Generation of human parallel chimeric antigen receptor (pCAR) T cells to achieve synergistic T cell co-stimulation

Dual co-stimulation may be harnessed using parallel chimeric antigen receptors (pCARs) in which two distinct co-stimulatory units are adjacently localized on the plasma membrane. This protocol summarizes construct design, human T cell isolation, retroviral transduction, tissue culture expansion, and preclinical testing of pCAR T cells, exemplified by receptors that co-target avb6 integrin and ErbB dimers.

For complete details on the use and execution of this protocol, please refer to Muliaditan et al. (2021).

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A protocol to enable robust generation of pCAR T cells

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Effective dual co-stimulation is provided by this platform

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Sustained and enhanced antitumor activity by pCAR T cells

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Detailed in vitro and in vivo evaluation of pCAR technology

Publisher’s note: Undertaking any experimental protocol requires adherence to local institutional guidelines for laboratory safety and ethics.

Engineering of chimeric natural killer cell receptors to develop precision adoptive immunotherapies for cancer

Natural killer (NK) cells are innate immune effectors which play a crucial role in recognizing and eliminating virally infected and cancerous cells. They effectively distinguish between healthy and distressed self through the integration of signals delivered by germline‐encoded activating and inhibitory cell surface receptors. The frequent up‐regulation of stress markers on genetically unstable cancer cells has prompted the development of novel immunotherapies that exploit such innate receptors. One prominent example entails the development of chimeric antigen receptors (CAR) that detect cell surface ligands bound by NK receptors, coupling this engagement to the delivery of tailored immune activating signals. Here, we review strategies to engineer CARs in which specificity is conferred by natural killer group 2D (NKG2D) or other NK receptor types. Multiple preclinical studies have demonstrated the remarkable ability of chimeric NK receptor‐targeted T cells and NK cells to effectively and specifically eliminate cancer cells and to reject established tumour burdens. Importantly, such systems act not only acutely but, in some cases, they also incite immunological memory. Moreover, CARs targeted with the NKG2D ligand binding domain have also been shown to disrupt the tumour microenvironment, through the targeting of suppressive T regulatory cells, myeloid‐derived suppressor cells and tumour vasculature. Collectively, these findings have led to the initiation of early‐phase clinical trials evaluating both autologous and allogeneic NKG2D‐targeted CAR T cells in the haematological and solid tumour settings.

CAR T-Cells Targeting the Integrin αvβ6 and Co-Expressing the Chemokine Receptor CXCR2 Demonstrate Enhanced Homing and Efficacy against Several Solid Malignancies

Despite the unprecedented clinical success of chimeric antigen receptors (CAR) T-cells against haematological malignancy, solid tumors impose a far greater challenge to success. Largely, this stems from an inadequate capacity of CAR T-cells that can traffic and maintain function within a hostile microenvironment. To enhance tumor-directed T-cell trafficking, we have engineered CAR T-cells to acquire heightened responsiveness to interleukin (IL)-8. Circulating IL-8 levels correlate with disease burden and prognosis in multiple solid tumors in which it exerts diverse pathological functions including angiogenesis, support of cancer stem cell survival, and recruitment of immunosuppressive myeloid cells. To harness tumor-derived IL-8 for therapeutic benefit, we have co-expressed either of its cognate receptors (CXCR1 or CXCR2) in CAR T-cells that target the tumor-associated αvβ6 integrin. We demonstrate here that CXCR2-expressing CAR T-cells migrate more efficiently towards IL-8 and towards tumor conditioned media that contains this cytokine. As a result, these CAR T-cells elicit superior anti-tumor activity against established αvβ6-expressing ovarian or pancreatic tumor xenografts, with a more favorable toxicity profile. These data support the further engineering of CAR T-cells to acquire responsiveness to cancer-derived chemokines in order to improve their therapeutic activity against solid tumors.

The role of the interleukin (IL)-6/IL-6 receptor axis in cancer

Interleukin-6 (IL-6) is a pleiotropic cytokine that activates a classic signalling pathway upon binding to its membrane-bound receptor (IL-6R). Alternatively, IL-6 may 'trans-signal' in a manner that is facilitated by its binding to a soluble derivative of the IL-6 receptor (sIL-6R). Resultant signal transduction is, respectively, driven by the association of IL-6/IL-6R or IL-6/sIL-6R complex with the membrane-associated signal transducer, gp130 (Glycoprotein 130). Distinct JAK (Janus tyrosine kinase)/STAT (signal transducers and activators of transcription) and other signalling pathways are activated as a consequence. Of translational relevance, overexpression of IL-6 has been documented in several neoplastic disorders, including but not limited to colorectal, ovarian and breast cancer and several haematological malignancies. This review attempts to summarise our current understanding of the role of IL-6 in cancer development. In short, these studies have shown important roles for IL-6 signalling in tumour cell growth and survival, angiogenesis, immunomodulation of the tumour microenvironment, stromal cell activation, and ultimate disease progression. Given this background, we also consider the potential for therapeutic targeting of this system in cancer.

Predicting the Dose of Warfarin for Therapeutic Anticoagulation

The validity of a previously described technique for predicting warfarin requirements based on the anticoagulant response to a fixed loading dose was assessed prospectively in 57 patients. There was a close relationship between the predicted and initially observed daily warfarin dose required to maintain the patient within the therapeutic range for anticoagulation. The significant relationship between predicted and observed maintenance dose persisted at 4 and 12 weeks although it decreased with increasing time.

The relationship between observed and predicted maintenance requirement of warfarin was not affected by the concomitant use of intermittent intravenous injections of heparin when 9 hr was allowed to elapse between the previous dose of heparin and the thrombotest estimation on which the prediction was based.

It is concluded that the method is valuable in predicting an individual’s warfarin requirement, although it does not obviate the need for regular monitoring of anticoagulant control.

Abstract B125: Antigen density determines the efficacy of chimeric antigen receptor (CAR) re-targeted T-cells

The embryonic antigen Receptor Tyrosine Kinase Receptor 1 (ROR1) is expressed by cells of various B-cell malignancies, but is absent in almost all healthy tissues, including B-cells. Whilst such an expression pattern suggests it could represent an attractive target for Chimeric Antigen Receptor (CAR) T-cell immunotherapy, it is present at much lower levels than other antigens that are commonly targeted on malignant B-cells. Consequently, we determined whether the level of antigen density affects the ability of CAR-expressing T-cells to recognise and destroy tumour cells, using Chronic Lymphocytic Leukaemia (CLL) as the model disease.

A CAR specific for ROR1 was generated and specificity and optimisation of targeting was determined using matched positive and negative cell lines. The level of ROR1 expression on the surface of primary CLL cells isolated from 19 patients was determined by flow cytometry. Co-cultures between CLL cells and ROR1_CAR+ T-cells were undertaken at a 1:1 ratio, with CLL survival determined by flow cytometry at defined timepoints.

A range of ROR1 expression levels was noted across our patient cohort, but this did not correlate with any known prognostic markers. Interestingly, whilst T-cells expressing a CD19-specific CAR showed substantial anti-tumour activity against autologous CLL cells from all patients, efficacy of ROR1_CAR T-cells was not observed uniformly across the cohort. Importantly, efficacy of the ROR1_CAR T-cells appeared to correlate with ROR1 expression as antigen density was significantly lower in patient samples that were not lysed, compared to those that were. To investigate this further, we are currently determining whether CLL cells isolated from patients that failed in vitro ROR1_CAR T-cell therapy and manipulated via electroporation to express enhanced ROR1 levels are subsequently susceptible to ROR1_CAR T-cell destruction. A similar phenomenon has been observed in a panel of matched cell lines, with those engineered to express a high level of ROR1 significantly more susceptible to in vitro ROR1_CAR-mediated destruction. Importantly, equivalent destruction by a CD19-specific CAR demonstrated that this increased susceptibility was not an intrinsic property of the engineered tumour cells.

The data presented here suggest that antigen density may play a key role in the efficacy of CAR-mediated T-cell retargeting. Tumour cells bearing low levels of ROR1 were significantly more resistant to CAR-mediated destruction than equivalent cells expressing higher ROR1 antigen levels. We are currently confirming whether this observation is recapitulated with other targets.

Citation Format: David Marc Davies, Solange Paredes-Moscosso, Satyen Gohil, Marco Della-Peruta, Vania Coelho, Amit Nathwani. Antigen density determines the efficacy of chimeric antigen receptor (CAR) re-targeted T-cells. [abstract]. In: Proceedings of the CRI-CIMT-EATI-AACR Inaugural International Cancer Immunotherapy Conference: Translating Science into Survival; September 16-19, 2015; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2016;4(1 Suppl):Abstract nr B125.

Breast augmentation: Part III--preoperative considerations and planning

The past four decades since the introduction of silicone mammary prostheses have seen significant improvements in their quality and durability. Advances in our understanding of the aetiopathology and prevention of adverse capsular contracture (ACC) have occurred such that surgical technique itself has now probably become the single most important determinant of both immediate and long-term outcome. Considered a simple, and in some quarters mindless, procedure it has evolved such that high-quality short- and stable long-term results are now expected. Whilst the fundamentals of breast augmentation (BA) remain, evolutionary philosophies confront today's surgeon with a wealth of options. Of fundamental importance has been the paradigm shift from a purely, or predominantly, volumetric, through biodimensional to a tissue-based approach. With BA, more than any other aesthetic procedure, possessing more variables, choice and influential external factors a thorough understanding of the myriad options available is essential. This review seeks to cover the key elements in obtaining an optimal primary result. It provides a rational basis for the selection of an option tailored to both the patient and the individual tissue characteristics in addition to the pertinent medico-legal issues.

Absence of the Birt-Hogg-Dubé gene product is associated with increased hypoxia-inducible factor transcriptional activity and a loss of metabolic flexibility

Under conditions of reduced tissue oxygenation, hypoxia-inducible factor (HIF) controls many processes, including angiogenesis and cellular metabolism, and also influences cell proliferation and survival decisions. HIF is centrally involved in tumour growth in inherited diseases that give rise to renal cell carcinoma (RCC), such as Von Hippel-Lindau syndrome and tuberous sclerosis complex. In this study, we examined whether HIF is involved in tumour formation of RCC in Birt-Hogg-Dubé syndrome. For this, we analysed a Birt-Hogg-Dubé patient-derived renal tumour cell line (UOK257) that is devoid of the Birt-Hogg-Dubé protein (BHD) and observed high levels of HIF activity. Knockdown of BHD expression also caused a threefold activation of HIF, which was not as a consequence of more HIF1α or HIF2α protein. Transcription of HIF target genes VEGF, BNIP3 and CCND1 was also increased. We found nuclear localization of HIF1α and increased expression of VEGF, BNIP3 and GLUT1 in a chromophobe carcinoma from a Birt-Hogg-Dubé patient. Our data also reveal that UOK257 cells have high lactate dehydrogenase, pyruvate kinase and 3-hydroxyacyl-CoA dehydrogenase activity. We observed increased expression of pyruvate dehydrogenase kinase 1 (a HIF gene target), which in turn leads to increased phosphorylation and inhibition of pyruvate dehydrogenase. Together with increased protein levels of GLUT1, our data reveal that UOK257 cells favour glycolytic rather than lipid metabolism (a cancer phenomenon termed the 'Warburg effect'). UOK257 cells also possessed a higher expression level of the L-lactate influx monocarboxylate transporter 1 and consequently utilized L-lactate as a metabolic fuel. As a result of their higher dependency on glycolysis, we were able to selectively inhibit the growth of these UOK257 cells by treatment with 2-deoxyglucose. This work suggests that targeting glycolytic metabolism may be used therapeutically to treat Birt-Hogg-Dubé-associated renal lesions.

Adoptive T-cell immunotherapy of cancer using chimeric antigen receptor-grafted T cells

Harnessing the power of the immune system to target cancer has long been a goal of tumor immunologists. One avenue under investigation is the modification of T cells to express a chimeric antigen receptor (CAR). Expression of such a receptor enables T-cell specificity to be redirected against a chosen tumor antigen. Substantial research in this field has been carried out, incorporating a wide variety of malignancies and tumor-associated antigens. Ongoing investigations will ensure this area continues to expand at a rapid pace. This review will explain the evolution of CAR technology over the last two decades in addition to detailing the associated benefits and disadvantages. The outcome of recent phase I clinical trials and the impact that these have had upon the direction of future research in this field will also be addressed.

Standard anatomical medullary locking (AML) versus tricalcium phosphate-coated AML femoral prostheses

OBJECTIVES

To compare the preliminary rate and amount of bony ingrowth and calcar resorption between patients receiving either a standard anatomical medullary locking (AML) or a tricalcium phosphate (TCP)-coated AML femoral prosthesis and to compare preliminary clinical results.

DESIGN

A prospective, randomized, double-blind clinical trial.

SETTING

An acute care tertiary institution.

PATIENTS

Between January 1993 and March 1995, 92 patients underwent primary total hip arthroplasty (THA). They were randomized to 2 groups of 46--a control group or a treatment group. Of the 46 subjects enrolled in each group, no significant differences were seen preoperatively with respect to age, sex, diagnosis, clinical and radiographic assessment. Seventy-one patients were followed up for 24 months.

INTERVENTIONS

Insertion of either a standard AML femoral implant (control group) or a TCP-coated AML femoral implant (treatment group).

OUTCOME MEASURES

The degree of hypertrophy, calcar atrophy and the number of spot welds on standard postoperative radiographs at 6, 12 and 24 months. Clinically, assessment according to the Société internationale de chirurgie orthopédique et de traumatologie (SICOT) scale and a 100-point visual analogue scale (VAS) for pain.

RESULTS

There were no prosthetic stem revisions in either group at the 24-month follow-up. Radiographically, bony ingrowth was not significantly different in the TCP-coated stem, by chi2 analysis of the degree of hypertrophy and number of spot welds present. Also by chi2 analysis, the degree of calcar atrophy was not significantly different between groups. The mean VAS score for pain at 24 months was 12.5 for the control and 12.1 for the treatment group. No significant differences were seen in any of the clinical categories of the SICOT Scale over the 24-month interval.

CONCLUSION

The objective of TCP-coating--to increase the rate and amount of bony ingrowth while reducing the rate of calcar resorption in non-cemented THA--was not achieved by 24 months postoperatively in our study.

Exercise combined with continuous passive motion or slider board therapy compared with exercise only: a randomized controlled trial of patients following total knee arthroplasty

BACKGROUND AND PURPOSE

The primary purpose of this randomized controlled trial was to determine which method of mobilization - (1) standardized exercises (SE) and continuous passive motion (CPM), (2) SE and slider board (SB) therapy, using an inexpensive, nontechnical device that requires minimal knee active range of motion (ROM), or (3) SE alone-achieved the maximum degree of knee ROM in the fIrst 6 months following primary total knee arthroplasty (TKA). The secondary purpose was to compare health-related quality of life among these 3 groups.

SUBJECTS

The subjects were 120 patients (n=40/group) who received a TEA at a teaching hospital between June 1997 and July 1998 and who agreed to participate in the study.

METHODS

Subjects were examined preoperatively, at discharge, and at 3 and 6 months after surgery. The examination consisted of measurement of knee ROM and completion of the Western Ontario and McMaster Universities (WOMAC) Osteoarthritis Index and the Medical Outcomes Study 36-Item Short-Form Health Survey (SF-36).

RESULTS

The 3 treatment groups were similar with respect to age, sex, and diagnosis at the start of the study. There were no differences in knee ROM or in WOMAC Osteoarthritis Index or SF-36 scores at any of the measurement intervals. The rate of postoperative complications also was not different among the groups.

DISCUSSION AND CONCLUSION

When postoperative rehabilitation regimens that focus on early mobilization of the patient are used, adjunct ROM therapies (CPM and SB) that are added to daily SE sessions are not required. Six months after TEA, patients attain a satisfactory level of knee ROM and function.

Reducing arthroplasty costs via vendor contracts

OBJECTIVE

To describe a method of reducing the costs of implants in hip and knee arthroplasty.

DESIGN

Implant costs were compared before and after the implementation of a 2-year contract with implant vendors, providing increased volume for decreased implant cost. An additional 20% of arthroplasties could be done outside the contract for research or special purposes.

SETTING

A regional health authority involving 2 acute care hospitals.

METHOD

Costs were obtained for 942 hip and knee arthroplasties performed in 1993/94 and compared with costs of 1656 hip and knee arthroplasties performed in 1996/97.

OUTCOME MEASURES

Implant cost and number of joint arthroplasty procedures performed.

RESULTS

A 40% decrease in the cost per implant for primary knee arthroplasty and an 18% decrease in the cost per implant for primary hip arthroplasty were achieved. A rebate, calculated as a percentage of volume used, was received from the vendor to support general orthopedic research and education. A new contract for 3 years has recently been signed with 3 vendors designated as primary vendors for 80% of the volume.

CONCLUSION

The vendor-contract economic strategy effectively reduced the cost of hip and knee arthroplasty and may be useful at other centres looking for cost reduction methods that maintain adequate patient care and support clinical research and education.

British Airways flightdeck mortality study, 1950-1992

OBJECTIVE

To study the mortality and life expectancy of male British Airways flightdeck crew and to establish whether proportionate mortality excesses shown earlier for brain/CNS cancer, colon cancer and melanoma remained evident.

METHODS

A Standardized Mortality Ratio study (SMR) using England and Wales as the comparison population was carried out for 6209 male pilots and 1153 male flight engineers employed for at least 1 yr between January 1, 1950 and December 31, 1992. Internal relative risk comparisons were made between shorthaul and longhaul operations defined broadly as flights within Europe and beyond Europe, respectively.

RESULTS

The all-causes SMR for pilots of 61 (592 deaths) and 56 for flight engineers (127 deaths) confirmed the expected Healthy Worker Effect. In pilots apart from the known excess of deaths from aircraft accidents (SMR 14694), most of the comparisons showed significant deficits in mortality. The SMR's for brain/CNS cancer (143) and colon cancer (111) were no longer statistically significant. The SMR of 333 for melanoma was significantly raised in pilots but was not evident in flight engineers. Life expectancy for longhaul pilots and flight engineers was 4-5 yr better than England and Wales for ages 55-65 while the advantage for shorthaul pilots was reduced to between 2-3 yr. Cases of leukemia and aleukaemia in pilots were less than expected and less than the positive excess predicted from modeling based on radiation dose.

CONCLUSION

The study confirms that flightdeck crew live longer than the England and Wales population and do not exhibit patterns of death that could be directly attributable to occupation.

Vertical scar breast reduction with medial flap or glandular transposition of the nipple-areola

Vertical scar breast reduction is a well accepted technique which we believe improves the shape and projection of the breast and leaves no horizontal scars. Lassus and Lejour described superiorly based nipple flaps; we describe a medially based flap or glandular transposition of the nipple in small reductions. Fifty-seven consecutive patients are presented. Thirty-three patients had medial transposition of the nipple-areola with a mean resection of 608 g (range 220-1250 g). Twenty-four patients had a glandular transposition of the nipple-areola, with a mean resection of 380 g (range 220-600 g); transposition of the areola should be less than 5 cm in this group. After a short learning curve, the complications have been few and minor.

Exposure to cosmic radiation of British Airways flying crew on ultralonghaul routes

British Airways has carried out radiation monitoring in Concorde for more than 20 years and has used a heuristic model based on data quoted by the National Aeronautics and Space Administration (NASA) to model radiation exposure in all longhaul fleets. From these data it has been calculated that no flight deck crew would exceed the control level of 6 mSv/y currently under consideration by regulatory authorities, which is three tenths of the occupational dose limit of 20 mSv/y recommended by the International Commission on Radiological Protection (ICRP). The model suggested that less than 4% of cabin crew based in Tokyo flying only between London and Japan could reach or exceed the 6 mSv/y level, based on a predicted effective dose rate of 7 microSv/h. To validate this calculation a sampling measurement programme was carried out on nine round trips flown by a Boeing 747-400 between London and Tokyo. The radiation field was measured with dosimeters used for routine personal monitoring (thermoluminescence dosimeters (TLDs) and polyallydiglycol carbonate neutron dosimeters). The limitations of the methodology are acknowledged, but the results indicate that the effective dose rate was 6 microSv/h which is consistent with the predicted effective dose rate of 7 microSv/h. This result, which is in accordance with other reported studies indicates that it is unlikely that any of the cabin crew based in Tokyo exceeded the 6 mSv/y level. In accordance with "as low as reasonably achievable" principles British Airways will continue to monitor flying crew routes and hours flown to ensure compliance.

Nail gun injury: a barbed problem

A case of nail gun injury is reported. Preoperative radiographs are essential to determine whether copper barbs project from the nail shaft before any attempt is made to remove the nail. Thorough exploration is required.

Use of split-skin grafting in the treatment of chronic leg ulcers

Chronic leg ulcers are a common problem for which many different forms of treatment have been used. In this study we reviewed the results of split-skin grafting of ulcers of different aetiologies; 26 patients were reviewed. The mean duration of ulceration was 27.5 months. Of the 28 ulcers, ten were due to venous disease, three arterial disease, six rheumatoid arthritis, seven traumatic, and two diabetic. Healing rates of 85% for traumatic and 67% for rheumatoid ulcers were achieved, whereas rates of only 20% and 33% were achieved for venous and arterial ulcers (P < 0.02 Fisher's exact test). We conclude that in the presence of vascular disease, split-skin grafting is not an effective treatment for chronic leg ulceration. Vascular assessment and treatment should be carried out before attempting skin grafting.

Sensory innervation of the little finger by an anomalous branch of the median nerve associated with recurrent, atypical carpal tunnel syndrome

Superficial sensory communication between the ulnar and median nerves is well recognized. In the vast majority of cases this communication is from the ulnar nerve to the median nerve. We report a case in which a communicating branch passed from the median nerve to the ulnar nerve immediately proximal to the wrist to supply sensation to the little finger. The presence of this branch correlated with the presence of symptoms which had persisted in spite of conventional open carpal release 7 years earlier. Surgical decompression of this branch led to complete resolution of those symptoms.

Multidisciplinary approach to the management of head and neck arteriovenous malformations

Arteriovenous malformations (AVM) of the head and neck are quite rare in contrast to low-flow vascular anomalies, but often present with significant haemorrhage or cosmetic defects. Treatment of these high-flow vascular anomalies is hazardous and has a predictably high incidence of recurrence if not managed correctly. Intervention is indicated for complications such as pain, haemorrhage, pressure symptoms, ischaemic ulceration and even congestive cardiac failure. A multidisciplinary team approach is required in the assessment and treatment of these lesions, and involves preoperative angiography with superselective embolisation, followed by resection of the lesion, ideally within 72 h. Recent advances in microsurgery and in therapeutic radiology have greatly improved the prognosis for patients with these malformations. We present a series of four patients who have undergone preoperative embolisation and subsequent surgical excision, with a mean follow-up of 28 months. The complication rate has remained low and there has been no re-expansion of the lesions to date.

Malignant schwannoma mistakenly diagnosed as carpal tunnel syndrome

A rare nerve sheath tumour masquerading as carpal tunnel syndrome is described. It arose in a digit, with perineural spread proximally along the median nerve.

The mortality of British Airways pilots, 1966-1989: a proportional mortality study

Of 446 deaths among serving and retired British Airways pilots between 1966 and 1989, 411 were analysed using the Proportional Mortality Ratio (PMR) technique. After removal of the predictable excess of aircraft accidents, excesses of cancer (PMR 1.31) and other accidents (1.60) were balanced by deficits in diseases of the circulatory (0.83) and respiratory (0.49) systems. While lung cancer was close to expectation (1.10), consistent excesses were shown in all analyses for malignant melanoma (6.68), cirrhosis of the liver (2.88), colon cancer (2.30) and brain/CNS cancer (2.68). Consideration of these ratios in relation to pilots' lifestyle and occupation leads to the conclusion that the brain/CNS cancer excess must be studied further.

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Morphological and morphometric changes in revascularised bowel grafts reconstructing the cervical oesophagus

Revascularised grafts of jejunum and colon have been used to reconstruct the cervical oesophagus in dogs. The grafts were examined at 2 months to assess their morphological and morphometric behaviour in their new position in the oesophagus. The colonic grafts appeared to adapt completely, while the jejunal ones manifest persisting mucosal changes attributable to their new environment.

Kinetics and mechanism of electron transfer from dithionite to microsomal cytochrome b5 and to forms of the protein associated with charged and neutral vesicles

The kinetics of the dithionite reduction of calf liver microsomal cytochrome b5, both free in solution and bound to dimyristoyl phosphatidylcholine vesicles, are consistent with electron transfer between SO2- and the exposed haem edge of the protein. The vesicle membrane does not hinder the approach of SO2- to the site of electron transfer on the protein. In 0.01 M-Tris/HCl buffer, pH 8.1, ket (25 degrees C), delta H et and delta S et are estimated to be 1.44 x 10(6) M-1.s-1, 7.8 kJ.mol-1 and -92.3 J.K-1.mol-1 respectively. The cytochrome exhibits an acid dissociation, pKa 9.3 +/- 0.3, and the rate of electron transfer from dithionite to the high-pH form is about one-third of that to the neutral-pH form. The effect of ionic strength on the kinetics is consistent with a reaction between like-charged species and is discussed in terms of a number of theoretical models. In systems comprising cytochrome b5 and negatively charged vesicles, the effect of increasing the charge density of mixed dimyristoyl phosphatidylcholine/dicetyl phosphate vesicles and of increasing the concentration of dicetyl phosphate vesicles is to lower the rate of electron transfer from dithionite to the haem moiety of the cytochrome. With vesicles of high charge density, however, the kinetics are complicated by vesicle-induced conformation changes of the cytochrome.

The innervated trapezius flap in facial paralysis

The use of an innervated lateral trapezius flap to allow movement of the paralysed face is described. Five cases are presented, all of whom achieved some facial movement postoperatively. The place of this technique in the armamentarium of procedures for facial reanimation is discussed.

Interaction of cytochrome b5 with surfactant vesicles

Changes in the u.v.-visible absorption spectrum of cytochrome b5 which occur upon addition of dicetyl phosphate, dimyristoyl phosphatidic acid (DMPA), or mixed DMPA/dimyristoyl phosphatidylcholine vesicles are consistent with haem transfer from the cytochrome to the membrane via an intermediate haemoprotein species. The effects of vesicle charge and concentration on the kinetics of haem transfer are discussed.

A method of phalloplasty using the deep inferior epigastric flap

Penile reconstruction remains a difficult surgical problem. To produce a phallus capable of erection and with a water-tight urethra to the tip has not been solved satisfactorily even by the introduction of free flap transfers. We present a method used in four cases, three transsexuals and one pseudohermaphrodite, in which a phallus was successfully constructed using the deep inferior epigastric flap.

Phalloplasty using the free radial forearm flap

Our experience of phalloplasty using the radial forearm flap in five transsexual cases is reported. The results are disappointing due to the high incidence of complications. We had partial success in two cases, both complicated by a fistula, and complete failure in three cases due to vascular thrombosis.

Doppler waveforms in the fetal aorta and umbilical artery in patients with hypertension in pregnancy

Pulsed Doppler ultrasound assessment of blood flow was performed in the fetal aorta and umbilical arteries of 41 patients with hypertension in pregnancy. Patients were grouped according to severity of the hypertension and the presence or absence of chronic hypertension. Doppler abnormalities were seen in two patients with chronic hypertension, both of whom delivered small for gestational age infants. Only one patient with mild to moderate preeclampsia had abnormal aortic Doppler assessment and was also delivered of a small for gestational age infant. The highest number of abnormal Doppler waveforms in both fetal aorta and umbilical artery were found in patients with severe preeclampsia. Abnormalities were detected more frequently in the fetal aorta than in the umbilical artery. Doppler assessment was often abnormal before a nonstress test or biophysical profile. The number of abnormal Doppler values correlated with perinatal outcome in patients with severe preeclampsia.

The functional recovery of revascularised colon and jejunum replacing the cervical oesophagus

An experimental animal model was set up to study the comparative behaviour of revascularised transplants of colon and jejunum used to reconstruct the cervical oesophagus. Age, sex and size matched greyhound dogs were used in the study. An investigation of the physiological behaviour of the graft mucosa was carried out at 8 weeks using the mucosal specific activity of the enzyme Na+K+ATPase. The findings demonstrate a clear depression in the functional behaviour of the jejunal graft mucosa, while the colonic graft mucosa remained biochemically unchanged. The significance of these findings is discussed, and the conclusion drawn that they support the hypothesis that colon makes a more stable and functionally superior free graft than jejunum when replacement of the cervical oesophagus is required.