bluuebunny/crossref_metadata_2025_split huggingface dataset:
Incomplete rematching of nerve and muscle properties in motor units after extensive nerve injuries in cat hindlimb muscle
Authors: Rafuse Victor F. , Gordon Tessa 
Published: September 2004

Motor units were characterized in partially denervated or completely denervated and reinnervated cat medial gastrocnemius (MG) muscles where the number of innervating motor axons was severely reduced to determine (1) to what extent the nerve and muscle properties are rematched in enlarged motor units, (2) whether the normal size relationships between axon size, unit tetanic force and contractile speed are re‐established, and (3) whether the type of nerve injury and/or repair affects the re‐establishment of nerve and muscle properties.
Single MG units were sampled in (1) partially denervated muscles and in reinnervated muscles after either (2) crushing or (3) transecting the nerve and suturing its proximal end to either the distal nerve stump (N‐N), or (4) directly to the muscle fascia (N‐M).
The majority (75‐88 %) of motor units in all muscles were classified as S (slow), FR (fast fatigue resistant), FI (fast fatigue intermediate) and FF (fast fatigable). However, there was an increased number of FI and unclassifiable motor units compared to normal. These results suggest that motor unit properties are not entirely regulated by the reinnervating motoneurone.
Despite more overlap in the range of unit force between different motor unit types the tetanic force of each type increased in all muscles when reinnervated by few (< 50 %) motor axons. This increase in unit force was due to an expansion in motor unit innervation ratio.
The normal relationships between axon size, unit tetanic force, and contractile speed were re‐established in all muscles except when reinnervated by < 50 % of their normal complement of motor units after N‐M suture. This lack of correlation was due to the reduced fast glycolytic (FG) fibre size and the proportionately greater increase in force of the S units.
After reinnervation the ranges in fibre cross‐sectional area within single FF units were very similar to those found within the entire FG fibre population.
These results show that when few axons make functional connections in partially denervated or reinnervated muscles the normal relationships between axon size and motor unit contractile properties are re‐established provided the nerves regenerate within the distal nerve sheath. This rematching of motoneurone size and motor unit contractile properties occurs primarily because the size of the motor axon governs the number of muscle fibres it supplies.
The mechanics of running in children
Authors: Schepens B. , Willems P. A. , Cavagna G. A. 
Published: September 2004

The effect of age and body size on the bouncing mechanism of running was studied in children aged 2‐16 years.
The natural frequency of the bouncing system (fs) and the external work required to move the centre of mass of the body were measured using a force platform.
At all ages, during running below ≈11 km h−1, the freely chosen step frequency (f) is about equal to fs (symmetric rebound), independent of speed, although it decreases with age from 4 Hz at 2 years to 2.5 Hz above 12 years.
The decrease of step frequency with age is associated with a decrease in the mass‐specific vertical stiffness of the bouncing system (k/m) due to an increase of the body mass (m) with a constant stiffness (k).Above 12 years, k/mand fremain approximately constant due to a parallel increase in both kand mwith age.
Above the critical speed of ≈11 km h−1, independent of age, the rebound becomes asymmetric, i.e. f< fs.
The maximum running speed (Vf,max) increases with age while the step frequency at remains constant (≈4 Hz), independent of age.
At a given speed, the higher step frequency in preteens results in a mass‐specific power against gravity less than that in adults. The external power required to move the centre of mass of the body is correspondingly reduced.
Osmotic hypertonicity of the renal medulla during changes in renal perfusion pressure in the rat
Authors: Dobrowolski Leszek , Badzynska Bozena , Walkowska Agnieszka , Sadowski Janusz 
Published: September 2004

The relationship between renal perfusion pressure (RPP) and ion concentration in renal medulla was studied in anaesthetized rats. RPP was changed in steps within the pressure range 130‐80 mmHg, while tissue electrical admittance (Y, index of interstitial ion concentration) and medullary and cortical blood flow (MBF and CBF; laser Doppler flowmetry) were measured, along with glomerular filtration rate (Cin) and renal excretion.
With a RPP reduction from 130 to 120 mmHg, tissue Y remained stable; at 100 and 80 mmHg, Y was 5 and 17 % lower, respectively, than at 120 mmHg.
CBF fell less than RPP (partial autoregulation) in the range 130‐100 mmHg only. MBF was autoregulated within 120‐100 mmHg, but not above or below this range.
Each step of RPP reduction was followed by a decrease in sodium and water excretion (UNaV and V). The osmolality of excised inner medulla fragments was similar at 120 and 105 mmHg (586 ± 45 and 618 ± 35 mosmol (kg H2O)−1, respectively) but lower at 80 mmHg (434 ± 31 mosmol (kg H2O)−1, P < 0.01); the ion concentration changed in parallel.
The data show that medullary hypertonicity was well preserved during RPP fluctuations within 130‐100 mmHg, but not below this range. RPP‐dependent changes of UNaV and V were not clearly associated with changes in solute concentration in medullary tissue.
Developmental regulation of glucogenesis in the sheep fetus during late gestation
Authors: Fowden Abigail L. , Mundy Linda , the late Silver Marian 
Published: September 2004

Using tracer methodology, endogenous glucose production was measured in twenty‐six chronically catheterized sheep fetuses during normal fed conditions and in response to a 48 h period of maternal fasting at different gestational ages during the last 10‐15 days of gestation (term, 145 ± 2 days).
In normal fed conditions, the rate of fetal glucose production was negligible until 143‐145 days when it rose significantly to account for 50 % of the glucose used by the fetus. The rise in fetal glucogenesis towards term closely parallelled the normal prepartum rise in fetal plasma cortisol and catecholamines.
Maternal fasting for 48 h induced endogenous glucose production in fetuses at 139‐141 days but not at 133‐135 days of gestation. Maternal fasting also induced increases in the plasma cortisol and noradrenaline levels in all the fetuses studied. Fetal plasma cortisol levels at the end of the fast and the increment in fetal plasma cortisol during maternal fasting were significantly greater in the older groups of fasted animals.
When the data from all the fetuses were combined, partial correlation analysis of fetal glucose production and the log plasma concentrations of cortisol and total catecholamines showed that plasma cortisol was the predominant regulator of fetal glucogenesis during late gestation. However, once plasma cortisol levels exceeded 17.5 ng ml−1, plasma catecholamines were a major influence on fetal glucogenesis.
The results show that glucogenesis occurs in fetal sheep during late gestation in conditions in which the fetal plasma concentrations of cortisol and catecholamines are elevated. They also suggest that cortisol enhances the capacity for glucogenesis in utero, while catecholamines actually activate glucose production in sheep fetuses close to term.
A cross‐bridge mechanism can explain the thixotropic short‐range elastic component of relaxed frog skeletal muscle
Authors: Campbell K. S. , Lakie M. 
Published: September 2004

The passive tension and sarcomere length of relaxed frog skeletal muscle fibres were measured in response to imposed length stretches. The tension response to a constant‐velocity stretch exhibited a clear discontinuity. Tension rose more rapidly during the initial ∼ 0.4 %L0 of the stretch than during the latter stages (where L0 is the resting length of the fibre). This initial tension response is attributed to the short‐range elastic component (SREC).
The use of paired triangular stretches revealed that the maximum tension produced during the SREC response of the second stretch was significantly reduced by the first stretch. This history‐dependent behaviour of the SREC reflects thixotropic stiffness changes that have been previously described in relaxed muscle.
The biphasic nature of the SREC tension response to movement was most apparent during the first imposed length change after a period at a fixed length, irrespective of the direction of movement.
If a relaxed muscle was subjected to an imposed triangular length change so that the muscle was initially stretched and subsequently shortened back to its original fibre length, the resting tension at the end of the stretch was reduced relative to its initial pre‐stretch value. Following the end of the stretch, tension slowly increased towards its initial value but the tension recovery was not accompanied by a contemporaneous increase in sarcomere length. This finding suggests that the resting tension of a relaxed muscle fibre is not entirely due to passive elasticity. The results are compatible with the suggestion that a portion of the resting tension ‐ the filamentary resting tension (FRT) ‐ is produced by a low level of active force generation.
If a second identical stretch was imposed on the muscle at a time when the resting tension was reduced by the previous stretch, the maximal tension produced during the second stretch was the same as that produced during the first, despite the second stretch commencing from a lower initial resting tension.
In experiments using paired triangular length changes, an inter‐stretch interval of zero did not produce a substantially greater thixotropic reduction in the second stretch elastic limit force than an inter‐stretch interval in the range 0.5‐1 s.
A theoretical model was developed in which the SREC and FRT arise as manifestations of a small number of slowly cycling cross‐bridges linking the actin and myosin filaments of a relaxed skeletal muscle. The predictions of the model are compatible with many of the experimental observations. If the SREC and FRT are indeed due to cross‐bridge activity, the model suggests that the cross‐bridge attachment rate must increase during interfilamentary movement. A mechanism (based on misregistration between the actin binding sites and the myosin cross‐bridges) by which this might arise is presented.
Evidence that interleukin‐6 is produced in human skeletal muscle during prolonged running
Authors: Ostrowski K. , Rohde T. , Zacho M. , Asp S. , Pedersen B. K. 
Published: September 2004

This study was performed to test the hypothesis that inflammatory cytokines are produced in skeletal muscle in response to prolonged intense exercise. Muscle biopsies and blood samples were collected from runners before, immediately after, and 2 h after a marathon race.
The concentration of interleukin (IL)‐6 protein in plasma increased from 1.5 ± 0.7 to 94.4 ± 12.6 pg ml−1 immediately post‐exercise and to 22.1 ± 3.8 pg ml−1 2 h post‐exercise. IL‐1 receptor antagonist (IL‐1ra) protein in plasma increased from 123 ± 23 to 2795 ± 551 pg ml−1, and increased further to 4119 ± 527 pg ml−1 2 h post‐exercise.
The comparative polymerase chain reaction technique was used to evaluate mRNA for IL‐6, IL‐1ra, IL‐1β and tumour necrosis factor (TNF)‐α in skeletal muscle and blood mononuclear cells (BMNC) (n= 8). Before exercise, mRNA for IL‐6 could not be detected either in muscle or in BMNC, and was only detectable in muscle biopsies (5 out of 8) after exercise. Increased amounts of mRNA for IL‐1ra were found in two muscle biopsies and five BMNC samples, and increased amounts of IL‐1β mRNA were found in one muscle and four BMNC samples after exercise. TNF‐α mRNA was not detected in any samples.
This study suggests that exercise‐induced destruction of muscle fibres in skeletal muscles may trigger local production of IL‐6, which stimulates the production of IL‐1ra from circulating BMNC.
The Premonitory Symptoms (Prodrome): A Tertiary Care Study of 893 Migraineurs
Authors: Kelman Leslie 
Published: September 2004

Objectives.—This study of premonitory symptoms in migraine was performed to document the frequency, duration, and types of symptoms in a large group of migraine patients.Background.—Prodrome importance continues to be debated. Intervention early in the migraine attack is assuming more importance and necessitates better knowledge of the prodrome.Methods.—A total of 893 migraine patients (IHS 1.1‐1.7) were evaluated at first visit. Prodrome frequency, duration, and characteristics were analyzed in the total migraine population IHS 1.1‐1.7 and IHS 1.1‐1.6 migraine.Results.—A total of 32.9% of IHS migraine 1.1‐1.6 patients reported prodrome symptoms with an average of 9.42 hours. IHS 1.1‐1.7 migraine reported 29.7% and 6.8 hours, respectively. The most commonest symptoms were tiredness, mood change, and gastrointestinal symptoms; all three of these symptoms were present together in 17% of the patients with prodrome. The duration of prodrome was less than 1 hour in 45.1%, 1‐2 hours in 13.6%, 2‐4 hours in 15.0%, 4‐12 hours in 13.1%, and greater than 12 hours in 13.2%. IHS 1.1‐1.7 patients showed similar findings.IHS 1.1‐1.6 patients with prodrome differed from patients without prodrome in having more triggers as a whole (P < .01), more individual triggers including alcohol (P < .01), hormones (P < .01), light (P < .001), not eating (P < .05), perfume (P < .01), stress (P < .01), and weather changes (P < .05), a longer duration of aura (P < .05), longer time between aura and headache (P < .05), more aura with no headache (P < .05), longer time to peak of headache (P < .05), longer time to respond to triptan (P < .05), longer maximum duration of headache (P < .05), and more headache associated nausea (P < .05), more headache associated running of the nose or tearing of the eyes (P < .05), more postdrome syndrome (P < .05), and longer duration of postdrome syndrome (P < .001).Conclusions.—This study provides a portrait of prodrome in a large cohort of patients. It highlights differences between patients with prodrome and patients not having prodrome, and it draws attention to the potential of preventing the headache phase of the acute migraine attack.
Quantifying Headache Symptoms and Other Headache Features From Chart Notes
Authors: Hasse Lora A. , Ritchey P. Neal , Smith Robert 
Published: September 2004

Objectives.—To describe a method for quantifying headache symptoms/features in family practice charts for patients diagnosed with headache NOS (not otherwise specified, ICD‐9: 784) and to determine the share of NOS headache diagnoses with clinical data strongly suggestive of migraine or probable migraine headache.Background.—Headache is one of the most common pain symptoms that brings patients to a family physician. However, the majority of headache sufferers do not receive a specific headache diagnosis when they visit physicians.Methods.—We examined the chart notes of 454 patients exclusively diagnosed with one or more ICD‐9 coded headache NOS diagnoses from July 1, 1995 through December 31, 1999 at a large suburban, university‐affiliated practice. We developed a template containing 20 headache items combining International Headache Society diagnostic criteria and additional headache symptoms/features, and decision rules for coding symptoms/features and collected data from patient charts. We then developed decision rules and reclassified NOS headaches into categories strongly suggestive of migraine, probable migraine headache, or other diagnosis. Our main outcome measure is the consistency in the application of decision rules and diagnostic criteria.Results.—With this method we estimate 3 in 10 (29%) headache NOS patients may have had migraine (8%) or probable migraine headache (21%). Reclassified migraine visits averaged 6.5 migraine symptoms and reclassified probable migraine headache visits 4.7 migraine symptoms. Logistic regression analysis supports the consistency of diagnostic criteria for classifying headache based on coded symptoms/features—our model correctly predicted 96% of visits. Evidence of physical examination was recorded at 75% of visits suggesting that physician attention is focused on elimination of secondary headache.Conclusions.—We think the use of our rigorous procedures reveals that a substantial amount of migraine and probable migraine headache may be missed in everyday practice. We hope our findings will provide a basis for the development of diagnostic methods more closely suited to the needs of nonspecialists, and contribute to a better standard of care for headache patients seen in primary care practice. Finally, we are hopeful that other researchers will consider using our template and guideline procedures in their efforts to identify diagnostic patterns and study headache and other health problems.
Headache Profile in Patients With Idiopathic Hypertrophic Cranial Pachymeningitis
Authors: Wang Yuh‐Jen , Fuh Jong‐Ling , Lirng Jiing‐Feng , Lu Shiang‐Ru , Wang Shuu‐Jiun 
Published: September 2004

Background.—Idiopathic hypertrophic cranial pachymeningitis (IHCP) is an uncommon disorder due to localized or diffuse thickening of the dura mater. While headache is the most common manifestation, the clinical characteristics of the headache in IHCP have not been well characterized.Methods.—From 1996 to 2002, 6 consecutive patients with IHCP presenting with headache were reviewed (3 women, 3 men; mean age: 49 years). Diagnosis was based on characteristic neuroimaging findings and the exclusion of secondary causes of cranial pachymeningitis. This study reported the headache characteristics, neuroimaging features, and longitudinal follow‐up.Results.—Chronic daily headache, especially chronic migraine, was the most common headache pattern observed (4/6 patients). Lateralization of headache location appeared to correlate with the distribution of the hypertrophied dural lesions. Diagnostic delay was due to failure to evaluate with gadolinium‐enhanced MRI. After treatment, headache (5/6, 83%) and neurologic deficits (2/3, 67%) improved in most patients; however, follow‐up MRIs (n = 5) showed deterioration in 3 patients.Conclusion.—The headache of IHCP is typically a chronic daily headache, often resembling chronic migraine. Correspondingly, IHCP should be considered in the differential diagnosis of refractory chronic daily headache, with or without associated cranial neuropathy or other associated neurologic deficits. The typical imaging finding on gadolinium‐enhanced MRI is localized or diffuse pachymeningitis and failure to order a gadolinium‐enhanced MRI is the primary reason for delayed diagnosis. Despite symptomatic improvement on longitudinal follow‐up, the MRI abnormalities may not improve in parallel with the clinical symptoms.
The societal unit cost of allogenic red blood cells and red blood cell transfusion in Canada
Authors: Amin Mo , Fergusson Dean , Wilson Kumanan , Tinmouth Alan , Aziz Ashique , Coyle Doug , Hébert Paul 
Published: September 2004

BACKGROUND:  There is a dearth of information about the cost of allogenic red blood cells (RBCs) and RBC transfusion in Canada in the aftermath of the Canadian blood system reorganization and the introduction of various safety measures. The unit cost of allogenic RBCs and RBC transfusion in Canada in 1994 was estimated at US$152.17. The objective of this study was to determine the unit cost of allogenic RBC transfusion in Canada from a societal perspective.STUDY DESIGN AND METHODS:  A cost‐structure analysis using the cost information from 2001 through 2002 was used. Costs of blood collection, production, distribution, delivery (hospital transfusion service processing and patient administration), transfusion reaction management, and opportunity cost of donor's time were included in the analysis. Canadian Blood Services and Héma‐Québec supplied the data for collection, production, and distribution stages. Delivery and transfusion reaction costs were collected from eight hospitals across six Canadian provinces. In‐patient costs were assessed for the intensive care unit, emergency, general medicine ward, and operating room.RESULTS:  The aggregate mean societal unit cost of RBCs transfused on an inpatient basis in 2002 was US$264.81 (95% confidence interval [CI], $256.29‐$275.65). The mean cost of blood collection, production, and distribution was US$202.74 (95% CI, $199.63‐$204.31), the mean opportunity cost of donor time was US$18.21 (95% CI, $17.11‐$21.63), the mean cost of hospital transfusion service processing was US$16.65 (95% CI, $13.50‐$19.79), of RBC transfusion was US$26.92 (95% CI, $25.33‐$28.52), and of transfusion reaction management was US$0.29 (95% CI, $0.22‐$0.36). There were substantial variations in hospital transfusion service processing and RBC transfusion costs across hospitals.CONCLUSION:  The societal unit cost of RBC transfusion has doubled since 1994 to 1995. Further increases in unit costs would be expected as additional safety measures are introduced. This will have important financial implications for treating patient populations that require a high level of RBC transfusions.
Red cell requirements for intensive care units adhering to evidence‐based transfusion guidelines
Authors: Walsh Timothy S. , Garrioch Magnus , Maciver Caroline , Lee Robert J. , MacKirdy Fiona , McClelland D. Brian , Kinsella John , Wallis Charles ,   Audit of Transfusion in Intensive Care in Scotland (ATICS) Study Group
Published: September 2004

BACKGROUND:  Anemia commonly complicates critical illness. Restrictive transfusion triggers are appropriate in this setting, but no large studies have measured red cell (RBC) requirements for intensive care patients when evidence‐based transfusion guidelines are followed consistently.STUDY DESIGN AND METHODS:  Data were recorded daily for 1023 of 1042 sequential admissions to 10 intensive care units (ICUs) over 100 days. The sample comprised 44 percent of all ICU admissions in Scotland during this period. RBC transfusions and the occurrence of clinically significant hemorrhage were recorded for every ICU day. Transfusion episodes were classified as either associated with or not associated with hemorrhage. Measures of RBC use were derived for the cohort and for Scotland with national audit data.RESULTS:  A total of 39.5 percent (95% confidence interval [CI], 36.5%‐42.5%) of admissions received transfusions. Eighteen percent of admissions received at least one transfusion associated with hemorrhage and 26 percent received at least one transfusion not associated with hemorrhage. The median (interquartile range) transfusion trigger in the absence of hemorrhage was 78 (73‐78) g/L. The overall mean RBC use was 1.87 (95% CI, 1.79‐1.96) units per admission or 0.34 (95% CI, 0.33‐0.36) units per ICU‐day. Forty‐seven percent of RBCs administered were not associated with clinically significant hemorrhage. Mean RBC requirements for intensive care in Scotland were estimated to be 3950 (95% CI, 3780‐4140) per million‐adult‐population per year. This represented 7 to 8 percent of the Scottish blood supply.CONCLUSIONS:  Despite evidence‐based transfusion practice, 40 percent of ICU patients receive transfusions, which account for 7 to 8 percent of the national blood supply.