Rapid Magnetic 3D Printing of Cellular Structures with MCF-7 Cell Inks.

A contactless label-free method using a diamagnetophoretic ink to rapidly print three-dimensional (3D) scaffold-free multicellular structures is described. The inks consist of MCF-7 cells that are suspended in a culture medium to which a paramagnetic salt, diethylenetriaminepentaacetic acid gadolinium (III) dihydrogen salt hydrate (Gd-DTPA), is added. When a magnetic field is applied, the host fluid containing the paramagnetic salt is attracted towards regions of high magnetic field gradient, displacing the ink towards regions with a low gradient. Using this method, 3D structures are printed on ultra-low attachment (ULA) surfaces. On a tissue culture treated (TCT) surface, a 3D printed spheroid coexists with a two-dimensional (2D) cell monolayer, where the composite is termed as a 2.5D structure. The 3D structures can be magnetically printed within 6 hours in a medium containing 25 mM Gd-DTPA. The influence of the paramagnetic salt on MCF-7 cell viability, cell morphology, and ability of cells to adhere to each other to stabilize the printed structures on both ULA and TCT surfaces is investigated. Gene expressions of hypoxia-inducible factor 1-alpha (HIF1α) and vascular endothelial growth factor (VEGF) allow comparison of the relative stresses for the printed 3D and 2.5D cell geometries with those for 3D spheroids formed without magnetic assistance. This magnetic printing method can be potentially scaled to a higher throughput to rapidly print cells into 3D heterogeneous cell structures with variable geometries with repeatable dimensions for applications such as tissue engineering and tumour formation for drug discovery.

Quality assurance: monitoring lithotriptor output and its clinical implications.

Serial acoustic output measurements performed on the an electromagnetic lithotriptor consistently showed significant decreases in the output of the shock heads. A decrease in output during the lifetime of the shock head to less than 50% of its original output was observed. Decreased output was related to a higher number of shocks per treatment and a higher retreatment rate. Quality control of the lithotriptor output was reflected in better clinical results, a lower mean number of shocks per treatment, a lower retreatment rate and less time on the table, which has important clinical and financial implications. Acoustic output measurements on lithotriptors should be mandatory to achieve the best possible clinical results from extracorporeal shock wave lithotripsy.

Choosing a powerful lithotriptor.

Clinicians have no yardstick to help them choose the most efficient lithotriptor. Their leading priority is a system allowing complete disintegration of the stone with the minimum number of shocks and a low re-treatment rate. One of the prerequisites of this system is a powerful shock wave generator. "Power" is as yet ill defined in lithotripsy. Therefore clinicians' choice depends upon other factors. Acoustic output measurements were recorded on 3 commercial lithotriptors representing the 3 main shock wave generating systems. These were the Dornier MPL 9000 (standard and X-155 electrodes), the Siemens (Lithostar, Lithostar Plus and System C) and the Wolf Piezolith 2300. The shock wave measurements were correlated to the capability of the lithotriptors to disintegrate standard stone models in vitro. Two factors were identified. The pulse intensity integral in the focus and the size of the focal zone proved to be the most important factors to assess and compare the efficacy or "power" of different lithotriptors. Together they can help clinicians to identify and choose the most efficient shock wave generating systems.

Surgical audit: variations in wound infection rates according to definition.

A prospective study of 702 postoperative surgical patients was undertaken to determine whether clinicians showed consistency in their interpretation of signs of infection in wounds. In the 62 cases where symptoms suggestive of such infection were noted, clinical signs were recorded, as were the clinicians' subjective impressions. The application of different criteria would have resulted in a substantial variation in the apparent rates of infection, which raises questions about the need for an agreed definition of the term 'wound infection'. The lack of a specific definition has implications for surgical audit.

Urological audit: the role for an aggressive approach to high grade superficial bladder tumours.

A retrospective study was undertaken of the different treatment modalities for bladder tumours under the care of 3 consultants in the urology department of a district general hospital. The aim was to review the results of the various forms of treatment. In all, 261 patients' case records were reviewed and 19 variables extracted. There was an average delay of 4.2 months from the onset of symptoms to the initial cystoscopy. Over 50% of high grade tumours were invasive on initial presentation (G3T2/G3T3). A range of treatments for the more aggressive tumours was adopted by the urologists, ranging from a conservative resection (TURBT) to an aggressive approach (cystourethrectomy) at the earliest sign of progression. A strong association between aggressive treatment and higher survival was noted. This study has proved valuable in demonstrating to the urology team the value of routine audit and questioning "established" surgical practice. As a result, a more standard regime for the treatment of bladder tumours has been advocated and a prospective randomised controlled trial will be introduced.

Ureteric stone management using a second generation lithotriptor.

A series of 209 consecutive patients with ureteric calculi underwent 296 extracorporeal shock wave lithotripsy treatments on the Siemens Lithostar over a 25-month period; 123 stones were upper ureteric, 30 mid-ureteric and 56 lower ureteric; 46.9% were right-sided stones, 53.6% were left-sided and 0.5% (1 patient) were bilateral. On referral, 60 patients had stents and 15 had nephrostomies for obstruction. All treatments were performed without anaesthesia except for 9 patients in whom stent insertion or ureteroscopic manipulations were attempted concomitant to ESWL. The average number of treatments was 1.42, with 27.5% of patients requiring more than 1 treatment. The average number of shocks per treatment was 3995 and the average hospital stay was 1.79 days. Complete clearance of the stone was achieved in 82% of upper ureteric stones, 89% of mid-ureteric and 80% of lower ureteric stones. The facility for X-ray localisation of stones allows a high proportion of ureteric calculi to be treated successfully by ESWL, including the more taxing middle and lower ureteric calculi.

Extracorporeal shock wave lithotripsy for renal calculi in children.

Fifteen children (8 male and 7 female) with an age range of 18 months to 15 years were treated with extracorporeal shock wave lithotripsy (ESWL) using the Siemens Lithostar. Two children had a history of metabolic stone disease and 1 child had previously undergone open stone surgery. Four children were treated with a ureteric stent in place and 1 nephrostomy was inserted before treatment. All children were treated under general anaesthesia and all of the stones treated were confined to the kidney and ranged in size from 5 mm to a complete staghorn. The number of treatments ranged from 1 to 6 and generator voltage ranged from 16 to 19 kV with a maximum number of 30,000 shocks to a complete staghorn. Complications were minimal, with 3 children presenting with colic, 1 child requiring a stent and none requiring a nephrostomy after treatment. The overall stone clearance rate at 3 months was 65%. ESWL provides an effective treatment for selected calculi in children. In the short term, complications are minimal but the long-term effects on children need to be monitored.

Fixation of a single testis: always, sometimes or never.

If it is necessary to perform an orchiectomy for an intravaginal testicular torsion it is the usual practice of surgeons to fix the contralateral testis. When faced with a child with only one testis for another reason it is our practice to fix this single testis to eliminate the small but disastrous risk of a torsion. We were interested to see whether this practice was usual and therefore sent out a questionnaire to the 67 consultant paediatric surgeons and urologists in Great Britain. Sixty-six surgeons replied. Seven surgeons (11%) always fix the single testis, 28 (42%) sometimes and 31 (47%) never fix a single testis. Five surgeons had looked after 6 patients who had a torsion of a second unfixed testis after losing the first for a reason other than intravaginal torsion. Four of these patients had initially had a neonatal supravaginal torsion, 1 had a torsion of an undescended testis and the sixth had severe testicular atrophy following an inguinal herniotomy. In our opinion the devastating loss of these solitary testes makes contralateral testicular fixation after an orchiectomy for whatever reason mandatory.

How much do junior staff influence patient throughput in a surgical unit?

A study was undertaken of inpatient throughput in a surgical department on a 'split site' District General Hospital. The study compared the individual contribution of equally qualified and experienced surgical registrars working at both sites. The results show that one registrar was associated with a statistically significant higher patient throughput, which appeared to be the result of a more expeditious approach to patient management. There was no evidence of an accompanying reduction in the quality of care delivered. The additional throughput amounted to approximately 300 extra patients in two years, and made a substantial contribution to the surgical workload in the District.

Wound infection: the surgeon's responsibility.

Surgical audit has two main purposes: the pursuit of efficiency through the review of clinical workload and the pursuit of quality by reviewing clinical outcomes. In-house quality control is an important aspect of surgical practice. This prospective study aimed to determine the incidence of infection, describe the time distribution of presentation and identify contributory factors. There were 1 242 consecutive patients in the survey (1 086 inpatients and 156 day cases), of whom 83 became infected (79 in-patients and four day cases) - an overall infection rate of 6.7%. Over 55% presented during the first week and 89% within the first two weeks. Of 23 specific aetiological variables studied, four - age, preoperative stay, shaving and the surgeon - were shown to have a statistically significant association with the development of wound infection. A strong association between the surgeon and the development of wound infection was demonstrated. In addition to obvious strong resource implications, it supports the need for routine audit supervision and training of junior staff and peer review for senior clinicians.

Measurement of lithotripsy pulses through biological media.

Lithotripsy is now the method of choice for the treatment of renal calculi. The mechanism of destruction is not clearly understood, and detailed knowledge of the shock-wave characteristics at the calculus would aid understanding of the phenomenon. Current methods of measuring the pressure pulse by observing it through a water path are not well characterized, and the results may not represent the actual pressure fluctuations produced in vivo. In order to determine the actual pressure pulse experienced at the site of the calculus, measurements have been made through a variety of biological media. The results show that there are considerable differences between measurements taken through a water path and through biological media. This paper describes the pressure fluctuations in the time domain. The implications of the results for lithotripsy are discussed.

Surgical audit: variations in wound infection rates of individual surgeons.

A prospective survey of 1086 general surgical in-patients was carried out in West Dorset district to determine the incidence of postoperative infections for individual surgeons. A total of 79 cases were diagnosed as having become infected, resulting in an overall infection rate of 7.3%. For all cases the infection rate for individual surgeons varied from 3.9 to 14.6% (P less than 0.005; chi 2 test). For the clean operative category only, the infection rate varied from 2.9 to 20.0% (P less than 0.0005; chi 2 test). The results demonstrate the value of routine surgical audit in elaborating the variation in clinical outcomes for individual surgeons. Clinical audit can identify the need for extra supervision and training of junior staff and peer review for senior clinicians.

Factors affecting the incidence of postoperative wound infection.

A prospective study of postoperative wounds was carried out in West Dorset to determine the incidence of infection, describe the time distribution of presentation before and after discharge from hospital and identify possible contributory factors. There were 702 consecutive patients admitted to the study (600 in-patients and 102 day cases). Fifty one became infected (47 in-patients and 4 day cases), corresponding to an overall infection rate of 7.3%. Over 50% of infections presented during the first week after operation, and almost 90% were diagnosed within 2 weeks of surgery Twenty-eight (55%) wounds that became infected presented after hospital discharge. Of 23 specific aetiological variables studied, four (age, preoperative stay, shaving and the surgeon) were shown to have a statistically significant association with the development of wound infection. A strong association between the individual surgeon and the development of a wound infection was demonstrated and this supports the need for routine surgical audit.

The importance of surveillance after discharge from hospital in the diagnosis of postoperative wound infection.

A prospective survey was carried out in West Dorset to determine the incidence of postoperative wound infection. A total of 1242 patients were included in the survey (1086 inpatients and 156 day cases). The overall infection rate was 6.7%. Although the incidence of infection was consistent with that reported by other studies, the infection rate in the 'clean' surgical category was higher than in most other published reports. Careful surveillance after discharge from hospital may have been responsible for identifying cases of wound infection which otherwise might not have come to the attention of the study. Of patients whose wounds became infected, 34 (41%) cases were diagnosed in hospital and 49 (59%) cases were diagnosed in the community. Failure to pursue patients after discharge would have resulted in a substantial underestimation of the true wound infection rate.