Employing mesenchymal stem cells to support tumor-targeted delivery of extracellular vesicle (EV)-encapsulated microRNA-379.

Adult Mesenchymal Stem Cells (MSCs) have a well-established tumor-homing capacity, highlighting potential as tumor-targeted delivery vehicles. MSCs secrete extracellular vesicle (EV)-encapsulated microRNAs, which play a role in intercellular communication. The aim of this study was to characterize a potential tumor suppressor microRNA, miR-379, and engineer MSCs to secrete EVs enriched with miR-379 for in vivo therapy of breast cancer. miR-379 expression was significantly reduced in lymph node metastases compared to primary tumor tissue from the same patients. A significant reduction in the rate of tumor formation and growth in vivo was observed in T47D breast cancer cells stably expressing miR-379. In more aggressive HER2-amplified HCC-1954 cells, HCC-379 and HCC-NTC tumor growth rate in vivo was similar, but increased tumor necrosis was observed in HCC-379 tumors. In response to elevated miR-379, COX-2 mRNA and protein was also significantly reduced in vitro and in vivo. MSCs were successfully engineered to secrete EVs enriched with miR-379, with the majority found to be of the appropriate size and morphology of exosomal EVs. Administration of MSC-379 or MSC-NTC cells, or EVs derived from either cell population, resulted in no adverse effects in vivo. While MSC-379 cells did not impact tumor growth, systemic administration of cell-free EVs enriched with miR-379 was demonstrated to have a therapeutic effect. The data presented support miR-379 as a potent tumor suppressor in breast cancer, mediated in part through regulation of COX-2. Exploiting the tumor-homing capacity of MSCs while engineering the cells to secrete EVs enriched with miR-379 holds exciting potential as an innovative therapy for metastatic breast cancer.

Computer simulation of trabecular remodeling using a simplified structural model.

A simplified three-dimensional simulation of trabecular bone remodeling has been developed. The model utilizes 441 planar structural units to represent approximately 50 mm3 of initial bone volume with 199 basic multicellular units (BMUs). The simulation takes into account trabecular perforation in the structural model. The cases of male bone remodeling with no menopause and female bone remodeling with menopause are examined from the period of simulated age 25-80 years. Menopause is arbitrarily started at age 45 and extends for 7.5 years. Zero-, first-, and second-order BMU activation responses are employed to examine how the bone would be affected by the method of increase of BMU activation during menopause. At age 80, the female bone remodeling simulation produced a bone volume loss of approximately 49% for all three activation responses. This compared to a 38% bone volume loss for the case of no menopause. For the menopause simulations, an average of about 40% of the total bone loss was due to perforation.

Investigation of a pseudo-outbreak of orthopedic infections caused by Pseudomonas aeruginosa.

OBJECTIVE: To report a pseudoepidemic of Pseudomonas aeruginosa infections discovered during an investigation of postoperative joint infections. DESIGN: A retrospective review of case patients' hospital charts, operative reports, and laboratory data, as well as environmental culturing, polymerase chain reaction (PCR) ribotyping of outbreak isolates, and in vitro analysis of P aeruginosa growth characteristics. SETTING: A 510-bed, university-affiliated adult tertiary care hospital. RESULTS: Between October 1 and December 1, 1992, seven postsurgical joint infections were diagnosed, including four caused by P aeruginosa. A bottle of "sterile" saline used to process tissue specimens was found to be contaminated with P aeruginosa. Further investigation revealed that P aeruginosa had grown from seven additional tissue cultures, all of which had been processed with the contaminated saline. PCR ribotypes of the contaminant matched those of the clinical isolates. In vitro, P aeruginosa strains were viable in commercial nonbacteriostatic saline, but never caused visible turbidity. Six patients received antibiotics for their presumed infections; four patients had peripherally inserted central catheters placed, and one experienced severe anaphylactic reactions to several antibiotics. CONCLUSIONS: Pseudoepidemics due to common organisms are often difficult to detect, and delayed recognition can result in substantial morbidity. This outbreak investigation illustrates the potential for contamination of diluents in the microbiology laboratory and emphasizes the need for meticulous quality control.

Analysis of the torque applied to bone screws by trauma surgeons. Comparisons based on years of experience and material of implant construction.

Stability of an internal fixation construct is dependent on the torque placed on the screws holding the plate, the number of screws in the construct, and the number of cortices purchased by each screw. This study addresses the ability of surgeons to apply uniform torque and the variability between stainless steel and titanium. A total of 630 measurements were made by trained orthopedists using a device to measure the torque applied to 3.5 mm screws when tightening them to a plate. Variations were found to be significant depending on the number of years the orthopedist was in practice and the type of construct material used. The average torque applied to a stainless steel construct is 5.82 in-lb, while the torque applied to titanium is 5.41 in-lb (P < 0.01). The longer an orthopedist is in practice, the more torque will be applied to the screw/plate construct.

A prospective satisfaction study and cost analysis of a pilot child telepsychiatry service in Newfoundland.

We evaluated user satisfaction with a PC-based videoconferencing system used for child psychiatry assessments and performed a cost analysis. Thirty patients (aged 5-16 years), accompanied by a parent, completed a psychiatric assessment using the videoconferencing system. One of five child psychiatrists was randomly assigned to each assessment. Satisfaction questionnaires were completed after each assessment by the psychiatrist, patient and parent. Parents also completed a cost questionnaire. The telecommunications bandwidth was 336 kbit/s. The psychiatrists stated that they were either 'very satisfied' or 'satisfied' with the telepsychiatry assessments. On a five-point Likert scale (1 = lowest, 5 = highest), 28 of the 30 parents (93%) rated their satisfaction level as 5; the other two rated it 4. All 30 parents (100%) stated that they 'liked' the telepsychiatry assessment and would use the system again. Twenty-nine parents (97%) indicated that they would prefer to use the telepsychiatry system to travelling to see a child psychiatrist in person. Eleven children (aged 5-12) participated and all (100%) said they 'liked' using the telepsychiatry system. Five out of nine children (56%) stated they liked the 'television doctor' better than the 'real' doctor; four said they had no preference. Nineteen adolescents (aged 13-16 years) participated and most were very satisfied or satisfied with the system. Seventeen of the 19 adolescents (89%) said they would prefer to see the psychiatrist on the videoconferencing system to travelling for an assessment, and the same number said that they would use telepsychiatry again. The estimated total travel cost for the 30 patients was $12,849, an average of $428 per patient. The total cost of the telepsychiatry service for the three-month pilot was $12,575, or $419 per patient.

A randomized, controlled trial of child psychiatric assessments conducted using videoconferencing.

We used a PC-based videoconferencing system to conduct child psychiatry assessments. The telecommunications link was six digital lines, giving a total bandwidth of 336 kbit/s. Twenty-three patients (aged 4-16 years), accompanied by their parents, completed two psychiatric assessments, one via videoconferencing and another face to face (FTF). The order of assessments was randomized. Questionnaires were used to record the diagnosis, treatment recommendations and the psychiatrists', patients' and their parents' satisfaction with each assessment. An independent evaluator concluded that in 22 cases (96%) the diagnosis and treatment recommendations made via the videoconferencing system were the same as those made FTF. The psychiatrists stated that videoconferencing assessments were an adequate alternative to FTF assessments and did not interfere with diagnosis. However, the responses from the psychiatrist satisfaction questionnaire showed that they preferred FTF assessments. No significant difference was found in the patients' or parents' satisfaction responses after the two types of assessment. The majority of children (82%) 'liked' using the telepsychiatry system and six (26%) preferred it to a FTF assessment. Most parents (91%) indicated that they would prefer to use the videoconferencing system than to travel a long distance to see a psychiatrist in person.

Comparison of anterior cervical fusions using autogenous bone graft obtained from the cervical vertebrae to the modified Smith-Robinson technique.

Anterior cervical discectomy and interbody grafting provide excellent results in treating cervical radiculopathy. This prospective study compares the results of the technique obtaining autogenous bone from the cervical vertebrae for grafting to the modified Smith-Robinson technique using autogenous iliac crest graft. Seven levels in six patients were fused using the vertebral body autograft technique and 43 levels in 40 patients using the standard technique. All patients had radiculopathy and neck pain. Statistically significant differences in fusion rate (4/7 vertebral body autograft; 40/43 modified Smith-Robinson) (p = 0.029), disc height maintenance (p = 0.001), and neck pain improvement (p = 0.05) occurred between the techniques. We do not recommend vertebral body autograft over the modified Smith-Robinson technique for anterior cervical fusion following discectomy.

Adolescent and pre-adolescent suicide in Newfoundland and Labrador.

This study investigated suicides by people aged ten to 19 in Newfoundland and Labrador from 1977 to 1988. It is the first study of suicide in the province to use the records of death from all eight hospital pathology departments in the province and from the office of the Chief Forensic Pathologist. Cases were selected for the study using standardized criteria, independent of the manner of death recorded on the death certificate. A suicide rate of 4.37 per 100,000 was found. This rate and the age- and sex-specific suicide rates are lower than the official figures for Canada but higher than those reported in earlier Newfoundland studies. The rate for males was nearly five times the female rate, and the rate for people aged 15 to 19 was nearly six times that of people aged ten to 14. Suicide rates for Labrador were higher than for the island portion of the province for both Native and for non Native adolescents. Extremely high rates of suicide were found only among the Native population living in Northern Labrador, while none were recorded for Native people elsewhere. Firearms accounted for 54% and hanging for 33% of all suicides. Thirty percent of suicides occurred on a Saturday. Only 36 of the 63 deaths included in this study were designated as suicide on death certificates. The higher rate of under-reporting of suicide than in other jurisdictions suggests that official rates may not be useful for comparisons. The reasons for the high rate of under-reporting are discussed.

Blood pressure measurement by junior hospital doctors--a gap in medical education?

A questionnaire survey, combined with an observational study, evaluated the knowledge of doctors in training grades on the practical aspects of blood pressure measurement. Eighty (non-consultant) junior hospital doctors, graduates from 30 separate medical schools, participated in the study. The results show that 27 (33%) doctors acknowledged no formal education on how to measure blood pressure. This lack of precise theoretical knowledge was matched by an observed poor clinical technique in over one third of the study group. The precision and accuracy of blood pressure recording is fundamental to the clinical examination of patients, and crucial in their management in both hospital and community settings. The findings of this study support the urgent need for further training and assessment of blood pressure measurement at undergraduate, and postgraduate level.

Holding power of cortical screws after power tapping and hand tapping.

Paired equine third metacarpal bones were drilled and tapped for 4.5 mm and 5.5 mm cortical screws. Tapping was done by hand or with an air-driven reversible orthopedic drill. Screws were inserted and subjected to extraction forces to failure of the osseous threads or the screws. There was no difference in holding power of either screw size between hand-tapped and power-tapped holes.

Designing fast converging phylogenetic methods.

Absolute fast converging phylogenetic reconstruction methods are provably guaranteed to recover the true tree with high probability from sequences that grow only polynomially in the number of leaves, once the edge lengths are bounded arbitrarily from above and below. Only a few methods have been determined to be absolute fast converging; these have all been developed in just the last few years, and most are polynomial time. In this paper, we compare pre-existing fast converging methods as well as some new polynomial time methods that we have developed. Our study, based upon simulating evolution under a wide range of model conditions, establishes that our new methods outperform both neighbor joining and the previous fast converging methods, returning very accurate large trees, when these other methods do poorly.

Regulation of RpoS by a novel small RNA: the characterization of RprA.

Translational regulation of the stationary phase sigma factor RpoS is mediated by the formation of a double-stranded RNA stem-loop structure in the upstream region of the rpoS messenger RNA, occluding the translation initiation site. The interaction of the rpoS mRNA with a small RNA, DsrA, disrupts the double-strand pairing and allows high levels of translation initiation. We screened a multicopy library of Escherichia coli DNA fragments for novel activators of RpoS translation when DsrA is absent. Clones carrying rprA (RpoS regulator RNA) increased the translation of RpoS. The rprA gene encodes a 106 nucleotide regulatory RNA. As with DsrA, RprA is predicted to form three stem-loops and is highly conserved in Salmonella and Klebsiella species. Thus, at least two small RNAs, DsrA and RprA, participate in the positive regulation of RpoS translation. Unlike DsrA, RprA does not have an extensive region of complementarity to the RpoS leader, leaving its mechanism of action unclear. RprA is non-essential. Mutations in the gene interfere with the induction of RpoS after osmotic shock when DsrA is absent, demonstrating a physiological role for RprA. The existence of two very different small RNA regulators of RpoS translation suggests that such additional regulatory RNAs are likely to exist, both for regulation of RpoS and for regulation of other important cellular components.

Response of canine bone to a synthetic bone graft material.

A model simulating a spiral diaphyseal fracture with butterfly fragments and bone loss was utilized to evaluate an hydroxyapatite/tricalcium phosphate, and collagen composite bone graft substitute in twelve dogs. The resultant grafted and contralateral control femora were tested in torsion at one year. This study examines the histological response to the graft material as well as crack propagation and fracture surface morphology using light microscopy and SEM. SEM and gross evaluation of the grafted bones revealed that 8/12 had fractured through bone outside the osteotomy site and all fractures included bone outside the graft site. No graft material was demonstrated at the points of initiation or termination of fracture for any of the bones. It was apparent that recorticalization had begun to occur at the graft site but the canal had not yet fully formed. The HA/TCP was seen to be tightly bound in tissue which had the appearance of new bone. Bone was found to be in direct apposition to the surface of the ceramic and within pores with no intervening soft tissue. Much of the new bone had remodeled into well organized Haversian systems with some patchy areas of woven bone and osteoid seen with polarized light illumination.

Serum cefazolin levels during spinal fusion: effect of blood loss and duration of surgery.

Perioperative cefazolin prophylaxis is commonly employed in posterior spinal fusion (PSF) procedures, which are often lengthy and involve significant blood loss. In this study, serum levels of prophylactically administered cefazolin were measured serially during spinal fusion procedures, and the possible relationship of antibiotic concentrations to blood loss and fluid therapy were examined. Serum antibiotic levels, measured at 30-min intervals, declined with a half-life of 90 min, similar to the previously reported experience with normal adult volunteers. There was no relationship between serum half-life and blood loss or fluid replacement. An explanation for these findings is offered, along with recommendations for dosing.

Torsional properties of healed canine diaphyseal defects grafted with a fibrillar collagen and hydroxyapatite/tricalcium phosphate composite.

The need for alternatives to autogenous bone grafts is widely recognized. This study compared the torsional strength of canine femora 1 year after grafting with one of three forms of a collagen/hydroxyapatite/tricalcium phosphate bone grafting material (COLLAGRAFTTM), autogenous bone, or no graft. The groups were compared to each other and to the unoperated contralateral femora. Results of torsional testing were evaluated for torsional strength, torsional displacement, total energy to fracture and White fracture mode. Data analysis showed lower torsional strength of the operated vs. unoperated femora with the exception of morsellized COLLAGRAFTTM material, which had higher strength. However, the only difference in the operated groups was that the morsellized COLLAGRAFTTM had greater strength than several groups including the autogenous bone group. There was no difference found in angular displacement between any of the groups. However, there was a difference in the energy to fracture in both strip forms of the COLLAGRAFTTM. The final conclusion is that in this model, grafting with COLLAGRAFTTM provided torsional properties at one year postoperatively at least equivalent to autogenous bone.

Histological and electron microscopic analysis of tissue response to synthetic composite bone graft in the canine.

A synthetic composite bone graft material, composed of fibrillar collagen, hydroxyapatite, and tricalcium phosphate, was evaluated in canine femoral shaft defects and compared to ungrafted defects and defects grafted with autogenous bone. The results of mechanical testing of the grafted femora in torsion at 1 year postoperatively were previously reported. This report details the histological and microscopic features of the graft sites. The results of this study suggest that the healing of the graft site is not yet complete at 1 year and that healing may be more complete in defects that received the synthetic graft as compared to ungrafted sites and autogenous bone graft. The bone tissue appears to respond to the graft particles as if they were bone particles.