Strength and flexibility of lithium disilicate bonded to polyetherketoneketone.

STATEMENT OF PROBLEM: Polyetherketoneketone (PEKK) is a high-performance polymer gaining popularity in dentistry for the fabrication of crowns, fixed partial dentures, removable partial denture frameworks, and frameworks for implant-supported fixed complete dentures. Despite a lack of performance data, lithium disilicate crowns have been bonded to retentive elements in PEKK frameworks. PURPOSE: The purpose of this in vitro study was to compare the bond strengths and flexibility of lithium disilicate to PEKK or zirconia. MATERIAL AND METHODS: Forty-five PEKK, 15 zirconia, and 60 lithium disilicate beam-shaped specimens (12.5×2×2 mm) were fabricated. The ends of the PEKK beams were subjected to 3 different surface treatments before the application and light polymerization of a primer: 50-µm aluminum oxide airborne-particle abrasion, nonthermal air plasma, and argon-oxygen plasma. The zirconia specimen bonding surfaces were prepared with 50-µm aluminum oxide airborne-particle abrasion and the application of primer. Lithium disilicate specimens were etched with 4.5% hydrofluoric acid, and primer was applied. The lithium disilicate specimens were luted with an adhesive resin cement to the PEKK and zirconia specimens by using light-activated and chemically activated polymerization. Fifteen monolithic specimens of PEKK, lithium disilicate, and zirconia (25×2×2 mm) were also fabricated. All specimens were incubated overnight in 100% humidity before testing. Bonded and monolithic specimens were loaded in a universal testing machine, and 4-point bend tests were conducted until failure (n=15). The flexural modulus and strength were calculated and statistically analyzed with 1-way analysis of variance and Student-Newman-Keuls post hoc tests (α=.05). RESULTS: All bonded specimens failed at the adhesive interface. The zirconia-lithium disilicate bond strength was approximately twice that of the strongest group of PEKK (airborne-particle abrasion group) bonded to lithium disilicate (42 ±12 MPa and 24 ±13 MPa, respectively) and was approximately 9 times more rigid (71 ±19 GPa and 8 ±2 GPa, respectively). Monolithic PEKK fractured at 238 ±22 MPa, monolithic zirconia at 771 ±128 MPa, and monolithic lithium disilicate at 173 ±26 MPa. Monolithic PEKK was approximately 30 times more flexible than monolithic zirconia (6 ±1 GPa and 178 ±16 GPa, respectively). All values were statistically significantly different (P<.05), except for the bond strength between lithium disilicate and PEKK treated with airborne-particle abrasion and nonthermal air plasma and the flexural moduli of PEKK to lithium disilicate. CONCLUSIONS: Bond strength between PEKK and lithium disilicate was significantly weaker than that between zirconia and lithium disilicate. Monolithic PEKK was significantly more flexible than monolithic zirconia.

Bronchial thermoplasty increases airway volume measured by functional respiratory imaging.

BACKGROUND: The purpose of this study was to use CT scanning with computational fluid dynamics to evaluate the mechanisms by which Bronchial Thermoplasty (BT) improves asthmatic symptoms. METHODS: The study was conducted in a university teaching hospital, experienced in performing BT. Imaging studies were performed before, and after, BT of the left lung, and prior to treatment of the right lung, which therefore acted as a control. On each occasion, two high-resolution CT scans were performed, one at full inspiration (TLC) and the other at Functional Residual Capacity (FRC). The study protocol was offered to 10 patients, all of whom met the definition of severe asthma, despite high dose inhaled corticosteroids and dual long acting bronchodilators. RESULTS: Significant increases in airway luminal volume were observed on the treated side, compared with control, at both full inspiration (by 27%) and at FRC (by 17%). The ratio of distal airway volume to lung volume significantly increased on the treated side. The change in airway volume with inspiration from FRC increased by 48% on the treated side compared to 5% in the control lung, suggesting treatment increased airway distensibility. No effect was observed on airway wall thickness, nor air trapping. There was a trend towards correlation between the improvement in airway volume at TLC and improvement in symptoms. CONCLUSION: This study demonstrates that BT increases the luminal airway volume on the treated side compared to the control lung. We suggest that this is an important link between the airway smooth muscle atrophy demonstrated pathologically, and the improvement in symptoms observed clinically.

Iron-catalysed, general and operationally simple formal hydrogenation using Fe(OTf)3 and NaBH4.

An operationally simple and environmentally benign formal hydrogenation protocol has been developed using highly abundant iron(iii) salts and an inexpensive, bench stable, stoichiometric reductant, NaBH4, in ethanol, under ambient conditions. This reaction has been applied to the reduction of terminal alkenes (22 examples, up to 95% yield) and nitro-groups (26 examples, up to 95% yield). Deuterium labelling studies indicate that this reaction proceeds via an ionic rather than radical mechanism.

Thiopentone-based total intravenous anaesthesia for a patient with carnitine palmitoyltransferase II deficiency and malignant hyperthermia susceptibility.

In this case report, we discuss the use of a thiopentone infusion for the maintenance of anaesthesia in a patient with confirmed malignant hyperthermia susceptibility and carnitine palmitoyltransferase 2 deficiency. The concurrence of both diagnoses precluded the use of both propofol-based total intravenous anaesthesia and volatile inhalational anaesthesia. This patient had been anaesthetised previously with a triple infusion regimen of thiopentone, midazolam and remifentanil and this was a unique opportunity to compare the two instances. Electroencephalogram-based depth of anaesthesia monitoring was in routine use by the time of the second anaesthetic, and thus, the thiopentone infusion could be adjusted accordingly, resulting in a more rapid emergence time. We hope that this case may serve as an example of suitable anaesthetic alternative should both propofol infusion and inhalational anaesthesia not be an option.

Community mental health nurses' and compassion: an interpretative approach.

WHAT IS KNOWN ON THE SUBJECT?: The concept of compassion is well documented in the healthcare literature but has received limited attention in mental health nursing. WHAT THIS PAPER ADDS TO EXISTING KNOWLEDGE?: Mental health nurses struggle with defining compassion. The study, with its limitations, brings greater clarity to the meaning of compassion for community mental health nurses and NHS organizations. Mental health nurses need time to reflect on their provision of compassionate care. WHAT ARE THE IMPLICATIONS FOR PRACTICE?: The study has shown that compassion is important for NHS healthcare management, frontline mental health nurses and policy-makers in UK, and there is potential for sharing practice and vision across NHS organisations. Mental health nurses could benefit from training to facilitate their understanding of compassionate practices. Emphasis should be placed on the importance of self-compassion and how this can be nurtured from the secure base of clinical supervision. ABSTRACT: Introduction There is increasing emphasis in policy, research and practice in the UK and internationally on the importance of caring in health care. Compassion needs to be at the core of all healthcare professionals' practice. Recently, health care has received negative attention through media and government reports which cite a lack of compassion in care. Rationale The concept of compassion has received limited attention in community mental health nursing. Aim Based on data taken from semi-structured interviews with community mental health nurses, this paper aims to describe interpretations and perspectives of compassion to gain insight and development of its meaning. Method A naturalistic, interpretive approach was taken to the study. Semi-structured interviews with nine mental health nurses were analysed using Burnard's 14-step model of thematic analysis. Findings The research illuminates the complexity of compassion and how its practice impacts on emotional responses and relationships with self, patients, colleagues and the employing organization. Participants identified difficulties engaging with compassionate practice whilst recognizing it as a driving force underpinning provision of care. Implications for practice Mental health nurses need to be supported to work towards a greater understanding of compassionate care for clinical practice and the need for self-compassion.

Nutritional effects of surgery, radiation therapy, and adjuvant chemotherapy for soft tissue sarcomas.

To determine the nutritional effects of aggressive combined modality cancer therapy, 35 consecutive patients undergoing surgery, radiation therapy, and adjuvant chemotherapy for soft tissue sarcomas of the head, neck, and trunk were prospectively studied. Changes in body weight, total protein, albumin, total lymphocyte count, and creatinine/height ratio were studied. Significant weight loss occurred with surgery, radiation therapy, and doxorubicin/cyclophosphamide, but not methotrexate, chemotherapy. Total protein and albumin did not change significantly with any of the individual therapies. On long-term follow-up (mean 27 months), patients who survived free of sarcoma showed little nutritional morbidity. Patients with progressive sarcoma, however, showed decreases of 9% in body weight (NS), 11% in total protein (p less than 0.01), 17% in serum albumin (p less than 0.05), and 64% in total lymphocyte count (p less than 0.02). These data indicate that aggressive combined modality cancer therapy can have significant acute nutritional effects. Long-term nutritional morbidity, however, is minimal in patients without recurrent disease. In contrast, patients with recurrent disease show severe nutritional deficits which seem more a consequence of the progressive disease than of the aggressive therapy.

Hair-thread tourniquet syndrome .

We have witnessed six cases of the hair-thread tourniquet syndrome, an entity characterized by strangulation of an appendage (toes, fingers, or external genitalia) by hair or hair-like fibers in the pediatric population. All six of our cases were in infants, 12 days to 5 months of age. The offending fibers were hair in three of the four patients with toe injuries and synthetic fibers from mittens in the finger cases. All six patients were treated by immediate removal of the constricting fibers, and, in spite of the worrisome appearance of the tissue distal to the constriction, all six eventually healed without significant tissue loss. A review of the literature indicated 60 similar cases of this type reported, 24 involving toes, 14 involving fingers, and 22 involving genitals. The majority of the toe and external genitalia cases were caused by hair, whereas the majority of finger strangulations were caused by thread from mittens. At greatest risk for strangulation are the middle finger and third toe, followed by the index finger and second toe. Patients with finger or penile involvement were more likely to suffer significant complications from the injuries than those patients with toe involvement. Based on our own experience and that described in the literature, we recommend prompt removal of the offending fiber, followed by prolonged conservative management of the damaged distal tissue, in the hope of maximal tissue salvage. Increased physician awareness of this syndrome is mandatory for prevention, diagnosis, and early treatment.

Granulocyte functions during maturation of human promyelocytic leukemia cells.

Human promyelocytic leukemia cells (HL-60) mature into functional granulocytes in response to in vitro treatment with several classes of chemical agents. Compounds that increase intracellular adenosine 3':5' -cyclic monophosphate induce a modified program of maturation in which the cells demonstrate functional properties characteristic of mature phagocytic cells while remaining morphologically immature. We compared the developmental programs initiated by two well-studied inducers, retinoic acid and dimethyl sulfoxide, with the programs initiated by two inducers known to raise intracellular adenosine 3':5' -cyclic monophosphate; N6, O2-dibutyryl adenosine 3':5' -cyclic monophosphate and the combination of prostaglandin E2 and theophylline. In response to the increase in intracellular adenosine 3':5' -cyclic monophosphate, the cells ceased proliferation, expressed chemotactic receptors and demonstrated stimulated enzyme release within 24 h. Chemotaxis, adherence, NBT reduction and superoxide production appeared by 72 h, although the cells remained unchanged morphologically. A similar developmental program was induced by dimethylsulfoxide, but appearance of the markers was delayed by 48 h. Expression of these markers was delayed and incomplete in response to retinoic acid.

Zoocin A immunity factor: a femA-like gene found in a group C streptococcus.

A 6.8-kb fragment of Streptococcus equi subsp. zooepidemicus 4881 DNA containing the zoocin A gene (zooA) was cloned in Escherichia coli and sequenced. We have identified a gene we call zoocin A immunity factor (zif), which protects the producer cell from the otherwise lethal action of its own product. Transformation of Streptococcus gordonii DL1 with zooA and zif changed its phenotypic character from a non-zoocin A producing-zoocin A sensitive cell to a zoocin A producing-zoocin A resistant cell. zif has sequence homology to femA (factor essential for methicillin resistance) and lif (lysostaphin immunity factor). No differences were observed in amino acid or amino sugar compositions of peptidoglycan purified from zoocin A sensitive vs. zoocin A immune cells.

Extracellular proteolytic activation of bacteriolytic peptidoglycan hydrolases of Staphylococcus simulans biovar staphylolyticus.

Staphylococcus simulans biovar staphylolyticus secreted two bacteriolytic peptidoglycan hydrolases as proproteins that were activated as they were processed by an extracellular sulphydryl protease. This processing resulted in the production of multiple molecular-mass forms of each enzyme. Cells from early exponential phase cultures were susceptible to lysis by the mature forms of each of the peptidoglycan hydrolases whereas stationary phase cells were resistant. Thus secretion of these bacteriolytic enzymes during early exponential growth as precursors that are activated later by the protease would provide time for the cells to become resistant.

Beta-lactamase is encoded on plasmid pACK3 in Staphylococcus simulans biovar staphylolyticus.

Staphylococcus simulans biovar staphylolyticus, the lysostaphin-producing organism, contains five plasmids designated pACK1 through pACK5. Hybridization analysis using cloned beta-lactamase gene (bla) as probe and characterization of cured strains revealed that bla resides on pACK3 rather than on the lysostaphin endopeptidase plasmid (pACK1) as reported by others.

Plasmid-encoded catalase of Staphylococcus simulans biovar staphylolyticus.

Staphylococcus simulans biovar staphylolyticus contains five plasmids designated pACK1 through pACK5. Non-denaturing electrophoretic analysis of an extract prepared from wild-type cells revealed three bands of catalase activity, whereas an extract of cells cured of pACK1 produced only two catalase bands. Cloning and Southern hybridization analysis showed that there is a catalase structural gene on pACK1. The plasmid-specified catalase was the major activity produced under both aerobic and anaerobic conditions of growth.

Characteristics of extracellular protein production by a plasmidless derivative of Staphylococcus simulans biovar staphylolyticus.

A derivative of Staphylococcus simulans biovar staphylolyticus cured of all five plasmids present in the wild-type organism was developed, and the characteristics of extracellular protein production by this plasmidless strain were compared to those of the wild type. Although staphylolytic endopeptidase (lysostaphin) and beta-lactamase are known to be plasmid encoded, analysis of this cured strain revealed that most other extracellular proteins are chromosomally encoded.

Wall-associated processing of extracellular enzymes of Staphylococcus simulans biovar staphylolyticus.

Staphylococcus simulans biovar staphylolyticus produces a staphylolytic glycylglycine endopeptidase (lysostaphin) and a micrococcolytic endo-beta-N-acetylglucosaminidase (hexosaminidase) as proenzymes that are proteolytically processed through multiple intermediates to their mature forms by an extracellular sulfhydryl protease. Analysis of protease production by immunoblots using antiserum prepared against purified protease and by renaturing activity gels using gelatin as the substrate has revealed that the lysostaphin-processing protease also is produced as a proenzyme, which appears to be autocatalytically processed. Very little proprotease could be detected in supernatants from cultures of S. simulans biovar staphylolyticus, which suggested that the protein was being processed before it was released to the culture medium. Analysis of wall-associated proteins revealed that processing of proprotease occurred primarily in the cell wall. Furthermore, processing of prolysostaphin and prohexosaminidase also occurred in the cell wall matrix.

Noninvasive monitoring of tissue viability.

Noninvasive monitoring techniques are procedures of little or no morbidity that may be repeated frequently to assess tissue viability. The ideal noninvasive technique would be safe, sensitive, reliable, reproducible, simple to use, and inexpensive. Although no such ideal technique yet exists, several currently available methods have clinical usefulness. Visual fluorescein, fluorescein photography, and surface fluorometry all work by the same principle. We prefer the surface fluorometer because of its greater sensitivity, the more objective nature of the data it provides, and the greater frequency with which it can be repeated. Ultrasound Doppler techniques are useful preoperatively in locating vessels and assessing their patency, and we have found the bidirectional Doppler quite helpful in the postoperative monitoring of replanted or revascularized digits. The laser Doppler, photoplethysmograph, and surface thermometer have not been as helpful in our experience. Transcutaneous oxygen measurement shows great promise for the postoperative monitoring of replants and free tissue transfers.

Cranioplasty in frontometaphyseal dysplasia.

Frontometaphyseal dysplasia is an extremely rare craniotubular bone disorder predominantly manifested by supraorbital bossing. Although recognizable with findings at birth, it is usually identified successfully before the onset of puberty. These patients often are stigmatized related to their appearance and may present to the plastic surgeon for intervention. We present a case of successful cranioplasty in correcting the fronto-orbital deformity in a 9-year-old child with frontometaphyseal dysplasia.

Distinguishing soft-tissue hemangiomas from vascular malformations using technetium-labeled red blood cell scintigraphy.

Soft-tissue vascular lesions in children can be classified as either hemangiomas or vascular malformations. The distinction between the two has important prognostic and therapeutic implications. Over the past 8 years, we have evaluated 64 vascular lesions with the technetium-labeled red blood cell (Tc-RBC) scan. Twenty-eight lesions imaged as hemangiomas with intense focal uniform uptake. This diagnosis was confirmed in 27 lesions, or 96 percent. Thirty-six lesions imaged as vascular malformations with abnormal vessels or diffusely increased activity. This diagnosis was confirmed in 35 lesions, or 97 percent. Overall, the Tc-RBC scan was 97 percent accurate in distinguishing hemangiomas from vascular malformations. It is particularly useful when the clinical diagnosis of the lesion may not be evident. Not only can biopsy be avoided, but parents can be reassured at an earlier age and given accurate information regarding prognosis.

Scalp infections in black children: think kerion.

Treatment of tinea capitis consists of a 5-week course of griseofulvin. A 1-week course of a systemic corticosteroid may be considered in addition to griseofulvin therapy to accelerate the subsidence of inflammation in kerion lesions. Kerion is an inflammatory form of tinea capitis which may progress rapidly into a fulminant infection if untreated. This case report underscores the need for prompt recognition and appropriate treatment of this disorder.

A simple method for preventing misplaced electrocauterization.

A small segment of universally available and inexpensive rubber catheter can be easily fitted to insulate electrocautery tips. This technique can prevent numerous thermal injuries and potential litigation arising from accidently burning adjacent tissues. The routine use of this modification in the operating room can save time, anxiety, and potential litigation by preventing misplaced cauterization.

Intralesional corticosteroid therapy for infantile hemangiomas.

Intralesional corticosteroid injections were performed in 31 hemangiomas in 30 infants aged 1 to 10 months at first injection. One to five injections were given, spaced 6 weeks apart. Lesions were located throughout the head and neck region, except one that was on the buttock. A mixture of betamethasone acetate and triamcinolone acetonide was used. Four lesions (13 percent) virtually disappeared, ten (32 percent) showed greater than 50 percent reduction in volume, ten (32 percent) showed definite but less than 50 percent reduction in volume, and seven (23 percent) showed little or no decrease in size. None showed further growth. All injections were performed without anesthesia, and there were not significant complications. We conclude that intralesional corticosteroid injections are safe and effective in properly selected infants with hemangiomas.