Utilization of Augmented Reality Head-Mounted Display for the Surgical Management of Thoracolumbar Spinal Trauma

Background and Objectives: Augmented reality head-mounted display (AR-HMD) is a novel technology that provides surgeons with a real-time CT-guided 3-dimensional recapitulation of a patient's spinal anatomy. In this case series, we explore the use of AR-HMD alongside more traditional robotic assistance in surgical spine trauma cases to determine their effect on operative costs and perioperative outcomes. Materials and Methods: We retrospectively reviewed trauma patients who underwent pedicle screw placement surgery guided by AR-HMD or robotic-assisted platforms at an academic tertiary care center between 1 January 2021 and 31 December 2022. Outcome distributions were compared using the Mann-Whitney U test. Results: The AR cohort (n = 9) had a mean age of 66 years, BMI of 29.4 kg/m2, Charlson Comorbidity Index (CCI) of 4.1, and Surgical Invasiveness Index (SII) of 8.8. In total, 77 pedicle screws were placed in this cohort. Intra-operatively, there was a mean blood loss of 378 mL, 0.78 units transfused, 398 min spent in the operating room, and a 20-day LOS. The robotic cohort (n = 13) had a mean age of 56 years, BMI of 27.1 kg/m2, CCI of 3.8, and SII of 14.2. In total, 128 pedicle screws were placed in this cohort. Intra-operatively, there was a mean blood loss of 432 mL, 0.46 units transfused units used, 331 min spent in the operating room, and a 10.4-day LOS. No significant difference was found between the two cohorts in any outcome metrics. Conclusions: Although the need to address urgent spinal conditions poses a significant challenge to the implementation of innovative technologies in spine surgery, this study represents an initial effort to show that AR-HMD can yield comparable outcomes to traditional robotic surgical techniques. Moreover, it highlights the potential for AR-HMD to be readily integrated into Level 1 trauma centers without requiring extensive modifications or adjustments.

Interpretation of the endocrinology of hospital inpatients

Blood tests to assess the endocrine system are commonly performed in patients admitted to hospital. This may be because an endocrinopathy is thought to be aetiological in the presenting disease or suspected as an incidental occurrence by the clinician. Many patients, in addition to the pathology leading to admission, frequently have one or more comorbidities, a change in nutritional status and polypharmacy. Added to this, presentation with acute illness is a major life stress. All of these are likely to impact on one or more endocrine axes, although often only transiently. Endocrine evaluation in the vast majority of cases can be safely deferred to the outpatient setting. This article considers the most common endocrine anomalies discovered in hospital, the confounders, and provides guidance on how to investigate these further.

Management of persistent acromegaly following primary therapy: The current landscape in the UK

Acromegaly is the clinical consequence of chronic exposure of the tissues to excess GH and IGF-I. It is almost exclusively the result of a GH-secreting pituitary adenoma. In addition to the somatic features, uncontrolled acromegaly is associated with a number of complications and excess mortality. Management is aimed at control of the tumour; normalization of GH and IGF-I secretion and relief of symptoms. Initial management of GH-secreting pituitary adenoma is widely accepted as endonasal trans-sphenoidal surgery, with second-line therapy where disease is uncontrolled in most cases being somatostatin analogue therapy. With the combination of surgery and somatostatin analogue therapy, control is achieved in around 75% of patients; however, this leaves a significant proportion of patients requiring multimodality therapy to achieve remission. Within the UK, the health system has finite resources, and decisions for management require consideration of efficacy and cost-effectiveness. To add to the complexity, subtle differences exist in availability of high-cost medications used in the treatment of patients with acromegaly across the devolved nations of the UK. In this article, we discuss options for the management of persistent acromegaly following initial surgery and somatostatin analogue therapy, and explore earlier use of dopaminergics and conservative management.

Does Peri-Implant Mucosa Have a Prognostic Value?

The need for keratinized tissue around implants remains a controversial topic. However, reconstruction of keratinized mucosa may be needed to facilitate restorative procedures, improve aesthetics, and control plaque during oral hygiene. Free gingival grafts, connective tissue grafts, allogenic/xenograft materials, and apically positioned flaps have been used to augment soft tissue around implants. Four different timing protocols have been explored with regard to soft-tissue augmentation: before and during implant placement, during the second-stage surgery, or after restoration. The timing and technique of soft-tissue augmentation remain controversial and lack support from literature. Long-term clinical studies to establish clear guidelines are warranted.

Design of chronomodulated drug delivery system of valsartan: in vitro characterization

The aim of the present study was to design and evaluate a chronomodulated time-clock pulsatile tablets of valsartan to release it after a certain lag time, independent of the gastrointestinal pH, in its absorption window to cope with the circadian rhythm of human body for blood pressure elevation. Core tablets were prepared by direct compression of a homogenous mixture of valsartan, Avicel PH101, croscarmellose sodium, magnesium stearate and Aerosil. The core tablets were then sprayed coated with a sealing layer formed of ethyl cellulose that was subsequently coated with a release-controlling layer. Three different aqueous dispersions namely; carnauba wax or beeswax or a mixture in a ratio of 2.5:1, respectively, were used to form five time-clock tablet formulations having the release controlling layer with different thickness {B5, B10, B20, BW5 and CW5}. Quality control testing were carried out to the core tablets. Differential scanning calorimetry was also performed to detect the possible drug excipient interaction in the core tablet formulation. The release was carried out, for the prepared time-clock tablet formulations, in 0.1 N hydrochloric acid for the first 2 h, followed by phosphate buffer (pH 6.8) for 4.5 h. The effect of pH on valsartan release was studied through a release study in 0.1 N hydrochloric acid for 6.5 h. Two phase dissolution study was performed to the selected time-clock tablet formulation to predict the drug permeation through the gastrointestinal tract. Stability study of the selected formula was performed at 25°/60% RH and at 40°/75% RH for 3 months. Results showed that a release-controlling layer composed of a mixture of carnauba wax and beeswax in a ratio of 2.5:1 showed a reasonable release lag time. The release lag time of the tablets increased with the increase of the coat thickness, thus B20>B10>B5 with corresponding lag time values of 4.5, 3 and 2.5 h, respectively. Selected B5 tablet formula exhibited a reasonable lag time after which the highest, complete % drug release at pH 6.8 was obtained. In addition, a good partitioning of valsartan, between the aqueous and organic phases in a ratio of 1:7, was observed. The selected formula was stable for at least 3 months under standard long-term and accelerated storage conditions. In conclusion, in vitro studies revealed that the novel time-clock system could be used successfully to deliver valsartan in a pulsatile pH-independent manner. It provided a desirable lag time followed by a rapid and complete drug release accompanied by an expected effective permeation through the biological membranes upon release in the duodenum; the window of absorption, as indicated by the two phase release study.

Preclinical report on allogeneic uterus transplantation in non-human primates

STUDY QUESTION

Is it possible to perform allogeneic uterus transplantation (UTx) with a donation from a live donor in a non-human primate species and what immunosuppression is needed to prevent rejection?

SUMMARY ANSWER

Allogeneic UTx in the baboon is a donor- and recipient-safe surgical procedure; immunosuppression with induction therapy and a triple protocol should be used.

WHAT IS KNOWN ALREADY

UTx may become a treatment for absolute uterine factor infertility. Autologous UTx models have been developed in non-human primates with reports on long-term survival of the uterine grafts. STUDY DESIGN, SIZEAND DURATION: This experimental study included 18 female baboons as uterus donors and 18 female baboons as uterus recipients. The follow-up time was 5-8 weeks.

PARTICIPANTS/MATERIALS, SETTING AND METHODS

Uterus retrieval was performed with extended hysterectomy including bilateral uterine and internal iliac arteries and ovarian veins. After UTx, with vascular anastomoses unilateral to the internal iliac artery and the external iliac vein, the uterus recipients received one of the following: no immunosuppression (n = 4); monotherapy (oral slow release tacrolimus) (n = 4) or induction therapy (antithymocyte globulin) followed by triple therapy (tacrolimus, mycophenolate, corticosteroids; n = 10). Surgical parameters, survival, immunosuppression and rejection patterns were evaluated.

MAIN RESULTS AND THE ROLE OF CHANCE

The durations of uterus retrieval and recipient surgery were around 3 and 3.5 h, respectively. The total ischemic time was around 3 h. All the recipients and the donors survived the surgery. All the recipients presented rejection to some extent within the first weeks following UTx. In one recipient, the uterus was of normal appearance at the end of the study period. In spite of occasional high (>60 ng/ml) blood levels of tacrolimus, there was no evidence of nephrotoxicity.

LIMITATIONS AND REASONS FOR CAUTION

This initial non-human primate allogeneic UTx study indicates that further research is needed to optimize immunosuppression protocols in order to avoid uterine rejection.

WIDER IMPLICATIONS OF THE FINDINGS

The findings suggest that allogeneic UTx in primate species is feasible but continued work on this issue is needed.

STUDY FUNDING/COMPETING INTEREST(S)

The study was funded by the Swedish Research Council, ALF University of Gothenburg, Hjalmar Svensson Foundation and by Jane and Dan Olsson Research Foundation. The authors do not have any competing interest.

Pharmacokinetic evaluation of oral fenofibrate nanosuspensions and SLN in comparison to conventional suspensions of micronized drug

An increasing number of newly developed drugs show bioavailability problems due to poor water solubility. Formulating the drugs as nanosuspensions may help to overcome these problems by increasing saturation solubility and dissolution velocity. In the present study the bioavailability of the poorly soluble fenofibrate following oral administration was investigated in rats. Four formulations were tested: a nanosuspension type DissoCube(R), one solid lipid nanoparticle (SLN) preparation and two suspensions of micronized fenofibrate as reference formulations, one suspension in sirupus simplex and a second in a solution of hydroxyethy-cellulose in physiological saline. Both colloidal drug delivery systems showed approximately two-fold bioavailability enhancements in terms of rate and extent compared to the reference formulations. No significant differences were found in AUC(0-22 h) as well as in C(max) and t(max) between the two colloidal delivery systems. In conclusion, nanosuspensions may be a suitable delivery system to improve the bioavailability of drugs with low water solubility.

In Vitro Antifungal Activities of Sulfa Drugs against Clinical Isolates of Aspergillus and Cryptococcus Species

In vitro susceptibilities of ten clinical isolates, including five strains of Cryptococcus neoformans var. grubii and five strains of Aspergillus fumigatus, were determined against nine sulfa drugs using a microdilution method. Among the five tested media, minimum inhibitory concentration (MIC) values were observed only in YNB medium: no detectable level MIC value of less than 125 microg/ml was observed in the four remaining media against Cryptococcus species. Of the nine sulfa drugs, of which sulfaphenazole showed the highest antifungal activity, the MIC values for A. fumigatus and C. neoformans var. grubii were, respectively, 64 microg/ml and 4-8 microg/ml, suggesting high susceptibility of C. neoformans to sulfa drugs.

Majority of Actinomadura clinical isolates from sputa or bronchoalveolar lavage fluid in Japan belongs to the cluster of Actinomadura cremea and Actinomadura nitritigenes, and the description of Actinomadura chibensis sp. nov

In Japan during 1996-2004, 21 actinomycete strains that have madurose as the diagnostic cell-wall sugar and show true branching in their substrate and aerial mycelia were isolated from sputa or bronchoalveolar lavage (BAL) fluid of patients with pulmonary infections or who were suspected of having related infections. Chemotaxonomic studies showed that all the isolates belong to the genus Actinomadura. Among them, six and seven strains were classified respectively into clusters of Actinomadura nitritigenes and Actinomadura cremea based on 16S rDNA analyses because their 16S rDNA similarities to those respective species were greater than 99.5%. To our knowledge, this is first report that strains of above two species were isolated from clinical specimens. Neither Actinomadura madurae nor Actinomadura pelletieri strain was isolated, and one new species, Actinomadura chibensis, was proposed; the remaining seven strains were not assigned into any known species, suggesting the presence of another new Actinomadura species.

Clinical and therapeutic studies on mange in horses

At Kafr El-Sheikh province, Egypt, out of 117 examined drafting horses, mites were detected in 20 (17.09%) horses. The recovered mites were 14 Chorioptes, four Psoroptes and two Sarcoptes whereas mites were not detected in four cases clinically showed typical mange lesions. Interestingly, neither the age nor the sex of the examined horses had a clear influence on the prevalence of the infection. Clinical signs observed in mange infested horses were in the form of irregular skin lesions, severe itching and sometimes biting of affected skin areas and decrease feed consumption. The skin lesions mainly start as erythematous area followed by developing of papules and crust formation. Skin scratches as a result of traumatized lesions usually occurred. Hair was lost on the affected parts developing irregular alopecic areas. Distribution of the lesions was varied according to the type of mite. Chorioptic mite was detected in para-anal fold, distal portion of legs and tail lesions, Psoroptic mite was detected in withers, mane, shoulder and flank lesions whereas Sarcoptic mite was isolated mainly from lesions on the head and neck. Complete clinical and parasitological cure for mite infestation were obtained within 2 weeks in both moxidectin and ivermectin treated groups with 100% recovery rate. Our results indicated that moxidectin oral gel is effective and good alternative for the treatment of chorioptic mange in horse to avoid drug resistance that may develop as a result of the intensive use of ivermectin alone for long periods.

Nanosuspension formulations for low-soluble drugs: pharmacokinetic evaluation using spironolactone as model compound

Various particle sizes of spironolactone as a model low solubility drug were formulated to yield micro-and nanosuspensions of the type solid lipid nanoparticles and DissoCubes. Seven oral and one i.v. formulations were tested in an in vivo pharmacokinetic study in rats with the aim of characterizing the bioavailability of spironolactone on the basis of its metabolites canrenone and 7-alpha-thiomethylspirolactone. In addition, a dose escalation study was carried out using nonmicronized spironolactone suspension as well as a nanosuspension type DissoCubes. On the basis of AUC as well as Cmax ratios, three groups of formulations were distinguished. The biggest improvement was seen with a solid lipid nanoparticle formulation yielding a 5.7-fold increase in AUC for canrenone and a similar improvement based on the Cmax metric, followed by a group of three formulations containing nanosized, micronized, and coarse drug material and surfactant. The DissoCubes nanosuspension yielded highly significant improvements in bioavailability averaging 3.3-fold in AUC and 3.0-fold in terms of Cmax for canrenone. The third class encompasses all other formulations, which showed very little to no improvement in bioavailability. The results show that the particle size minimization was not the major determining factor in the bioavailability improvement. Rather, the type of surfactant used as stabilizer in the formulations was of greater importance. Improvement in drug solubility in the intestine as well as in dissolution rate of spironolactone are the most likely mechanisms responsible for the observed effect, although additional mechanisms such as permeability enhancement may also be involved.

Intestinal drug efflux: formulation and food effects

The intestine, primarily regarded as an absorptive organ, is also prepared for the elimination of certain organic acids, bases and neutral compounds depending on their affinity to intestinal carrier systems. Several of the transport systems known to mediate efflux in the major clearing organs--liver and kidney--are also expressed in the intestine. Examples of secretory transporters in the intestine are P-glycoprotein, members of the multidrug resistance associated protein family, breast cancer resistance protein, organic cation transporters and members of the organic anion polypeptide family. In this communication, the P-glycoprotein mediated intestinal secretion of talinolol, a model compound showing metabolic stability, has been investigated in the jejunum, ileum and colon of rat intestine by single-pass perfusion. A model has been developed which demonstrates an increase in carrier-mediated secretion in the order jejunum<ileum<colon. Furthermore, the potency of common excipients in peroral drug products towards inhibition of P-gp mediated secretion has been investigated using a radioligand-binding assay and transport studies in Caco-2 cell monolayers. Finally, evidence is provided which demonstrates that constituents of grapefruit juice not only may influence intestinal drug metabolism, but can also interfere with secretory transport systems, leading to a new and yet undescribed mechanism in drug-food interactions.

Pretreatment with potent P-glycoprotein ligands may increase intestinal secretion in rats

The expression of P-glycoprotein is induced in cell cultures upon exposure to various inducers. Therefore, the aim of the present study was to evaluate the in-vivo relevance of this observation, i.e. the influence of chronic pretreatments with selected drugs -- all of which are ligands to P-glycoprotein (P-gp) as demonstrated in radioligand binding studies and all of which have some or a considerable effect on P-gp expression in Caco-2 cells -- on the effective intestinal permeabilities of the model compound talinolol in rats employing in-situ single-pass intestinal perfusion of three different gut segments. Talinolol was selected, because it shows high selectivity for one of the exsorptive transporters (P-gp) and its intestinal permeability is very sensitive to changes in exsorption when the perfusate concentration is low. Prior to the induction study the perfusion model was optimized regarding the type and concentration of a competitive inhibitor which may be used to block the exsorption-related permeability reduction (through intestinal exsorption) during an ongoing perfusion and would permit an intra-individual comparison of the effective permeability without and with blockade of exsorption. While repetitive verapamil and talinolol dosing had no statistically significant exsorption-inducing effect, vinblastine and rifampicin pretreatments resulted in decreased intestinal talinolol permeabilities in the three tested gut segments, duodenum, jejunum, and colon [e.g., S-talinolol in jejunum: control, 2.50 x 10(-4) cm/s; vinblastine induction, 1.48 x 10(-4) cm/s (P<0.05); rifampicin induction, 1.51 x 10(-4) cm/s (P<0.05)]. Addition of an efficient secretion inhibitor (vinblastine) to the perfusate permitted the determination of the impact of inhibitable secretory processes on the total effective permeabilities and an estimation of passive permeability in the respective individual. The inhibitable permeability fractions were higher for vinblastine than for any other pretreatment and the difference from control pretreatment was statistically significant for all intestinal segments (duodenum, 61.8%; jejunum, 63.1%; colon, 43,7%; S-talinolol). Statistically significant differences were also detected for rifampicin in the perfused duodenum and jejunum (33.1 and 27.5% increase in inhibitable fraction, respectively, for S-talinolol). These differences are explained by a significant induction of outside-directed transport in the intestinal enterocytes by vinblastine and rifampicin.

P-glycoprotein transporters and the gastrointestinal tract: evaluation of the potential in vivo relevance of in vitro data employing talinolol as model compound

Among the different application routes peroral administration remains the one most widely used. Hence, mechanisms affecting p.o. bioavailability are of particular interest, also in drug development. In recent years, intestinal drug secretion mediated by the multi-drug resistance gene product P-glycoprotein (Pgp) has been discovered as a possible mechanism of low and erratic bioavailability. Due to the saturability of this process, a dose-dependent apparent oral clearance may be observed which decreases upon increasing dose. However, in vivo intestinal secretion might be revealed only in the lower or subtherapeutic dose range. In permeability studies with Caco-2 cell monolayers, the MDR-reversing agent verapamil inhibits secretion of P-glycoprotein substrates and, hence, increases apical-to-basolateral permeability. The aim of the rat studies with talinolol presented here was to test the relevance of the intestinal secretion process as well as the extent of inhibition by verapamil in ex vivo, in situ, and in vivo talinolol/verapamil drug-drug interaction studies. Intestinal secretion of talinolol was detected indirectly in ex vivo studies via transport inhibition with verapamil and directly in in situ intestinal perfusions in rats following a talinolol i.v. bolus. Both i.v. and p.o. verapamil appear to affect the concentration-time profiles of talinolol. Relevant observations with respect to drug absorption are the decreased apparent oral clearance upon verapamil coadministration as well as the decreased tmax and mean absorption times at high verapamil doses. Talinolol may be regarded as a potential model compound for mechanistic studies on Pgp interactions, including permeability as well as binding studies and the involvement of transporters other than Pgp.

Twin-reversed arterial perfusion (TRAP) sequence: case reports and review of literature

The twin reversed-arterial-perfusion (TRAP) sequence found in monozygotic twins is a consequence of primary or secondary cardiac development disruption and direct arterioarterial and venovenous placental anastomoses. Associated findings include the presence of a single umbilical artery (66%) and chromosomal abnormalities in the acardiac twin (33%). Morphological abnormalities in the acardiac twin are consistent with perfusion of tissues supplied by the common iliac and lower branches of the aorta with deoxygenated blood. The pump or donor twin may develop cardiac failure because of the anomalous perfusion circuit. Polyhydramnios is significantly associated with presence of renal tissue in the acardiac twin. An acardiac pump twin weight ratio (> 50%) is associated with the development of polyhydramnios and preterm labour. Identified high-risk factors for poor obstetrical outcome include: acardiac anceps, polyhydramnios, acardiac twin with ears, and pump twin cardiac failure. Management options include elective termination, observation (serial cardiotocography (CTG), ultrasonography and echocardiography) and selective nonsurgical interventions (indomethacin, digitalis, tocolysis). Additionally, surgical interventions (hysterotomy with selective delivery of the acardiac twin or ligation of the acardiac twin's umbilical cord), and ultrasound-guided embolization of the acardiac twin's umbilical artery with absolute alcohol, platinum coils, or thrombogenic coils have been reported. The most appropriate interventions for the various clinical presentations of this disorder are as yet undetermined, and conservative nonintervention is often appropriate. Long-term follow-up data on surviving pump twins are lacking. It is anticipated that centres with active study protocols for these conditions will best serve patient care and clinical research needs.

Vibration analysis of single element transducer in acoustic arrays

This paper offers a method for the vibration analysis of single element transducer in acoustic arrays as a damped multi-degree of freedom mechanical system with forced excitation at the fundamental thickness mode. The link between the frequency response and the element structural modal shape is analyzed and a method for controlling these modes such that they introduce no artifacts in the performance of the final array and imaging system is discussed.

Real time acoustic imaging by holographic interferometry

A two-step real time acoustic imaging system is presented. The system incorporates a novel acoustic image coupler which transfers an acoustical interference pattern from a water-bounded to an air-bounded surface with vibration amplitude amplification. An original technique termed step-biased real time holographic interferometry is used to convert the amplified mechanical vibration pattern, which carries all information about the insonified object, into a visual image with improved sensitivity.

Dead zone elimination in acoustic arrays

Acoustic imaging systems utilizing multi-element acoustic transducers in the transmit receive mode suffer from an artifact named dead zone area due to the loss of the acquired information in that area. The artifact shows up on the displayed image as a very bright region due to the receivers saturation next to the transducer face and extending further out in the field as a fixed pattern noise. An investigation of the cause of this artifact, and a method for its elimination is presented in this paper.

Characterization of multielement acoustic arrays by acousto-optic diffraction methods

The characterization of multielement acoustic arrays for diagnostic ultrasound has always been a thorny problem. This paper describes optical techniques for determining the essential parameters of wideband multielement arrays. These parameters which are measured are the spatial frequency response of both the single element and full array, the acoustic cross-coupling between elements, the focusing properties of the array, and the acoustic field intensity.