classes of repeat DNA sequences studied. DNA sequences suitable for DNA fingerprinting gave genotype-specific patterns for all of the cultivars and species examined. The DNA polymorphisms detected indicates a moderate to high level of heterozygosity in grapevine cultivars.

Hydrogen peroxide stimulates the synthesis of platelet-activating factor by endothelium and induces endothelial cell-dependent neutrophil adhesion

Oxidant-induced damage to the intima of pulmonary and systemic vessels is thought to be an important mechanism of injury in a variety of syndromes of vascular damage. Hydrogen peroxide (H2O2) is an active oxygen metabolite that may induce intimal injury by cytolytic attack or by inducing biochemical and functional alterations in the endothelial cells (EC); however, mechanisms involved in noncytolytic perturbation of EC are largely unknown. We found that H2O2 stimulated the synthesis of platelet-activating factor (PAF) by primary cultures of bovine pulmonary artery endothelium (BPAEC) and by human umbilical vein endothelium (HUVEC). In each cell type the incorporation of [3H]acetate into [3H-acetyl]PAF was concentration- and time-dependent and was temporally dissociated from severe plasma membrane disruption and cytolytic cell injury; the newly synthesized PAF remained associated with the EC. H2O2 caused permeabilization of EC to 45Ca2+ and an increase in intracellular Ca2+, suggesting that a transmembrane Ca2+ flux is the signal that initiates PAF synthesis. H2O2 also induced the endothelial cell-dependent adhesion of neutrophils to HUVEC monolayers. This response was rapid, with an onset within minutes and a subsequent time course that paralleled the time course of PAF accumulation, and was dependent on extracellular Ca2+ but not on de novo protein synthesis. These studies demonstrate that H2O2 can induce two rapid activation responses of endothelium, PAF synthesis and EC-dependent neutrophil adhesion, events that may be important in physiologic and pathologic inflammation.

[Colonoscopic follow up of rectocolonic cancer surgeries. Assessment of 64 examinations]

A collation of 64 colonoscopic examinations performed on 41 patients operated on for cancer of the colon or rectum is reported. Eleven patients (26.8 percent) had positive follow-up endoscopic findings. In 13 enumerated tumoral proliferations. 8 benign polyps and 5 malignant growths were found, one of the latter on the anastomosis, and the other 4 on the remaining colon. 80 percent of these tumoral growths and all malignant tumors were discovered in the two years following surgery. When colonic strictures present before operation prevent total colonoscopic exploration, such an endoscopic examination of the colon in its entirety must be made immediately following passage of three post-operative months. It is prudent not to wait for attendant alarming signs but rather to integrate total colonoscopy including excision of "overlooked" or newly-formed polyps into the follow-up protocol of all colon surgery cancer patients who have become high-risks for either a relapse or recurrence of polyps. In the initial two post-operative years, when there is a maximal risk. Colonoscopy should be performed every six months and thereafter at longer but regular intervals throughout survival.

[Multiple endocrine neoplasms associated with Zollinger-Ellison syndrome and hyperparathyroidism]

We report the case of a 43 year old man with multiple endocrine neoplasia (Zollinger-Ellison syndrome-hyperparathyroidism) diagnosed during investigations for a severe ulcer with diarrhoea. The history suggested Zollinger-Ellison syndrome, especially as basal acid production and blood gastrin levels were high. Hypercalcaemia and low blood phosphate levels suggested hyperparathyroidism, which was confirmed by ultra-sound of the neck, showing two parathyroid adenomas. The aim of treatment was two-fold: suppress the hyperparathyroidism and treat the Zollinger-Ellison syndrome. The approach is surgical in most cases, but the tumour is often impossible to remove and total gastrectomy has become rare with the progress in anti-secretory therapy. When the tumour behind a case of Zollinger-Ellison syndrome cannot be found, complementary chemotherapy is indicated. Other endocrine lesions must always be sought and the family investigated to exclude Wermer syndrome.

Effect of halothane on the rate of acid production, lactate production and pyruvate dehydrogenase activity of malignant hyperpyrexia human muscle

The rates of acid production were compared in thin strips of muscle biopsy samples isolated from malignant hyperpyrexia and control vastus internus human muscle. Halothane doubled the rate of acid production by malignant hyperpyrexia susceptible muscle but had no effect on control samples. This increased rate of release of acid from muscle was not from lactate. In addition, the pyruvate dehydrogenase activity of both control and malignant hyperpyrexia muscle samples was not stimulated by halothane.