21 results on '"Fath F"'
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2. EFEKTIVITAS EKSTRAK LAMUN Cymodocea rotundata, Thalassia hemprichii, DAN Enhalus acoroides DARI PERAIRAN JEPARA SEBAGAI ANTIBAKTERI PADA FILLET IKAN NILA (Oreochromis niloticus) SELAMA PENYIMPANAN DINGIN (Effects Of Seagrass Extracts Cymodocea rotundata, Thalassia hemprichii, and Enhalus acoroides From Jepara As Antibacterials On Tilapia (Orechromis niloticus) Fillets During Cold Storage)
- Author
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Pradana, Nikolaus Eric, primary, Wardiwira, Fath F, additional, Hakim, Luqmanul, additional, Imamah, Azizatul Nur, additional, and Istianisa, Winne, additional
- Published
- 2018
- Full Text
- View/download PDF
3. EFEKTIVITAS EKSTRAK LAMUN Cymodocea rotundata, Thalassia hemprichii, DAN Enhalus acoroides DARI PERAIRAN JEPARA SEBAGAI ANTIBAKTERI PADA FILLET IKAN NILA (Oreochromis niloticus) SELAMA PENYIMPANAN DINGIN (Effects Of Seagrass Extracts Cymodocea rotundata, Thalassia hemprichii, and Enhalus acoroides From Jepara As Antibacterials On Tilapia (Orechromis niloticus) Fillets During Cold Storage)
- Author
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Winne Istianisa, Fath F Wardiwira, Luqmanul Hakim, Nikolaus Eric Pradana, and Azizatul Nur Imamah
- Subjects
General Medicine - Abstract
Penanganan fillet ikan nila segar merupakan bagian penting karena dapat mempengaruhi mutu. Ikan nila memiliki pH mendekati netral yang merupakan media untuk pertumbuhan bakteri pembusuk maupun mikroorganisme lain sehingga mudah mengalami pembusukan. Penambahan bahan antibakteri dari jenis lamun diharapkan mampu menambah masa simpan fillet ikan nila. Ketiga jenis lamun, yaitu Cymodocea rotundata, Thalassia hemprichii, dan Enhalus acoroides digunakan pada penelitian pendahuluan, selanjutnya diambil salah satu yang terbaik untuk masuk dipenelitian utama. Lamun dikeringkan dengan cara diangin-anginkan, lamun kering diekstrak dengan etanol 96% selama 2 x 24 jam dengan perbandingan bahan : pelarut (1 : 5). Ekstrak lamun disaring untuk memisahkan residu dan pelarut, filtrat diuapkan menggunakan rotary evaporator . F illet ikan nila direndam ekstrak lamun dengan konsentrasi 20%, 25%, dan 30% selama 2 jam, kemudian diuji TPC dan organoleptik. Berdasarkan hasil penelitian pendahuluan didapatkan Enhalus accoroides dengan konsentrasi 25% merupakan konsentrasi terbaik berdasarkan nilai TPC dan organoleptik. Penelitian selanjutnya adalah menambahkan ekstrak lamun Enhalus acoroides 25% dan tanpa penambahan ekstrak Enhalus acoroides sebagai control. Fillet dikemas menggunakan plastik seal dan disimpan pada suhu dingin 4 o C dalam refrigerator dengan lama penyimpanan 0, 3, 6, 9, dan 12 hari. Fillet ikan nila yang disimpan pada suhu dingin menunjukkan bahwa perbedaan penambahan lamun dan lama penyimpanan memberikan pengaruh yang nyata terhadap nilai TPC pada hari ke-12 yaitu 1,16 x 10 5 CFU/g, nilai TVBN 26,67 mgN/100g, dan nilai pH sebesar 7,01 Handling fresh tilapia fillets is an important part because it can affect quality. Tilapia has a pH close to neutral which is a medium for the growth of decomposing bacteria and other microorganisms so that it can easily decay. The addition of antibacterial ingredients from seagrass species is expected to increase the shelf life of tilapia fillets. The three types of seagrass, namely Cymodocea rotundata, Thalassia hemprichii, and Enhalus acoroides were used in the preliminary study, then taken one of the best to enter in the main study. Seagrass is dried by aerating, dried seagrass is extracted with 96% ethanol for 2 x 24 hours with a ratio of ingredients: solvent (1: 5). Seagrass extract is filtered to separate the residue and solvent, the filtrate is evaporated using a rotary evaporator. Tilapia fillets were soaked with seagrass extract with concentrations of 20%, 25%, and 30% for 2 hours, then tested for TPC and organoleptic. Based on the results of preliminary research, Enhalus accoroides with a concentration of 25% was the best concentration based on the value of TPC and organoleptic. The next study was to add 25% seaweed extract Enhalus acoroides and without the addition of Enhalus acoroides extract as a control. Fillets are packaged using a plastic seal and stored at a cool temperature of 4oC in a refrigerator with a storage time of 0, 3, 6, 9, and 12 days. Tilapia fillets stored at cold temperatures showed that the difference in the addition of seagrass and storage time had a significant effect on the value of TPC on day 12, that is 1,16 x 105 CFU/g, the TVBN value was 26.67 mgN / 100g, and the pH value was 7.01.
- Published
- 2018
4. How Does The Additional Benefit Extent of Orphan Drugs Impact Price Negotiations In The German Outpatient Sector?
- Author
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Freiberg, M, primary, Schwarz, R, additional, and Fath, F, additional
- Published
- 2015
- Full Text
- View/download PDF
5. Factors influencing maximum ROM at the ankle joint: different results from cross-sectional vs. longitudinal studies
- Author
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Blazevich, Anthony J., Waugh, C., Cannavan, D., Fath, F., Miller, S., and Anthony Kay
- Subjects
musculoskeletal diseases ,musculoskeletal system - Abstract
Introduction The ability to move through large joint ranges of motion (ROM) is important for the successful performance of activities of daily living and athletic tasks, however the factors affecting ROM are not currently known. Two common approaches to studying these factors are to: (1) compare neuromuscular differences between 'flexible' and 'inflexible' subjects, and (2) determine which neuromuscular factors change temporally with ROM. We have compared the results obtained by these two approaches. Methods In study one, 21 healthy men were divided into two groups (flexible, n=11; inflexible, n=10) based on their maximum dorsiflexion ROM (median = 46 deg) measured on an isokinetic dynamometer with the knee straight. Muscle and tendon lengths, passive muscle and tendon stiffness, fascicle length, angle, strain (lengthening) and rotation, peak passive torque (i.e. stretch tolerance), gastrocnemius and soleus EMG records, and H wave amplitudes (maximum and at 10% Mmax) were measured using dual-transducer ultrasound, isokinetic dynamometry, EMG and tibial nerve stimulation procedures. In study two, these measures were obtained in 12 subjects who performed twice daily straight-leg plantarflexion stretches for 3 weeks and 9 subjects who acted as non-stretching controls. Five additional subjects were tested for fascicle length, strain and rotation only, in order to improve statistical power. Results In study one, subjects with a greater ROM (flexible) tolerated a greater peak passive torque (48.6%) and exhibited greater fascicle rotation during stretch to 30 deg dorsiflexion (9.7 vs. 5.9%) than inflexible subjects; there was a greater tendon length at stretch termination only due to the greater loads tolerated. There were no differences in H-reflex magnitudes, EMG maximum amplitudes or EMG at stretch termination, but there was a moderate correlation between the angle of EMG onset and maximum ROM (r=0.60, p
- Published
- 2013
6. Age-related changes in mechanical properties of the Achilles tendon
- Author
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Waugh, C M, Blazevich, A J, Fath, F, and Korff, T
- Subjects
musculoskeletal diseases ,Adult ,Male ,Aging ,Electromyography ,Age Factors ,Original Articles ,musculoskeletal system ,Achilles Tendon ,Weight-Bearing ,Young Adult ,Child, Preschool ,Humans ,Regression Analysis ,Female ,Stress, Mechanical ,Child - Abstract
The stiffness of a tendon, which influences muscular force transfer to the skeleton and increases during childhood, is dependent on its material properties and dimensions, both of which are influenced by chronic loading. The aims of this study were to: (i) determine the independent contributions of body mass, force production capabilities and tendon dimensions to tendon stiffness during childhood; and (ii) descriptively document age-related changes in tendon mechanical properties and dimensions. Achilles tendon mechanical and material properties were determined in 52 children (5–12 years) and 19 adults. Tendon stiffness and Young's modulus (YM) were calculated as the slopes of the force–elongation and stress-strain curves, respectively. Relationships between stiffness vs. age, mass and force, and between YM vs. age, mass and stress were determined by means of polynomial fits and multiple regression analyses. Mass was found to be the best predictor of stiffness, whilst stress was best related to YM (< 75 and 51% explained variance, respectively). Combined, mass and force accounted for up to 78% of stiffness variation. Up to 61% of YM variability could be explained using a combination of mass, stress and age. These results demonstrate that age-related increases in tendon stiffness are largely attributable to increased tendon loading from weight-bearing tasks and increased plantarflexor force production, as well as tendon growth. Moreover, our results suggest that chronic increases in tendon loading during childhood result in microstructural changes which increase the tendon's YM. Regarding the second aim, peak stress increased from childhood to adulthood due to greater increases in strength than tendon cross-sectional area. Peak strain remained constant as a result of parallel increases in tendon length and peak elongation. The differences in Achilles tendon properties found between adults and children are likely to influence force production, and ultimately movement characteristics, which should be explicitly examined in future research.
- Published
- 2011
7. Effects of resistance training on tendon mechanical properties and rapid force production in prepubertal children
- Author
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Waugh, C. M., primary, Korff, T., additional, Fath, F., additional, and Blazevich, A. J., additional
- Published
- 2014
- Full Text
- View/download PDF
8. Rapid force production in children and adults: Mechanical and neural contributions
- Author
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Waugh, CM, Korff, T, Fath, F, Blazevich, Anthony J, Waugh, CM, Korff, T, Fath, F, and Blazevich, Anthony J
- Abstract
Purpose: Children demonstrate lower force production capacities compared with adults, which has often been attributed to "neuromuscular immaturity." However, tendon stiffness, which influences both the electromechanical delay (EMD) and rate of force development (RFD) in adults, is lower in children and may influence rapid force production. The aims of this study were 1) to document EMD and RFD variation as a function of age, 2) to determine the relationships between tendon stiffness and parameters relating to rapid force production in children and adults, and 3) to estimate the relative neural and mechanical contributions to age-related changes in force production by examining the effects of tendon stiffness and muscle activation rate (rate of EMG increase [REI]) on RFD. Methods: Achilles tendon stiffness, EMD, RFD, and REI were measured during plantarflexion contractions in 47 prepubertal children (5-12 yr) and 19 adults. Relationships were determined between 1) stiffness and EMD, 2) stiffness and RFD, and 3) REI and RFD. The relative contributions of age, stiffness, and REI on RFD were determined using a multiple regression analysis. Age-related differences in tendon stiffness, EMD, RFD, and REI were also examined according to chronological age (5-6, 7-8, and 9-10 yr) and compared with adults. Results: Increases in tendon stiffness with age were correlated with decreases in EMD (r < -0.83). Stiffness and REI could account for up to 35% and 30% of RFD variability in children, respectively, which increased to 58% when these variables were combined. Conclusions: Both neural and mechanical factors influence rapid force production in prepubertal children. Children's longer EMD and slower RFD indicate a less effective development and transfer of muscular forces, which may have implications for complex movement performance.
- Published
- 2013
9. Neuromuscular factors influencing the maximum stretch limit of the human plantar flexors
- Author
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Blazevich, A. J., primary, Cannavan, D., additional, Waugh, C. M., additional, Fath, F., additional, Miller, S. C., additional, and Kay, A. D., additional
- Published
- 2012
- Full Text
- View/download PDF
10. Plantarflexor stretch training increases reciprocal inhibition measured during voluntary dorsiflexion
- Author
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Blazevich, A. J., primary, Kay, A. D., additional, Waugh, C., additional, Fath, F., additional, Miller, S., additional, and Cannavan, D., additional
- Published
- 2012
- Full Text
- View/download PDF
11. Age-related changes in mechanical properties of the Achilles tendon
- Author
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Waugh, C. M., primary, Blazevich, A. J., additional, Fath, F., additional, and Korff, T., additional
- Published
- 2011
- Full Text
- View/download PDF
12. PHP206 - How Does The Additional Benefit Extent of Orphan Drugs Impact Price Negotiations In The German Outpatient Sector?
- Author
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Freiberg, M, Schwarz, R, and Fath, F
- Published
- 2015
- Full Text
- View/download PDF
13. Effects of resistance training on tendon mechanical properties and rapid force production in prepubertal children
- Author
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Waugh, C M, Korff, T, Fath, F, Blazevich, Anthony J, Waugh, C M, Korff, T, Fath, F, and Blazevich, Anthony J
- Abstract
Waugh C.M., Korff T., Fath F., Blazevich A.J. (2014). Effects of resistance training on tendon mechanical properties and rapid force production in prepubertal children. Journal of Applied Physiology, 117(3), 257-266. Available here
14. PHP206 How Does The Additional Benefit Extent of Orphan Drugs Impact Price Negotiations In The German Outpatient Sector?
- Author
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Freiberg, M, Schwarz, R, and Fath, F
- Full Text
- View/download PDF
15. Adsorption and immobilization performance of pine-cone pristine and engineered biochars for antimony in aqueous solution and military shooting range soil: An integrated novel approach.
- Author
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Khan BA, Ahmad M, Iqbal S, Ullah F, Bolan N, Solaiman ZM, Shafique MA, and Siddique KHM
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- Humans, Antimony analysis, Soil, Adsorption, Charcoal, Iron analysis, Water analysis, Kinetics, Military Personnel, Water Pollutants, Chemical analysis
- Abstract
Antimony (Sb-V), a carcinogenic metalloid, is becoming prevalent in water and soil due to anthropogenic activities. Biochar could be an effective remedy for Sb(V)-contaminated water and soil. In this study, we used pristine and engineered pinecone-derived biochar as an innovative approach for treating Sb(V)-contaminated water and shooting range soil. Biochar was produced from pine-cone waste (pristine biochar) and enriched with Fe and Al salts via saturation (engineered biochar). Adsorption tests in water revealed that iron-modified biochar showed higher adsorption capacity (8.68 mg g
-1 ) than that of the pristine biochar (2.49 mg g-1 ) and aluminum-modified biochar (3.40 mg g-1 ). Isotherm and kinetic modeling of the adsorption data suggested that the adsorption process varied from monolayer to multilayer, with chemisorption as the dominant interaction mechanism between Sb(V) and the biochars. The post-adsorption study of iron-modified biochar by Fourier Transform Infrared (FTIR) and X-ray diffraction (XRD) further supported the chemical bonding and outer-sphere complexation of Sb(V) with Fe, N-H, O-H, C-O and CC components. The pristine and iron-modified biochars also successfully immobilized Sb(V) in a shooting range soil, more so in the latter. Subsequent sequential extractions and post-analysis by scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), and elemental dot mapping revealed that Sb in the treated soil transformed to a more stable form. It was concluded that iron-modified biochar could act as an efficient material for the adsorption and immobilization of Sb(V) in water and soil, respectively., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Ltd. All rights reserved.)- Published
- 2023
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16. Calpains as novel players in the molecular pathogenesis of spinocerebellar ataxia type 17.
- Author
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Weber JJ, Anger SC, Pereira Sena P, Incebacak Eltemur RD, Huridou C, Fath F, Gross C, Casadei N, Riess O, and Nguyen HP
- Subjects
- Animals, Neurons metabolism, Rats, Trinucleotide Repeat Expansion, Calpain genetics, Calpain metabolism, Spinocerebellar Ataxias metabolism
- Abstract
Spinocerebellar ataxia type 17 (SCA17) is a neurodegenerative disease caused by a polyglutamine-encoding trinucleotide repeat expansion in the gene of transcription factor TATA box-binding protein (TBP). While its underlying pathomechanism is elusive, polyglutamine-expanded TBP fragments of unknown origin mediate the mutant protein's toxicity. Calcium-dependent calpain proteases are protagonists in neurodegenerative disorders. Here, we demonstrate that calpains cleave TBP, and emerging C-terminal fragments mislocalize to the cytoplasm. SCA17 cell and rat models exhibited calpain overactivation, leading to excessive fragmentation and depletion of neuronal proteins in vivo. Transcriptome analysis of SCA17 cells revealed synaptogenesis and calcium signaling perturbations, indicating the potential cause of elevated calpain activity. Pharmacological or genetic calpain inhibition reduced TBP cleavage and aggregation, consequently improving cell viability. Our work underlines the general significance of calpains and their activating pathways in neurodegenerative disorders and presents these proteases as novel players in the molecular pathogenesis of SCA17., (© 2022. The Author(s).)
- Published
- 2022
- Full Text
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17. FH ALERT: efficacy of a novel approach to identify patients with familial hypercholesterolemia.
- Author
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Fath F, Bengeser A, Barresi M, Binner P, Schwab S, Ray KK, Krämer BK, Fraass U, and März W
- Subjects
- Adolescent, Adult, Cholesterol blood, Cholesterol, LDL blood, Genetic Testing, Humans, Hyperlipoproteinemia Type II blood, Hyperlipoproteinemia Type II genetics, Laboratory Critical Values, Male, Middle Aged, Primary Health Care methods, Program Evaluation, Young Adult, Hyperlipoproteinemia Type II diagnosis, Mass Screening methods
- Abstract
Diagnosis rates of familial hypercholesterolemia (FH) remain low. We implemented FH ALERT to assess whether alerting physicians for the possibility of FH impacted additional diagnostic activity. The study was conducted from SYNLAB laboratory Weiden (Bavaria). Beyond common reporting of LDL-C or TC, 1411 physicians covering approximately a population of 1.5 million people were eligible to receive an alert letter (AL) including information on FH, if laboratory results exceeded thresholds as follows: adults LDL-C ≥ 190-250 mg/dl (to convert into mmol/l multiply with 0.0259), TC ≥ 250 to ≤ 310 mg/dl (probable suspicion); LDL-C > 250 mg/dl and TC > 310 mg/dl (strong suspicion). Persons below 18 years were alerted for LDL-C 140 mg/dl and TC ≥ 200 mg/dl (strong suspicion). Patients above 60 years were excluded. Our readouts were characteristics of involved physicians, rate of ALs issued, acceptance, and subsequent diagnostic activity. Physicians were mainly general practitioners in ambulatory care. 75% of the ordered tests were for TC, 25% for LDL-C. We issued 3512 ALs (~ 5% of tests) triggered by 2846 patients. 86% of eligible physicians stayed with the initiative, 32.7% were alerted, and 70% were positive upon call-center survey. We registered 101 new visitors of www.fhscore.eu and sent out 93 kits for genetics. Thereof, 26 were returned and 5 patients were positive for FH. Physicians were in general open to our approach. Although genetic testing was taken up with caution, this 3-months pilot examination resulted in a greater rate of patients with FH diagnosed than previous screening projects. Further education on FH in primary care is required to improve FH detection in the community., (© 2021. The Author(s).)
- Published
- 2021
- Full Text
- View/download PDF
18. Tibialis anterior moment arm: effects of measurement errors and assumptions.
- Author
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Miller SC, Korff T, Waugh C, Fath F, and Blazevich AJ
- Subjects
- Adult, Ankle diagnostic imaging, Ankle physiology, Female, Humans, Magnetic Resonance Imaging, Male, Muscle Contraction physiology, Muscle Strength Dynamometer, Muscle, Skeletal diagnostic imaging, Rotation, Talus physiology, Tendons diagnostic imaging, Ultrasonography, Young Adult, Muscle, Skeletal physiology, Tendons physiology
- Abstract
Unlabelled: Accurate estimates of tibialis anterior (TA) muscle force are important in many contexts. Two approaches commonly used to estimate moment arms are the tendon excursion (TE) and geometric (GEO) methods. Previous studies report poor agreement between the two approaches., Purpose: The purposes of this study were to 1) assess the effect of methodological variations in the two methods of moment arm estimation and 2) determine how these variations affect agreement between the methods., Methods: TA moment arms were determined using TE and GEO. Errors associated with tendon stretch/hysteresis, talus rotation relative to the foot, and the location of the line of action were investigated., Results: For TE, large errors in moment arm estimates across the range of motion were found when tendon length changes (P = 0.001) were not corrected for. For GEO, the estimated moment arm was reduced at an ankle angle of -15° when discrepancies between talus and foot rotations were accounted for or when an alternative tendon line of action was used either separately (effect size (ES), 0.46 and 0.58, respectively; P > 0.05) or together (ES, 0.89; P > 0.05). TE-derived moment arms were smaller than GEO-derived moment arms (ES, 0.68-4.86, varying by angle) before accounting for sources of error. However, these differences decreased after error correction (ES, 0.09-1.20, P > 0.05). Nonetheless, the shape of the moment arm-joint angle relation was curvilinear for TE but linear for GEO., Conclusions: Of all methodological modifications, accounting for tendon length changes had the largest effect on TA moment arm estimates. We conclude that the TE method is viable to determine TA moment arms as long as changes in tendon length are accounted for.
- Published
- 2015
- Full Text
- View/download PDF
19. Comparison of patients diagnosed with gonorrhoea through community screening with those self-presenting to the genitourinary medicine clinic.
- Author
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Cook PA, Evans-Jones J, Mallinson H, Wood M, Alloba F, Jones K, Strodtbeck S, and Hanna-Bashara L
- Subjects
- Adult, Age Factors, Cross-Sectional Studies, England epidemiology, Female, Gonorrhea epidemiology, Humans, Male, Neisseria gonorrhoeae, Nucleic Acid Amplification Techniques, Residence Characteristics, Retrospective Studies, Sex Factors, Sexual Behavior, Social Class, Young Adult, Ambulatory Care Facilities, Community Health Services, Gonorrhea diagnosis, Mass Screening
- Abstract
Objectives: To compare the clinical, socioeconomic and demographic characteristics of individuals diagnosed with Neisseria gonorrhoeae (NG) in the community using a concomitant nucleic acid amplification test (NAAT, AptimaCombo2) as part of the (community-based) UK Chlamydia Screening Programme (CSP), with those diagnosed in hospital-based genitourinary medicine (GUM) services., Design: A retrospective case note review of all 643 patients treated for NG at a GUM in north west England (January 2007-April 2009)., Participants: All 643 treated for NG (including CSP cases, since all cases were referred to GUM for treatment). Limited data were available for 13 CSP cases who failed to attend GUM., Primary Outcome Measure: Whether the case was detected in the community or GUM services. Predictors were demographics (age, gender, postcode for deprivation analysis), sexual history (eg, number of partners) and clinical factors (eg, culture positivity)., Results: 131 cases were diagnosed by CSP (13 of whom did not attend GUM). A further four cases were contacts of these. The GUM caseload was thus inflated by 23% (from 521 to 643). Community cases were overwhelmingly female (85% vs 27% in GUM, p<0.001) and younger (87% females were <25 years vs 70% GUM females, p=0.001). Logistic regression analysis restricted to the target age of the CSP (<25 years) revealed that CSP cases, compared with GUM cases, were more likely to reside in deprived areas (adjusted OR=5.6, 95% CI 1.4 to 21.8 and 5.3, CI 1.7 to 16.6 for the most and second most deprived group respectively, compared with the averagely deprived group, p=0.037) and be asymptomatic (adjusted OR=1.9, CI 1.1 to 3.4, p=0.02)., Conclusions: Community screening for NG led to a 79% increase in the number of infections detected in women aged <25 years. Screening is targeted at young people, and tends to disproportionately attract young women, a group under-represented at GUM. Screening also contributed further to case detection in deprived areas.
- Published
- 2014
- Full Text
- View/download PDF
20. Rapid force production in children and adults: mechanical and neural contributions.
- Author
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Waugh CM, Korff T, Fath F, and Blazevich AJ
- Subjects
- Achilles Tendon diagnostic imaging, Adult, Age Factors, Child, Child, Preschool, Electromyography, Female, Humans, Male, Regression Analysis, Ultrasonography, Young Adult, Achilles Tendon physiology, Elasticity physiology, Muscle Contraction physiology, Muscle Strength physiology, Psychomotor Performance physiology
- Abstract
Purpose: Children demonstrate lower force production capacities compared with adults, which has often been attributed to "neuromuscular immaturity." However, tendon stiffness, which influences both the electromechanical delay (EMD) and rate of force development (RFD) in adults, is lower in children and may influence rapid force production. The aims of this study were 1) to document EMD and RFD variation as a function of age, 2) to determine the relationships between tendon stiffness and parameters relating to rapid force production in children and adults, and 3) to estimate the relative neural and mechanical contributions to age-related changes in force production by examining the effects of tendon stiffness and muscle activation rate (rate of EMG increase [REI]) on RFD., Methods: Achilles tendon stiffness, EMD, RFD, and REI were measured during plantarflexion contractions in 47 prepubertal children (5-12 yr) and 19 adults. Relationships were determined between 1) stiffness and EMD, 2) stiffness and RFD, and 3) REI and RFD. The relative contributions of age, stiffness, and REI on RFD were determined using a multiple regression analysis. Age-related differences in tendon stiffness, EMD, RFD, and REI were also examined according to chronological age (5-6, 7-8, and 9-10 yr) and compared with adults., Results: Increases in tendon stiffness with age were correlated with decreases in EMD (r < -0.83). Stiffness and REI could account for up to 35% and 30% of RFD variability in children, respectively, which increased to 58% when these variables were combined., Conclusions: Both neural and mechanical factors influence rapid force production in prepubertal children. Children's longer EMD and slower RFD indicate a less effective development and transfer of muscular forces, which may have implications for complex movement performance.
- Published
- 2013
- Full Text
- View/download PDF
21. Direct comparison of in vivo Achilles tendon moment arms obtained from ultrasound and MR scans.
- Author
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Fath F, Blazevich AJ, Waugh CM, Miller SC, and Korff T
- Subjects
- Achilles Tendon physiology, Adult, Ankle Joint physiology, Biomechanical Phenomena, Female, Humans, Image Interpretation, Computer-Assisted, Male, Muscle Contraction, Muscle, Skeletal physiology, Range of Motion, Articular, Reproducibility of Results, Rotation, Time Factors, Achilles Tendon anatomy & histology, Achilles Tendon diagnostic imaging, Magnetic Resonance Imaging, Ultrasonography
- Abstract
Accurate and reliable estimation of muscle moment arms is a prerequisite for the development of musculoskeletal models. Numerous techniques are available to estimate the Achilles tendon moment arm in vivo. The purposes of this study were 1) to compare in vivo Achilles tendon moment arms obtained using the center of rotation (COR) and tendon excursion (TE) methods and 2) to assess the reliability of each method. For the COR method, magnetic resonance (MR) images from nine participants were obtained at ankle angles of -15°, 0°, and +15° and analyzed using Reuleaux' method. For the TE method, the movement of the gastrocnemius medialis-Achilles tendon junction was recorded using ultrasonography as the ankle was passively rotated through its range of motion. The Achilles tendon moment arm was obtained by differentiation of tendon displacement with respect to ankle angular excursion using seven different differentiation techniques. Moment arms obtained using the COR method were significantly greater than those obtained using the TE method (P < 0.01), but results from both methods were well correlated. The coefficient of determination between moment arms derived from the COR and TE methods was highest when tendon displacement was linearly differentiated over a ± 10° interval (R(2) = 0.94). The between-measurement coefficient of variation was 3.9% for the COR method and 4.5-9.7% for the TE method, depending on the differentiation technique. The high reliabilities and strong relationship between methods demonstrate that both methods are robust against their limitations. The large absolute between-method differences (∼ 25-30%) in moment arms have significant implications for their use in musculoskeletal models.
- Published
- 2010
- Full Text
- View/download PDF
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