Biomedical subjects

C Rolf

Publications and source records attributed to C Rolf.

At least 73 records · Page 4Linked to original sources

PubMed1996

The validity of isokinetic knee extensor endurance measurements with reference to treadmill running capacities.

The validity of isokinetic knee extensor endurance measurements with reference to treadmill running capacities was investigated. Nine male elite middle-distance runners completed a test consisting of 100 repetitive maximal eccentric and 100 concentric knee extensor actions where peak torque (Nm) and work (J) were measured. On a different day, submaximal and maximal treadmill tests were performed. Stepwise regression analysis was applied to determine the isokinetic variables with the greatest influence on the selected treadmill running capacities, including submaximal oxygen uptake (VO(2)) and maximal blood lactate. Eccentric total work was significantly and negatively related to submaximal VO(2) at all three running velocities investigated (12, 14, and 15 km.h(-1)). The R(2) values ranged from 0.48-0.59 for V0(2) ml.kg(-0.75).min(-1), indicating that 48-59 % of the variability in VO(2) ml.kg(-0.75).min(-1) could be accounted for by eccentric total work. The corresponding R(2) values for VO in ml.kg(-1).min(-1) were 0.50-0.58. Concentric relative endurance was significantly and negatively related to maximal blood lactate (R(2) = 0.73). This study has shown that isokinetic knee extensor endurance measurements of eccentric total work and concentric relative endurance are substantially related to measures of treadmill running capacity, as expressed by submaximal V02 and maximal blood lactate. It is suggested that these isokinetic measures may be used to evaluate specified running capacities in male elite middle-distance runners.

Adult↗

PubMed1996

The role of phosphocreatine kinase in the motility of human spermatozoa supported by different metabolic substrates.

In the spermatozoa of some species creatine kinase (CK: E.C. 2.7.3.2) is involved in shuttling energy, in the form of creatine phosphate, between the mid-piece mitochondria and flagellum. In this study, the effects of the CK inhibitor dinitrofluorobenzene (DNFB) on human sperm CK activity, motility and ATP concentrations were assessed with different energy substrates. There was a dose-dependent inhibition of CK activity by DNFB but inhibition was incomplete and there was no effect on the percentage of flagellating cells, irrespective of substrate. However, when lactate alone supported the cells DNFB decreased velocities and increased amplitude of head displacement (fewer progressively motile forms were observed), whereas ATP concentrations in spermatozoa were unaltered. Demembranated sperm models could be reactivated by ADP plus creatine phosphate, but not to the extent caused by ATP, and were able to be inhibited by myokinase inhibitors. Increased velocities, linearity (LIN) and beat cross frequency (BCF) were demonstrated for spermatozoa incubated with lactate, in contrast to glucose as sole energy source, and higher velocities and BCF were generated in the presence of both substrates. This suggests that the production of ATP by glycolysis and respiration are independent and complementary. CK is not obligatory for sperm motility but supplements energy provision under certain conditions.

Adenosine Triphosphate↗

PubMed1996

An increase in sudden unexpected cardiac deaths among young Swedish orienteers during 1979-1992.

BACKGROUND: Sixteen cases of sudden unexpected cardiac death, 15 males and one female, are known to have occurred among young Swedish orienteers from 1979 to 1992, of which seven cases occurred between 1989 and 1992. This is considered to be indicative of an increased death rate. RESULTS: Histopathological evaluation showed myocarditis in a higher than expected proportion of cases. In one such case, which we studied before the sudden unexpected death occurred, the victim had suffered a Chlamydia pneumoniae infection verified by serology, and a nucleotide sequence was found in the heart and lung by means of the polymerase chain reaction (PCR) that hybridized with a probe specific for that organism. Male Swedish orienteers do not, however, seem to have an increased rate of exposure to this agent. No further sudden unexpected deaths among young orienteers have occurred over the past 3.5 years. At the beginning of that period, attempts were made to modify training habits and attitudes.

Adolescent↗

PubMed1996

Echocardiographic right and left ventricular measurements in male elite endurance athletes.

Echocardiography was used to assess normal values in the right and left ventricular cavity and wall in 127 male elite endurance athletes. M-mode and two dimensional measurements of left ventricle and left and right atria were also obtained. All subjects were high-performance orienteers, cross-country skiers and middle-distance runners. They all had a normal electrocardiogram at rest and no echocardiographic evidence of heart disease. With the use of multiple right ventricular cross-sections and two-dimensional measurements, we found a significantly greater right ventricular inflow tract and right and left atrial measurements in endurance athletes compared with earlier studies of normal, active subjects. The right ventricular free wall was slightly thicker than reported in normal active subjects but the differences were small. Left ventricular diastolic diameter was consistent with previous reports of endurance athletes. Of the 127 subjects, 13% had left ventricular wall thickness above 13 mm but none of the athletes had wall thickness above 15 mm. These data suggest that cardiac enlargement occurs symmetrically in both right and left cavities, probably reflecting increased haemodynamic loading, a mechanism by which athletes sustain a high cardiac output during exercise.

Adult↗

PubMed1996

Reproductive parameters of older compared to younger men of infertile couples.

In order to evaluate possible age-dependent influences on male infertility, semen parameters, sex hormone levels and pregnancy rates were compared retrospectively in three groups of men attending our fertility clinic: group A: 39 patients > 50 years. Group B (39 patients < 30 years) was established as the 'standard infertile patient' seen in our Institute. These patients were matched with patients of group A according to the year of their first visit to the clinic. Group C: 39 young patients (< 30 years) who were selected on the basis of their wives' advanced age. The frequency of sexual intercourse in group A was significantly lower compared to group C. The period of sexual abstinence was longer in group A than in group B. Ejaculate volume and sperm motility in group A were lower compared to groups B and C. The differences in other semen parameters were only minor. The differences in serum levels of testosterone and FSH were significant between group A and groups B and C. Pregnancies were reported in 6 of 26 couples from group A (duration of infertility: mean 79 months, range 16-187), in 17 of 28 couples from group B (duration of infertility; mean 54 months, range 16-104) and in nine of 30 couples from group C (duration of infertility; mean 66 months, range 25-125). Since the infertility pattern of the older patients desiring offspring was not significantly different from that of younger patients, it is concluded that the age of the female partner, rather than the age of the husband, is most important in determining the fertility chances of couples presenting with infertility.

Adult↗

PubMed1996

Ankle arthroscopy under local and general anaesthesia for diagnostic evaluation and treatment.

Improvements in techniques and instrumentation are extending the diagnostic and therapeutic indications for ankle arthroscopy. We aimed to study the diagnostic and therapeutic benefits and complication rate from 112 consecutive ankle arthroscopies performed between 1991 and 1994 under local and general anaesthesia. One-hundred and twelve outpatient ankle arthroscopies were performed in 72 male and 37 female patients, 16-64 years old. The patients were comparable in terms of gender and age in the arthroscopies done under local (n = 69) and the arthroscopies done under general anaesthesia (n = 43). The indications for surgery were pain in 75%, instability in 15%, limited function in 7% and swelling in 4%, and these criteria were similar in both groups. Antero-medial and anterolateral portals were used in all cases. No tourniquet was used and an external distractor was used in one case only. In 64 cases (57%) surgery was performed and included synovectomy, removal of loose bodies, shaving drilling of osteochondritic or other cartilage lesions, resection of impinging osteophytes, fibrosis and meniscoid lesions. In 95 ankles (85%) a definite diagnosis was established. Comparable diagnostic and therapeutic potentials were found between local and general anaesthesia. The complication rate was low. One patient who was operated on under general anaesthesia sustained a deep infection, and three suffered minor superficial nerve injuries. In conclusion, ankle arthroscopy may be performed under local or general anaesthesia with similar diagnostic value and with a low complication rate.

Adolescent↗

PubMed1996

A study of intrinsic factors in patients with stress fractures of the tibia.

We aimed to study intrinsic factors in 29 consecutive patients with well-documented unilateral stress fractures of the tibia. Anthropometry, range of motion, isokinetic plantar flexor muscle performance, and gait pattern were analyzed. The uninjured leg served as the control. A reference group of 30 uninjured subjects was compared regarding gait pattern. Anterior stress fractures of the tibia (N = 10) were localized in the push-off/ landing leg in 9/10 athletes, but were similarly distributed between legs in posteromedial injuries (N = 19). Ten (30%) of the stress fracture subjects had bilateral high foot arches, similar to those found in the reference group. There were no other systematic differences in anthropometry, range of motion, gait pattern, or isokinetic plantar flexor muscle peak torque and endurance between injured and uninjured legs. No other differences were found between anterior and posteromedial stress fractures. We conclude that anterior stress fractures of the tibia occur mainly in the push-off/landing leg in athletes. Within the limitations of our protocol, no registered intrinsic factor was found to be directly associated with the occurrence of a stress fracture of the tibia.

Adolescent↗

PubMed1995

The epidemiology of infectious myocarditis, lymphocytic myocarditis and dilated cardiomyopathy.

Infectious myocarditis is a common condition which often passes unrecognized, and the true incidence is thus unknown. Lymphocytic myocarditis has been recorded in 1.06% of 12,747 unselected routine autopsies performed over a 10-year period. Dilated cardiomyopathy (DCM) has an estimated frequency of 7.5-10% per 100,000 inhabitants per year. Overall, the enteroviruses, and particularly the Coxsackie-B viruses, predominate among viruses as the cause of myocarditis. As new molecular biological techniques have become available, the cytomegaloviruses (CMV) seem to have emerged as a more common cause of myocarditis than was previously recognized. Among the bacterial myocarditides, diphtheric myocarditis has become a serious threat in Russia and adjacent states during the 1990s. Among newly identified bacteria, Borrelia burgdorferi infection is accompanied by cardiac involvement in 1-8% of cases, where myocarditis with conduction disturbances is the most prominent feature. Chlamydia pneumoniae may be associated with myocarditis and sudden unexpected death. In AIDS, myocarditis with variable aetiology occurs in up to 50% of patients, although asymptomatic in most cases. In lymphocytic myocarditis and DCM, enteroviral-specific nucleotide sequences have been detected in about 30% of patients, and CMV-specific nucleotide sequences in 14%. Borrelia burgdorferi may occasionally be implicated in DCM. In this contribution we focus also on sudden unexpected death (SUD) in young athletes, since, in Sweden, an increased frequency of SUD has recently been observed in young orienteers and myocarditis was a common feature.

Bacterial Infections↗

PubMed1995

Overuse injuries of the lower extremity in runners.

The purpose of this article is to review the literature on overuse injuries of the lower extremity in runners and to discuss briefly today's knowledge concerning etiology, diagnosis and treatment. Running is a natural entity in many sports and a majority of runners will sustain one or more overuse injuries throughout the career, in most cases affecting the lower extremity. A runner may be regarded as an athlete who regularly runs as the predominant physical activity. From that point, we should subdivide the definition "runner" considering the character of different sports or recreational activities performed. Overuse injuries are often described merely from symptoms, including several different etiological and pathoanatomic correlates covering a variety of ailments. The clinical approach should be focused on a thorough history and physical examination. Analysis of possible injury mechanisms, correction of associated extrinsic and intrinsic factors and advice on alternative training should be given. A knowledge of specific demands from the type of running performed is necessary to evaluate the symptoms presented. Overuse etiology has to be considered multifactorial with a yet unsolved exact pathophysiology needing further research. The definition of a "runner", of "running" and of "overuse injury" should be established and agreed upon. This review attempts to draw attention to the huge multidisciplinary work that has to be done to better understand the mechanisms causing an overuse injury in a runner and to define diagnoses on a scientific base, whether or not excentric or intrinsic factors predispose or trigger.

Cumulative Trauma Disorders↗

PubMed1995

Infectious and lymphocytic myocarditis: epidemiology and factors relevant to sports medicine.

Myocarditis is a disease entity of permanent actuality and of special concern in the sports setting. This is because the probability of complications or sequelae increases if exercise is imposed. Myocarditis may pass unrecognized by the sufferer or be easily overlooked by the physician, especially in athletes, where electrocardiographic changes often exist normally. Furthermore, although the immune system of the conditioned individual may be more efficient than that of the sedentary individual, very strenuous and frequently repeated or long-lasting exercise may cause immunosuppression and an increased susceptibility to respiratory tract infections (RTI). Several causative agents of RTI can give rise to myocarditis as well. The true incidence of proven infectious myocarditis in society is unknown. Histopathologically defined myocarditis (lymphocytic myocarditis), on the other hand, has been found in about 1% of unselected routine autopsies. In general, the long-term prognosis in myocarditis is favorable but exercise stress may cause long-term sequelae or sudden death. It is thus essential to refrain from strenuous exercise during RTI.

Death, Sudden, Cardiac↗

PubMed1994

Modulation of intracellular metabolism of cytosine arabinoside in acute myeloid leukemia by granulocyte-macrophage colony-stimulating factor.

The current study investigated the effect of granulocyte-macrophage colony-stimulating factor (GM-CSF) on the intracellular metabolism and cytotoxicity of 1-beta-D-arabinofuranosylcytosine (araC) in leukemic cells of 45 patients with acute myeloid leukemia (AML). AML blasts from bone marrow (BM) (n = 39) and peripheral blood (PB) (n = 17) were incubated for 48 h with or without GM-CSF (100 U/ml) followed by a concurrent treatment with increasing concentrations of araC (0.06-100 microM) for an additional 24 h. After GM-CSF a 1.5-8.4-fold (median 2.3) increase in 3H-araC incorporation into the DNA was observed in ten of 14 peripheral blast specimens and in 23 of 28 bone marrow samples, 18 of whom also showed an enhanced 3H-TdR incorporation (1.5-8.5-fold, median 2.0-fold). Four different types of response were identified when analyzing 3H-araC incorporation into the DNA of bone marrow samples in relation to the applied araC dose: (i) 8/28 cases had increases of the araC incorporation at all araC dose levels applied (0.06-100 microM), (ii) 12/28 at low araC concentrations only (0.06-1.0 microM), (iii) 3/28 at high araC concentrations only (10-100 microM), and (iv) 5/28 showed no increase at any dose level given. Hence, 20 of the 23 responding patients revealed a GM-CSF induced enhancement of araC incorporation at low or conventional doses of araC (0.06-1.0 microM). Fourteen of the 18 cases with concomitant rises of 3H-TdR and 3H-araC incorporation into the DNA after GM-CSF had elevated DNA polymerase alpha activity (16-531%, median 72%) and in ten cases overall DNA polymerase activity was enhanced (10-70%, median 22.5%). In contrast, thymidine kinase (TK) and deoxycytidine kinase (dCK) activity were elevated after GM-CSF in only ten and five patients, respectively. An increase in the fraction of cells in S phase was found in 11/21 bone marrow specimens and in 5/9 peripheral blast samples. However, no correlation was observed between increases in the proportion of cells in S phase and enhancements in enzyme activities. In 13 cases the cytotoxicity of araC with and without GM-CSF was assessed by means of a blast cell colony assay. Preincubation with GM-CSF increased the araC mediated cytotoxicity in ten of 13 patients by a median of 3.2-fold (range 2.2-229-fold). The respective LD50 values for araC were reduced from 0.45 to 0.19 microM on average.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗

PubMed1993

Column-switching solid-phase trace-enrichment high-performance liquid chromatographic method for measurement of buprenorphine and norbuprenorphine in human plasma and urine by electrochemical detection.

We describe a new high-performance liquid chromatographic method using electrochemical detection for the determination of buprenorphine and norbuprenorphine in plasma and urine. The minimum concentration for detection of buprenorphine and norbuprenorphine is 40 pg/ml. The intra-assay coefficient of variation (C.V.) in plasma and urine samples ranges from 6 to 17% depending on the drug concentration. At a plasma concentration of 500 pg/ml the inter-assay C.V. is 8% for buprenorphine and 9% for norbuprenorphine. The analysis duration is 16 min. After solid-phase extraction and evaporation a valve-switching system with two Rheodyne valves enables sample enrichment, optimal sample cleaning and rapid elution of long-retained substances.

Buprenorphine↗

PubMed1992

Differences in the intracellular pharmacokinetics of cytosine arabinoside (AraC) between circulating leukemic blasts and normal mononuclear blood cells.

The increasing insights into the pharmacokinetics and the metabolism of cytosine arabinoside (AraC) have improved the rationale for its application in leukemia therapy and have led to a pharmacologically directed design of antileukemic treatment. The current study aims at adding to this approach by detecting differences in the intracellular metabolism of AraC 5'-triphosphate (AraCTP) between leukemic and normal mononuclear blood cells. Measurements of intracellular AraCTP levels were complemented by determinations of plasma AraC and AraU concentrations and were performed in 32 patients with acute myeloid leukemia undergoing combination therapy including either conventional (100 mg/m2 daily) or high-dose (1.0 or 3.0 g/m2 twice daily) AraC. Plasma AraC concentration showed a linear relationship to the applied AraC dose but did not correlate with intracellular AraCTP levels. During conventional-dose AraC therapy little interpatient variation was observed in AraCTP retention times in leukemic blasts from 5 patients with t1/2 values ranging from 1.70 to 2.50 h (median 2.14 h). In all cases AraCTP levels declined rapidly after the end of the AraC infusion. Substantial differences in AraCTP retention times were revealed, however, during 3 h infusions of either 1.0 or 3.0 g/m2 AraC in leukemic blasts from 10 patients with t1/2 values between 1.60 to 7.63 h (median 2.42 h). In addition, AraCTP levels declined in only one patient by > 10% within the first hour after the end of therapy and remained constant or even increased up to 1.5-fold in a post-treatment period of 1 to 2.5 h in the other nine cases. In contrast, AraCTP retention times were relatively uniform in normal mononuclear blood cells from 11 patients with t1/2 values of 3.34 to 5.29 h (median 3.85 h). More importantly, AraCTP levels dropped by > 10% within the first hour after the end of the high-dose AraC infusion in eight of 11 cases. A post-therapeutic increase > 10% was not observed in any patient. Similar findings emerged after in vitro exposure of normal bone marrow cells from six healthy volunteers to 20 mumol/l AraC for 3 h revealing a > 10% decrease of intracellular AraCTP within the first post-treatment hour in all cases with AraCTP retention times of 2.29 to 8.63 h (median 3.20 h). These differences in AraCTP pharmacokinetics between leukemic and normal blood cells may provide the basis for a modified timing of AraC administration with the aim of selectively maintaining cytotoxic AraCTP levels in leukemic blasts while allowing an intermittent drop of AraCTP levels in normal cells.(ABSTRACT TRUNCATED AT 400 WORDS)

Acute Disease↗

PubMed1985

Acute and long-term airway hyperreactivity in aluminium-salt exposed workers with nocturnal asthma.

Nineteen young male workers exposed occupationally from 1975-1977 to inhaled particles of aluminium fluoride or sulphate at 2 plants, developed nocturnal wheezing and breathlessness with reversible airways obstruction after an average of 4 months employment. At standardized methacholine provocation tests (MPT), 17 of 19 workers with normal spirometry showed airway hyperreactivity with a fall of FEV1 of greater than or equal to 15% after 0.1% methacholine. We followed 15 initially asthmatic workers for 2-5 years with MPT. Mean TD 15% FEV1 in 11 workers did not change significantly after an average of 41 months of non-exposure. Six workers continuously exposed for 48 months also failed to change their TD 15% FEV1 MCh. In 1983, only one subject had returned to normal airway reactivity. We have no reason to suspect inducing agents other than aluminium salts.

Adult↗

PubMed1984

Effects of medroxalol on renal function and the renin-angiotensin-aldosterone axis.

Ten subjects with hypertension received medroxalol, which blocks both alpha- and beta-adrenergic receptors, has intrinsic sympathomimetic beta 2-agonist properties and is a direct vasodilator. Renal function tests consisting of inulin clearance and p-amino hippuric acid (PAH) clearance, plasma renin activity (PRA) in recumbent and upright postures, and aldosterone excretion rate were performed. After intravenous medroxalol, inulin clearance and PAH clearance rose, renal vascular resistance fell, recumbent PRA was unchanged, and the rise in PRA with upright posture was blunted. After 1 mo on oral medroxalol, blood pressure was controlled while inulin clearance, PAH clearance, and renal vascular resistance were unchanged. The rise in PRA with upright posture remained blunted. Urinary aldosterone excretion was unchanged after 1 mo on medroxalol.

Adrenergic alpha-Antagonists↗

PubMed1982

Bronchial reactivity to methacholine in ten non-obstructive heavy smokers before and up to one year after cessation of smoking.

We studied non-specific bronchial reactivity to methacholine (MCh) before and during 1 year after cessation of smoking in four female and six male "smoke resistant" heavy cigarette smokers without severe respiratory symptoms or airways obstruction. The patients had smoked an average of 33 cigarettes a day since age 16. A standardized test of non-specific bronchial reactivity to methacholine was performed prior to cessation and 1 week, 1, 6 and 12 months after cessation of smoking proven by a decrease to normal COHb. Before cessation only two subjects showed a greater than or equal to 15% decrease of FEV1 after inhalation of 0.1% MCh which is compatible with bronchial hyperreactivity. Already 1 week after cessation there was a significant increase in FEV1 and VC to values around 100% of predicted. Bronchial reactivity was judged to decline after 1 month of non-smoking in four subjects but was unchanged in the others, and there was no statistically significant decrease of bronchial reactivity in the group of 10 after a 12-month smoke-free period.

Adult↗

PubMed1981

Drug-induced changes in airways obstruction reflected by forced expiratory flows and airway resistance measured with an oscillometric method using quiet breathing.

14 patients with partially reversible airways obstruction were studied with forced expiratory flows (FEV1, PEFR) and with airway resistance measured by an oscillometric method (Siregnost FD-5) before and after drug-induced changes in airways obstruction. 10 inhaled methacholine to induce bronchoconstriction, and 4 inhaled salbutamol and an additional dose of neosynephrine to induce bronchodilation. Intraindividual changes in resistance (Rosc) measured by the oscillometer with quiet breathing showed a fair significant correlation with changes in FEV1 (r = 0.54, p less than 0.05) and changes in PEFR measured by the Wright peak flow meter (r = 0.59, p less than 0.05). The present type of oscillator can be used for provocations starting from normal airway resistance but not for measures of treatment effects in markedly obstructive patients.

Adult↗

PubMedDate not supplied

Dislocation of the tibialis posterior tendon: diagnosis and treatment.

Traumatic dislocation of the tibialis tendon occurred from minor ankle sprains in a 37-year-old male and a 53-year-old female. Both complained of local pain at the medial malleolus, and both walked with a limp. The diagnosis was suspected by clinical examination, in one case with 2 months' delay, and verified by ultrasound, computed tomography, and magnetic resonance imaging. The male patient was initially treated for an "uncomplicated ankle sprain." For various reasons surgery was delayed 4 months. During this interval the male patient complained of pain and severe dysfunction, requiring analgesic treatment. A medial Achilles tendon flap was used to support the repositioned tendon. The female patient was operated on within 1 week from injury, by resuturing of the retinaculum over the tendon. Postoperatively, both patients were immobilized with below-knee casts for 6 weeks, allowing full weightbearing, followed by strength and stretching exercises. They were free of symptoms 2 and 3 months, respectively, after surgery. At follow-up 1 year postoperatively, both were asymptomatic and participated in activities like those before their injuries.

Adult↗