Modified PATIO technique for urethrocutaneous fistula after hypospadias repair: Experience from a tertiary referral hospital

INTRODUCTION

Urethrocutaneous fistula (UCF) is a common complication after hypospadias repair with an incidence of 5-10%. Several techniques are described for its repair: small UCFs are frequently corrected by isolation, excision, and closure with apposition of a protective second layer. In 2008 Malone described the PATIO technique: the fistula tract is turned inside out in the urethral lumen preventing contact with passing urine without direct urethral sutures.

OBJECTIVE

Aim of our study is to present our outcomes using a modified version of the PATIO technique, with a more reproducible isolation of the tract and without its fixation at the urethral meatus.

STUDY DESIGN

We retrospectively reviewed all cases of UCFs corrected with a modified PATIO technique at our center between 2016 and 2020. Data collected from electronical clinical notes were age at UCF closure, location of UCF, presence of meatal stenosis and clinical outcomes. Data are presented as median and IQR.

RESULTS

In the study period we performed 425 urethroplasties for distal and mid penile hypospadias. The incidence of UCFs was 7% (30/425) and 25 patients underwent UCF correction with modified PATIO. Median age at repair was 4.5 years (IQR: 2.5-6.2). At a median follow-up of 3 years (IQR: 2-4) recurrence was observed in 5 cases out of 24 with one patient who was lost at follow-up (20.8%). One case was corrected successfully with re-do modified PATIO technique, while 4 are awaiting repair. One cases was lost at follow-up. UFC-recurrence was homogeneously distributed along the study period.

DISCUSSION

Risk factors for UCF recurrence are mostly the type of hypospadias, neo-urethral length, and quality of the urethral plate. Among the many existing techniques, we propose a modified version of Malone's PATIO repair. We believe that the use of four stay-suture to isolate the fistula allows a well-defined dissection of the tract along its surface, compared to the use of a single stay-suture. In our experience, there is no need to keep and fix the traction on the fistula tract to the urethral meatus, probably reflecting the efficacy of the fistula closure during the introflection, which is then maintained without traction. Limitations to our study include the retrospective nature of the review, the small sample size of the cohort and the absence of control groups.

CONCLUSIONS

Our results appear consistent with literature regarding the efficacy of PATIO principles in treating UCF. Modified PATIO seem to be particularly reproducible, showing encouraging results.

A Structured Training for Trans Anal Irrigation in Pediatric Patients Improves Outcomes and Reduce Failures: Results of an Interventional Multicenter Prospective Study

BACKGROUND

Continence issues due to organic causes including previous colorectal surgery or neurological issues might benefit from Transanal irrigation (TAI) that proved to be highly effective but with a number of limitations including a relatively high discontinuation rates. Our study was aimed at evaluating the efficacy of an advanced protocol tailored to each patient to prevent dropout and increase satisfaction, independence, and quality of life.

MATERIALS AND METHODS

This was a prospective, interventional, multicenter, nonrandomized study involving children aged 4-18 years with bowel dysfunction unresponsive to conventional treatments who required TAI. TAI was performed in accordance to the best standards of care with a total irrigation volume that was determined based on low emission X-Ray barium enemas performed at the very beginning of the study. All patients underwent training and assessments of continence, patients' perspectives and quality of life were performed at different timepoints from enrollment (T0) up to 6 months since TAI was introduced (T3).

RESULTS

A total of 78 patients were enrolled. Male to female ratio was 1.4:1. Mean age at enrollment was 106.1 ± 42.8 months. Discontinuation was reported by 3 patients (3.8 %). Continence, satisfaction and a number of other outcome measures increased from baseline (T0) to the last visit (T3). In particular, mean Rintala total score increased linearly from 7.8 to 14.8 during the study period (T0 to T3 timepoints). On a multivariate analysis, the only parameter that proved to be inversely associated with continence as well as with other outcome measures was the use of laxatives at enrollment and during the study.

CONCLUSIONS

This study has demonstrated the high efficacy of this innovative patient-tailored TAI protocol across all assessed scores. Of note, given the negative impact of laxatives, our findings suggest limiting their use in this patient population to further increase the efficacy of the procedure.

Investigation of monoclonal antibody dimers in a final formulated drug by separation techniques coupled to native mass spectrometry

Therapeutic monoclonal antibodies (mAbs) are highly complex proteins that must be exhaustively characterized according to the regulatory authorities' recommendations. MAbs display micro-heterogeneity mainly due to their post-translational modifications, but also to their susceptibility to chemical and physical degradations. Among these degradations, aggregation is quite frequent, initiated by protein denaturation and then dimer formation. Here, we investigated the nature and structure of the high molecular weight species (HMW) present at less than 1% in an unstressed formulated roledumab biopharmaceutical, as a model of high purity mAb. HMW species were first purified through preparative size-exclusion chromatography (SEC) and then analyzed by a combination of chromatographic methods (ion-exchange chromatography (IEX), SEC) coupled to native mass spectrometry (MS), as well as sodium dodecyl sulfate–polyacrylamide gel electrophoresis and capillary gel electrophoresis under non-reducing conditions. Both covalently and non-covalently bound dimers were identified at a proportion of 50/50. In-depth characterization of the HMW fraction by SEC and IEX hyphenated to native MS revealed the presence of three mAb dimer forms having the same mass, but differing by their charge and size. They were attributed to different compact and elongated dimers. Finally, high-resolution middle-up approaches using different enzymes (IdeS and IgdE) were performed to determine the mAb domains implicated in the dimerization. Our results revealed that the roledumab dimers were associated mainly by a single Fab-to-Fab arm-bound association.

Check cystoscopy in the management of anterior urethral valves in a cohort of pediatric patients

INTRODUCTION

Anterior urethral valves (AUV) are a rare cause of lower urinary tract obstruction which could progress to renal damage, Clinical presentation varies according with patient's age and severity of obstruction, but, in most cases, diagnosis is based on voiding cysto-urethrogram (VCUG). To date, the treatment of choice is endoscopic ablation even if approved guidelines about the overall management of AUVs, including the recognition and treatment of residual valves, are not available.

OBJECTIVE

We describe our protocol for AUV treatment based on primary endoscopic valve ablation followed by check cystoscopy 15 days later.

STUDY DESIGN

Medical records of 5 patients with AUVs admitted from 2008 to 2018 to our Pediatric Urology Unit were retrospectively reviewed. Blood tests, urinalysis, renal US and VCUG were performed in all children, while urodynamic evaluation was performed in the 3/5 patients who could void spontaneously. All patients underwent endoscopic valves ablation and after 15 days after a second look cystoscopy was performed. Follow up was based on clinical and radiological evaluation with US, urinalysis and blood tests. Postoperative non-invasive urodynamic studies were performed in the 3/5 patient toilet-trained patients and VCUG was performed in 1/5 patient.

RESULTS

and Discussion: At primary endoscopic ablation cystoscopy revealed AUVs in the penile urethra in three patients, in the penoscrotal urethra in one case, in the bulbar urethra in another case. In 3/5 patients check cystoscopy found residual valves and a second endoscopic ablation was performed. All patients achieved symptoms release and improved urodynamic parameters. No intra or post-operative complication were reported. The assessment of residual valves is variable in literature and it is usually described for posterior urethral valves (PUVs). Few series report the use of VCUG within the first week after valve ablation, our experience instead suggests that performing a second look cystoscopy, is very effective to evaluate the presence of residual AUVs and eventually proceed with further ablation.

CONCLUSION

Endoscopic ablation is the gold standard treatment for AUV, but residual valves management is not clearly defined. According to our experience, a check cystoscopy 15 days after primary ablation allows to identify and treat possible residual valves showing good results in terms of safety and efficacy.

Exclusive Neurogenic Bladder and Fecal Incontinency in an Achondroplasic Child Successfully Treated with Lumbar Foraminal Decompression

INTRODUCTION

Achondroplasia is a genetic disorder characterized by defects in the development of endochondral bone resulting in skeletal abnormalities like stenosis of the foramen magnum and of the spine, shortened limb bones, and macrocephaly. Congenital spinal stenosis is frequent and due to premature fusion of the pedicles to the laminae.

CASE PRESENTATION

We report a case of neurogenic bladder and fecal incontinence due to lumbar stenosis successfully treated with L1-L5 partial laminectomy and foraminotomy in a 7-year-old achondroplasic child.

DISCUSSION/CONCLUSION

To our knowledge, this is the first case report of exclusive neurogenic bladder and fecal incontinence in an achondroplasic child. Neurogenic bladder and fecal incontinence without motor impairment may be early and exclusive clinical findings of lumbar stenosis in children with achondroplasia.

Venous thromboembolism in critically ill patients affected by ARDS related to COVID-19 in Northern-West Italy

OBJECTIVE

Coronavirus disease 2019 (COVID-19) is an emerging infectious disease that was first reported in Wuhan, China, and has subsequently spread worldwide. An association between increased venous thromboembolism in patients with pneumonia-related to COVID-19 has not yet been well described.

PATIENTS AND METHODS

We aimed to illustrate cases of pulmonary thromboembolism in patients with acute respiratory distress syndrome related to COVID-19 treated in our intensive care unit. The medical records of patients affected by COVID-19 with acute respiratory distress syndrome in our institute from 1/3/2020 to 31/3/2020 were retrospectively reviewed.

RESULTS

Our center registered a high prevalence of thromboembolic events among 62 patients affected by acute respiratory distress syndrome related to COVID-19 despite a regular antithrombotic prophylaxis. Out of these, 32 patients were transferred to other hospitals, and 30 were treated in our center. Venous thromboembolism was registered in 12 (19.3%) cases. In particular, 11 diagnoses of pulmonary embolism and 1 diagnosis of deep vein thrombosis were formulated. We described a case series of venous thromboembolism in nine patients treated in our Intensive Care Unit (ICU). Main pulmonary arteries were always involved in these patients. None of them died.

CONCLUSIONS

In conclusion, critically ill patients with ARDS related to COVID-19 may have an increased risk of VTE that could be a leading cause of mortality. These patients require a high index of clinical suspicion and an accurate diagnostic approach, in order to immediately start an appropriate anticoagulant treatment.

Quantification of aflatoxin M1 carry-over rate from feed to soft cheese

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The levels of AFM₁ in milk produced in Argentina are relatively low.

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Milk production, fiber particle size and AFB₁ level affected the carry-over rate.

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The greatest proportion of AFM₁ in milk is detected in whey during cheese. production.

From January to December 2016, samples of milk and feeds of dairy cattle were monthly collected. The concentration of mycotoxins in all matrices was determined using the enzymatic immunoassay technique. The average concentration of aflatoxin B₁ (AFB₁), deoxynivalenol (DON) and zearalenone (ZEA) in feed was 3.01, 218.5 and 467 ug/kg, respectively. The average AFB₁ carry-over rate was 0.84% with a variation between 0.05 to 5.93%. Particle size of the feed (P = 0.030) and individual milk production (P = 0.001) affected this rate. Mini-soft cheeses were produced using milk naturally contaminated with aflatoxin M₁ (AFM₁) as raw material to study its distribution both in whey and in cheese. The average level of AFM₁ in milk was 0.014 μg/l. None of milk samples exceeded the maximum level accepted for AFB₁ by the Southern Common Market (MERCOSUR) legislation (0.5 μg/l) and only 5.5% of samples exceeded the European Union (UE) regulations (0.05 μg/l). After the cheese elaboration, the concentration of AFM₁ was determined in whey and in cheese. The greatest proportion (60%) was detected in whey while 40% AFM₁ remained in the cheese. However, the concentration of AFM₁ was higher in the cheese compared to the original milk.

Proximal hypospadias repair with bladder mucosal graft: Our 10 years experience

INTRODUCTION AND OBJECTIVE

A great variety of different surgical techniques has been described for proximal hypospadias repair and an ideal tissue has not been determined yet. We present our 10 years of surgical experience using a bladder mucosal graft for urethroplasty.

STUDY DESIGN

Bladder mucosal graft urethroplasty was performed between 2005 and 2015 in 50 patients with severe proximal hypospadias. The mean age of patients was 45.1 months (range 24-164 months). Hypospadias were perineal in 18 patients, scrotal in 22, and penoscrotal in 10. In all cases a chordee correction was performed and median time between the first and the second stages was 12 months (mean 17 months, range 4-68 months). Both foley catheter and a suprapubic cystostomy were positioned and maintained for 2-4 weeks. Follow-up was performed at 1-3 and 6-12 months after surgery, and afterwards annually with clinical examination and flowmetry test.

RESULTS

Mean follow-up was 5.3 years (median 5, range 1-10 years). Mean graft length was 57.4 mm (median 55 mm, range 35-85 mm). Among all the only early complication registered was a postoperative infection in one patient (2%) at the site of anastomosis. The long-term complications observed were urethrocutaneous fistula in nine patients (18%), urethral stricture in 15 patients (30%), meatal stricture in four patients (8%), and prolapse of meatus in seven patients (14%). The mean time of complication occurrence was 15 months (median 15.5 months, range 1-96 months). The functional and cosmetic appearance after surgery was satisfactory in 42/50 patients (84%) during the follow-up period.

DISCUSSION

There is still an open debate regarding the optimal surgical approach for management of severe proximal hypospadias. Compared with other approaches, our technique showed acceptable results even though encumbered by slightly higher complication rates.

CONCLUSION

Our results show that bladder mucosal graft for primary severe proximal hypospadias in selected patients is a possible alternative to other commonly used techniques, with the aim of restoring recovery of the normal continuity of the distal urinary tract see figure below.

β-Hairpin mimics containing a piperidine-pyrrolidine scaffold modulate the β-amyloid aggregation process preserving the monomer species

Alzheimer's disease is a neurodegenerative disorder linked to oligomerization and fibrillization of amyloid β peptides, with Aβ_1-42 being the most aggregative and neurotoxic one. We report herein the synthesis and conformational analysis of Aβ_1-42-amyloid related β-hairpin peptidomimetics, built on a piperidine-pyrrolidine semi rigid β-turn inducer and bearing two small recognition peptide sequences, designed on oligomeric and fibril structures of Aβ_1-42. According to these peptide sequences, a stable β-hairpin or a dynamic equilibrium between two possible architectures was observed. These original constructs are able to greatly delay the kinetics of Aβ_1-42 aggregation process as demonstrated by thioflavin-T fluorescence, and transmission electron microscopy. Capillary electrophoresis indicates their ability to preserve the monomer species, inhibiting the formation of toxic oligomers. Furthermore, compounds protect against toxic effects of Aβ on neuroblastoma cells even at substoichiometric concentrations. This study is the first example of acyclic small β-hairpin mimics possessing such a highly efficient anti-aggregation activity. The protective effect is more pronounced than that observed with molecules which have undergone clinical trials. The structural elements made in this study provide valuable insights in the understanding of the aggregation process and insights to explore the design of novel acyclic β-hairpin targeting other types of amyloid-forming proteins.

Vaccination: Developing and implementing a competency-based-curriculum at the Medical Faculty of LMU Munich

BACKGROUND

In Germany medical students should gain proficiency and specific skills in the vaccination field. Especially important is the efficient communication of scientific results about vaccinations to the community, in order to give professional counseling with a complete overview about therapeutic options. AIM OF THE PROJECT: The aim of this project is to set up a vaccination-related curriculum in the Medical Faculty at the Ludwig-Maximilians-University in Munich. The structure of the curriculum is based on the National catalogue for competency-based learning objectives in the field of vaccination (Nationaler Kompetenzbasierter Lernzielekatalog Medizin NKLM). Through this curriculum, the students will not only acquire the classical educational skills concerning vaccination in theory and practice, but they will also learn how to become independent in the decision-making process and counseling. Moreover, the students will become aware of consequences of action related to this specific topic.

METHODS

According to defined guidelines, an analysis was performed on courses, which are currently offered by the university. A separate analysis of the NKLM was carried out. Both analyses identified the active courses related to the topic of vaccination as well as the NKLM learning objectives. The match between the topics taught in current courses and the NKLM learning objectives identified gaps concerning the teaching of specific content. Courses were modified in order to implement the missing NKLM learning objectives.

RESULTS

These analyses identified 24 vaccination-related courses, which are currently taught at the University. Meanwhile, 35 learning objectives on vaccination were identified in the NKLM catalogue. Four of which were identified as not yet part of the teaching program. In summary, this interdisciplinary work enabled the development of a new vaccination-related curriculum, including 35 learning objectives, which are now implemented in regular teaching courses by the Medical Faculty.

CONCLUSIONS

This project successfully describes a method to develop and implement a competency-based teaching program on the topic of vaccination. Importantly, the process presented here can serve as a guide to develop and implement similar teaching programs on other subjects and Universities.

Amenorrhea after Endoscopic Third Ventriculostomy for a Failed Shunt in Spina Bifida: Case Report and Review of the Literature

BACKGROUND

Secondary endoscopic third ventriculostomy (ETV) for the management of shunt failure may be efficacious, though it may be followed by more frequent complications (including endocrinological impairment, e.g., amenorrhea) compared to primary ETV. These complications are usually underreported in the literature.

AIM

We report a case of secondary amenorrhea after ETV for the management of shunt failure in a young woman with hydrocephalus associated with myelomeningocele.

METHODS

A 25-year-old woman affected by hydrocephalus and myelomeningocele was admitted for secondary ETV for the management of shunt failure. The endoscopic procedure was preferred over shunt revision based on good results of secondary ETV, especially in patients with hydrocephalus associated with Chiari II malformation and spina bifida.

RESULTS

Despite the surgery being uneventful, the patient had early (postoperative seizure) and late (secondary amenorrhea) complications. In the early postoperative period, she received external ventricular drainage followed by VP shunt reimplantation 2 weeks later. There was no neurological morbidity, but 1 month after the ETV she reported secondary amenorrhea and weight gain. Laboratory investigations ruled out hyperprolactinemia, which had been treated with cabergoline administration with no efficacy since the patient was still without regular periods 1 year later.

CONCLUSION

ETV may be followed by endocrinological complications like amenorrhea that are rarely reported.

Melatonin reduces the need for sedation in ICU patients: a randomized controlled trial

BACKGROUND

Critically ill patients suffer from physiological sleep deprivation and have reduced blood melatonin levels. This study was designed to determine whether nocturnal melatonin supplementation would reduce the need for sedation in patients with critical illness.

METHODS

A single-center, double-blind randomized placebo-controlled trial was carried out from July 2007 to December 2009, in a mixed medical-surgical Intensive Care Unit of a University hospital, without any form of external funding. Of 1158 patients admitted to ICU and treated with conscious enteral sedation, 82 critically-ill with mechanical ventilation >48 hours and Simplified Acute Physiology Score II>32 points were randomized 1:1 to receive, at eight p.m. and midnight, melatonin (3+3mg) or placebo, from the third ICU day until ICU discharge. Primary outcome was total amount of enteral hydroxyzine administered.

RESULTS

Melatonin treated patients received lower amount of enteral hydroxyzine. Other neurological indicators (amount of some neuroactive drugs, pain, agitation, anxiety, sleep observed by nurses, need for restraints, need for extra sedation, nurse evaluation of sedation adequacy) seemed improved, with reduced cost for neuroactive drugs. Post-traumatic stress disorder prevalence did not differ between groups, nor did ICU or hospital mortality. Study limitations include the differences between groups before intervention, the small sample size, and the single-center observation.

CONCLUSION

Long-term enteral melatonin supplementation may result in a decreased need for sedation, with improved neurological indicators and cost reduction. Further multicenter evaluations are required to confirm these results with different sedation protocols.

A chemically-modified inactive antithrombin as a potent antagonist of fondaparinux and heparin anticoagulant activity

BACKGROUND

Heparin and its analogs, mediating their anticoagulant activity through antithrombin (AT) activation, remain largely used for the preventive and curative treatment of thrombosis. The major adverse reaction of these drugs is the bleeding risk associated with overdose. Unfractionnated heparin (UFH) can be efficiently and rapidly neutralized by protamine sulfate, but this reversal partially neutralizes low-molecular-weight heparin (LMWH) and is inefficient in reversing fondaparinux. To secure administration of AT-mediated anticoagulants and counteract bleeding disorders, we previously designed a recombinant inactive AT as an antidote to heparin derivatives.

OBJECTIVES

To get around the limited production level of recombinant AT, we propose in this study an alternative strategy to produce a chemically modified inactive AT, exhibiting increased heparin affinity, as an antagonist of heparin analogs.

METHODS

Plasma-derived AT was chemically modified with 2,3 butanedione, a diketone known to specifically react with the arginine side chain. The chemical reaction was conducted in the presence of heparin to preserve basic residues within the heparin binding site from modifications.

RESULTS

AT treated by butanedione and selected for its high heparin affinity (AT-BD) was indeed modified on reactive Arg393 and thus exhibited decreased anticoagulant activity and increased heparin affinity. AT-BD was able to neutralize anticoagulant activity of heparin derivatives in vitro and in vivo and was devoid of intrinsic anticoagulant activity, as assessed by activated partial thromboplastin time assay.

CONCLUSIONS

AT-BD appears to be as efficient as protamine to neutralize UFH in vivo but could be more largely used because it also reverses fondaparinux and LMWH.

A new cell culture-based assay quantifies vitamin K 2,3-epoxide reductase complex subunit 1 function and reveals warfarin resistance phenotypes not shown by the dithiothreitol-driven VKOR assay

BACKGROUND

Warfarin directly inhibits the vitamin K 2,3-epoxide reductase complex subunit 1 (VKORC1) enzyme to effect anticoagulation. VKORC1 function has historically been assessed in vitro using a dithiothreitol (DTT)-driven vitamin K 2,3-epoxide reductase (VKOR) assay. Warfarin inhibits wild-type VKORC1 function by the DTT-VKOR assay. However, VKORC1 variants with warfarin resistance-associated missense mutations often show low VKOR activities and warfarin sensitivity instead of resistance.

OBJECTIVES

A cell culture-based, indirect VKOR assay was developed and characterized that accurately reports warfarin sensitivity or resistance for wild-type and variant VKORC1 proteins.

METHODS

Human coagulation factor (F)IX and VKORC1 variants were coexpressed in HEK 293T cells under standardized conditions at various warfarin concentrations. Secreted FIX activity served as surrogate marker to report wild-type and variant VKORC1 inhibition by warfarin.

RESULTS AND CONCLUSIONS

Warfarin dose-response curves fit to the secreted FIX activity data for coexpressed hVKORC1 wild-type, Val29Leu, Val45Ala and Leu128Arg variants. The corresponding calculated IC50 values were 24.7, 136.4, 152.0 and 1226.4 nm, respectively. Basal activities in the absence of warfarin for all VKORC1 variants were similar to that of wild-type VKORC1. Ranked IC50 values from the cell culture-based assay accurately reflect elevated warfarin dosages for patients with VKORC1 missense mutation-associated warfarin resistance.

Sleep and delirium in the intensive care unit

Intensive Care Unit (ICU) patients almost uniformly suffer from sleep disruption. Even though the role of sleep disturbances is not still adequately understood, they may be related to metabolic, immune, neurological and respiratory dysfunction and could worsen the quality of life after discharge. A harsh ICU environment, underlying disease, mechanical ventilation, pain and drugs are the main reasons that underlie sleep disruption in the critically ill. Polysomnography is the gold standard in evaluating sleep, but it is not feasible in clinical practice; therefore, other objective (bispectral index score [BIS] and actigraphy) and subjective (nurse and patient assessment) methods have been proposed, but their adequacy in ICU patients is not clear. Frequent evaluation of neurological status with validated tools is necessary to avoid excessive or prolonged sedation in order to better titrate patient-focused therapy. Hypnotic agents like benzodiazepines can increase total sleep time, but they alter the physiological progression of sleep phases, and decrease the time spent in the most restorative phases compared to the phases normally mediated by melatonin; melatonin production is decreased in critically ill patients, and as such, exogenous melatonin supplementation may improve sleep quality. Sleep disruption and the development of delirium are frequently related, both because of sleep scarcity and inappropriate dosing with sedatives. Delirium is strongly related to increased ICU morbidity and mortality, thus the resolution of sleep disruption could significantly contribute to improved ICU outcomes. An early evaluation of delirium is strongly recommended because of the potential to resolve the underlying causes or to begin an appropriate therapy. Further studies are needed on the effects of strategies to promote sleep and on the evaluation of better sleep in clinical outcomes, particularly on the development of delirium.

Chromatographic behaviour of peptides on a mixed-mode stationary phase with an embedded charged group by capillary electrochromatography and high-performance liquid chromatography

Retention behaviour of biological peptides was investigated on a stationary phase bearing an embedded quaternary ammonium group in a C21 alkyl chain by both high-performance liquid chromatography (HPLC) and capillary electrochromatography (CEC). In HPLC experiments, variation of acetonitrile (ACN) content in the mobile phase showed that peptides are mainly separated by RP mechanism. The weak or negative retention factors observed as compared to C18 silica stationary phase suggested the involvement of an electrostatic repulsion phenomenon in acidic conditions. Comparison of HPLC and CEC studies indicated that (i) ion-exclusion phenomenon is more pronounced in HPLC and (ii) higher ACN percentage in mobile phase induce for some peptides an increase of retention in CEC, pointing out the existence of mechanisms of retention other than partitioning mainly involved in chromatographic process. This comparative study demonstrated the critical role of electric field on peptide retention in CEC and supports the solvatation model of hydrolytic pillow proposed by Szumski and Buszewski for CEC using mixed mode stationary phase in CEC.

Effects of dipeptide administration on hypoglycaemic counterregulation in type 1 diabetes

OBJECTIVES

To investigate if a dipeptide made of glutamine and alanine is able to contribute to the recovery from insulin-induced hypoglycaemia in type 1 diabetes.

RESEARCH DESIGN AND METHODS

Fifteen adult type 1 patients were randomly assigned to study group (n=7): intravenous infusion of 20 g Dipeptiven in normal saline (i.e., 8 g alanine and 13 g glutamine), or control group (n=8): same infusion, normal saline only. A 150 min gradual hypoglycaemic hyperinsulinemic clamp was administered after 2 h of infusion. Counterregularory hormones, symptoms, and cognitive function (4 choice reaction test) were regularly measured during the study.

RESULTS

Blood glucose and glucose infusion rates were similar in the 2 groups. Circulating levels of alanine and glutamine peaked at 90 min and remained elevated throughout the test. This was associated with significant differences in: glucagonemia 107 +/- 20 vs 58 +/- 8 pg/ml, and neuroglycopenic symptoms scores: 7 +/- 3 vs 18 +/- 13, at t 150 min, in study and control group, p<0.05. Dysautonomic symptoms, cognitive tests as well as epinephrine, norepinephrine, cortisol and growth hormone were similar between groups.

CONCLUSION

Intravenous infusion of a dipeptide made of alanine and glutamine is capable to reactivate glucagon secretion during insulin-induced hypoglycaemia and to reduce hypoglycaemic symptoms.

Analysis of intact heparin by capillary electrophoresis using short end injection configuration

A capillary electrophoresis method for the analysis of intact heparin was developed using a phosphate buffer and a fused silica capillary. Operational parameters such as pH and concentration of the running buffer were investigated. The short end injection configuration permitted a gain on peak efficiency, on the analysis time and on the repeatability of both migration times and peak areas, through a reduction of the migration distance. Moreover, the beneficial effect of the presence of sodium chloride in the heparin sample on the peak efficiency was demonstrated and the influence of the salts on the conformation of the heparin was discussed. The optimized method (short end injection configuration, 50mM phosphate buffer pH 3, heparin sample prepared in 10 g/L NaCl solution) was validated in terms of linearity, reproducibility and specificity according to ICH requirements.

Routine o-glycan characterization in nutritional supplements--a comparison of analytical methods for the monitoring of the bovine kappa-casein macropeptide glycosylation

Analytical procedures, including capillary isoelectric focusing (CIEF), high-performance anion-exchange chromatography coupled to amperometric detection (HPAEC-PAD) and normal-phase chromatography with fluorescence detection are presented for the characterization of a highly O-glycosylated caseinomacropeptide (CGMP) and the detection of subtle glycosylation differences between CGMP Batches obtained with two different preparation procedures. Modified two-step CIEF allowed monitoring of glycopeptide heterogeneity and determination of the isoelectric points of acidic glycoforms. The mixture of wide and narrow pH range ampholytes was optimized to improve glycoform resolution. The pI of the different CGMP glycoforms was evaluated with pI internal standards and found to range between 3.08 and 3.58, which indicates a very acidic glycopeptide. Moreover, the monosaccharide composition was determined with HPAEC-PAD after neutral and amino sugars release by using adequate acidic hydrolysis of CGMP. Results indicated a similar composition for Batches I and II, but the monosaccharide percentages were 3-4 fold higher in Batch I, particularly for galactose and glucose. This likely reflects a higher content in lactose in the case of Batch I. Finally, O-linked oligosaccharides were released with an automated hydrazinolysis and derivatized with a sensitive labelling reagent, 2-aminobenzamide. The derivatives were then analyzed by normal-phase HPLC coupled with fluorescence detection, and separated on the basis of hydrophilic interaction, which allowed oligosaccharide mapping of the two CGMP. It appeared that the two CGMP preparations had an almost identical O-glycan population, but CGMP Batch I was more glycosylated than Batch II. Additionally, the sizes of the separated glycans, expressed as the number of glucose units, were tentatively assigned using calibration with a partial hydrolysate of dextran. In conclusion, a combination of electrophoretic and chromatographic techniques was found powerful in studying glycoprotein heterogeneity and assessing batch-to-batch consistency.

[Acquired partial lipodystrophy. Insulin resistance, hepatic lipase activity and small and dense LDL particles]

Partial lipodystrophy (PLD) is an infrequent condition characterized by symmetric loss of subcutaneous adipose tissue in the upper or lower part of the body, although occasionally it affects only the extremities. In all cases it appears along with acantosis nigricans (AN), insulin resistance and impairment in the metabolism of lipids and carbohydrates. The case depicted pertains to a 49 year old female with no family history involving loss of adipose tissue in face and upper body. No fat in lower part of body was observed. The patient showed facial thinning at age 8, AN at 11 and gestational diabetes during her fourth pregnancy at 33. At present, the patient presents severe hyperglycemia and hyperinsulinemia with a marked insulin resistance. Type IV hyperlipoproteinemia (OMS), declined C-HDL and Apo A1 and low C-LDL but with a high proportion of small and dense LDL particles were present. Non esterified fatty acids were high. Lipoprotein lipase and hepatic lipase activities are in the lower limit and increased respectively. Fraction C3 of the complement was diminished. No mutations were observed either in codons 170, 809 and 972 of the IRS-1 receptor or in codon 276 of the adrenergic beta 2 gene.

A sensitive mapping strategy for monitoring the reproducibility of glycan processing in an HIV vaccine, RGP-160, expressed in a mammalian cell line

The external envelope glycoprotein (gp160) of HIV-1 is a candidate for vaccines against AIDS. Most of the surface of the molecule is shielded by carbohydrate and the structures and locations of these glycans may be important in defining the immunogenicity of the viral coat. Here we report a sensitive mapping strategy for profiling and analysing the N-glycosylation of gp160, based on chemical release of glycans, fluorescent labelling and HPLC analysis. This approach has been validated in terms of establishing the reproducibility of all steps in the analytical procedure and on overall reproducibility on a run-to-run and day-to-day basis. The validated analysis technique was used to monitor the consistency of N-glycosylation of one rgp 160 vaccine candidate produced in baby hamster kidney (BHK) cell culture. It was demonstrated that the variation in the glycan profiles of 6 different lots was not statistically significant.

One-step capillary isoelectric focusing for the separation of the recombinant human immunodeficiency virus envelope glycoprotein glycoforms

One-step capillary isoelectric focusing was investigated as a rapid method to resolve the glycoforms of the heterogeneous recombinant human immunodeficiency virus (HIV) envelope glycoprotein (rgp 160sMN/LAI). The separation was performed in a poly(vinyl alcohol) (PVA) coated capillary using a mixture of ampholyte of narrow and wide pH range. A combination of saccaharose and 3-(cyclohexylamino)-1-propanesulfonic acid was shown to be the most efficient additive to avoid protein precipitation which occurs at a pH close to its pI. Although the calibration curve [isoelectric point (pI) vs. migration times] showed a non-linear relationship, an adequate linearity could be yielded for short pI ranges permitting to exhibit the acidic character of the different glycoforms of the rgp 160s MN/LAI (pI from 4.00 to 4.95). Reproducibility evaluated by comparing the performance of a polyacrylamide and a PVA coated capillary showed that low RSD values were obtained for intra-day (0.5 to 1.9%) and inter-day (1.6 to 7.6%) measurements using the PVA capillary. Moreover, the long term stability of the PVA capillary was demonstrated by measuring the variation of migration times of the protein markers for a long period of use. Finally, this method was able to differentiate the glycoform pattern of two close glycoproteins such as the rgp 160 of two sub-populations of the virus HIV-1.

A multi-mode chromatographic method for the comparison of the N-glycosylation of a recombinant HIV envelope glycoprotein (gp160s-MN/LAI) purified by two different processes

The glycosylation pattern of a recombinant gp160s-MN/LAI variant of human immunodeficiency virus type 1 (HIV-1) was studied in relation to two alternative purification techniques one of which involves an immunoprecipitation step. For analysis a multi-mode high performance liquid chromatography (HPLC) method which combines gel permeation chromatography on the RAAM 2000 GlycoSequencer, weak anion exchange chromatography and normal phase chromatography was developed and profiles were obtained for the fluorescently-labelled glycans released from the two gp160s-MN/LAI preparations. Charged glycans accounted for 77 and 80% of the total glycans for the IAP- and SP-purified samples, respectively. The acidic character of these glycans was mainly due to the presence of sialic acids. However, following sialidase treatment, residual charged glycans were still found. No differences were found in the glycan distributions of the two gp160s-MN/LAI preparations either in their degree of sialylation or in their relative proportion of each separated structure. Although this did not reach statistical significance, a lower proportion of large glycan structures regardless of their charge status was found on the gp160s-MN/LAI prepared by the procedure which involved an immunoaffinity chromatography step.

Investigation of micelles and anionic cyclodextrins as pseudostationary phases for the capillary electrophoresis separation of oligosaccharides derivatized with 2-amino-benzamide

Oligomers of glucose and oligosaccharides released from glycoproteins were derivatized with 2-aminobenzamide. As this fluorophore imparts no charge to the oligosaccharides, several strategies were investigated to achieve capillary electrophoresis (CE) separation of both neutral and charged derivatized glycans. Micellar electrokinetic capillary chromatography (MEKC) with the addition of anionic surfactants was evaluated as a first approach: sodium dodecyl sulfate (SDS) produced the best separation of the oligoglucose fragments, where the migration was inversely related to their degree of polymerization. To demonstrate the applicability of this method for complex carbohydrate analysis, oligosaccharide mixtures derived from ribonuclease B (RNase B) and alpha-acid glycoprotein (alpha-AGP) were analyzed. A satisfactory separation for the high-mannose structures found in RNase B could be obtained, whereas charged oligosaccharides from alpha-AGP were poorly resolved. Cyclodextrin-modified CE was chosen as the second approach: the effect of the addition of sulfobutylether-beta-cyclodextrin (SBE-beta-CD) or sulfobutylether-gamma-cyclodextrin (SBE-gamma-CD) on the electrophoretic mobilities and resolution of neutral and charged oligosaccharides was then studied. Selectivity of sialylated structures could be further improved by using anionic cyclodextrins (CDs) instead of micelles. However, this latter approach failed to baseline-resolve the different high-mannose structures of RNase B. A successful separation of the complex mixture of oligosaccharides from alphaalpha-AGP was obtained with the addition of 4% of SBE-gamma-CD and triethylamine (TEA) in a phosphate buffer, pH 6.7.

Electrophoretic methods for process monitoring and the quality assessment of recombinant glycoproteins

In many ways electrophoretic techniques appear ideal for quality monitoring of proteins and are thus well suited for the analysis of recombinant glycoproteins. The requirements of high throughput, comparative analysis and resolution of many variants are met by several electrophoretic techniques. A wide variety of such techniques are available to biotechnologists in the rapidly developing area of recombinant glycoproteins. It is the aim of this review to specifically cover recent work which has been applied to the analysis of DNA-derived glycoproteins, both from a process control standpoint and final product validation. All major areas of electrophoresis including sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), isoelectric focusing and techniques utilizing capillary electrophoresis are covered, with emphasis on analysis of glycoforms and oligosaccharide profiles of recombinant glycoproteins. As illustration, actual examples rather than standard glycoproteins are given to indicate the potential and limitations which may be encountered. It is anticipated that this review will prove a useful and practical guide to the latest developments by indicating the relevant merits of different methods.

Physicochemical characterization of different batches of ethylated beta-cyclodextrins

Different ethylated beta-cyclodextrin (Et-beta-CD) derivatives were obtained by various synthetic routes and their chemical structures and physical properties were elucidated. The aqueous solubility studies were carried out at 25 and 37 degrees C. A gas phase chromatography analysis, with head space extraction, was developed to detect the presence of residual solvents in the dry preparations. Electrospray ionization mass spectrometry allowed the determination of the average degree of substitution and the molecular mass of the Et-beta-CDs. Nuclear magnetic resonance analysis was used to elucidate the relationship between the solubility behavior and substituted positions of ethyl groups on the CD glucopyranose units. Finally, this paper deals with different physico-chemical methods used to fully characterize the different batches of Et-beta-CD to correlate the data obtained with the pharmacotechnical behavior of these cyclodextrins.

Capillary electrophoresis of glycosaminoglycan-derived disaccharides: application to stability studies of glycosaminoglycan chitosan complexes

Capillary zone electrophoresis (CZE) was used to separate the disaccharides produced by chondroitinase digestion of chondroitin sulfates. The main disaccharides formed upon depolymerization have identical charge and mass. Baseline resolution of these two compounds was achieved by selecting appropriate concentration and pH of a borate buffer. Validation of the method showed a good linearity of the response and a very satisfactory reproducibility of migration times with a relative standard deviation (RSD) of less than 0.4%. The reproducibility of peak areas was improved by using an internal standardization. The addition of cinnamic acid (internal standard) to the incubation medium allowed us to perform kinetic measurements of the depolymerization while keeping a baseline resolution of the two main disaccharides analyzed during the complete digestion course even when their concentration in the incubation medium increased. Application of this method to the comparison of the rate of hydrolysis of chondroitin sulfate and of a complex associating chondroitin sulfate with chitosan showed clearly that, at the physiological pH, chitosan protected the chondroitin sulfate from depolymerization. This phenomenon was more pronounced as the pH of the incubation medium was far from the optimum pH activity of the chondroitinase.

Contribution of capillary zone electrophoresis to the analysis of cecal mucins

The ability of capillary electrophoresis to perform the separation of mucin glycoforms has been investigated. Adsorption of mucins to the capillary was observed in most cases, leading to unreproducible results. This was due in part to the characteristic structure of mucin (highly charged, large size) and also to its poor solubility. Various buffers were therefore investigated; it was found that a zwitterionic electrolyte, such as a (3-[cyclohexylamino]-1-propanesulfonic acid) (CAPS) buffer, pH 8.8, greatly improved the separation. Using this buffer, mucin was resolved into five main fractions. The use of several additives, such as cationic molecules (1,4-diaminobutane [DAB]) or hydrophilic polymers (hydroxypropylmethylcellulose [HPMC], polyethylene glycol [PEG]) was also investigated. PEG and HPMC did not affect the separation and the electroosmotic flow (EOF) in the same manner. The favorable effect of the addition of PEG was clearly demonstrated and it was postulated that some interaction of this polymer with the mucins occurred. Finally, the application of the method to the comparison of glycoform patterns of mouse cecal mucins showed a marked difference for mucins derived from two sources: germ-free and gnotobiotic mice. These results indicate that mucins from gnotobiotic mice have been degraded due to the glycosidic activity of the bacterial strains present in these mice.

Interferon-beta can induce progesterone receptors in human endometrial adenocarcinoma

BACKGROUND

The induction of estrogen and progesterone receptors (ER and PGR) has been reported in breast and endometrial cancer cells exposed to human fibroblast interferon-beta (hIFN-beta). Clinical verification of this finding might provide the rationale for new therapeutic approaches. This study was designed to evaluate whether clinical treatment with high doses of hIFN-beta induced ER and PGR in patients with endometrial adenocarcinoma.

METHODS

Two biopsies were obtained, 1 before and 1 after hIFN-beta treatment (3 x 10(6) i.m. every other day for 3 weeks) from 36 patients with endometrial adenocarcinoma. ER and PGR were determined with standard procedures using radiolabeled ligands.

RESULTS

hIFN-beta treatment did not affect the proportion of ER-positive (i.e., >15 fmol/mg protein) or PGR-positive (i.e., >20 fmol/mg protein) cases. However, in patients with detectable ER and PGR at baseline, hIFN-beta raised the levels. Using a 35% difference before and after therapy as a cut-off, 72 and 79% of cases had increases in ER and PGR, respectively. The difference was highly significant for PGR.

CONCLUSIONS

In patients with endometrial adenocarcinoma with undetectable ER or PGR, hIFN-beta did not induce the expression of these receptors. When the receptors were present they were upregulated by hIFN-beta. Whether this increase in receptor levels, particularly PGR, has therapeutic applications remains to be established.

In vitro synergism between 5-fluorouracil and natural beta interferon in human colon carcinoma cells

The combination of 5-fluorouracil (FUra) plus IFN-beta was studied in vitro using a human colon carcinoma cell line, HCT-8. Continuous exposure to high concentrations of IFN-beta is cytotoxic to these cells (ED50, 600 +/- 50 IU/ml). A strong synergism (P < 0.002) was observed when a short-term (1-h), high-concentration exposure to fluoropyrimidine (300 or 1000 microM) was followed by IFN-beta given continuously. In fact, the mean ratio between the expected (product of the survival of each agent alone) and the observed clonogenic cell survival rates of the combination was 3.4 (range, 2.4-4.9). Longer exposures to the fluoropyrimidine (24 h, 7 days) produced less than additive effects with IFN-beta, indicating strong schedule dependency for this synergism. The mechanism of interaction was studied at four levels. First, thymidylate synthase (TS) activity, inhibition, and recovery were measured by an in situ assay in cells treated with FUra, IFN-beta, and their combination. When the prolonged infusion of IFN-beta followed a 1-h exposure to FUra, the observed TS inhibition and recovery, at each time point, were very similar to the expected values, indicating that the interactions between these drugs at the level of TS are not the determinant of the synergism. Second, cell cycle analysis was done. During the continuous exposure to IFN-beta, a significant accumulation of HCT-8 cells in S-phase was observed at 24, 48, and 72 h compared to untreated controls (P = 0.003); however, under the same experimental conditions producing synergy in the clonogenic assay, no significant cell cycle perturbations were produced by the combination of FUra followed by IFN-beta compared to those caused by each agent alone. Third, using the alkaline elution test, we also demonstrated that the synergism is not due to enhanced FUra-induced DNA single-strand break frequency in high molecular weight DNA. Finally, nucleic acid incorporation experiments, using tritiated FUra, showed that the cytokine, given continuously (300 IU/ml), enhanced the amount of FUra incorporated into nucleic acids 24 h after a 1-h exposure to 300 and 1000 microM of FUra. The median percentage of enhancement values were 31.6 +/- 11.5%,m for the lower drug concentration and 18. 4 +/- 8.1% for the higher drug concentration tested. These results suggest that the mechanism of this synergism may be related to the ability of IFN-beta to promote the incorporation of intracellular FUra metabolites into nucleic acids and/or to inhibit the cleavage of FUra nucleotides from RNA/DNA.

N-glycosylation site mapping of recombinant tissue plasminogen activator by micellar electrokinetic capillary chromatography

This report describes the N-glycosylation mapping of recombinant tissue plasminogen activator (rt-PA) using micellar electrokinetic capillary chromatography. The carbohydrate structures were tentatively assigned by comparison with the anion-exchange fractionated oligosaccharides and by a comparison with previously reported data. The separation was shown to rely mainly on the degree of sialylation of the oligosaccharides, allowing a quantitative determination of the proportion of neutral and mono- to tetrasialylated structures. Significant differences in the oligosaccharide distribution of the two variants of rt-PA, which differ by the presence (type I) or the absence (type II) of oligosaccharides at the Asn-184 site, were observed. The distribution of the oligosaccharides at each of the rt-PA glycosylation sites was then determined. Glycopeptides were prepared by tryptic digestion of rt-PA and isolated using two consecutive chromatographic procedures. The glycopeptides were finally treated with N-glycanase, and the resulting oligosaccharides were analysed by capillary electrophoresis. Oligosaccharide mapping revealed that the Asn-448 and Asn-184 sites carry the same population of complex-type oligosaccharides but that the relative amounts of each oligosaccharide vary markedly. High-pH anion-exchange chromatography performed on the desialylated oligosaccharides at each glycosylation site showed that the degree of microheterogeneity was related not only to the degree of sialylation but also to structural differences in the oligosaccharide sequences. From the results as a whole, we concluded that the Asn-448 site contains a greater proportion of heavily sialylated structures and has a higher degree of microheterogeneity.(ABSTRACT TRUNCATED AT 250 WORDS)

Capillary electrophoresis monitoring of the competitive adsorption of albumin onto the orosomucoid-coated polyisobutylcyanoacrylate nanoparticles

The simultaneous and rapid quantitation of a glycoprotein, human orosomucoid, and a protein, human serum albumin (HSA), by micellar electrokinetic capillary electrophoresis was developed and optimized (pH and sodium dodecyl sulfate concentration) in order to study the competitive adsorption of HSA onto orosomucoid-coated nanoparticles of polyisobutylcyanoacrylate. This method provided satisfactory repeatability and the response was linear for concentrations of orosomucoid and HSA ranging from 0.025 to 0.500 mg/mL (r > 0.994 for both proteins). To study the competitive adsorption of HSA, the amounts of free orosomucoid and free HSA were determined in the supernatant obtained after centrifugation of the orosomucoid-coated nanoparticle suspension incubated with HSA. Furthermore, the quantities of both orosomucoid and HSA absorbed onto nanoparticles were also determined after desorption of these molecules from the nanoparticle surface, using sodium dodecyl sulfate. No analytical interference was observed with this surfactant. The results showed that HSA did not at all absorb onto the orosomucoid-coated nanoparticles and, thus, that this protein did not displace the layer of absorbed orosomucoid from the nanoparticle surface.

Fosfomycin determination in serum by capillary zone electrophoresis with indirect ultraviolet detection

Capillary zone electrophoresis with indirect ultraviolet detection was used for the determination of fosfomycin in serum. Running buffer consisted of a mixture of 200 mM sodium borate with 10 mM phenylphosphonic acid used as ultraviolet absorbing background electrolyte. Relationships between the pH of the buffer and the efficiency of the separation (migration times and selectivities) or the sensitivity of detection were investigated. The method was then validated over a 10-100 micrograms ml-1 concentration range to be applied to further therapeutic drug monitoring. The choice of ethylphosphonic acid as internal standard is discussed. The specificity and the linearity of the technique are demonstrated. The inter-day precision was satisfactory with a relative standard deviation of less than 2%. Accuracy was calculated with a standard error near 0.5 and 18% for 100 and 10 micrograms ml-1, respectively.

Analysis of carbohydrate-mediated heterogeneity and characterization of N-linked oligosaccharides of glycoproteins by high performance capillary electrophoresis

Capillary zone electrophoresis (CZE) has been investigated as an alternative method to analyze the carbohydrate moieties of glycoproteins. Carbohydrate-mediated microheterogeneity of the recombinant plasminogen activator (rt-PA) was examined. The glycoprotein was resolved in multiple electrophoretic species using CZE but the separation was complicated by adsorption of the molecules to the wall of the capillary. The influence of several parameters, such as pH, molarity of the buffer and addition of a cationic additive, on the separation of glycopeptides was investigated. High resolution and reproducible separations of rt-PA glycopeptides carrying hybrid and complex type chains were obtained using either a 100 mM phosphate buffer, pH 6.6, or a 100 mM Tricine buffer, pH 8.2, containing 1.25 mM of putrescine. N-Oligosaccharides from fetuin, t-PA and alpha 1-acid glycoprotein were separated within 20 min on the basis of both their sialic acid content and their structure. The use of an oligosaccharide fingerprinting technique, such as the present one, could have many applications in biotechnology to assess, for example, the consistency of production of a glycoprotein or for analytical glycoprotein chemistry.