DEcrease STress through RESilience training for Students (DESTRESS) Study: Protocol for a randomized controlled trial nested in a longitudinal observational cohort study

INTRODUCTION

Chronic stress and burnout are highly prevalent among academically trained healthcare professionals, negatively affecting their well-being and capacity to engage in their work. Resilience to stress develops early in one's career path, hence offering resilience training to university students in these professions is one approach to fostering well-being and mental health. The aim of this study is to assess whether offering mindfulness-based resilience training to university students in healthcare professions reduces their perceived chronic stress.

METHODS AND ANALYSIS

The study has a hybrid design combining a longitudinal observational cohort with a nested randomized controlled trial (RCT) with sequential multiple assignment and multistage adaptive interventions while taking participants' preferences into account. All students in healthcare related programmes at the Erasmus University Rotterdam are invited to participate. Within the observational cohort, students with a score of 14 or higher on the Perceived Stress Scale (PSS) are invited to take part in the RCT (n = 706). Eligible participants are randomized to control or active intervention in a ratio of 1:6. Those randomized to the control group and non-randomized participants in the cohort receive passive web-based psychoeducation about chronic stress and burnout through referral to specific websites. Participants randomized to the intervention group receive one of 8 active mindfulness-based interventions. They select a rank order of 4 preferred interventions and are randomized across these with equal probability. Non-response to the intervention is followed by sequential randomized assignment to another intervention, for a total maximum of 3 sequential interventions. All participants receive questionnaires at baseline, before and after each 8-week intervention period, and at 1- and 2-year follow-up. The primary outcome is perceived chronic stress measured with the PSS. Secondary outcomes include mental well-being, burnout, quality of life, healthcare utilization, drug use, bodyweight, mental and physical stress-related symptoms, resilience, and study progress.

ETHICS AND REGISTRATION

Approval from the Medical Ethics Review Committee was obtained under protocol number MEC-2018-1645. The trial is registered in the Netherlands National Trial Register by registration number NL7623, 22/03/2019, https://www.trialregister.nl/.

Are We Missing Something Pertinent? A Bias Analysis of Unmeasured Confounding in the Firearm-Suicide Literature

Despite the magnitude and consistency of risk estimates in the peer-reviewed literature linking firearm availability and suicide, inferring causality has been questioned on the theoretical basis that existing studies may have failed to account for the possibility that members of households with firearms differ from members of households without firearms in important ways related to suicide risk. The current bias analysis directly addresses this concern by describing the salient characteristics that such an unmeasured confounder would need to possess in order to yield the associations between firearm availability and suicide observed in the literature when, in fact, the causal effect is null. Four US studies, published between 1992 and 2003, met our eligibility criteria. We find that any such unmeasured confounder would need to possess an untenable combination of characteristics, such as being not only 1) as potent a suicide risk factor as the psychiatric disorders most tightly linked to suicide (e.g., major depressive and substance use disorders) but also 2) an order of magnitude more imbalanced across households with versus without firearms than is any known risk factor. No such confounder has been found or even suggested. The current study strongly suggests that unmeasured confounding alone is unlikely to explain the association between firearms and suicide.

Assessing eating disorder symptoms in adolescence: is there a role for multiple informants?

OBJECTIVES

Studies of adolescent psychiatric disorders often collect information from adolescents and parents, yet most eating disorder epidemiologic studies only rely on adolescent report.

METHOD

We studied the eating disorder symptom reports, from questionnaires sent at participants' ages 14 and 16 years, provided by 7,968 adolescents from the Avon Longitudinal Study of Parents and Children (ALSPAC), and their parents. Adolescents and parents were asked questions about the adolescent's eating disorder symptoms (binge eating, vomiting, laxative use, fasting, and thinness). We assessed cross-sectional concordance and prevalence using kappa coefficients and generalized estimating equations. Generalized estimating equations were used to assess prospective associations between symptom reports and adolescent weight outcomes measured at a face-to-face assessment at 17.5 years.

RESULTS

Parents and adolescents were largely discordant on symptom reports cross-sectionally (kappas < 0.3), with the parent generally less likely to report bulimic symptoms than the adolescent but more likely to report thinness. Female adolescents were more likely to report bulimic symptoms than males (e.g., two to four times more likely to report binge eating), while prevalence estimates according to parent reports of female vs. male adolescents were similar. Both informants' symptom reports were predictive of body mass and composition measures at 17.5 years; compared to adolescent report, parentally reported binge eating was more strongly predictive of body mass index.

DISCUSSION

Parent report of eating disorder symptoms seemed to measure different, but potentially important, aspects of these symptoms during adolescence. Epidemiologic eating disorder studies should consider the potential value added from incorporating parental reports, particularly in studies of males.

Antidepressant class, age, and the risk of deliberate self-harm: a propensity score matched cohort study of SSRI and SNRI users in the USA

BACKGROUND

The US Food and Drug Administration's meta-analyses of placebo-controlled antidepressant trials found approximately twice the rate of suicidal behaviors among children and adults aged 24 years and younger who were randomized to receive antidepressant medication than among those who were randomized to placebo. Rates of suicidal behavior were similar for subjects aged 25-64 years whether they received antidepressants or placebo, and subjects aged 65 years or older randomized to antidepressants were found to have lower rates of suicidal behavior. The age-stratified FDA meta-analyses did not have adequate power to investigate rates of suicidal behaviors by antidepressant drug class.

OBJECTIVE

Our objective was to assess the risk of deliberate self-harm associated with the two most commonly prescribed classes of antidepressant agents.

DESIGN

Propensity score matched cohort study of incident users of antidepressant agents.

SETTING

Population-based healthcare utilization data of US residents.

PATIENTS

US residents aged 10-64 years with a recorded diagnosis of depression who initiated use of selective serotonin reuptake inhibitors (SSRIs) or serotonin norepinephrine reuptake inhibitors (SNRIs) between 1 January 1998 and 31 December 2010.

MAIN OUTCOME MEASURES

ICD-9 external cause of injury codes E950.x-E958.x (deliberate self-harm).

RESULTS

A total of 102,647 patients aged between 10 and 24 years, and 338,021 aged between 25 and 64 years, initiated therapy with antidepressants. Among 10-24 year olds, prior to propensity score matching, 75,675 initiated therapy with SSRIs and 5,344 initiated SNRIs. After matching, there were 5,344 SNRI users and 10,688 SSRI users. Among the older cohort, 36,037 SNRI users were matched to 72,028 SSRI users (from an unmatched cohort of 225,952 SSRI initiators). Regardless of age cohort, patients initiating SSRIs and patients initiating SNRIs had similar rates of deliberate self-harm. Restriction to patients with no antidepressant use in the past 3 years did not alter our findings.

CONCLUSIONS

Our findings of similar rates of deliberate self-harm for depressed patients who initiate treatment with either an SSRI or an SNRI suggests that physicians who have decided that their patients would benefit from initiating antidepressant therapy need not weigh differential suicide risk when deciding which class of antidepressant to prescribe.

Polyimide Nanofoams For Low Dielectric Applications

Foamed polyimides have been developed in order to obtain thin film dielectric layers with very low dielectric constants for use in microelectronic devices. In these systems the pore sizes are in the nanometer range, thus, the term “nanofoam”. The polyimide foams are prepared from block copolymers consisting of thermally stable and thermally labile blocks, the latter being the dispersed phase. Foam formation is effected by thermolysis of the thermally labile block leaving pores the size and shape corresponding to the initial copolymer morphology. Nanofoams prepared from a number of polyimides as matrix materials, were investigated as well as a number of thermally labile polymers. The foams were characterized by a variety of experiments including, TEM, SAXS, WAXD, DMTA, density measurements, refractive index measurements and dielectric constant measurements. Thin film foams, with high thermal stability and dielectric constants approaching 2.0, can be prepared using the copolymer/nanofoam approach.

How should DSM-V classify eating disorder not otherwise specified (EDNOS) presentations in women with lifetime anorexia or bulimia nervosa?

OBJECTIVE

Anorexia nervosa (AN) and bulimia nervosa (BN) are marked by longitudinal symptom fluctuations. DSM-IV-TR does not address how to classify eating disorder (ED) presentations in individuals who no longer meet full criteria for these disorders. To consider this issue, we examined subthreshold presentations in women with initial diagnoses of AN and BN.

METHOD

A total of 246 women with AN or BN were followed for a median of 9 years; weekly symptom data were collected at frequent intervals using the Longitudinal Interval Follow-up Evaluation of Eating Disorders (LIFE-EAT-II). Outcomes were ED presentations that were subthreshold for 3 months, including those narrowly missing full criteria for AN or BN, along with binge eating disorder (BED) and purging disorder.

RESULTS

During follow-up, most women (77.6%) experienced a subthreshold presentation. Subthreshold presentation was related to intake diagnosis (Wald chi2=8.065, df=2, p=0.018). Individuals with AN most often developed subthreshold presentations resembling AN; those with BN were more likely to develop subthreshold BN. Purging disorder was experienced by half of those with BN and one-quarter of those with AN binge/purge type (ANBP); BED occurred in 20% with BN. Transition from AN or BN to most subthreshold types was associated with improved psychosocial functioning (p<0.001).

CONCLUSIONS

Subthreshold presentations in women with lifetime AN and BN were common, resembled the initial diagnosis, and were associated with modest improvements in psychosocial functioning. For most with lifetime AN and BN, subthreshold presentations seem to represent part of the course of illness and to fit within the original AN or BN diagnosis.

Evidence of enhanced iron excretion during systemic phosphorothioate oligodeoxynucleotide treatment

BACKGROUND

Phosphorothioate oligonucleotides, in general, possess properties that could be utilized in the development of therapeutic heavy metal chelators.

METHODS

Iron excretion was measured in 16 patients participating in studies to test the safety of OL(1)p53, a 20-mer phosphorothioate oligonucleotide complementary to p53 mRNA. Patients were given OL(1)p53 at doses of 0.05 to 0.25 mg/kg/h for 10 days by continuous intravenous infusion. Urine was collected during the study and analyzed for iron, copper, cadmium, and zinc.

RESULTS

We found that phosphorothioate oligonucleotides have a high affinity for iron as well as several other clinically relevant toxic metals. Analysis of patient urine following administration of OL(1)p53 reveals a 7.5-fold increase in iron excretion at low doses (0.05 mg/kg/h).

CONCLUSIONS

Phosphorothioate oligonucleotides may have therapeutic potential as heavy metal chelators. Low doses of phosphorothioate oligonucleotide facilitated the excretion of iron. Renal clearance of iron-phosphorothioate oligonucleotide complexes most likely involves secretion into proximal tubules.

Modulation of the phosphatase activity of calcineurin by oxidants and antioxidants in vitro

Previous research has indicated that oxidants, antioxidants and the intracellular redox state regulate the activities of a variety of protein tyrosine kinases, protein tyrosine phosphatases, phospholipases and transcription factors. In order to explore the redox regulation of the serine/threonine phosphatase calcineurin, we have investigated the effects of a variety of oxidants and antioxidants on calcineurin phosphatase activity in vitro. The oxidants hydrogen peroxide, superoxide and glutathione disulfide inhibited the phosphatase activity of calcineurin in a dose-dependent manner. Incubation of purified calcineurin with the antioxidants ascorbate, ascorbate 2-phosphate, alpha-lipoic acid, N-acetyl-L-cysteine and glutathione increased phosphatase activity relative to untreated controls. In contrast, several other commonly used antioxidants, including butylated hydroxytoluene, butylated hydroxyanisole, TEMPOL (4-hydroxy-2,2,6, 6-tetramethylpiperidine-N-oxyl), Trolox (6-hydroxy-2,5,7, 8-tetramethyl-chroman-2-carboxylic acid) and dihydrolipoic acid decreased the activity of purified calcineurin, possibly through prooxidative mechanisms. Although the antioxidant pyrrolidine dithiocarbamate increased the activity of purified calcineurin, it significantly inhibited the activity of calcineurin present in crude fibroblast lysates. These results support and extend the hypothesis that redox factors modulate the phosphatase activity of calcineurin and suggest that further in vivo studies are warranted.

Cyclosporin A has low potency as a calcineurin inhibitor in cells expressing high levels of P-glycoprotein

Cyclosporin A (CsA) is a widely-used immunosuppressant drug whose therapeutic and toxic actions are mediated through inhibition of calcineurin (CN), a calcium- and calmodulin-dependent phosphatase. Inhibition of CN by CsA requires drug binding to its protein cofactor in the inhibition, cyclophilin. Because cyclophilin is a high affinity target for CsA it is expected that this protein can act as a reservoir for the drug in the cell and may be able to inhibit cellular efflux of CsA. P-glycoprotein (P-gp) is known to increase the rate of CsA efflux from CsA loaded cells but it is not clear if the P-gp drug efflux pump can compete effectively with cyclophilin at therapeutically relevant concentrations of CsA. To test the hypothesis that increased expression of P-gp confers protection against CsA-dependent inhibition of CN phosphatase activity, KB-V cells expressing varying levels of P-gp were analyzed to determine the potency of CsA as a CN inhibitor. When intact cells were treated with CsA, a positive correlation was observed between P-gp expression and resistance to CsA-dependent inhibition of CN: the IC50 is approximately 20-fold higher in the multidrug resistant epidermal carcinoma cell line, KB-V, which expresses P-gp at a high level than in the parental, KB, cell line expressing very low levels of P-gp. The resistance displayed by KB-V cells is abrogated by co-administration of the P-gp inhibitor verapamil, whereas verapamil has no effect on CsA potency in control KB cells. In cell lysates from KB-V cells with different amounts of P-gp CsA exhibits equivalent potency, indicating that the difference in sensitivity to CsA among the cell types requires maintenance of cell integrity. These observations support the view that resistance to CN inhibition by CsA occurs in cells with moderately elevated P-gp activity. Therefore, P-gp activity appears to be an important determinant of CsA cellular specificity for both therapeutic and toxic effects.

Pyrethroid insecticides as phosphatase inhibitors

In this study we tested the hypothesis that pyrethroid insecticides inhibit calcineurin directly and that inhibition is unaffected by the immunophilin cofactors necessary for calcineurin inhibition by cyclosporin A and FK506. The type II pyrethroid insecticides cis-cypermethrin (c-Cyp), trans-cypermethrin, deltamethrin (Delt), and fenvalerate A alpha (Fen), as well as the type I pyrethroid insecticides cis- and trans-permethrin and S-bioallethrin, were unable to inhibit the phosphatase activity of purified calcineurin under conditions of maximal activation by Ca2+ and calmodulin. Furthermore, c-Cyp, Delt, and Fen did not affect the Ca2+ dependence of calcineurin at 0.1 microM of calmodulin, indicating that Ca2+ binding to calmodulin was not affected by these agents. c-Cyp, Delt, and Fen also failed to inhibit calcineurin phosphatase activity in rat brain supernatant and cultured IMR-32 cells, although potent inhibition was displayed by both cyclosporin A and FK506 in each of these systems. Neither the Ca2+-dependent nor the okadaic acid-inhibitable phosphatase activity toward a 24-amino acid 32P-phospho-peptide substrate was affected by any of the pyrethroid insecticides, indicating that neither type-1 or type-2A phosphatase nor calcineurin is inhibited by pyrethroids. To determine if these results were dependent upon experimental conditions, experiments were repeated using polyethylene glycol-treated glass tubes in place of the standard polypropylene tubes. Regardless of the type of tube, no inhibition of calcineurin by any of the pyrethroid insecticides was observed. These data indicate that the pyrethroid insecticides are not effective inhibitors of calcineurin or other phosphatases.

The application of thermoelastic analysis to study stresses in human teeth

The aims of this investigation were to use a full-field thermoelastic technique to study the stress distribution on human teeth subjected to dynamic loads and derive a value for the thermoelastic constant for human enamel. Surface stresses were observed on extracted intact human molar teeth subjected to a load of 200 N cycled at 20 Hz. Measurements were repeated for the same teeth following mesio-occluso-distal cavity preparation and restoration with amalgam and adhesively bonded composite restorations. A value for the thermoelastic constant for human enamel (Km) of 2.25 X 10(-12)m2/N was calculated from physical coefficients in the literature. Unprepared specimens exhibited a comparable magnitude and distribution of stresses to those seen when teeth were restored with adhesively bonded composite restorations. Higher stresses were observed on prepared teeth and there was little change following restoration with amalgam. It can be concluded that a full-field thermoelastic stress analysis technique can be successfully applied to study teeth subjected to axial dynamic loads in vitro and that the resultant stresses are greater in prepared teeth than those restored with bonded composite materials.

Measurement of the microhardness and Young's modulus of human enamel and dentine using an indentation technique

Conventional quasi-static and dynamic test methods have a number of limitations when used to measure the mechanical properties of enamel and dentine. These are due to the complex structure of the material and the small specimen size. In this investigation, a microindentation technique was used to measure the hardness and Young's modulus of human enamel and dentine and any variations with location. Freshly extracted molar teeth were sectioned, and the cut surfaces were ground and polished progressively to 1 micron. The polished surfaces were indented at different distances from the surface and amelodentinal junction with a Knoop indentor. Measurements of the length of the long indentation diagonal were used to calculate a value for hardness. It has been shown that the a-value for Young's modulus of a material can be calculated by comparing the ratio of the long and short diagonals on an indented specimen with the actual ratio of the indentor as any changes will be due to elastic recovery in the specimen. Values obtained for the Knoop hardness of enamel and dentine were in good agreement with those of other workers. It was also possible to show that there was a decrease in hardness with depth from the surface in enamel. The hardness of dentine increased with distance from the amelodentinal junction. Values for Young's modulus for dentine were in good agreement with those of other workers, and there was an increase in modulus with depth from the amelodentinal junction from 8.7 to 11.2 GNm-2. Values for Young's modulus of enamel were not as easy to calculate because of surface- and subsurface damage.

Osteotoxicity of cadmium and lead in HOS TE 85 and ROS 17/2.8 cells: relation to metallothionein induction and mitochondrial binding

Epidemiological, experimental and clinical data indicate that cadmium and lead are osteotoxins in man and other species. The relative sensitivities of a clonal human osteosarcoma cell line (HOS TE 85) and a clonal rat osteosarcoma cell line (ROS 17.28) to the cytotoxic effects of cadmium and lead were tested in serum-free media without added growth factors. The rat osteosarcoma cells were more sensitive to cadmium with cytotoxicity and inhibition of proliferation at 0.25 versus 0.75 and 1.0 mumol l-1 cadmium, respectively, for human osteosarcoma cell lines. The lower sensitivity to cadmium of human osteosarcoma cells is attributed, at least partly, to induction of metallothionein synthesis by cadmium and zinc in this cell line; in the rat osteosarcoma cell line, they do not induce metallothionein synthesis. Human osteosarcoma cells were more sensitive than rat osteosarcoma cells to lead with inhibition (IC50) of proliferation at 4 mumol l-1 lead and cytotoxicity at 20 versus 6 and over 20 mumol l-1 lead, respectively, for these variables in rat osteosarcoma cells. Both cell lines attained the highest lead concentration in the 15,000 x g (mitochondrial) fraction. The lead in the mitochondrial, microsomal, nuclear and cytosolic fractions of the human cell line did not decrease during 24 h post-washout. Binding of lead was much less stable in the less sensitive rat cells, with 50-100% loss of mitochondrial, microsomal and nuclear lead during 24 h post-washout.

Polyethylene wear from retrieved acetabular cups

Laboratory wear testing of ultra high molecular weight polyethylene from 12 Charnley acetabular cups, removed after periods of up to 17.5 years showed that the large patient-to-patient variations in clinical penetration rate cannot be explained by batch-to-batch variation in the wear resistance of the material. Nor was there any evidence of a time-dependent degradation in wear resistance of the material.

Effect of sodium butyrate on metallothionein induction and cadmium cytotoxicity in ROS 17/2.8 cells

ROS 17/2.8 cells, a cloned rat osteosarcoma cell line, are exceptionally sensitive to the cytotoxic effects of cadmium. This sensitivity is associated with the inability of this metal to induce the synthesis of metallothionein, a transition metal-binding protein, which detoxifies this metal by its sequestration. Sodium butyrate induces the synthesis of metallothionein in these cells in a concentration-dependent manner. Treatment with this agent also significantly increases the resistance of these cells to the cytotoxic effects of cadmium and the protective effect of butyrate is reversed upon its removal from culture medium. Butyrate treatment did not significantly alter the accumulation of cadmium by these cells. Hence, the increased synthesis of metallothionein in butyrate-treated cells is not due to increased cellular uptake of cadmium. Inhibition of DNA synthesis due to butyrate was not a sufficient condition to alter metallothionein synthesis or to protect against Cd-induced cytotoxicity. Equivalent inhibition of DNA synthesis with hydroxyurea failed to increase metallothionein synthesis in cadmium-treated cells. These results indicate that modulation of metallothionein gene expression in this cell line is the critical factor in determining cellular sensitivity to the cytotoxic effects of cadmium.

Effect of 5-azacytidine on metallothionein inducibility and sensitivity to lethality of cadmium in rat osteosarcoma (ROS 17/2.8) cells

ROS 17/2.8 cells, a cloned rat osteoblastic osteosarcoma cell line, were found to be extremely sensitive to the lethal effects of cadmium and to synthesize little, if any, metallothionein in response to cadmium exposure. Culture of cells for 24 h in the presence of 1 microM 5-azacytidine, a cytidine analog, increased the inducibility of metallothionein by cadmium and significantly reduced (P less than 0.001) cytotoxicity. Anion exchange chromatographic analysis of cadmium binding to low molecular mass cytotoxicity. Anion exchange chromatographic analysis of cadmium binding to low molecular mass cytosolic proteins showed that cells treated with cadmium and 5-azacytidine expressed at least 2 isoforms of metallothionein. One isoform of metallothionein with a low affinity for cadmium was constitutively expressed by these cells. The association of poor inducibility of metallothionein by cadmium with extreme sensitivity of cells to cadmium emphasizes the role of this protein in the cellular response to this toxic metal. The modulation of metallothionein inducibility and sensitivity to cadmium by 5-azacytidine treatment suggest that metallothionein gene structure and regulation are altered in ROS 17/2.8 cells.

Proliferation markers Ki-67 and p105 in soft-tissue lesions. Correlation with DNA flow cytometric characteristics

Frozen tissue immunoreactivity with Ki-67, a monoclonal antibody that recognizes a nuclear antigen in nonresting or proliferating cells, was compared to DNA flow cytometry results (from fresh tissue) in a diverse group of 60 soft-tissue lesions. Both DNA index and Ki-67 score were independently reported to be associated with grade and prognosis in sarcomas, but no direct comparison of these two variables was made. It was attempted to measure proliferative activity in fixed paraffin-embedded tissues immunohistochemically in a subset of lesions using an antibody to another nuclear proliferation antigen, p105. Lesions were given a grade according to lesion category (reactive, 1; benign, 2; low-grade malignant, 3; and high-grade malignant, 4). Ki-67 reactivity correlated relatively well with this grading system (r = 0.59); benign lesions usually exhibited a low Ki-67 score and malignant lesions usually but not always exhibited a high score. For example, some malignant fibrous histiocytomas contained only rare positive cells. Some disparity between Ki-67 score and grade and within histologic types indicates some independence from these features, a fact that may be important when correlation with prognosis is performed. However Ki-67 did not correlate well with flow data such as percentage S phase (r = 0.30), percentage S + G2M phases (r = 0.37), or DNA index (r = 0.39). This probably is due to the fact that Ki-67 also marks cells in the G1 phase, whereas these are excluded in flow data analyses. Anti-p105 highlighted almost all nuclei in all cases tested, including fibromatosis, and did not correlate with Ki-67 score, histologic grade or DNA flow cytometric data. Results with p105 could not be favorably affected by titration experiments. It is reasonable to conclude that the Ki-67 score is a variable related to but independent of histologic grade, histologic type, and DNA flow values. Whether it is prognostically important in human sarcomas, as has been suggested, awaits further clinicopathologic study.

DNA content of juvenile granulosa tumors determined by flow cytometry

Juvenile granulosa tumors (JGT) often exhibit worrisome morphologic features, yet usually behave in a benign fashion. Thirteen JGT were examined by flow cytometric analysis of paraffin material to determine if DNA content and cell kinetics are related to prognosis. The patients ranged in age from stillborn to 16 years. Unilateral salpingoophorectomy was the most common therapy. Eleven patients with follow-up were free of disease. Marked nuclear atypia was evident in three cases, and high mitotic counts were observed in six, but only marked atypia correlated with DNA content. Flow cytometry revealed that 46% of the JGT had abnormal DNA content and increased average growth fraction. The neoplasms with the highest DNA indices were found predominantly in postmenarchal girls. JGT may exhibit abnormal DNA content, nuclear atypia, and numerous mitoses, yet behave benignly. DNA flow cytometric studies of higher stage JGT are warranted.

Lead inhibits the basal and stimulated responses of a rat osteoblast-like cell line ROS 17/2.8 to 1 alpha,25-dihydroxyvitamin D3 and IGF-I

Low-level exposure to lead impairs longitudinal growth in children and in experimental animals. The proposed mechanisms include decreased osteocalcin secretion in response to 1 alpha,25-(OH)2 vitamin D3 and decreased response to insulin-like growth factor-I. The interaction of lead, 1 alpha,25-(OH)2 vitamin D3, and insulin-like growth factor-I was investigated in an osteoblast-like cell line from rat osteosarcoma, ROS 17/2.8. Cells were cultured 24 hr in a serum-free medium with lead, 1 alpha,25-(OH)2 vitamin D3, and insulin-like growth factor-I. 1 alpha,25-(OH)2 vitamin D3 (10 nM) evoked a 4-5 X increase in osteocalcin secretion and a 100% increase in cellular alkaline phosphatase activity but no increase in DNA/cell layer. Insulin-like growth factor-I (92.5 ng/ml) evoked a 100% increase of osteocalcin secretion and a 20% increase in cellular DNA contents but no change in cellular alkaline phosphatase activity. Basal and stimulated cellular osteocalcin secretion, cellular alkaline phosphatase activity, and DNA contents were significantly inhibited by addition of 1-10 microM lead. The data are consistent with a toxic effect of lead on osteoblastic function and the cellular responses to 1 alpha,25-(OH)2 vitamin D3 and insulin-like growth factor-I. This interaction may be relevant to impaired childhood growth at low levels of lead exposure.

Toxicity of cadmium to rat osteosarcoma cells (ROS 17/2.8): protective effect of 1 alpha,25-dihydroxyvitamin D3

Inadequate vitamin D intake is an important cofactor in clinical and experimental bone disease induced by chronic cadmium exposure. The interaction was investigated by culture of rat osteoblastic osteosarcoma cells (ROS 17/2.8) in a serum-free medium with equimolar concentrations of cadmium chloride and 1 alpha,25-(OH)2 vitamin D3. After addition of cadmium alone to culture medium, the unstimulated secretion of osteocalcin and cellular alkaline phosphatase activity were inhibited at 10 pM, and of DNA synthesis and proline incorporation into collagen at 500 nM. In the presence of equimolar amounts of cadmium and 1 alpha,25-(OH)2 vitamin D3, all four responses paralleled those of 1 alpha,25-(OH)2 vitamin D3 alone up to the inhibitory concentration of 500 nM cadmium. Neither 10 nM 1 alpha,25-(OH)2 vitamin D3 nor 1 microM cadmium induced synthesis of metallothionein in these cells indicating that the protective effect of D3 was not related to the induction of a metallothionein-like protein in ROS 17/2.8 cells. In the presence or absence of D3, cadmium inhibited osteoblastic function at concentrations below the whole-organ concentration of cadmium in bone as reported in experimental and clinical cadmium-induced osteotoxicity. The extreme sensitivity of ROS 17/2.8 cells to cadmium may relate to the absence of metallothionein synthesis.

Analysis of lymphoepithelioma and lymphoepithelioma-like carcinomas for Epstein-Barr viral genomes by in situ hybridization

Lymphoepithelioma of the nasopharynx has a strong association with Epstein-Barr virus (EBV). To test the hypothesis that lymphoepithelioma-like carcinomas occurring at other sites are also associated with EBV virus, we used in situ hybridization to analyze 20 cases of lymphoepithelioma and histologically similar lesions and five basaloid squamous cell carcinomas for evidence of EBV genomes. EBV genomes were demonstrated in six of six lymphoepitheliomas of the nasopharynx but in none of five basaloid squamous cell carcinoma. Only one of 14 lymphoepithelioma-like carcinomas was found to contain EBV genomes. The single positive lymphoepithelioma-like carcinoma occurred in the lung of an Asian patient, suggesting that ethnic or geographic influences may be important in determining whether EBV is associated with these nonnasopharyngeal neoplasms. Despite their histologic similarity, most lymphoepithelioma-like carcinomas probably have a different pathogenesis from nasopharyngeal lymphoepithelioma.

Lymphoepithelioma-like carcinoma of the skin

Carcinomas histologically resembling nasopharyngeal lymphoepithelioma have been identified in the salivary gland, thymus, tonsil, and uterine cervix. Five patients with similar tumors primary in the skin are described. The patients ranged in age from 50 to 81 yr. Four neoplasms were situated on the head, and one was located on the shoulder. Microscopically, they were concentrated in the mid- and deep dermis and lacked connections with epidermis. The pattern was of multiple nodules, smaller irregular islands, and cords. The uniform tumor cells had moderate amounts of lightly eosinophilic cytoplasm and vesicular nuclei with one or two prominent nucleoli. A lymphoid infiltrate was intimately associated with each neoplasm and obscured the malignant epithelium in one. Neither squamous nor glandular differentiation was present, but all tumors exhibited intracytoplasmic mucin. Immunohistochemistry was positive for cytokeratin (5 of 5; diffuse) and epithelial membrane antigen (4 of 5; 3 diffuse, 1 focal). Focal reactivity was also noted for carcinoembryonic antigen (1 of 5), neuron-specific enolase (1 of 5), and vimentin (1 of 5). S100 protein, leukocyte common antigen, Factor VIII-related antigen, prostate-specific antigen (males), Leu M1, and salivary amylase reactivity were absent. One patient developed local recurrence and metastases after 39 mo and was dead of disease at 57 mo. The remaining four were free of disease after 46, 27, 25, and 6 mo of follow-up. The diagnosis of lymphoepithelioma-like carcinoma of the skin is based on microscopic findings and exclusion of occult malignancy. The tumor can be confused with a lymphoid infiltrate and is differentiated from Merkel cell carcinoma primarily on cytologic grounds. The neoplasm may be of adnexal origin.

Ectopic midline spinal ganglion in diastematomyelia: a study of its connections

The connections of an ectopic midline spinal ganglion associated with an asymptomatic sacral diastematomyelia were studied. The ganglion was intercalated in the ventral root of one hemicord and sent its efferents to the dorsal root of the other hemicord. The afferents joined the anterior root to form a midline intradural spinal nerve in the cauda equina. Islands of ectopic glia were present in both roots and the spinal nerve. Both the midline position of the ganglion and the glial heterotopias can be tentatively explained by the failure of incorporation of the dorsal cell wedge ("Zwischenstrang") into the divided neural tube.

Traumatic false aneurysm of descending aorta with aortoesophageal fistula

We report a case of traumatically induced false aneurysm with secondary bacterial aortitis of the descending aorta and fistula formation between the aorta and esophagus. This lesion was diagnosed at autopsy and caused death in a 68-year-old female 19 years after an automobile accident. Aortoesophageal fistula (AEF) formation as a result of any cause is rare. To our knowledge, this is the second reported case of traumatic aortic aneurysm as a result of an automobile accident with subsequent AEF formation.

Direct measurement of local pressures in the cadaveric human hip joint during simulated level walking

Eleven piezoelectric pressure transducers, each supporting an area of articular cartilage about 3 mm in diameter, were inserted through the bone of the acetabulum. Nine cadaveric hip joints, thus instrumented, were subjected to forces representing six instants in a typical level walking cycle, including the highest and lowest force. Under the highest force, the maximum pressure measured ranged from 4.93 to 9.57 MN m-2. The transducer positions which were subjected to the highest pressures were subjected at some other instant in the cycle to pressures which were an order of magnitude lower, or to zero pressure.

Passive eustachian tube opening pressure. Its measurement, normal values, and clinical implications

To measure passive eustachian tube opening pressure (PETOP) we have developed a pressure recording instrument that is activated by the sudden fall in output voltage of a sensitive acoustic impedance meter that occurs at the moment of transnasal insufflation of the middle ear. The PETOP was measured in 112 normal subjects aged 2 to 40 years. Normal values rose significantly throughout childhood and stabilized in early adolescence. When sequential insufflations were performed in the same subject, the PETOP fell, even though middle ear pressures had completely returned to baseline values before succeeding measurements were taken. Falls were enhanced by sequential swallowing. Our observations may be explained by the activity of surfactants in the eustachian tube. Measurement of PETOP may provide a more direct means of studying eustachian tube function than that provided by tympanometry alone.

Constraints and fixation for implanted joint replacements

Observations made on both cemented and uncemented joint prostheses after about two years of use show a layer of fibrous tissue next to the bone. The fibrous layer smooths over surface features up to 1mm in size, and must be assumed to be weak in tension and shear. Prosthesis-bone interfaces should therefore be designed to transmit all forces acting on the prosthesis as compressive stresses. The forces acting across prostheses are controlled by the constraints exerted by the articulating surfaces; if the useful ligaments present are allowed to do their job of transmitting tension, the articulating surfaces can be designed to transmit only such forces and moments as can safely be transmitted across the prosthesis-bone interfaces.

Loosening of the femoral component in surface replacement of the knee

The incidence of loosening of the femoral component of the ICLH knee has been found to be lower than that of the tibial component. This is thought to be due to the fact that the compressive strength of the distal femur has been found to be greater than that of the proximal tibia. It has further been shown that the strength of even the femur can be so reduced by the osteoporosis accompanying Rheumatoid Arthritis that it becomes insufficient for adequate prosthetic fixation.

Engineering considerations in the design of double-cup hip replacement prostheses

The diameter of the femoral neck ought not to be reduced, and to provide sufficient ranges of motion without impingement requires the largest practicable articular surface radius and perhaps a less than hemispherical acetabular articular surface. Wear is less with plastic cups and metallic balls than vice versa, and wearing life requires some minimum acetabular wall thickness, which depends on the diameter of the articular surface. Fixation grooves etc. should not reduce the effective wall thickness in highly-stressed regions. In practice, a nearly hemispherical acetabular component will often protrude medially or (preferably) laterally; such a protrusion is unlikely to weaken the fixation but could cause impingement, and could be removed with no loss. The available volume is best used by having the thickest acetabular wall where the wear should be greatest. For the femoral component, the simplest internal surface, a flat-ended cylinder, is also the best. A part-spherical inner surface cannot easily be filled with cement, and a skirt surrounding part or all of the femoral neck offers no advantages and some disadvantages.

Mechanical tests on the tibial components of non-hinged knee prostheses

Cadaveric knees replaced with the Geomedic, ICLH, Marmor and Total Condylar prostheses were tested in axial compression, in rotation and in hyperextension in order to observe the strength of fixation of the tibial components. In axial compression the strengths at failure varied widely, both with any one prosthesis and between prostheses. This is attributed largely to the strength of the cancellous bone of the tibia, which was measured in each case and also varied widely. Three natural knees failed at loads of 7300, 7600 and 8300 newtons respectively, whereas the strengths of replaced knees ranged from 3000 to 15750 newtons. At least one example of each design failed at less than 7300 newtons, suggesting little or no reserve of strength. The strength of fixation was greater when the tibial prosthesis was large enough to rest on the whole cross-section of the tibia. In rotation the three prostheses embodying rollers in troughs were stiffer than the Marmor which had a nearly flat tibial-bearing surface. The presence or absence of the cruciate ligaments had a negligible effect on torsional stiffness. In hyperextension, knees replaced with the ICLH, Marmor and Total Condylar prostheses failed by rupture of the posterior capsule at moments of about 60 newton-metres, compared with about 100 for natural knees. With the Marmor prosthesis the anterior cruciate ligament was avulsed at about 20 newton-metres compared with about 75 in natural knees, suggesting that in this respect the retention of the cruciate ligaments contributes little. None of the four knees tested after inserting a Geomedic prosthesis showed strengths as high as those replaced with the other three designs.

ICLH (Freeman/Swanson) arthroplasty in the treatment of arthritic knee: a 2 to 4-year review

A prospective follow-up using a standardized data recording form was carried out by independent, experienced orthopedic surgeons on a small number (116) of knees operated upon at The London Hospital in the period January 1, 1971 to October 31, 1973. An additional 93 knees have been operated upon at other hospitals and followed prospectively using the same data recording system. A total of 159 knees have been reviewed 2 to 4 years after operation. The complications specific to ICLH arthroplasty have been unremarkable and generally correctable. Two tibial components have sunk and have been revised at The London Hospital. The results show that ICLH arthroplasty has been used to correct satisfactorily flexion deformities up to 70 degrees, valgus deformities up to 45 degrees, and varus deformities up to 35 degrees. (Deformities of greater magnitude can be corrected but were not present among the knees in this study.) The operation may be said to be "worthwhile" with reference to pain in 94 per cent of the knees, with reference to the ability to walk in 80 per cent of the knees, and with reference to the range of movement in 71 per cent. Overall, 47 per cent of the knees had no complaint postoperatively, while a further 47 per cent were improved; thus for 94 per cent the procedure was "worthwhile."

Design and testing of replacement prostheses

The aim of the designer, in this as in other contexts, is to provide acceptable function for an acceptable working life at an acceptable cost. To decide what function is acceptable one must consider the general state of the patients to be treated, as well as the state of the particular joints to be replaced. Clinical experience shows that infection and loosening are the most serious limiters of working life. In attempts to remove or reduce these dangers, many recent designs have used the smallest practicable prosthetic components providing no more constraint than is necessary; this requires a careful consideration of the mechanical state of the diseased joint and the extent to which components of it should be retained. Some laboratory testing is clearly necessary, but the impossibility of exact simulation of the working conditions imposes a limit on its value; clinical testing in patients is therefore unavoidable.

Contact pressures in the loaded human cadaver hip

The purpose of the work described was to find the average pressure on each of several areas of the acetabular cartilage of the cadaver hip under physiological loads. By obtaining load-deflection curves for one chosen area of cartilage, firstly with all the cartilage present and then after the successive removal of other areas, the fractions of the original load carried by the several areas were found, and hence the average pressures on those areas. Seventeen hips (age range twenty-two to eighty-seven years) were examined. Local pressures varied from zero to 3.4 times the average pressure in each hip. The highest pressures in the series (about 4 to 5 megaNewtons per square metre) were on the areas of thin fibrocartilage which were identified at the zenith of certain acetabula. The results are too few to establish whether or not the pressure distribution was age-related. The higher pressures found are within the range which in other experiments has led to fatigue failure of femoral head cartilage, and it is suggested that hips in which such pressures exist under loads of three times body weight may be predisposed to osteoarthritis.