Association of objectively measured physical activity and bone health in children and adolescents: a systematic review and narrative synthesis

The influence of day-to-day physical activity on bone in adolescence has not been well characterized. Forty articles were identified that assessed the relationship between accelerometry-derived physical activity and bone outcomes in adolescents. Physical activity was positively associated with bone strength in peri-pubertal males, with less consistent evidence in females. Physical activity (PA) is recommended to optimize bone development in childhood and adolescence; however, the influence of day-to-day PA on bone development is not well defined. The aim of this review was to describe the current evidence for objectively measured PA on bone outcomes in healthy children and adolescents. MEDLINE, Embase, Cochrane Library, Scopus, Web of Science, CINAHL, PsycInfo, and ClinicalTrials.gov were searched for relevant articles up to April 2020. Studies assessing the relationship between accelerometry-derived PA and bone outcomes in adolescents (6-18 years old) were included. Two reviewers independently screened studies for eligibility, extracted data, and rated study quality. Forty articles met inclusion criteria (25 cross-sectional, 15 longitudinal). There was significant heterogeneity in accelerometry methodology and bone outcomes measured. Studies in males indicated a significant, positive relationship between moderate to vigorous PA (MVPA) and bone outcomes at the hip and femur, particularly during the peri-pubertal years. The results for MVPA and bone outcomes in females were mixed. There was a paucity of longitudinal studies using pQCT and a lack of data regarding how light PA and/or impact activity influences bone outcomes. The current evidence suggests that objectively measured MVPA is positively associated with bone outcomes in children and adolescents, especially in males. However, inconsistencies in methodology make it difficult to determine the amount and type of PA that leads to favorable bone outcomes. Given that the majority of research has been conducted in Caucasian adolescents, further research is needed in minority populations.

The Dps4 from Nostoc punctiforme ATCC 29133 is a member of His-type FOC containing Dps protein class that can be broadly found among cyanobacteria

Dps proteins (DNA-binding proteins from starved cells) have been found to detoxify H₂O₂. At their catalytic centers, the ferroxidase center (FOC), Dps proteins utilize Fe²⁺ to reduce H₂O₂ and therefore play an essential role in the protection against oxidative stress and maintaining iron homeostasis. Whereas most bacteria accommodate one or two Dps, there are five different Dps proteins in Nostoc punctiforme, a phototrophic and filamentous cyanobacterium. This uncommonly high number of Dps proteins implies a sophisticated machinery for maintaining complex iron homeostasis and for protection against oxidative stress. Functional analyses and structural information on cyanobacterial Dps proteins are rare, but essential for understanding the function of each of the NpDps proteins. In this study, we present the crystal structure of NpDps4 in its metal-free, iron- and zinc-bound forms. The FOC coordinates either two iron atoms or one zinc atom. Spectroscopic analyses revealed that NpDps4 could oxidize Fe²⁺ utilizing O₂, but no evidence for its use of the oxidant H₂O₂ could be found. We identified Zn²⁺ to be an effective inhibitor of the O₂-mediated Fe²⁺ oxidation in NpDps4. NpDps4 exhibits a FOC that is very different from canonical Dps, but structurally similar to the atypical one from DpsA of Thermosynechococcus elongatus. Sequence comparisons among Dps protein homologs to NpDps4 within the cyanobacterial phylum led us to classify a novel FOC class: the His-type FOC. The features of this special FOC have not been identified in Dps proteins from other bacterial phyla and it might be unique to cyanobacterial Dps proteins.

Differential biochemical properties of three canonical Dps proteins from the cyanobacterium Nostoc punctiforme suggest distinct cellular functions

DNA-binding proteins from starved cells (Dps, EC: 1.16.3.1) have a variety of different biochemical activities such as DNA-binding, iron sequestration, and H₂O₂ detoxification. Most bacteria commonly feature one or two Dps enzymes, whereas the cyanobacterium Nostoc punctiforme displays an unusually high number of five Dps proteins (NpDps1-5). Our previous studies have indicated physiological differences, as well as cell-specific expression, among these five proteins. Three of the five NpDps proteins, NpDps1, -2, and -3, were classified as canonical Dps proteins. To further investigate their properties and possible importance for physiological function, here we characterized and compared them in vitro Nondenaturing PAGE, gel filtration, and dynamic light-scattering experiments disclosed that the three NpDps proteins exist as multimeric protein species in the bacterial cell. We also demonstrate Dps-mediated iron oxidation catalysis in the presence of H₂O₂ However, no iron oxidation with O₂ as the electron acceptor was detected under our experimental conditions. In modeled structures of NpDps1, -2, and -3, protein channels were identified that could serve as the entrance for ferrous iron into the dodecameric structures. Furthermore, we could demonstrate pH-dependent DNA-binding properties for NpDps2 and -3. This study adds critical insights into the functions and stabilities of the three canonical Dps proteins from N. punctiforme and suggests that each of the Dps proteins within this bacterium has a specific biochemical property and function.

STRUCTURE AND DEVELOPMENT OF VIRUSES OBSERVED IN THE ELECTRON MICROSCOPE : IV. VIRUSES OF THE RI-APC GROUP

Representative viruses of the RI-APC group were observed with the electron microscope in thin sections of infected HeLa cells. The viral particles varied in density, were approximately 60 mµ in diameter and had a center to center spacing when close packed of about 65 mµ. Many of the less dense particles exhibited an internal body averaging 24 mµ in diameter. It was suggested that within the nucleus the virus differentiated from dense granular and reticular material and formed crystals. Disintegration of the crystals and disruption of the nuclear membrane with release of virus into the cytoplasm appeared to occur at any stage. No evidence to suggest development of the virus in the cytoplasm was obtained. It was possible to deduce the structure of the viral crystal from the electron micrographs. The viral particles are packed in a cubic body—centered lattice. Correlative histochemical observations in the light microscope which are now in progress revealed that the crystals and non-crystalline aggregates of virus were strongly Feulgen-positive.

PREPARATION FROM HUMAN RED CELLS OF A SUBSTANCE INHIBITING VIRUS HEMAGGLUTINATION

Methods have been described for the extraction and purification of an agent inhibiting the hemagglutination of red cells by influenza (PR8) and mumps viruses. Human red cells have served as the chief source of the inhibitor but the latter has also been found in human lung. The active extracts have been purified to the extent that 0.1 gamma of material suffices to inhibit one hemagglutinating dose of virus. Incomplete chemical characterization of the most highly purified fractions available indicates the presence of 2.6 per cent nitrogen, at least 50 per cent of polysaccharide, and no phosphorus. In the ultracentrifuge the purified preparation behaves as a polydisperse macromolecular substance. The active material can be obtained from red cell stroma in an ether- and chloroform-soluble form which, on further treatment, can be converted into chloroform-insoluble material. It is possible that the former represents more closely the virus receptor as it exists in the red cell. The purified inhibitor is inactivated on incubation with the virus at 37 degrees C. The nature of this effect is being investigated.

Electrical impedance scanning for melanoma diagnosis: a validation study

BACKGROUND

A multicenter study was conducted to test the ability of electrical impedance scanning to differentiate between benign and malignant skin lesions. The performance of a dual electrical impedance scanning/image analysis device was also assessed.

METHODS

Electrical impedance scanning measurements of 449 preoperative lesions found on 382 patients and including 53 melanomas from the trunk and extremities were performed. Results were correlated with histopathologic findings. In addition, ABCD parameters for the lesions were automatically calculated by the system.

RESULTS

Electrical impedance scanning detected melanomas of the trunk and extremities with 91 percent sensitivity and 64 percent specificity. Moreover, sensitivity of electrical impedance scanning was increased to 100 percent for in situ and thin melanomas of smaller size (n = 27). Visual examination identified as malignant only 67 percent of these early tumors (p = 0.002). Clinical examination detected 96 percent of the larger or thicker melanomas (n = 26), whereas electrical impedance scanning detected only 81 percent of them. Combined electrical impedance scanning and image analysis detected 100 percent of the melanomas, independent of their thickness, and with no significant decrease of specificity. Because of electrical differences between the head/neck and the rest of the body, the assessed electrical impedance scanning parameters were not adequate for the diagnosis of melanomas from the head and neck.

CONCLUSIONS

A validation study proved the value of electrical impedance scanning as a noninvasive technique for detection of melanoma lesions of the trunk and extremities, specifically, of in situ and thin type. In addition, image analysis was shown to be a valuable, complementary procedure. New parameters should be designed to optimize the performance of electrical impedance scanning for melanomas of the head and neck.

Testosterone release rate and duration of action of testosterone pellet implants

OBJECTIVE

Testosterone pellets are a highly effective subdermal depot administered at regular intervals with the timing individualized depending upon return of the patient's characteristic androgen deficiency symptoms. Yet the in vivo testosterone release rate and effective duration of action of these pellets has been little studied systematically.

DESIGN

Analysis of prospectively collected data from three randomized controlled clinical trials. Collection of extruded pellets.

PATIENTS

Androgen-deficient men (n = 136) undergoing long-term androgen replacement therapy with a standard dose (800 mg) of testosterone pellets implanted subdermally at intervals from 5 to 7 months.

MEASUREMENTS

Testosterone release rate of pellets, consisting of pure crystalline testosterone without excipients, is estimated by measuring the dry weight lost by pellets (n = 179) over their time in situ. The effective duration of the standard regimen, and the influence of extrusion and patient or procedural characteristics on it, was estimated by timing of return for re-implantation due to recurrence of the patient's familiar androgen deficiency symptoms.

RESULTS

The loss of dry weight of intact (n = 112) pellets was strongly correlated with time in situ (r2 = 0.969) providing an estimate of daily testosterone release rate per 200 mg pellet of 1.34 +/- 0.02 mg/pellet/day (95% CI 1.30-1.37 mg/day) for the first 3 months. After 756 implantations of the standard dose, men return for re-implantation at 5.8 calendar months following no or only a single pellet extrusion, but the time to return was significantly shorter after multiple extrusions. No patient or procedural features influenced the timing of return. Among men with primary hypogonadism, increases in plasma LH and FSH were more sensitive than plasma total or free testosterone to changes in testosterone delivery following an extrusion.

CONCLUSION

Testosterone pellet implants release testosterone at a steady rate of 1.3 mg/200 mg implant/day (95% CI). The duration of action is about 6 months in an uncomplicated cycle with timing of return shortened by extrusions only in the 3.6% of procedures followed by multiple extrusions. No other patient or procedural features influenced duration of action. Among men with an intact hypothalamo-pituitary unit, plasma gonadotropins are more sensitive than blood total or free testosterone to reduced testosterone delivery following an extrusion.

Detection of recombinant human erythropoietin abuse in athletes utilizing markers of altered erythropoiesis

BACKGROUND AND OBJECTIVES

The detection of recombinant human erythropoietin (r-HuEPO) abuse by athletes remains problematic. The main aim of this study was to demonstrate that the five indirect markers of altered erythropoiesis identified in our earlier work were reliable evidence of current or recently discontinued r-HuEPO use. A subsidiary aim was to refine weightings of the five markers in the initial model using a much larger data set than in the pilot study. A final aim was to verify that the hematologic response to r-HuEPO did not differ between Caucasian and Asiatic subjects.

DESIGN AND METHODS

Recreational athletes resident in Sydney, Australia (Sydney, n = 49; 16 women, 33 men) or Beijing, China (Beijing, n=24; 12 women, 12 men) were randomly assigned to r-HuEPO or placebo groups prior to a 25 day administration phase. Injections of r-HuEPO (or saline) were administered double-blind at a dose of 50 IU/kg three times per week, with oral iron (105 mg) or placebo supplements taken daily by all subjects. Blood profiles were monitored during and for 4 weeks after drug administration for hematocrit (Hct), reticulocyte hematocrit (RetHct), percent macrocytes (%Macro), serum erythropoietin (EPO) and soluble transferrin receptor (sTfr), since we had previously shown that these five variables were indicative of r-HuEPO use.

RESULTS

The changes in Hct, RetHct, %Macro, EPO and sTfr in the Sydney trial were qualitatively very similar to the changes noted in our previous administration trial involving recreational athletes of similar genetic origin. Statistical models developed from Fisher's discriminant analysis were able to categorize the user and placebo groups correctly. The same hematologic response was demonstrated in Beijing athletes also administered r-HuEPO.

INTERPRETATION AND CONCLUSIONS

This paper confirms that r-HuEPO administration causes a predictable and reproducible hematologic response. These markers are disturbed both during and for several weeks following r-HuEPO administration. This work establishes an indirect blood test which offers a useful means of detecting and deterring r-HuEPO abuse. Ethnicity did not influence the markers identified as being able to detect athletes who abuse r-HuEPO.

A novel method utilising markers of altered erythropoiesis for the detection of recombinant human erythropoietin abuse in athletes

BACKGROUND AND OBJECTIVE

The use of recombinant human erythropoietin (r-HuEPO) to enhance athletic performance is prohibited. Existing tests cannot readily differentiate between exogenous and endogenous EPO. Therefore the aim of our study was to investigate possible indirect detection of r-HuEPO use via blood markers of altered erythropoiesis.

DESIGN AND METHODS

Twenty-seven recreational athletes were assigned to three groups prior to a 25 day drug administration phase, with the following protocols: EPO+IM group (n = 10), 50 Ukg(-1) r-HuEPO at a frequency of 3wk(-1), 100 mg intramuscular (IM) iron 1wk(-1) and a sham iron tablet daily; EPO+OR group (n = 8), 50 U.kg(-1) r-HuEPO 3wk(-1), sham iron injection 1wk(-1) and 105 mg of oral elemental iron daily; placebo group (n = 9), sham r-HuEPO injections 3wk(-1), sham iron injections 1wk(-1) and sham iron tablets daily. Each group was monitored during and for 4 weeks after drug administration.

RESULTS

Models incorporating combinations of the variables reticulocyte hematocrit (RetHct), serum EPO, soluble transferrin receptor, hematocrit (Hct) and % macrocytes were analyzed by logistic regression. One model (ON-model) repeatedly identified 94-100% of r-HuEPO group members during the final 2 wk of the r-HuEPO administration phase. One false positive was recorded from a possible 189. Another model (OFF-model) incorporating RetHct, EPO and Hct was applied during the wash-out phase and, during the period of 12-21 days after the last r-HuEPO injection, it repeatedly identified 67-72% of recent users with no false positives.

INTERPRETATION AND CONCLUSIONS

Multiple indirect hematologic and biochemical markers used simultaneously are potentially effective for identifying current or recent users of r-HuEPO.

T cell receptor assembly and expression in the absence of calnexin

Most subunits of the alphabeta deltaepsilon gammaepsilon zetazeta T cell antigen receptor (TCR) complex associate with the molecular chaperone calnexin shortly after their synthesis in the endoplasmic reticulum, including clonotypic TCRalpha,beta molecules and invariant CD3gamma,delta,epsilon chains. While calnexin interaction is suggested to be important for the stability of newly synthesized TCRalpha subunits, the role of calnexin in the survival and assembly of remaining TCR components is unknown. Here we evaluated the expression of TCR proteins in CEM T cells and the calnexin-deficient CEM variant CEM.NK(R). We found that CEM and CEM.NK(R) cells constitutively synthesized all TCR subunits except for TCRalpha and that CD3gamma,delta,epsilon components and CD3-beta complexes were effectively assembled together in both cell types. The stability and folding of core CD3epsilon chains were similar in CEM and CEM.NK(R) cells. Interestingly, TCRalpha synthesis was differentially induced by phorbol myristate acetate treatment in CEM and CEM.NK(R) cells and TCRalpha proteins synthesized in CEM.NK(R) cells showed reduced survival compared to those made in CEM cells. Importantly, these data show that TCR complexes were inducibly expressed on CEM.NK(R) cells in the absence of calnexin synthesis. These results demonstrate that TCR complexes can be expressed in the absence of calnexin and suggest that the role of calnexin in the quality control of TCR assembly is primarily restricted to the stabilization of newly synthesized TCRalpha proteins.

Assessment of breastfeeding knowledge of nurse practitioners and nurse-midwives

The purpose of this study was to replicate a national study of physician knowledge, experience, and attitudes about breastfeeding. All family, pediatric, and women's health care nurse practitioners and nurse-midwives in a northwestern state were surveyed using a mail questionnaire; the response rate was 60.4%. Respondents were nearly unanimous in believing that "breast is best" and in recommending breastfeeding to expectant mothers as a part of their role. In general, 70% of respondents considered themselves effective or very effective in meeting the needs of breastfeeding patients. Although respondents were very supportive of breastfeeding, they were less knowledgeable about specific management strategies. There were differences in attitudes among nursing specialties and with years of experience. Overall, this statewide sample of nurse practitioners and nurse-midwives had a better understanding of the benefits of breastfeeding and an increased sense of effectiveness in managing breastfeeding problems than the physician participants in the national study. A national sample of nurse practitioners and nurse-midwives is needed to verify and expand on the results from this single jurisdiction, where 40% of the respondents were graduates of the home institution of the co-investigators.

Osteopenia and decreased bone formation in osteonectin-deficient mice

Bone continuously remodels in response to mechanical and physiological stresses, allowing vertebrates to renew bone as adults. Bone remodeling consists of the cycled synthesis and resorption of collagenous and noncollagenous extracellular matrix proteins, and an imbalance in this process can lead to disease states such as osteoporosis, or more rarely, osteopetrosis. There is evidence that the extracellular matrix glycoprotein osteonectin or secreted protein acidic and rich in cysteine (BM-40) may be important in bone remodeling. Osteonectin is abundant in bone and is expressed in areas of active remodeling outside the skeleton. In vitro studies indicate that osteonectin can bind collagen and regulate angiogenesis, metalloproteinase expression, cell proliferation, and cell-matrix interactions. In some osteopenic states, such as osteogenesis imperfecta and selected animal models for bone fragility, osteonectin expression is decreased. To determine the function of osteonectin in bone, we used contact x-ray, histomorphometry, and Northern blot analysis to characterize the skeletal phenotype of osteonectin-null mice. We found that osteonectin-null mice have decreased bone formation and decreased osteoblast and osteoclast surface and number, leading to decreased bone remodeling with a negative bone balance and causing profound osteopenia. These data indicate that osteonectin supports bone remodeling and the maintenance of bone mass in vertebrates.

Characterization of the epitope on murine T-cell receptor (TCR) alpha proteins recognized by H28-710 monoclonal antibody

Antigen recognition by alphabeta T lymphocytes is mediated via the multisubunit T-cell receptor (TCR) complex consisting of invariant CD3-gamma,delta,epsilon, and zeta chains associated with clonotypic TCRalpha,beta molecules. In the current report, we evaluated the molecular basis for recognition of murine TCRalpha proteins by H28-710 monoclonal antibody (MAb), specific for the constant region of murine TCRalpha chains. H28-710 is widely used in the study of the TCR complex as it is the only reagent currently available that recognizes all murine TCRalpha proteins, regardless of their clonotype. These data show that H28-710 is useful for the immunoprecipitation of TCRalpha proteins not associated with CD3 subunits, and that H28-710 effectively recognizes denatured TCRalpha proteins synthesized in several different cell types. Most importantly, these results demonstrate that H28 binding involves a serine/threonine-rich region between amino acids 150-177 on murine TCRalpha polypeptides.

Extrusion of testosterone pellets: a randomized controlled clinical study

BACKGROUND

It has previously been shown that testosterone implantation is an effective and well accepted form of androgen replacement therapy, but that pellet extrusion was the most frequent side-effect. The present study aimed to reduce the extrusion rate.

OBJECTIVE

To determine whether the washing of testosterone pellets to remove potentially surface-adherent particles decreased the rate of extrusion of pellet implants.

DESIGN

Prospective, randomized parallel group design in a single centre with consecutive procedures to be randomized (1 : 1) into a wash or control group.

PATIENTS

The study included 251 testosterone implantation procedures in men with known androgen deficiency.

MEASUREMENTS

The primary endpoint, extrusion rate per procedure, was evaluated prospectively by telephone contact at 1 week and then 3 and 6 month intervals. Secondary end-points included peri-procedure adverse events (bleeding, skin reaction, excessive discomfort) noted at the time of implant. Bruising, bleeding and infection were also evaluated as later adverse events by telephone and personal follow-up. Explanatory variables recorded as possible covariables included the number of implants used, production batch number of the implants, the operator, as well as other demographic and medical factors.

RESULTS

In the wash group, the extrusion rate was 12% per procedure (19 pellets from 15 subjects) whereas in the control group, the extrusion rate was 11.1% per procedure (18 pellets from 14 subjects), indicating no evidence of any benefit of the wash procedure (OR = 1. 09 [95% CI 0.47-2.6] per procedure). There was no evidence of benefit in secondary endpoints including total adverse events (7.1%, OR 1.28 [0.44-3.9], bleeding/bruising (8.8%, 1.23 [0.47-3.3]) and infection (4.0%, 1.54 [0.35-7.6]) per procedure. Among men reporting an infection requiring antibiotic treatment according to their own general practitioners, six/ten (60%) subsequently experienced an extrusion. There were no significant differences in extrusion rate between four different operators (P = 0.24) nor among 12 different batches of pellets used during the course of the study (P = 0.77).

CONCLUSIONS

The pellet washing procedure used during implantation does not reduce the subsequent extrusion rate. The higher rate of both primary and secondary adverse events in this prospective study compared with the previous retrospective survey may reflect either more rigorous follow-up or a secular trend.

Marrow transplantation from unrelated donors for patients with severe aplastic anemia who have failed immunosuppressive therapy

Allogeneic marrow transplantation offers curative therapy for patients with aplastic anemia. We analyzed retrospective results in 141 patients with severe aplastic anemia who received transplants between 1988 and 1995 from an unrelated volunteer donor identified through the National Marrow Donor Program (NMDP). All patients had failed one or more courses of immunosuppressive therapy. Of the patients, 121 (86%) received a radiation-containing conditioning regimen, and 20 (14%) were given chemotherapy only. Based on serologic human leukocyte antigen (HLA) typing (class I and II), 105 patients (74%) received HLA-matched marrow, and 36 (26%) received marrow mismatched for at least one HLA-A, -B, or -DR antigen. Allele-level (molecular) typing for HLA-DRB1 was available in 108 donor-recipient pairs; 77 patients received DRB -matched and 31 DRB1-mismatched transplants. All but 13% of patients were given a cyclosporine-containing regimen for graft-vs.-host disease (GVHD) prophylaxis, and 45 patients (32%) received marrow that was T cell-depleted. Among 131 evaluable patients, 116 (89%) achieved sustained engraftment and 15 (11%) did not. Among patients with engraftment, acute GVHD of grades II-IV developed in 60 patients (52%) and extensive chronic GVHD in 24 patients at risk (31%). Currently, 51 patients (36%) are surviving at 11-94 months (median 36) after transplantation. All but five have Karnofsky scores > or =80. Patients who received a serologically matched transplant fared somewhat better than did patients given a serologically mismatched transplant p = 0.03). Patients with donors matched by both serology and allele-level DRB1 typing had significantly better survival than DRB1-mismatched patients with 56 vs. 15% surviving at 3 years p = 0.001). Outcome in patients transplanted within 3 years of diagnosis was superior to that among patients transplanted with greater delay. Major causes of death were graft failure, GVHD, and infections. These data suggest that unrelated marrow transplantation offers successful therapy for a proportion of patients who have failed immunosuppressive therapy.

Experimental appraisal of personal beliefs in science: constraints on performance in the 9 to 14 age group

BACKGROUND

Recent curricula initiatives have promoted experimentation as a means by which relatively young children can appraise their personal beliefs and thereby modify these beliefs towards received scientific ideas. However, key psychological theories signal problems, and the enterprise is not in any event securely grounded in empirical research.

AIMS

As a consequence, the study reported here aimed to provide comprehensive information about children's abilities to use experimentation to appraise their beliefs, while allowing full exploration of theorized constraints.

SAMPLES

The study involved 24 children at each of three age levels within the 9 to 14 range.

METHODS

The children were first interviewed to establish their beliefs about influences on outcome in four educationally significant topic areas: flotation, pressure, motion and shadows. Subsequently, they were asked to conduct investigations to determine whether selected beliefs were correct.

RESULTS

The results showed that, regardless of age or topic, very few children appreciated that to explore whether some variable is influencing outcome it is necessary to manipulate that variable experimentally and that variable only. There was a strong tendency to manipulate other variables, a tendency attributed to the intrusion of everyday reasoning practices into the experimental context. Once extraneous variables had been introduced, the children experienced great difficulties with subsequent stages in the experimental process, e.g., predicting, observing and drawing conclusions.

CONCLUSIONS

It is concluded that experimentation as a means of appraising beliefs is not straightforward in the 9 to 14 age group, and that the pattern of difficulties has psychological significance given the background theories. Nevertheless, while not straightforward, experimental appraisal remains possible given appropriate teacher support, and proposals are made as to the form which the support should take.

Primary mesenchymal cells isolated from SPARC-null mice exhibit altered morphology and rates of proliferation

SPARC (secreted protein acidic and rich in cysteine)/BM 40/osteonectin is a matricellular protein shown to function as a counteradhesive factor that induces cell rounding and as an inhibitor of cell proliferation. These activities have been defined in cell culture, in which interpretation has been complicated by the presence of endogenous SPARC. We therefore sought to determine whether cell shape and proliferation would be affected by the absence of SPARC. Mesangial cells, fibroblasts, and aortic smooth muscle cells were isolated from SPARC-null and age-matched, wild-type mice. In contrast to wild-type cells, SPARC-null mesangial cells exhibited a flat morphology and an altered actin cytoskeleton. In addition, vinculin-containing focal adhesions were distributed over the center of SPARC-null cells, whereas in wild-type cells, the number of focal adhesions was reduced, and these structures were restricted largely to the cell periphery. Although the SPARC-null fibroblasts did not display overt differences in cell morphology, the cells responded to exogenous recombinant SPARC by rounding up in a manner similar to that of wild-type fibroblasts. Thus, the expression of endogenous SPARC is not required for the response of cells to SPARC. Additionally, SPARC-null mesangial cells, fibroblasts, and smooth muscle cells proliferated faster than their respective wild-type counterparts. Null cells also showed a greater sensitivity to the inhibition of cell cycle progression by the addition of recombinant SPARC. The increased proliferation rate of SPARC-null cells appeared to be mediated, at least in part, by an increase in the cell cycle regulatory protein cyclin A. We conclude that the expression of SPARC influences the cellular architecture of mesangial cells and that SPARC plays a role in the regulation of cell cycle in mesangial cells, fibroblasts, and smooth muscle cells.

General practitioner screening for melanoma: sensitivity, specificity, and effect of training

OBJECTIVE

To measure the performance of trained and untrained general practitioners (GPs) in screening men and women aged 50 or more for melanomas.

METHODS

GPs trained in melanoma diagnosis, untrained GPs, and skin cancer specialists examined groups of volunteers, each of which included a small number of subjects with prediagnosed suspicious pigmented lesions (SPLs) that were subsequently excised for histopathological examination.

RESULTS

Trained and untrained GPs achieved mean sensitivities of 0.73 and 0.71, and mean predictive values of 0.40 and 0.37, respectively, for the detection of prediagnosed SPLs. When the SPLs had been excised and examined histopathologically, reanalysis showed mean sensitivities of 0.98 and 0.95, mean specificities of 0.52 and 0.49, and mean positive predictive values of 0.24 and 0.22 for the detection of subjects with melanomas by trained and untrained GPs respectively. Trained GPs were significantly better than untrained GPs at diagnosing as melanomas SPLs that subsequently proved to be melanomas (p = 0.04).

CONCLUSIONS

GPs in this study achieved high sensitivities in screening older Australian men and women for melanomas, but at the cost of low specificities and positive predictive values. Training in melanoma diagnosis had no significant effect on sensitivity, specificity, and positive predictive value for screening. Data from the study were tested in a model of population screening for melanomas, and costs per life year saved for men aged 50-70 ranged from $A11,852 to $A40,259 depending upon the screening interval and whether the GPs excised the SPLs diagnosed, or referred all patients to skin cancer specialists; this would be as cost effective as cervical cancer screening.

An analysis of testosterone implants for androgen replacement therapy

OBJECTIVE

To review 13 years of experience using fused crystalline testosterone implants for androgen replacement therapy in order to identify pattern of usage (including continuation rates) and adverse events emerging during therapy and factors associated with adverse events including implant extrusions.

DESIGN

Retrospective review of prospectively collected data on characteristics of patients and implant procedures performed as well as adverse events reported during routine follow-up.

PATIENTS

Over 13 years 973 implant procedures using fused crystalline testosterone implants were performed in 221 men.

MEASUREMENTS

Continuation rates and adverse events such as extrusions, bleeding, infection or others were recorded and analysed in relationship to characteristics of the patient and the implant procedure performed.

RESULTS

Overall rate of adverse events (108/73, 11.1%) was significantly related to increased numbers of implants (4.2 +/- 0.1 vs 4.0 +/- 0.03, P = 0.031) and higher levels of physical activity at work (P = 0.030). The most common adverse effect was extrusion (83/973, 8.5%) which was related to occupational classification (P = 0.033) and increasing work activity (P = 0.044) and occurred more frequently than by chance in multiple (16 vs 3.3 expected) rather than single (65 vs 76.1 expected) episodes. Bleeding (22/973, 2.3%) was significantly associated with an increased number of implants (4.5 +/- 0.2 vs 4.0 +/- 0.03, P = 0.020) but even in the worst cases (3/22) it was of minor clinical importance. Infection was rare (6/973, 0.6%) but occurred more among thinner men. The overall continuation rate was 92.7% increasing from 86% after the first implantation to > 99% after the tenth implant.

CONCLUSIONS

This study demonstrates the very satisfactory clinical acceptability of testosterone pellet implants for androgen replacement therapy within a single unit with experienced operators. The only regular adverse effect is extrusion, which may be related to mechanical factors such as habitual work activity but also possibly procedural factors. Other adverse effects such as bleeding, infection and fibrosis were rare. An improved method of implant delivery would enhance this old but durable technology.

Allogeneic blood stem cell transplantation: considerations for donors

Allogeneic transplantation of cytokine-mobilized peripheral blood stem cells (PBSCs) is now being increasingly performed, but safety considerations for hematologically normal PBSC donors have not been fully addressed. Progenitors are generally mobilized for collection from normal donors using recombinant human granulocyte colony-stimulating factor (rhG-CSF). Although the short-term safety profile of rhG-CSF seems acceptable, experience remains limited and its optimal dose and schedule have not been defined. Minimal data exist regarding long-term safety of rhG-CSF, primarily derived from experience in patients with chronic neutropenia or cancer. An "ad hoc" workshop was recently convened among a group of investigators actively involved in the field of allogeneic stem cell transplantation to discuss the safety issues pertaining to normal PBSC donors. There was agreement on the following points: (1) On the basis of available data, it appears that rhG-CSF treatment and PBSC collection have an acceptable short-term safety profile in normal donors. However, the need for continued safety monitoring was recognized. (2) rhG-CSF doses up to 10 microg/kg/d show a consistent dose-response relationship with the mobilization (and collection) of CD34+ progenitor cells, and this dose is acceptable for routine clinical use. Whether higher doses are superior (or cost effective) remains to be determined, and they may produce more severe side effects. The potential risks of marked leukocytosis (arbitrarily defined as a leukocyte count of more than 70 x 10(9)/L) have been a concern, and rhG-CSF dose reduction is performed by many centers to maintain leukocyte counts below this level. (3) Transient post donation cytopenias, involving granulocytes, lymphocytes, and platelets, may occur and are at least partly related to the leukapheresis procedure. These are generally asymptomatic and self-limited; follow-up blood counts are not necessarily required. Reinfusion of autologous platelet-rich plasma should be considered for donors with expected postdonation thrombocytopenia (platelet count < 80 to 100 x 10(9)/L). (4) Donors should meet the eligibility criteria which apply to donors of apheresis platelets, with the exception that pediatric donors may also be considered. Any deviation from these criteria should have supporting documentation. There is insufficient information at this time to clearly establish definite contraindications for PBSC collection in a hematologically normal donor. Potential contraindications include the presence of inflammatory, autoimmune, or rheumatologic disorders, as well as atherosclerotic or cerebrovascular disease. (5) The creation of an International PBSC Donor Registry is desirable to facilitate monitoring the long-term effects of the procedure. Individual institutions or donor centers are encouraged to establish their own PBSC donor follow-up system, preferably with a standardized approach to data collection.

Intravesical morphine analgesia after bladder surgery

PURPOSE

A recent demonstration of peripheral opioid receptors suggested the possibility of delivering morphine locally into the bladder after reimplantation for ameliorating the discomfort of postoperative bladder irritation with spasms. Since we do not use bladder drainage after reimplantation, dripping a morphine solution into the bladder permits contact with the urothelium between voidings. A pilot trial using an arbitrary concentration was subjectively beneficial for treating these patients postoperatively. We now report a prospective randomized study evaluating the effectiveness and dosage of various concentrations of intravesical morphine infusions.

MATERIALS AND METHODS

A total of 52 children undergoing ureteral reimplantation was randomized to receive 1 of 3 concentrations of intravesical morphine (0.05, 0.375 or 0.5 mg./ml.). A small feeding tube remained in the bladder to drip a continuous infusion postoperatively. Subsequent postoperative pain was treated with meperidine, acetaminophen and codeine, and/or a belladonna and opium suppository. During each shift a nurse assisted the child in assessing pain using a Baker-Wong faces scale. Bladder infusion was discontinued after day 3 postoperatively and plasma morphine levels were measured on the first morning postoperatively. Kruskal-Wallis and paired t tests were used to evaluate significance.

RESULTS

Patients reported greater pain in the group infused with 0.05 mg./ml. on 4 of 6 shifts on the first 2 days postoperatively. No difference was noted on postoperative day 3. Plasma morphine was undetectable by high pressure liquid chromatography.

CONCLUSIONS

This study offers objective evidence that bladder morphine infusion is effective for ameliorating postoperative pain in the first 48 hours after intravesical ureteral reimplantation. The dose given today is 0.5 mg./ml. delivered at 0.04 ml./kg. per hour.

Pharmacokinetics and pharmacodynamics of nandrolone esters in oil vehicle: effects of ester, injection site and injection volume

We studied healthy men who underwent blood sampling for plasma nandrolone, testosterone and inhibin measurements before and for 32 days after a single i.m. injection of 100 mg of nandrolone ester in arachis oil. Twenty-three men were randomized into groups receiving nandrolone phenylpropionate (group 1, n = 7) or nandrolone decanoate (group 2, n = 6) injected into the gluteal muscle in 4 ml of arachis oil vehicle or nandrolone decanoate in 1 ml of arachis oil vehicle injected into either the gluteal (group 3, n = 5) or deltoid (group 4, n = 5) muscles. Plasma nandrolone, testosterone and inhibin concentrations were analyzed by a mixed-effects indirect response model. Plasma nandrolone concentrations were influenced (P < .001) by different esters and injection sites, with higher and earlier peaks with the phenylpropionate ester, compared with the decanoate ester. After nandrolone decanoate injection, the highest bioavailability and peak nandrolone levels were observed with the 1-ml gluteal injection. Plasma testosterone concentrations were also influenced (P < .001) by the ester and injection site, with the most rapid, but briefest, suppression being due to the phenylpropionate ester, whereas the most sustained suppression was achieved with the 1-ml gluteal injection. Plasma inhibin concentrations were also significantly influenced by injection volume and site, with the lowest nadir occurring after the nandrolone decanoate 1-ml gluteal injection. Thus, the bioavailability and physiological effects of a nandrolone ester in an oil vehicle are greatest when the ester is injected in a small (1 ml vs. 4 ml) volume and into the gluteal vs. deltoid muscle. We conclude that the side-chain ester and the injection site and volume influence the pharmacokinetics and pharmacodynamics of nandrolone esters in an oil vehicle in men.

Research utilization in a metropolitan children's hospital

A model of research utilization directing clinical practice has been described. Clinical practice is conceptualized as a pyramid, with research knowledge forming the base. Department and unit-level activities are designed to promote the identification of research-based practices for incorporation into practice. Practice Committee structures are designed to facilitate the dissemination and utilization of research-based practices. This model has evolved over the past 10 years, and current refinements include movement toward an interdisciplinary focus, support of unit level practice groups, and increased integration of the work of each practice committee.