Gene editing in CHO cells to prevent proteolysis and enhance glycosylation: Production of HIV envelope proteins as vaccine immunogens

Several candidate HIV subunit vaccines based on recombinant envelope (Env) glycoproteins have been advanced into human clinical trials. To facilitate biopharmaceutical production, it is necessary to produce these in CHO (Chinese Hamster Ovary) cells, the cellular substrate used for the manufacturing of most recombinant protein therapeutics. However, previous studies have shown that when recombinant Env proteins from clade B viruses, the major subtype represented in North America, Europe, and other parts of the world, are expressed in CHO cells, they are proteolyzed and lack important glycan-dependent epitopes present on virions. Previously, we identified C1s, a serine protease in the complement pathway, as the endogenous CHO protease responsible for the cleavage of clade B laboratory isolates of -recombinant gp120s (rgp120s) expressed in stable CHO-S cell lines. In this paper, we describe the development of two novel CHOK1 cell lines with the C1s gene inactivated by gene editing, that are suitable for the production of any protein susceptible to C1s proteolysis. One cell line, C1s-/- CHOK1 2.E7, contains a deletion in the C1s gene. The other cell line, C1s-/- MGAT1- CHOK1 1.A1, contains a deletion in both the C1s gene and the MGAT1 gene, which limits glycosylation to mannose-5 or earlier intermediates in the N-linked glycosylation pathway. In addition, we compare the substrate specificity of C1s with thrombin on the cleavage of both rgp120 and human Factor VIII, two recombinant proteins known to undergo unintended proteolysis (clipping) when expressed in CHO cells. Finally, we demonstrate the utility and practicality of the C1s-/- MGAT1- CHOK1 1.A1 cell line for the expression of clinical isolates of clade B Envs from rare individuals that possess broadly neutralizing antibodies and are able to control virus replication without anti-retroviral drugs (elite neutralizer/controller phenotypes). The Envs represent unique HIV vaccine immunogens suitable for further immunogenicity and efficacy studies.

Unusual Cysteine Content in V1 Region of gp120 From an Elite Suppressor That Produces Broadly Neutralizing Antibodies

Although it is now possible to produce recombinant HIV envelope glycoproteins (Envs) with epitopes recognized by the 5–6 major classes of broadly neutralizing antibodies (bNAbs), these have failed to consistently stimulate the formation of bNAbs in immunized animals or humans. In an effort to identify new immunogens better able to elicit bNAbs, we are studying Envs derived from rare individuals who possess bNAbs and are able to control their infection without the need for anti-retroviral drugs (elite supressors or ES), hypothesizing that in at least some people the antibodies may mediate durable virus control. Because virus evolution in people with the ES only phenotype was reported to be limited, we reasoned the Env proteins recovered from these individuals may more closely resemble the Envs that gave rise to bNAbs compared to the highly diverse viruses isolated from normal progressors. Using a phenotypic assay, we screened 25 controllers and identified two for more detailed investigation. In this study, we examined 20 clade B proviral sequences isolated from an African American woman, who had the rare bNAb/ES phenotype. Phylogenetic analysis of proviral envelope sequences demonstrated low genetic diversity. Envelope proteins were unusual in that most possessed two extra cysteines within an elongated V1 region. In this report, we examine the impact of the extra cysteines on the binding to bNAbs, virus infectivity, and sensitivity to neutralization. These data suggest structural motifs in V1 can affect infectivity, and that rare viruses may be prevented from developing escape.

Safety and efficacy of long-term nasobiliary drainage to treat intractable pruritus in cholestatic liver disease

INTRODUCTION

Cholestasis related pruritus, secondary to intrahepatic and/or extrahepatic biliary obstruction is a common manifestation in chronic liver disease. Pruritus is difficult to treat, and results are often suboptimal. A stepwise medical approach is usually employed, followed by a trial molecular adsorbents recirculation system in medication resistant cases. Pruritus resulting in reduced quality of life is a variant syndrome eligible for liver transplantation in the setting of preserved synthetic function.

AIM

This case series describes the use of long-term (LT) nasobiliary drainage (NBD) in three patients with intractable pruritus. This case series tests the hypothesis that LT-NBD could be successfully used to alleviate cholestasis related pruritus, and prevent or delay the need for liver transplantation.

METHOD

LT-NBD was carried out in three female patients (mean age 43 years) with intractable pruritus secondary to primary biliary cirrhosis (PBC) (n=2), and benign recurrent intrahepatic cholestasis (n=1). NBD was carried out through the endoscopic placement of a 6 French Cook Medical nasobiliary catheter into the common bile duct.

RESULTS

Symptomatic relief of pruritus was described by all three cases within 24 h of NBD placement. LT-NBD was stopped in the patient with benign recurrent intrahepatic cholestasis after 8 weeks due to complete resolution of pruritus. In one patient with PBC, LT-NBD was undertaken over 12 months, with complete resolution of pruritus. In the second patient with PBC, LT-NBD was carried out over 14 months, with complete resolution of pruritus.

DISCUSSION

This case series supports the efficacy of LT-NBD in the treatment of intractable pruritus. We propose that NBD offers an accessible modality for the treatment of intractable pruritus in liver disease, potentially avoiding the need for liver transplantation.

The development of comprehension and reading-related skills in children learning English as an additional language and their monolingual, English-speaking peers

BACKGROUND

A significant number of pupils in UK schools learn English as an additional language (EAL). Relative differences between the educational attainment of this group and monolingual, English-speaking pupils call for an exploration of the literacy needs of EAL learners.

AIMS

This study explores the developmental progression of reading and listening comprehension skills and a range of reading-related skills in EAL learners, whose first language is of South Asian origin, and their monolingual peers.

SAMPLE

Participants were 39 children learning EAL and 39 monolingual, English-speaking children who were all in school Year 3 at the start of the study.

METHOD

Children completed standardized measures of comprehension, vocabulary, reading accuracy, and reading fluency in school Year 3 and again in Year 4.

RESULTS

The results suggest that, although children learning EAL often demonstrate fast and accurate reading accuracy skills, lower levels of vocabulary knowledge place significant constraints on EAL learners' comprehension of spoken and written texts.

CONCLUSIONS

Reciprocal relationships between vocabulary and comprehension may lead to increasing gaps in reading comprehension between monolingual and EAL pupils over time. It is proposed that support for the development of vocabulary skills in children learning EAL is needed in early years' classrooms.

Long-term histological follow-up of people with coeliac disease in a UK teaching hospital

BACKGROUND

Coeliac disease is a relatively common condition which is usually managed by placing patients on a gluten free diet. Follow up biopsies to confirm histological recovery are controversial with a considerable variation in practice observed.

AIM

To determine the length of time to histopathological recovery in a group of coeliac disease patients and its associations with clinicopathological data.

DESIGN AND METHODS

All patients attending a specialist coeliac disease clinic prior to March 2009 were entered onto a database which recorded various clinicopathological data. The histopathology reports for all duodenal biopsies were reviewed and each biopsy was given a histopathological disease score based on a modified Marsh grade.

RESULTS

Two hundred and eighty-four patients underwent index and at least one subsequent biopsy. Two-hundred and twenty-seven (80%) showed histopathological improvement and 100 (35%) returned to normal (median recovery time 1.9 years, inter-quartile range 1.0-4.8 years). Patients with less severe disease at diagnosis were more likely to show a better response (r = 0.281, P < 0.0001). Older patients demonstrated a shorter time to histopathological recovery (r = -0.200, P = 0.001). Compliance with a gluten free diet was correlated with the best biopsy score (r = -0.134, P = 0.040) and degree of histological recovery (r = 0.161, P = 0.014).

CONCLUSION

Current guidelines for the timing of repeat biopsy after commencing a gluten free diet are unclear, although 4-6 months has been recommended. This study shows that time to histological recovery is longer than traditionally thought and may need to take into account the patient's age at diagnosis, the initial disease score and the level of compliance with a gluten free diet.

High Pressure Differential Scanning Calorimetry Investigations on the Pressure Dependence of the Melting of Paracetamol Polymorphs I and II

A high pressure differential scanning calorimeter (HP-DSC) has been used to investigate the pressure dependence of the melting of the monoclinic (Form I) and orthorhombic (Form II) polymorphs of paracetamol (acetaminophen). DSC scans obtained at ambient pressure show that the stable monoclinic form melts at 442 K while the metastable orthorhombic form melts at 430 K. HP-DSC scans obtained for pressures up to about 450 MPa show that the melting temperatures of both Forms I and II increase with increasing pressure, but the latter more rapidly than the former. This results in a cross-over at about 250 MPa, where the two forms have approximately the same melting temperature, while at higher pressures Form II becomes the more stable phase. Although no solid-solid transitions have been observed, the coordinates of the I-II-liquid triple point have been found experimentally (p = 258.7 MPa and T = 489.6 K) for the first time, and confirm those predicted by Espeau et al. from a topological p-T diagram based on theoretical arguments and experimental data at ambient pressure.

Influence of population density on antibiotic resistance

Antibiotic consumption and population density as a measure of crowding in the community were related to the prevalence of antibiotic resistance of three cities in three different countries: St Johns in Newfoundland (Canada), Athens in Greece and Groningen in The Netherlands. Antibiotic consumption was expressed in DDD (defined daily dose), as DID (DDD/1000 inhabitants/day) and as DSD (DDD/km(2)). The prevalence of antibiotic-resistant Escherichia coli and enterococci was determined in faecal samples of healthy volunteers. In both Newfoundland (28 DID) and Greece (29 DID) the overall consumption of antibiotics was more than three times higher compared with that of The Netherlands (9 DID). The lowest prevalence of resistant E. coli against the majority of antibiotics tested was found for the samples from Newfoundland and was significant (P < 0.05) for cefazolin, oxytetracycline and trimethoprim. A poor correlation between the number of DID and the prevalence of resistance was observed [the Pearson correlation coefficient (Pcc) ranged between -0.93 and 0.87]. However, when population density was taken into consideration and antibiotic consumption was expressed in DSD, a strong correlation was observed (and Pcc ranged between 0.86 and 1.00). This study suggests that population density is an important factor in the development of antibiotic resistance and warrants special attention as a factor in resistance epidemiology.

Role of diagnostic labeling in antibiotic prescription

OBJECTIVE

To evaluate the association between diagnostic labeling of respiratory tract infections (RTIs) and antibiotic prescription rates in family practice.

DESIGN

Descriptive analysis of outpatient chart review supplemented by interviews with physicians. Charts of patients attending 73 general practitioners were reviewed between October 1997 and February 1998. Two days of practice were evaluated per physician.

SETTING

Urban family practices in greater St John's, Nfld.

PARTICIPANTS

Of 96 family physicians contacted, 73 (76%) agreed to participate.

MAIN OUTCOME MEASURES

Rates of diagnoses and antibiotic prescriptions for acute infections. Physicians were divided into "low prescribers" and "high prescribers" based on overall rates of prescription to patients with infections. Low prescribers were compared with high prescribers with respect to physician characteristics, patient characteristics, and diagnoses assigned.

RESULTS

Of all patients seen, 22% were seen for acute infections; RTIs accounted for 76% of diagnoses. Low prescribers and high prescribers were of similar ages and saw similar numbers of patients of similar ages with very similar presenting complaints. Both groups diagnosed urinary tract and skin and soft-tissue infections at similar rates, but differed markedly in their rates of diagnoses of RTIs. High prescribers diagnosed bacterial RTIs in 65.4% (147/225) of their patients; low prescribers diagnosed bacterial RTIs in 31.0% (66/213 (P < .001).

CONCLUSION

Family doctors frequently prescribe antibiotics. The difference in rates of prescription between high prescribers and low prescribers is largely explained by assignment of diagnoses of RTIs.

Heme oxygenase activity in term human placenta

Carbon monoxide (CO) is a novel gaseous chemical messenger, formed during heme oxygenase (HO)-catalysed oxidation of heme. CO is proposed to play a key role(s) in cell function in many organ systems, including vasodilator action in the cardiovascular system. Recently, it has been demonstrated that there is expression of HO protein in the human placenta and this appears to have a regulatory role in placental perfusion. The objective of the present study was to determine HO enzymatic activity in vitro in five different regions of term human placenta. HO activity was determined in the microsomal fraction of tissue homogenate by measuring the rate of formation of CO from heme, using a gas-chromatographic method. HO activity, expressed as nmol CO formed/g tissue wet weight/h, was higher (P< 0.05) in the chorionic plate, chorionic villi, basal plate and chorio-decidua compared with the amnion. The finding that HO enzymatic activity is present in different regions of term human placenta supports the concept that the heme-CO (HO) pathway plays a complementary role with the L -arginine-nitric oxide (nitric oxide synthase) pathway in the regulation of placental haemodynamics.

Ways to test stochastic dynamic programming models empirically

Stochastic dynamic programming (SDP) models are widely used to predict optimal behavioural and life history strategies. We discuss a diversity of ways to test SDP models empirically, taking as our main illustration a model of the daily singing routine of birds. One approach to verification is to quantify model parameters, but most SDP models are schematic. Because predictions are therefore qualitative, testing several predictions is desirable. How state determines behaviour (the policy) is a central prediction that should be examined directly if both state and behaviour are measurable. Complementary predictions concern how behaviour and state change through time, but information is discarded by considering behaviour rather than state, by looking only at average state rather than its distribution, and by not following individuals. We identify the various circumstances in which an individual's state/behaviour at one time is correlated with its state/behaviour at a later time. When there are several state variables the relationships between them may be informative. Often model parameters represent environmental conditions that can also be viewed as state variables. Experimental manipulation of the environment has several advantages as a test, but a problem is uncertainty over how much the organism's policy will adjust. As an example we allow birds to use different assumptions about how well past weather predicts future weather. We advocate mirroring planned empirical investigations on the computer to investigate which manipulations and predictions will best test a model. Copyright 2000 The Association for the Study of Animal Behaviour.

Method of physician remuneration and rates of antibiotic prescription

BACKGROUND

Rates of antibiotic prescription in Canada far exceed generally accepted rates of bacterial infection, which led the authors to postulate that rates of antibiotic prescription depend to some extent on factors unrelated to medical indication. The associations between antibiotic prescription rates and physician characteristics, in particular, method of remuneration and patient volume, were explored.

METHODS

The authors evaluated all 153,047 antibiotic prescriptions generated by 476 Newfoundland general practitioners and paid for by the Newfoundland Drug Plan over the 1-year period ending Aug. 31 1996, and calculated rates of antibiotic prescription. Linear and logistic regression models controlling for several physician characteristics, specifically age, place of education (Canada or elsewhere), location of practice (urban or rural) and proportion of elderly patients seen, were used to analyse rates of antibiotic prescription.

RESULTS

Fee-for-service payment (rather than salary) and greater volume of patients were strongly associated with higher antibiotic prescription rates. Fee-for-service physicians were much more likely than their salaried counterparts to prescribe at rates above the median value of 1.51 antibiotic prescriptions per unique patient per year. The association between rate of antibiotic prescription and patient volume (as measured by number of unique patients prescribed to) was evident for all physicians. However, the association was much stronger for fee-for-service physicians. Physicians with higher patient volumes prescribed antibiotics at higher rates.

INTERPRETATION

In this study factors other than medical indication, in particular method of physician remuneration and patient volume, played a major role in determining antibiotic prescribing practices.

An intercomparison study of 237Np determination in artificial urine samples

An intercomparison study of low-level 237Np determination in artificial urine samples has been carried out. The purpose of this study was to find the "optimal" method presently available for use in a routine in-vitro radiobioassay program for occupationally exposed workers. Four synthetic urine samples with differing 237Np concentrations were prepared: (1) 3 mBq kg-1 of 237Np; (2) 3 mBq kg-1 of 237Np with natural uranium, 239Pu and 241Am as interferences; (3) 50 mBq kg-1 of 237Np; and (4) a matrix blank. The solutions were submitted to 10 alpha-particle and 10 inductively coupled plasma-mass spectrometry (ICP-MS) laboratories of which six and four laboratories, respectively, returned results. Two laboratories performed assays using both techniques. The radiochemical method of choice used 239Np as the tracer, which utilized a combination of coprecipitation and anion-exchange separation. The best results obtained by ICP-MS were comparable with but not better than the most accurate results obtained by alpha-particle spectrometry. Alpha-particle spectrometry measurements overall gave consistently better agreement with known values.

Congenital hypothyroidism missed on screening

Three patients with congenital hypothyroidism missed on routine screening due to normal low thyrotrophin concentrations in the neonatal period presented in later childhood. Clinicians should remain aware of hypothyroidism as a cause of morbidity in early childhood despite a national screening programme.

The influence of the onset of phonation on the frequency of disfluency among children who stutter

This study was designed to assess the effects of on-off voice adjustments on the frequency of stuttering in children. Essentially, this is a replication of the experimental paradigm used by Adams and Reis (1971, 1974) with adult stutterers who were asked to read two passages: one contained a normal distribution of voiced and voiceless sounds; the other contained nearly all voiced sounds. The latter passage was associated with less stuttering and more rapid adaptation. In this study, 15 childhood stutterers in the third through the seventh grades were asked to read these same two passages. Contrary to the previous results with adults, however, the children did not stutter less nor adapt more rapidly with the all-voiced passage. These results are discussed with reference to previous literature and to the influence of pausing.

Verbal transformation patterns in children with articulation defects

If the motor theory of speech perception is at least partially true, children with articulation problems should do relatively poorly in a typical verbal transformation task. Twelve children aged from 6 yrs 10 mo to 8 years 10 mo with misarticulation of /s/ were compared with 12 matched children with normal speech. Since children with articulation errors have difficulty processing time-compressed speech, the two groups were differentiated also on the basis of a speech discrimination task involving time-compressed stimuli. All Ss listened to three 1-min presentations of the nonsense word /sus/ played repeatedly with a 400-msec interstimulus interval; they pressed one of 4 buttons for each stimulus indicating perception of /sus/, /theta us/, /fus/, and "other." There were fewer transformations for the experimental group and different response profiles for the two groups, suggesting a less mature perception-production linkage in those with articulatory problems.

Acoustic and perceptual evaluation of hypernasality of mentally retarded persons

Acoustic and perceptual correlates of velopharyngeal competency in two groups of retarded (one Down syndrome, one idiopathic) and one group of nonretarded subjects, equally divided between males and females, was evaluated. There were 20 young adults in each group. Acoustic measures of hypernasality were obtained through analysis by TONAR II. Perceptual judgments were rendered by 15 listeners. Results of perceptual and acoustic analyses revealed that those persons with Down syndrome were significantly more hypernasal than were the other two groups. Those with idiopathic retardation were more hypernasal than were nonretarded subjects.

Learning visual correlates of fricative production by normal-hearing subjects: a preliminary evaluation of the video articulator

This investigation provides a preliminary evaluation of the use of the video articulator, a phonemic recognition device for the hearing impaired. The subjects were five young adults with normal hearing and vision (corrected) who were matched with respect to age, sex, dialect, education, and phonological sophistication. Each subject received 150 min of programmed training to learn the video configurations of the eight English fricatives both in isolation and consonant-vowel contexts. Following the training period, the subjects were given a test to determine adequacy of learning and retention of the video configurations for the training stimuli, in the absence of auditory cues. The subjects' responses were analyzed using a common covariance measure. The results demonstrated generally low transmission values for consonants in isolation. Moreover, identification of consonants in context was less accurate. The subjects, as a group, had greater difficulty in recognizing the productions of other subjects when compared with recognition of their own utterances. The clinical implications of these findings are discussed.

Continuous measurement of arterial oxygen tension during one-lung anaesthesia. A new type of polarograhic oxygen electrode

A new type of intra-arterial oxygen electrode was evaluated. In 14 patients, undergoing one-lung ventilation for thoracic surgery, the electrode was inserted into the radial artery and changes in PaO2 were recorded continuously. Methods of improving PaO2 during one-lung ventilation were demonstrated.