Exogenous mineralization of hard tissues using photo-absorptive minerals and femto-second lasers; the case of dental enamel.

A radical new methodology for the exogenous mineralization of hard tissues is demonstrated in the context of laser-biomaterials interaction. The proposed approach is based on the use of femtosecond pulsed lasers (fs) and Fe3+-doped calcium phosphate minerals (specifically in this work fluorapatite powder containing Fe2O3 nanoparticles (NP)). A layer of the synthetic powder is applied to the surface of eroded bovine enamel and is irradiated with a fs laser (1040 nm wavelength, 1 GHz repetition rate, 150 fs pulse duration and 0.4 W average power). The Fe2O3 NPs absorb the light and may act as thermal antennae, dissipating energy to the vicinal mineral phase. Such a photothermal process triggers the sintering and densification of the surrounding calcium phosphate crystals thereby forming a new, dense layer of typically ∼20 µm in thickness, which is bonded to the underlying surface of the natural enamel. The dispersed iron oxide NPs, ensure the localization of temperature excursion, minimizing collateral thermal damage to the surrounding natural tissue during laser irradiation. Simulated brushing trials (pH cycle and mechanical force) on the synthetic layer show that the sintered material is more acid resistant than the natural mineral of enamel. Furthermore, nano-indentation confirms that the hardness and Young's modulus of the new layers are significantly more closely matched to enamel than current restorative materials used in clinical dentistry. Although the results presented herein are exemplified in the context of bovine enamel restoration, the methodology may be more widely applicable to human enamel and other hard-tissue regenerative engineering. STATEMENT OF SIGNIFICANCE: In this work we provide a new methodology for the mineralisation of dental hard tissues using femtosecond lasers and iron doped biomaterials. In particular, we demonstrate selective laser sintering of an iron doped fluorapatite on the surface of eroded enamel under low average power and mid-IR wavelength and the formation of a new layer to substitute the removed material. The new layer is evaluated through simulated brushing trials and nano-indentation. From the results we can conclude that is more acid resistant than natural enamel while, its mechanical properties are superior to that of current restorative materials. To the best of our knowledge this is the first time that someone demonstrated, laser sintering and bonding of calcium phosphate biomaterials on hard tissues. Although we here we discuss the case of dental enamel, similar approach can be adopted for other hard tissues, leading to new strategies for the fixation of bone/tooth defects.

ß-pyrophosphate: A potential biomaterial for dental applications.

Tooth hypersensitivity is a growing problem affecting both the young and ageing population worldwide. Since an effective and permanent solution is not yet available, we propose a new methodology for the restoration of dental enamel using femtosecond lasers and novel calcium phosphate biomaterials. During this procedure the irradiated mineral transforms into a densified layer of acid resistant iron doped ß-pyrophosphate, bonded with the surface of eroded enamel. Our aim therefore is to evaluate this densified mineral as a potential replacement material for dental hard tissue. To this end, we have tested the hardness of ß-pyrophosphate pellets (sintered at 1000°C) and its mineral precursor (brushite), the wear rate during simulated tooth-brushing trials and the cytocompatibility of these minerals in powder form. It was found that the hardness of the ß-pyrophosphate pellets is comparable with that of dental enamel and significantly higher than dentine while, the brushing trials prove that the wear rate of ß-pyrophosphate is much slower than that of natural enamel. Finally, cytotoxicity and genotoxicity tests suggest that iron doped ß-pyrophosphate is cytocompatible and therefore could be used in dental applications. Taken together and with the previously reported results on laser irradiation of these materials we conclude that iron doped ß-pyrophosphate may be a promising material for restoring acid eroded and worn enamel.

Single port laparoscopic right colonic resection using a 'vessel-first' approach.

AIM: Single port laparoscopic colorectal surgery (SPLC), performed through a single incision of ≤ 3 cm, has been shown to be feasible. This study aimed to assess its safety and efficacy when used as the method of choice for right hemicolectomy. METHOD: A prospective study was carried out of patients undergoing right hemicolectomy using a single port laparoscopic technique. They were compared with a historical series of patients undergoing right hemicolectomy using a multiport laparoscopic technique. Between December 2009 and September 2010, single port surgery replaced conventional laparoscopic colorectal surgery (LCS) for radical medial to lateral right hemicolectomy performed by a single surgeon. Histology, length of hospital stay, complications, conversions and readmissions were recorded. RESULTS: Fourteen patients were treated using single port laparoscopic surgery (SPLC): 10 for carcinoma (Dukes A1, B6, C3) and four for Crohn's disease. Twelve patients were treated using multiport laparoscopic colorectal surgery (LCS): eight for carcinoma (Dukes B4, C3, Carcinoid 1), three for Crohn's disease and one for adenoma. The median (interquartile range) operative time for the SPLC group was 120 (90-135) min and for the LCS group was 135 (116-150) min. The median (interquartile range) length of hospital stay was 3.5 (2.0-5.0) days for the SPLC group and for the LCS group was 4.0 (3.8-7.0) days. The median (interquartile range) number of lymph nodes removed for SPLC patients was 14.5 (9.8-19.5) and for the LCS patients was 14.5 (13.0-19.5). There were no conversions, no complications and no readmissions in either group. CONCLUSION: These data confirm the feasibility of the technique. Furthermore they suggest that it is safe and efficacious.

Short-term outcomes of the prone perineal approach for extra-levator abdomino-perineal excision (elAPE).

BACKGROUND: Many studies report that low rectal cancer treated with abdomino-perineal excision (APE) have higher rates of CRM involvement with associated local recurrence and worse survival when compared to low anterior resection. We present a single surgeon's short-term outcomes using the prone perineal extra-levator (elAPE) approach. METHODS: Thirty-one patients between 2006 and 2010 underwent elAPE with curative intent. Data was collected prospectively recording patient tumour characteristics and histological outcome. Outcome measures included circumferential resection margins, recurrence rates, 30-day morbidity and mortality. RESULTS: Mean distance of tumour from anal verge was 3.63 ± SD 1.52 cm. 14 patients had pre-operative chemo-radiotherapy. The involved circumferential resection margin rate was 3.2%. Median follow-up was 20 (0-45) months, with overall mortality of 13.3% and 30 day mortality of 6.6%. CONCLUSIONS: The prone position elAPE has a low circumferential resection margin involved rate and, through improved vision, reduces the risk of inadvertent tumour or specimen perforation.

Rectus abdominis myocutaneous flaps for perineal reconstruction: modifications to the technique based on a large single-centre experience.

INTRODUCTION: Perineal wound breakdown with delayed wound healing represents a significant cause of morbidity following surgery and radiotherapy to the perineum. The rectus abdominis myocutaneous (RAM) flap has been used increasingly to reconstruct the perineum with good effect. We describe our six-year experience of reconstruction of the perineum with the RAM flap and share some surgical adjuncts we believe are useful. METHODS: We conducted a retrospective case note review of all patients who underwent a reconstruction of the perineum using the RAM flap between August 2003 and October 2009. Indications for the flap, complication rates and outcomes were all observed. RESULTS: We conducted 16 RAM flap procedures, 15 of which (94%) were primary repairs and 1 (6%) a secondary repair. Three (19%) developed donor site hernias, two (12.5%) developed minor perineal wound infections, eight (50%) developed minor perineal wound breakdown and in one (6%) flap failure was observed. No perineal hernias were observed. There were no surgical mortalities. CONCLUSIONS: The RAM flap has a high success rate and an acceptable morbidity rate and is a useful tool in the reconstruction of complex perineal wounds. Modifications to the standard surgical technique may reduce complications and improve the versatility of this flap.

Local anaesthetic wound infiltration following paediatric appendicectomy: a randomised controlled trial: Time to stop using local anaesthetic wound infiltration following paediatric appendicectomy?

OBJECTIVE: This study sought to determine the efficacy of post-operative wound infiltration with local anaesthetic following paediatric appendicectomy. METHOD: In a randomised, controlled, prospective, clinical trial children aged between five and sixteen years were assigned to one of three treatment arms; infiltration of the surgical wound with bupivicaine, saline, or no infiltration. Anaesthetic and analgesic protocols were employed. Patients and observers were blinded to the treatment group. The primary end-points were post-operative pain, scored at intervals during the first twenty post-operative hours, and additional post-operative analgesic requirements beyond that which was provided by a standard protocol. In addition, adverse wound outcomes were recorded. RESULTS: Eighty-eight children were recruited. There were no differences in age, sex or other confounding variables between groups. There was no significant difference in mean pain scores or analgesic requirements between groups through-out the post-operative period. CONCLUSION: Wound infiltration with local anaesthetic following appendicectomy in children provides no additional benefit over regular simple analgesia. Its routine use represents dogmatic practise which ought to be challenged for this patient group.

Randomized clinical trial of preoperative intravenous iron sucrose to reduce blood transfusion in anaemic patients after colorectal cancer surgery.

BACKGROUND: The transfusion rate following colorectal cancer resection is between 10 and 30 per cent. Receipt of allogeneic blood is not without risk or cost. A preoperative adjunct that reduced the need for transfusion would mitigate these risks. This study was designed to determine whether iron sucrose reduces the likelihood of postoperative blood transfusion in patients undergoing elective colorectal cancer resection. METHODS: In this randomized prospective blinded placebo-controlled trial of patients undergoing resectional surgery with a preoperative diagnosis of colorectal cancer, 600 mg iron sucrose or placebo was given intravenously in two divided doses, at least 24 h apart, 14 days before surgery. The primary outcome measures were serum haemoglobin concentration, recorded at recruitment, immediately before surgery and at discharge, and perioperative blood transfusions. RESULTS: No difference was demonstrated between treatment groups (iron sucrose, 34 patients; placebo, 26) for any of the primary outcome measures, for either the whole study population or a subgroup of anaemic patients. CONCLUSION: This pilot study provided no support for the use of intravenous iron sucrose as a preoperative adjunct to increase preoperative haemoglobin levels and thereby reduce the likelihood of allogeneic blood transfusion for patients undergoing resectional surgery for colorectal cancer. REGISTRATION NUMBER: 2005-003608-13UK (Medicines and Healthcare products Regulatory Agency).

Regression analyses of southern African ethnomedicinal plants: informing the targeted selection of bioprospecting and pharmacological screening subjects.

ETHNOPHARMACOLOGICAL RELEVANCE: Regression analyses of local medicinal floras are considered potentially useful when prioritising candidate plant taxa for pharmacological/bioprospecting investigations. AIM OF THE STUDY: To identify plant orders and subsequently families within the highly diverse ethnomedicinal flora of southern Africa, towards which biases by traditional healers are demonstrable. Taxa so identified can subsequently be weighted appropriately in semi-quantitative selection systems. METHODOLOGY: Plant data sourced from the SANBI MedList database, the most comprehensive inventory of ethnomedicinal plants for the Flora of southern Africa region were grouped by order. A least squares regression analysis was applied to test the null hypothesis that the use of these plants by traditional healers is strictly random. Of 'hot' orders subsequently identified, characteristics of taxa therein were assessed to better determine the roles played by (i) growth forms, and (ii) inherent chemical diversity, in plant selections by ethnomedicinal practitioners. RESULTS: Analyses identified seven principally 'hot' plant orders (Malpigiales, Fabales, Gentianales, Asteraceae, Solanales, Malvales and Sapindales) and 'hot' families therein from a total of 55 regional ethnomedicinal orders. Five 'cold' ethnomedicinal orders (Rosales, Proteales, Poales, Asparagales and Caryophyllales) were shown to be significantly less represented in the medicinal flora than predicted. No clear growth form preferences were identified across orders. The presence of highly diverse bioactives was evident in the 'hottest' plant families from 'hot' plant orders. CONCLUSIONS: These 12 outliers identified by the regression analyses allowed for the falsification of the null hypothesis. Indications are that 'hot' taxa are selected traditionally on the basis of bioactivity, which is reflected in chemical diversity.

Refugia, dispersal and divergence in a forest archipelago: a study of Streptocarpus in eastern South Africa.

We describe a scenario of plant speciation across a relict forest archipelago in South Africa involving Pleistocene habitat expansion-contraction cycles, dispersal and adaptation to lower temperatures. This is the first population level study using molecular data in South African forests and has significant implications for conservation efforts in this area. Populations of the mesophytic forest floor herbs Streptocarpus primulifolius sensu lato and Streptocarpus rexii were sampled throughout their range in the naturally fragmented forests of eastern South Africa in order to investigate population genetic and phylogenetic patterns within the species complex, using nuclear microsatellites, nuclear ribosomal ITS (internal transcribed spacer) sequences and chloroplast genome sequences. S. primulifolius harbours high levels of genetic diversity at both the nuclear (mean HE = 0.50) and the chloroplast level (each population fixed for a unique haplotype). This is consistent with populations of these coastal species being Pleistocene relicts. In contrast, populations of S. rexii in cooler habitats at higher altitudes and lower latitudes harbour little or no nuclear genetic diversity (mean HE = 0.09) and most share a common chloroplast haplotype. The split of S. rexii from populations intermediate between the two species (S. cf. primulifolius) occurred between 0 and 0.44 million years ago according to the calibrated ITS phylogeny of the taxa. The low genetic diversity and homogeneity of S. rexii is congruent with this species having reached its current range during the Holocene. We found no evidence of monophyly of any of the taxa in this study, which we consider a consequence of recent evolution in a fragmented habitat.

Improving risk disclosure during the consent process.

OBJECTIVES: To provide guidance about the risks which should be disclosed to patients and documented during the consent process. METHODS: The Delphi Consensus Technique was used to decide what constitutes mandatory risk disclosure for three index procedures. Documentation of risk on consent forms was audited and compared to these locally agreed standards. A four stage strategy for change was undertaken following which practice was reviewed. RESULTS: Mean mandatory risk documentation rose from 61.2% (95% CI: 58.1-64.4) pre-intervention, to 78.1% (95% CI: 72.6-83.6) post-intervention (ccc2; P < 0.001). CONCLUSIONS: Although we demonstrated some benefit from this simple approach, the need for pragmatic means of achieving and sustaining complete discussion and documentation of risks across all surgical interventions based on universally accepted standards remains.

Damage control laparotomy.

BACKGROUND: Damage Control Surgery (DCS) is well established in the management of trauma. This study assessed the results of DCS in the management of critically ill patients who had not had trauma. METHODS: This was a prospective series of patients treated by DCS. The Physiological and Operative Severity Score for the enUmeration of Mortality and morbidity (POSSUM) and Portsmouth predictor equation (P-POSSUM) were used to predict the risk of death, which was compared with the observed mortality rate. RESULTS: Fourteen patients were studied. Nine had sepsis from gastrointestinal perforation. Eight of these underwent bowel resection without anastomosis or stoma formation at the initial laparotomy. Six patients later underwent bowel anastomosis and two had an end stoma formed at second laparotomy. A further three patients had a ruptured aortic aneurysm, one had a reactionary haemorrhage after elective aortic surgery, and one had a retroperitoneal bleed; all required haemostatic packing that was removed at second laparotomy. Mortality rates predicted by POSSUM and P-POSSUM scoring were 64.5 and 49.6 per cent respectively. One patient (7.1 per cent) died after operation, giving an observed mortality rate significantly lower than predicted (P = 0.002 and P = 0.038 versus values predicted by POSSUM and P-POSSUM, respectively). CONCLUSION: The use of DCS in the treatment of critically ill patients resulted in a lower mortality rate than that predicted by POSSUM or P-POSSUM. DCS should not be restricted to trauma.

The relationship between hematocrit and bleeding time in very low birth weight infants during the first week of life.

OBJECTIVES: The bleeding time is a measurement of platelet and capillary interaction following a small standardized cutaneous incision. In adults, anemia causes a prolongation of the bleeding time, and we hypothesized that the same would be true in very low birth weight (VLBW) infants during their first week of life. STUDY DESIGN: Template bleeding times, using the Surgicutt Newborn device, were performed on 20 VLBW weight infants 0.28 l/l had no significant reduction in bleeding time following transfusion. CONCLUSIONS: In VLBW infants, during their first week of life (the time when their risk of intraventricular hemorrhage is greatest), a low hematocrit is associated with a significant prolongation in the bleeding time.

Continuous-wave singly resonant optical parametric oscillator based on periodically poled RbTiOAsO(4).

We report a continuous-wave optical parametric oscillator (OPO) based on periodically poled RbTiOAsO(4) (PPRTA). The singly resonant OPO, which is located within a Ti:sapphire laser, has a high-finesse signal cavity and delivers a maximum output power of 270 mW to the nonresonant idler wave at 2.92mum , through a 4.5-mm PPRTA crystal. For room-temperature operation and a crystal with a 30-mu;m grating period, pump tuning over 838-848 nm results in OPO tuning over 1.13-1.27mum (signal) and 2.53-3.26mum (idler), limited by the bandwidth of optical coatings. PPRTA exhibits thermal properties superior to those of periodically poled LiNbO(3) .

Functional hemodynamic assessment of the 21-mm and 23-mm CarboMedics Top Hat aortic prosthetic valve.

Between 1993 and 1996 the CarboMedics Top Hat supraannular aortic valve was implanted in 41 patients at the Wessex Cardiothoracic Centre (age, 39 to 74 years; mean, 61.3+/-8.9 years). Comparisons of annular dimensions made at surgery indicate that conventional annular valve replacement would have required at least a size smaller valve. This was particularly marked when a prosthetic mitral valve was in place. Operative mortality was 2.4%. There were also three late deaths. Echocardiography before and after symptom-limited treadmill testing has been performed in 21 patients. The mean time to follow-up was 16.1 months. The Doppler-derived indices of forward flow pre- and postexercise were expressed as mean+/-standard deviation. For 23-mm valves the values were: peak valve gradient 21.43+/-7.46 mm Hg and 35.86+/-14.4 mm Hg, aortic valve area 1.13+/-0.39 cm2 and 1.24+/-0.54 cm2. For 21-mm valves the values were: peak valve gradient 24.84+/-8.2 mm Hg and 31.29+/-5.84 mm Hg, aortic valve area 1.08+/-0.44 cm2 and 0.95 +/-0.2 cm2. The Top Hat valve has a good hemodynamic profile at rest and during exercise. Surgical considerations make it particularly useful in patients with a small aortic annulus and in patients undergoing combined aortic and mitral valve replacement.

Effect of ovariectomy and steroid hormone replacement on the recovery of arterial blood pressure following haemorrhage in anaesthetized Brattleboro rats.

There is increasing evidence that ovarian steroids inhibit vascular responsiveness to the neurohypophysial hormone vasopressin. The present study examined the recovery of the arterial blood pressure following a single (2 ml/100 g body weight) haemorrhage in ovariectomized (OVX) Brattleboro rats with hereditary hypothalamic diabetes insipidus (BDI) and rats of the parent Long Evans (LE) strain. Some groups of OVX rats received subcutaneous implants of either 17 beta-oestradiol (E2) or progesterone 7 days prior to haemorrhage. The arterial blood pressure recovery immediately following haemorrhage was significantly impaired in both groups of steroid-treated OVX LE rats compared with the OVX controls (both comparisons P < 0.05). The impairment in blood pressure recovery seen in the steroid-replaced OVX LE rats was similar to that seen in pro-oestrous rats (when ovarian steroid levels are raised) compared with male rats of this strain (P < 0.05). In contrast, ovariectomy with or without steroid replacement in BDI rats had no further effect on the already attenuated recovery of arterial blood pressure after haemorrhage in this strain. Heart rate responses to haemorrhage also showed strain differences, which were dependent on steroid treatment. Pro-oestrous female LE rats showed a small decrease in heart rate after haemorrhage, followed by a recovery process, and this initial bradycardia was markedly enhanced in the OVX steroid-treated animals. In contrast, untreated OVX LE rats showed an initial and sustained increase in heart rate which was significantly higher than in the steroid-treated OVX animals (P < 0.05). All BDI rats, irrespective of treatment, consistently showed an increased heart rate after haemorrhage. In conclusion, ovarian steroid replacement in OVX LE, but not vasopressin-deficient BDI, rats was associated with an attenuated pressor recovery after haemorrhage. This provides further evidence for the existence of an important inhibitory interaction between ovarian steroids and vasopressin. The initial decrease in heart rate observed in pro-oestrous and steroid-treated OVX LE rats after haemorrhage also appears to be related to an ovarian steroid-vasopressin interaction.

A comparative study of miniplates used in the treatment of mandibular fractures.

The purposes of this study were to investigate the differences in mechanical properties of major miniplating systems used for noncompression miniplate osteosynthesis of mandibular fractures and to determine whether these properties influence treatment outcome. The study was conducted in two parts. First, six of the major miniplate systems currently used at the Royal Adelaide Hospital were subjected to bending tests at the University of Adelaide Engineering Department to quantify the relative stiffness of each plate. Second, a prospective sample of patients presenting with mandibular fractures was analyzed. These patients were treated with a variety of the miniplating systems. The results of treatment as a whole were compared to identify any direct benefit consequent on the miniplate selected. While significant differences in stiffness were identified between the plating systems, no significant differences in treatment outcome were identified, between the noncompression plates employed. Since no observable benefits have been identified by choice of miniplate, selection should be based on surgical preference, biocompatibility, CT compatibility and unit cost. Because of the variations in materials, design, properties, CT compatibility, and unit cost, it is important not to regard all miniplates as equal and interchangeable.

Biological valves beyond fifteen years: the Wessex experience.

Between 1975 and 1979, 443 biological valves (298 Carpentier-Edwards, 134 homograft, and 11 Hancock valves) were implanted in 415 patients (age, 16 to 77 years; mean, 59 years) with an operative mortality of 2.9%. Total follow-up was 4,248 patient-years. Overall event-free survival was 60% +/- 1.5% (standard deviation) at 10 years and 29% +/- 1.4% at 15 years. Ten-year and 15-year event-free survival were 72% +/- 3.4% and 41% +/- 3.3% for aortic homografts, 62% +/- 3% and 33% +/- 2.8% for isolated aortic xenografts, and 43% +/- 3.5% and 14% +/- 3.0% for isolated mitral xenografts. Freedom from structural valve degeneration was 87% +/- 1.3% and 63% +/- 2.5% for all patients at 10 and 15 years, respectively, 86% +/- 2.7% and 58% +/- 4.1% for aortic homografts, 93% +/- 1.8% and 76% +/- 5.1% for aortic xenografts, and 75% +/- 4.0% and 47% +/- 7.4% for mitral xenografts. Of the 110 remaining patients, echocardiography was performed in 61 patients (23 aortic xenograft, 24 aortic homograft, 9 mitral xenograft, and 5 tricuspid xenograft) between 14 and 17 years after implantation. An early diastolic murmur was heard in 57% of all aortic valve replacements (AVRs) 62.5% of homograft AVRs, and 52% of xenograft AVRs. Echocardiographically, aortic regurgitation was detected in 79%, 83%, and 74% of all AVRs, homografts, and xenografts, respectively. Aortic stenosis was present clinically in 11% of all AVRs, 4% of homograft AVRs, and 17% of xenograft AVRs.(ABSTRACT TRUNCATED AT 250 WORDS)

The relationship between fracture severity and complication rate in miniplate osteosynthesis of mandibular fractures.

There are many factors influencing the outcome of mandibular fracture management; however, the relationship between fracture severity and complication rate has only been recognised intuitively due to the absence of an accepted system of classification of the severity of these fractures. In 1989 Cooter and David described the alpha numeric system of computer based coding for craniofacial fractures. Using this system, a prospective sample of 324 patients with mandibular fractures presenting to the Royal Adelaide Hospital was coded for fracture severity and their progress followed with respect to complication rate. A strong correlation between complication rate and fracture severity was established.