Monoclonal antibody to human high-molecular-weight kininogen recognizes its prekallikrein binding site and inhibits its coagulant activity

We developed a mouse monoclonal antibody (MoAb 115-21) to human high- molecular-weight kininogen (HK) that recognizes its prekallikrein binding site (residues 565 through 595 of HK). The corresponding synthesized 31-amino acid peptide (peptide IV) was recently shown to retain native HK's prekallikrein binding property. The same peptide bound factor XI also, although less avidly. Our MoAb recognizes purified HK, peptide IV, and the light chain moiety of HK (where the peptide IV resides), as shown by enzyme-linked immunosorbent assay (ELISA) and Western blotting experiments. The apparent dissociation constant for the HK and MoAb 115-21 interaction was 2.2 nmol/L. It does not recognize low-molecular-weight kininogen (LK) with which HK shares its heavy chain moiety or any antigens in human plasma congenitally deficient in kininogens. The binding of MoAb 115-21 to purified light chain of HK was competitively inhibited by peptide IV. In addition, the antibody inhibits HK-dependent clotting activity of normal human plasma and dextran sulfate-mediated activation of prekallikrein in plasma and retards cleavage of HK in normal plasma after contact activation with dextran sulfate. Also, purified Fab fragments of MoAb 115-21 inhibited the HK-dependent coagulant activity and dextran sulfate-mediated prekallikrein activation in normal plasma. Since the kd for HK-MoAb 115- 21 interaction is ten times lower than that of HK-prekallikrein, our data suggest that binding of MoAb 115-21 to HK's peptide IV site increases the free prekallikrein concentration in plasma and thus results in the decreased efficiency of factor XIIa-mediated activation of prekallikrein. Decreased levels of kallikrein thus formed may be responsible for the inhibition of HK-dependent clotting activity and the decrease in rate and extent of HK cleavage in normal plasma on contact activation with dextran sulfate. MoAb 115-21 may thus prove very useful, especially with its high affinity for HK, in further delineation of the role of HK and prekallikrein in contact activation and kinin-related human pathology.     

Translational development of splice-modifying antisense oligomers

Introduction: Antisense nucleic acid analogues can interact with pre-mRNA motifs and influence exon or splice site selection and thereby alter gene expression. Design of antisense molecules to target specific motifs can result in either exon exclusion or exon inclusion during splicing. Novel drugs exploiting the antisense concept are targeting rare, life-limiting diseases; however, the potential exists to treat a wide range of conditions by antisense-mediated splice intervention.

Areas covered: In this review, the authors discuss the clinical translation of novel molecular therapeutics to address the fatal neuromuscular disorders Duchenne muscular dystrophy and spinal muscular atrophy. The review also highlights difficulties posed by issues pertaining to restricted participant numbers, variable phenotype and disease progression, and the identification and validation of study endpoints.

Expert opinion: Translation of novel therapeutics for Duchenne muscular dystrophy and spinal muscular atrophy has been greatly advanced by multidisciplinary research, academic-industry partnerships and in particular, the engagement and support of the patient community. Sponsors, supporters and regulators are cooperating to deliver new drugs and identify and define meaningful outcome measures. Non-conventional and adaptive trial design could be particularly suited to clinical evaluation of novel therapeutics and strategies to treat serious, rare diseases that may be problematic to study using more conventional clinical trial structures.     

ultrasonic array scanning of the kidney

An ultrasonic scanning system has been devised, utilizing an array of six plane transducers, each used as a separate transmitter-receiver. The transducers were arranged in a concave assembly so that their beams intersected at a point equidistant from each face. The array was mounted in a water-bath on a three-dimensional racking mechanism, so that it could be moved through a raster at various heights in the tank. In a fixed sequence, each individual transducer was excited, and the received ultrasonic echo amplitude information from the focus was selected by means of an electronic gate. The cartesian coordinates of the position of the array were also determined. Both sets of information were sampled, digitized and punched on to paper tape. A switching sequence was arranged so that eight successive characters on the paper tape represented the six echo amplitude data and the two positional data corresponding to a single point in the tank. The array was moved so that a two-dimensional matrix of points was interrogated.Experiments were performed to test the operating characteristics of the apparatus and to determine appropriate methods of signal processing and for the display of the information. It was found that the alignment of the ultrasonic beams was satisfactory and the data acquisition system was linear over a dynamic range approaching 40 dB. The apparatus was used to scan a simple model of wires and an isolated porcine kidney. Improved aximuthal resolution was achieved by combining the six amplitude data for each point. The product of these data seemed to be more useful than the sum. Contour mapping of received echo amplitude gave a satisfactorily wide dynamic range display.Possible future developments of the system are discussed.     

Sudden infant death syndrome and diphtheria-tetanus-pertussis-poliomyelitis vaccination status

Summary— Because diphtheria, tetanus, pertussis and poliomyelitis vaccine is routinely given during the period of highest incidence of sudden infant death syndrome (SIDS), we carried out a retrospective case-control study to assess whether such vaccination increased the risk of SIDS. The vaccination status of 118 SIDS and 332 control children, matched for sex, date of birth and age of the victims at death, was compared: the victims of SIDS were not significantly more often vaccinated than control children, the odds ratio was estimated at 1.9 with a 95% confidence interval from 0.9 to 3.9. There was a statistical difference between vaccination status of SIDS cases and controls aged less than three months. Nine percent of SIDS cases under 3 months had been vaccinated whereas the matched controls had not. In our study DTCP vaccination was not a risk factor for SIDS; although more of the SIDS infants less than 3 months of age had been vaccinated. This result however, concerns only one subgroup of the population studied and needs to be confirmed with another study of only SIDS infants less than 3 months of age, because DTCP vaccination was not a risk factor for SIDS when considering the total sample of the study.     

Transfusion-related acute lung injury caused by an NB2 granulocyte- specific antibody in a patient with thrombotic thrombocytopenic purpura

HLA and granulocyte-specific antibodies have been implicated in the production of transfusion-related acute lung injury (TRALI). Reported here is a case that suggests that the patient's preexisting condition may play an important role in determining whether TRALI develops upon transfusion of blood products containing anti-white cell (WBC) antibodies. A 29-year-old woman with thrombotic thrombocytopenic purpura (TTP) underwent an uneventful 1.5-volume plasma exchange, which was followed by the transfusion of 2 red cell (RBC) units. At the end of the second RBC transfusion, the patient developed clinical signs and symptoms of noncardiogenic pulmonary edema. Serologic studies demonstrated that the serum from the second RBC donor had no HLA antibodies but did have a granulocyte-specific antibody (anti-NB2) that caused the agglutination of the recipient's granulocytes, which were NB2 positive. Serum from the donor of the first RBC unit and serum from the donors of units used in the exchange had no HLA or granulocyte-specific antibodies that reacted with the recipient's WBCs. Because the donor implicated in this reaction had a history of 21 blood donations, none of which had been associated with a transfusion reaction, we suggest that the patient's preexisting condition played a significant role in this episode of TRALI, owing to the granulocyte-specific antibody.     

Mycobacterial Infections After Renal Transplantation

Mycobacterial infections occurred in 11 of 633 (1.7 per cent)recipients of successful renal transplants. There were no casesof tuberculosis in patients receiving chemoprophylaxis, butamongst those who did not receive prophylaxis disease occurredin six of the 27 (22 per cent) high-risk patients. The majorcause of morbidity during treatment was renal allograft rejection,largely due to reduction in immunosuppressive drug therapy.     

Laparoscopic Right Hemicolectomy for Ileocolic Intussusception Secondary to Caecal Neoplasm

Intussusception in adults is a rare cause of abdominal pain. Unlike its paediatric counterpart, intussusception in adults is associated with obvious pathology. We describe a case of ileocolic intussusception extending to the splenic flexure. We were able to reduce the intussusception partially and pedicle was stapled carefully. The specimen was delivered through a small incision and right hemicolectomy was performed adhering to oncological principles. We recommend laparoscopic-assisted surgery is considered for adult intussusceptions.     

Use of the Internet by Patients Undergoing Elective Hernia Repair or Cholecystectomy

INTRODUCTION

Patient-directed information available on the internet is not always regulated; it may be confusing and sometimes just overwhelming. We aimed to establish the proportion of patients undergoing two common surgical procedures, who searched the internet for information about their operations and to assess the usefulness of the information they received.

PATIENTS AND METHODS

A total of 105 consecutive patients undergoing elective abdominal wall hernia repair (n = 54) or laparoscopic cholecystectomy (n = 51) in a single surgical firm were included in the study. Patients were counselled about their operation in pre-operative assessment clinics and standard trust information leaflets were provided without any mention of this study. Patients were then asked to complete a questionnaire on the morning of their operation.

RESULTS

All patients completed the questionnaire. Of the patients, 59% stated that they had access to the internet and 77% of these accessed the internet over 2 h a week. Of the patients with internet access, 31% used it to acquire additional information about their operations and 58% used internet search engines. Of the patients who searched the internet regarding their operations, 26% were confused and/or worried by the information they received.

CONCLUSIONS

A significant proportion of patients undergoing common surgical procedures used the internet and about one-third of them specifically sought information about their operation on the internet. Such information can cause worry and confusion in patients. Our study highlights the need for regulated, comprehensible, patient information on hospital websites to which patients should be directed.     

Acoustic monitoring (RFM) of total hip arthroplasty results of a cadaver study

Introduction

At present there are no reliable non-traumatic and non-invasive methods to analyse the healing process and loosening status after total hip replacement. Therefore early as well as late loosening of prosthesis and interface component problems are difficult to be found or diagnosed at any time.

Methods

In a cadaver study the potential application of Resonance Frequency Monitoring (RFM) will be evaluated as a non-invasive and non-traumatic method to monitor loosening and interface problems in hip replacement. In a 65 year old female cadaver different stability scenarios for a total hip replacement (shaft, head/modular head and cup, ESKA, Luebeck, Germany) are simulated in cemented and cement less prosthesis and then analysed with RFM. The types of stability vary from secure/press-fit to interface-shaft disruption.

Results

The RFM shows in cemented as well as cement less prosthesis significant intra-individual differences in the spectral measurements with a high dynamic (20 dB difference corresponding to the factor 100 (10000%)), regarding the simulated status of stability in the prosthesis system.

Conclusion

The results of the study demonstrate RFM as a highly sensitive non-invasive and non-traumatic method to support the application of RFM as a hip prosthesis monitoring procedure. The data obtained shows the possibility to use RFM for osteointegration surveillance and early detection of interface problems, but will require further evaluation in clinical and experimental studies.