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Biomedical subjects

R Becker

Publications and source records attributed to R Becker.

At least 55 records · Page 3Linked to original sources
PubMed2001

Biomechanical properties of quadruple tendon and patellar tendon femoral fixation techniques.

Two femoral fixation techniques for quadruple hamstring tendon grafts were compared under cyclic loading with the patellar tendon: the rectangular inserted pin (TransFix) and biodegradable interference screw fixation of the quadruple tendon and titanium interference screw fixation of the middle third of the patellar tendon. Porcine specimens were mounted onto a tension load machine, and the tendon-fixation-femur-complex was tested for stiffness, displacement during 800 cycles of loading between 50 and 250 N and ultimate tension load. TransFix fixation showed the greatest stiffness at 183.6 N/mm ( P<0.05). The least displacement under cyclic loading was observed for the titanium interference screw followed by the TransFix and biodegradable interference screw ( P<0.01). The ultimate tension load was greatest for the TransFix fixation at 1303+/-282 N, followed by patellar tendon fixation with 763+/-103 N and the biodegradable interference screw fixation with 480+/-133 N ( P<0.001). To reduce initial elongation of the graft and displacement at the fixation site, preconditioning of both the tendon and tendon-fixation complex is especially important when using quadruple tendons. TransFix fixation provides better stability and greater stiffness and pull-out strength than the other techniques. This finding is of clinical relevance to surgeons of the anterior cruciate ligament.

Absorbable Implants↗
PubMed2001

Intercaval block in normal canine hearts : role of the terminal crest.

BACKGROUND: The intriguing monotony in the occurrence of intercaval conduction block during typical atrial flutter suggests an anatomic or electrophysiological predisposition for conduction abnormalities. METHODS AND RESULTS: To determine the location of and potential electrophysiological basis for conduction block in the terminal crest region, a high-density patch electrode (10x10 bipoles) was placed on the terminal crest and on the adjacent pectinate muscle region in 10 healthy foxhounds. With a multiplexer mapping system, local activation patterns were reconstructed during constant pacing (S(1)S(1)=200 ms) and introduction of up to 2 extrastimuli (S(2), S(3)). Furthermore, effective refractory periods were determined across the patch. If evident through online analysis, the epicardial location of conduction block was marked for postmortem verification of its endocardial projection. Marked directional differences in activation were found in the terminal crest region, with fast conduction parallel to and slow conduction perpendicular to the intercaval axis (1.1+/-0.4 versus 0.5+/-0.2 m/s, P<0.01). In the pectinate muscle region, however, conduction velocities were similar in both directions (0.5+/-0.3 versus 0.6+/-0.2 m/s, P=NS). Refractory patterns were relatively homogeneous in both regions, with local refractory gradients not >30 ms. During S(3) stimulation, conduction block parallel to the terminal crest was inducible in 40% of the dogs compared with 0% in the pectinate muscle region. CONCLUSIONS: Even in normal hearts, inducible intercaval block is a relatively common finding. Anisotropic conduction properties would not explain conduction block parallel to the intercaval axis in the terminal crest region, and obviously, refractory gradients do not seem to play a role either. Thus, the change in fiber direction associated with the terminal crest/pectinate muscle junction might form the anatomic/electrophysiological basis for intercaval conduction block.

Animals↗
PubMed2001

A critical review of clinical trials for low-molecular-weight heparin therapy in unstable coronary artery disease.

Unstable angina and non-ST-segment elevation myocardial infarction (MI) are collectively referred to as unstable coronary artery disease (UCAD). They are conditions that share a common pathophysiology and represent frequently encountered, potentially life-threatening clinical manifestations of advanced atherosclerosis. Therefore, treatment of UCAD is a major focus for practicing clinicians, and although pharmacologic agents have been developed that impact on patient outcome, recent data suggest that a further reduction in ischemic complications is possible. Acute-phase treatment with aspirin is associated with a significant reduction in death and nonfatal MI in patients with UCAD. This benefit is enhanced by the addition of unfractionated heparin (UFH) to the treatment strategy; however, UFH requires careful monitoring and titration. In contrast, low-molecular-weight heparins (LMWHs), produced by chemical or enzymatic depolymerization of UFH, yield a predictable and consistent pharmacokinetic profile and anticoagulant response, making them an attractive treatment alternative to UFH in patients with UCAD. The optimal duration of treatment with LMWH is an important question influenced by the observation that reactivation of coagulation occurs following the early and abrupt discontinuation of heparin treatment. Early trials, such as FRISC and FRIC, demonstrated the benefit of acute therapy with dalteparin sodium; however, the results of extended treatment with dalteparin were inconclusive. The extended phase of these studies included relatively low-risk patients, and a once-daily, relatively low-dose strategy was employed. The findings derived from the FRISC II trial, which used a twice-daily dose of dalteparin, suggest a benefit for at least 60 days with extended treatment in high-risk patients with UCAD. Although an early-invasive treatment strategy is particularly beneficial, patients in whom early revascularization is not possible should be considered for extended treatment with dalteparin for up to 45 days, especially those awaiting percutaneous coronary intervention. Extended treatment with dalteparin therefore provides a protective "bridge" to enhance the outcome of patients with UCAD awaiting revascularization.

Angina, Unstable↗
PubMed2001

Physiological alterations of maximal voluntary quadriceps activation by changes of knee joint angle.

The purpose of this study was to investigate the influence of different angles of the knee joint on voluntary activation of the quadriceps muscle, estimating the ability of a subject to activate a muscle maximally by means of voluntary contraction. Isometric torque measurement was performed on 6 healthy subjects in 5 degrees intervals between 30 degrees and 90 degrees of knee joint flexion. Superimposed twitches at maximal voluntary contraction (MVC) and at a level of 60% and 40% of the MVC were applied and the voluntary activation estimated. At between 30 degrees and 75 degrees of knee flexion, the maximal extension torque increased at an average rate of 2.67 +/- 0.6 Nm/degree, followed by a decline with further flexion. However, throughout the joint-angle range tested, voluntary activation increased on average by 0.37%/degree with a maximum at 90 degrees of flexion. Due to the influence of joint position it is not possible to generalize results obtained at the knee joint angle of 90 degrees of flexion, which is usually used for the quadriceps twitch-interpolation technique. Consequently, it is useful to investigate voluntary activation deficits in knee joint disorders at a range of knee joint angles that includes, in particular, the more extended joint angles used frequently during daily activity.

Adult↗
PubMed2001

[Semitendinosus tendon vs. patellar ligament. Results of a prospective randomized study after anterior cruciate ligament reconstruction].

UNLABELLED: The aim of our prospective randomised study was to evaluate the clinical results after arthroscopical reconstruction of the ACL using the midthird patellar ligament or semitendinosus tendon. METHODS: Forty patients were followed up two years postoperatively. Twenty of them received either a patellar ligament graft (BTB-group) or doubled semiteninosus tendon (SET-group). The clinical evaluation included the preoperative and two years postoperative assessment, based on the IKDC-Score, Tegener-Score and Mc-Carroll-Score. The a.p.-translation was evaluated using the KT-1000. RESULTS: Sixteen (80%) patients of the SET-group and 10 (50%) patients of the BTB-group showed good and excellent results in the over all assessment with the IKDC-Score. The mean side to side KT-1000 difference yielded 1.6 mm (-2-4 mm) in the BTB-group and 2.7 mm (0-7 mm) in the SET-group (p < 0.05). The retropatellar pain syndrome based on the Mc-Caroll-Score showed 17.4 points in the BTB-group in comparison to 19.5 points in the SET-group (p < 0.05). The level of activity using the Tegner-score showed preoperatively for both the SET- and BTB-group 6.9 points and postoperatively for the SET-group 6.7 points and for the BTB-group 5.6 points. CONCLUSIONS: Despite the inferior a.p.-stability for the patients who received doubled semitendinosus tendon grafts they presented clinically superior results compared to the BTB-group. Therefore this technique seems to be the alternative method. In order to improve the stability we recommend the usage of three or four stranded grafts and an improved fixation technique.

Adolescent↗
PubMed2001

[Predictive value of frequency, duration and rate of ventricular salvos in ambulatory ECG for inducibility of sustained ventricular tachycardia].

Identification of high risk patients with coronary artery disease (CAD) prone to sudden cardiac death still remains a difficult issue. In 211 patients with CAD diagnosed by coronary angiography and documented non-sustained ventricular tachycardia (NSVT), programmed ventricular stimulation (PVS) was performed. NSVTs documented during Holter monitoring were analysed concerning frequency, duration and rate. To relate those parameters to the inducibility of sustained monomorphic ventricular tachycardias (MVT) during PVS, the total population was divided in different groups; patients with 1, 2-5 or > 5 salvos within 24 h; patients having salvos with a rate of > or = 150/min or < 150/min; patients with 3-5, 6-10 or > 10 consecutive extra beats. It could be demonstrated that in patients with CAD and NSVTs, induction of MVTs during PVS is more likely if the rate of the spontaneously occurring NSVT is > or = 150/min (22.1 vs 8.9%; p = 0.042). In contrast, there is apparently no correlation between the duration and incidence of NSVTs and the prevalence of MVTs during PVS. Multivariate analysis revealed the rate of documented NSVTs (odds ratio 2.98, p = 0.0314) and a decrease of left ventricular ejection fraction (odds ratio 1.69; p = 0.0013) as independent risk factors for the inducibility of MVTs. Conclusions CAD patients with fast salvos (> or = 150 beats/min) and reduced left ventricular ejection fraction are more likely to reveal inducible MVT during PVS and should, therefore, preferably be subjected to invasive risk stratification. The number of salvos per day and the number of consecutive beats, on the other hand, do not seem to be of relevant predictive value.

Aged↗
PubMed2001

Effect of radiofrequency ablation on atrial myocardium.

OBJECTIVES: Successful RF ablation of atrial fibrillation supposedly requires the creation of continuous linear lesions. This study aimed to determine the potential role of functional modifications of atrial myocardium in the vicinity of anatomic RF lesions. METHODS: In 10 normal beagles (group A), a multiplexer mapping system and an epicardial multi-electrode were used to reconstruct atrial activation patterns during pacing at two cycle lengths before and after attempts to induce two linear right atrial lesions with a standard ablation catheter, respectively. An intercaval "drawback" was repeated 3 times over 5 min at a set temperature of 70 degrees C, followed by a transversal "point-by-point" ablation from the interatrial septum to the right-lateral tricuspid annulus at 70 degrees C/60 s each. Induction of atrial flutter was attempted before and after each ablation. In another 6 beagles (group B), a high-resolution multi-electrode was used to study epicardial functional effects resulting from single endocardial RF lesions on the free right atrial wall. Using three energy settings (60 degrees C/30 s, 60 degrees C/60 s, 70 degrees C/60 s), activation patterns were analyzed at two cycle lengths and local effective refractory periods were measured across the lesion. RESULTS: The lesions induced in group A only marginally affected atrial activation patterns and total activation times. However, as shown in dogs with atrial flutter, regional slow conduction was enhanced and functional conduction blocks were facilitated at high atrial rates, resulting in a significant prolongation in the revolution time of respective reentrant circuits. Apart from inducing anatomic lesions, single endocardial RF lesions (group B) were shown to delay epicardial conduction in adjacent myocardium in an energy- and rate-dependent way. Furthermore, an energy-dependent prolongation of effective refractory periods by far exceeding the size of anatomic lesions was observed. CONCLUSIONS: Continuous linear atrial lesions are hard to achieve with conventional ablation techniques. However, RF lesions induce changes in conduction and refractoriness around the anatomic lesion, which are likely to contribute to the overall effect of respective therapeutic interventions.

Animals↗
PubMed2001

Effects of propafenone on anisotropic conduction properties within the three-dimensional structure of the canine ventricular wall.

BACKGROUND: Structural complexities of the intact ventricular wall cause a very complex spread of activation. The effects of regional tissue damage and of antiarrhythmic drugs on directional differences in activation should help to further elucidate intramural conduction patterns. METHODS AND RESULTS: In 10 healthy dogs and in 5 dogs with subacute anterior wall infarction, 6 parallel rows of 6 needle electrodes with 4 bipolar electrode pairs per needle were inserted into the left anterior ventricular wall. Using a computerized multiplexer-mapping system, the spread of activation in epi-, endo- and midmyocardial muscle layers and in the surviving epicardium, respectively, was reconstructed. Marked differences in conduction velocities relative to fiber orientation were evident in the surviving epicardium of infarcted hearts. Directional differences in conduction velocities, although less pronounced, were still preserved throughout the intact ventricular wall. Epicardial transverse conduction in intact hearts was significantly faster than transverse conduction in infarcted hearts (0.87 +/- 0.11 m/s vs 0.68 +/- 0.1 m/s). In normal hearts, propafenone (2 mg/kg) decreased conduction velocities primarily in longitudinal directions (-27 +/- 10%), but also moderately in transverse directions (-13 +/- 7 %) of all muscle layers, with no significant effect on straight (-4 +/- 8 %), but on oblique transmural conduction (-33 +/- 18 %). In infarcted hearts propafenone decreased conduction particularly in longitudinal direction (-23 +/- 14 %) without affecting conduction transverse to the fiber orientation (+3 +/- 6%). CONCLUSIONS: Longitudinal intramural shortcircuits reduce directional differences in activation. Transmural infarction results in a loss of alternative intramural pathways, unmasking marked anisotropy in the surviving epicardium. Conduction delay in intramural pathways explains the effects of propafenone on transverse and oblique transmural conduction. Primarily longitudinal conduction delay results in reduced tissue anisotropy.

Animals↗
PubMed2001

Far-field R wave oversensing in a dual chamber arrhythmia management device: predisposing factors and practical implications.

Initial experience with the Medtronic Jewel 7250, the ICD designed to detect and treat ventricular and supraventricular tachyarrhythmias, is very promising. Its effectiveness, however, depends on sensing performance, which has not yet been systematically examined. The aim of the study was to determine the incidence of, predisposing factors for, and practical implications of far-field R wave oversensing (FFRWOS) in this dual chamber ICD. During a total follow-up of 797 months in 48 patients who had the Jewel 7250, follow-up strip charts, 12-channel Holter recordings and, in particular cases, Holter recordings with intracardiac markers were analyzed for the presence of FFRWOS. FFRWOS was documented in ten (21.3%) patients. Compared to other lead locations, the right atrial appendage lead position was most frequently associated with FFRWOS (7/27 vs 3/21, P < 0.05). Patients with FFRWOS had significantly more treated and nontreated atrial episodes, many of which were judged to have been detected inappropriately. In one case, inappropriate atrial antitachycardia pacing due to R wave oversensing triggered sustained ventricular tachycardia, terminated eventually with a high energy shock. In dual chamber ICDs, FFRWOS may represent a frequent phenomenon possibly leading to serious consequences. For atrial leads, a lateral atrial wall position seems to be preferable. In most cases, FFRWOS can be eliminated by optimization of atrial sensing parameters. Given the possibility of ventricular proarrhythmia with atrial pacing therapy, the capability of ventricular backup defibrillation in respective devices is at least reassuring.

Adult↗
PubMed2001

Prenatal diagnosis of familial absent pulmonary valve syndrome: case report and review of the literature.

We report on a case of absent pulmonary valve syndrome in a woman with a history of one healthy child and one child with tetralogy of Fallot with absent pulmonary valve. The diagnosis was missed at the first ultrasound examination performed at 13 + 5 weeks of gestation and correctly diagnosed at 21 + 5 weeks. Re-evaluation of the ultrasound examination recorded at 13 + 5 weeks exhibited severe insufficiency of the pulmonary valve at this time. However, neither dilatation of the right and left pulmonary arteries nor asymmetry of the ventricles were present at that time. The pregnancy was terminated at 22 + 1 weeks of gestation when autopsy confirmed the diagnosis of absent pulmonary valve syndrome. Karyotyping of the fetus after termination of pregnancy revealed normal chromosomes. Echocardiography of the parents and the healthy sibling revealed normal results.

Adult↗
PubMed2001

Perinatal diagnosis of cardiac tumors.

OBJECTIVE: As fetal cardiac tumors are a rare condition, we report the perinatal diagnosis and ultrasound findings of 12 cases. METHODS: In 10 cases the tumors were identified prenatally by fetal echocardiography; gestational age at detection ranged from 22 to 34 weeks. In two symptomatic infants cardiac tumors were diagnosed on the first day postpartum; prenatal ultrasound evaluation at 26 and 38 weeks of gestation did not reveal a cardiac lesion. RESULTS: Six fetuses had singular tumors, in six fetuses they were multifocal. The left ventricle was most often affected. Termination of pregnancy was chosen in three cases, one in association with trisomy 21 and tuberous sclerosis. One intrauterine and three neonatal deaths due to cardiac failure occurred. Histopathologic examination revealed cardiac rhabdomyoma in six fetuses and fibroma in one case. In the five surviving fetuses the size of the tumors spontaneously decreased postpartum. Rhabdomyomata were associated with tuberous sclerosis in four out of 11 cases. CONCLUSION: Cardiac tumors are detectable as early as 22 weeks of gestation. Presenting symptoms may be arrhythmia, dysfunction of the atrioventricular valves, pericardial effusion and fetal hydrops. The most common perinatal diagnosis is rhabdomyoma, which is often associated with tuberous sclerosis. Sequential examination in high risk patients should be considered as most tumors increase in size during pregnancy and may become evident in late second and third trimester of pregnancy. Postpartum, however, regression of tumor size is common.

Echocardiography↗
PubMed2001

Biomechanical investigations of different meniscal repair implants in comparison with horizontal sutures on human meniscus.

PURPOSE: The use of biodegradable implants for arthroscopic repair of meniscal lesions is becoming increasingly popular. The aim of this study was to test the biomechanical stability and the mode of failure of these implants. TYPE OF STUDY: Biomechanical testing study. METHODS: Biomechanical investigations were performed on human menisci using 6 commonly used biodegradable implants for meniscal repair to compare them with horizontal mattress suture using 2/0 Ethibond (Ethicon, Norderstedt, Germany). Included in this study were the Meniscus Arrow (Bionx, Tampere, Finland), Dart (Arthrex, Naples, FL), Stinger (Linvatec, Largo, FL), Meniscal Screw (Innovasive, Marlborough, MA), T-Fix (Acufex, Mansfield, MA), and the Fastener (Mitek, Westwood, MA). The tests were carried out using a material testing machine at a loading rate of 10 N/second. The ultimate tension load (UTL), elongation, and stiffness were evaluated for each implant technique. RESULTS: The highest UTL was shown by Ethibond (62 +/- 7.91 N) and the T-Fix (51.35 +/- 16.31 N), followed by the Fastener (32.67 +/- 2.97 N). All other implants had a significantly lower UTL (P =.001). Less elongation under a load of 5 N was noted for Ethibond (0.64 +/- 0.25 mm) and for T-Fix (0.43 +/- 0.32 mm) compared with the other implants. The greatest elongation was found for the Fastener (2.239 +/- 0.581 mm). The stiffness of the fixation was similar in all implants, except for the Dart and Fastener, which were significantly inferior (P <.05). CONCLUSIONS: All of the biodegradable implants had lower UTL than the suture techniques. Therefore, when using the implants, they should be inserted close together to provide sufficient stability. In cases of an extended lesion, there might even be an option to combine the implant and suturing techniques.

Absorbable Implants↗
PubMed2001

A new technique of arthroscopic capsular shift in anterior shoulder instability.

We describe a new arthroscopic technique to reinforce the torn inferior glenohumeral ligament (IGHL) and the elongated capsule to the glenoid rim. The arthroscope is inserted over the superior portal and, after the insertion of a suture anchor, both limbs are pulled out over the posterior portal. The IGHL is grasped and pulled upward onto the glenoid rim using a suture retriever clamp inserted over the posterior portal. A 45 degrees curved blunt clamp (Sidewinder; Arthrex, Naples, FL) coming from the anterior penetrates the IGHL, and 1 end of the suture limb is given into the branches of the clamp and pulled out anteriorly. After a second perforation of the capsule, a horizontal suture creating a neolabrum can be placed. This technique allows a suitable reinforcement of the capsule without intraoperative complications. In cases of capsular elongation, especially a torn IGHL, the capsular instability can be addressed by the described Sidewinder technique. More sophisticated arthroscopic techniques such as this will increase the indication for arthroscopic shoulder stabilization.

Arthroscopy↗
PubMed2001

A novel use of the hyperinsulinemic-euglycemic clamp technique to estimate insulin sensitivity of systemic lipolysis.

The aim of the present study was to assess whether a standard hyperinsulinemic-euglycemic clamp can provide an estimate for the antilipolytic insulin sensitivity. For this purpose, we infused 9 non-obese, healthy volunteers with [2H5]glycerol and used the glycerol rate of appearance (Ra) in plasma as an index for systemic lipolysis during a standard (1 mU/kg x min, 120 min) and a 3-step (0.1, 0.25, 1.0 mU/kg x min) hyperinsulinemic-euglycemic clamp. The insulin concentration, which half-maximally suppressed lipolysis (EC50) in the three-step clamp, was considered to be the gold standard for the antilipolytic insulin sensitivity. Glycerol Ra decreased from 1.53+/-0.11 micromol/kg x min to 0.60+/-0.09 micromol/kg x min (p <0.001) during the standard clamp. The decrease in Ra at most time points during the standard clamp significantly correlated with the EC50. The highest correlation for the % decrease of glycerol Ra from baseline was found at 60 min (r = 0.96, p < 0.001) making this parameter a useful index for the antilipoytic insulin sensitivity. Neither plasma glycerol nor plasma free fatty acid (FFA) concentrations were significantly correlated with the EC50. In conclusion, the standard hyperinsulinemic-euglycemic clamp in combination with isotopic determination of glycerol Ra provides a reasonable estimate for the antilipolytic insulin sensitivity. In healthy subjects, the parameter best suited to estimate the insulin EC50 (by linear correlation) was the percentage decrease of glycerol Ra at 60 min.

Adult↗
PubMed2001

Effects of reconstruction of the anterior cruciate ligament on voluntary activation of quadriceps femoris a prospective twitch interpolation study.

The loss of full muscle activation contributes to weakness of the quadriceps muscle in patients with deficiency of the anterior cruciate ligament (ACL). We examined whether a deficit of voluntary activation (VA) of the quadriceps muscle can be reversed by reconstruction of the ACL and assessed its influence on muscle strength and clinical parameters. We evaluated 12 male subjects with an isolated tear of the ACL and 12 matched control subjects before operation and two years after reconstruction of the ACL. Assessment included measurements of isometric knee-extension torque at maximal voluntary contraction (MVC force), knee stability tests, the International Knee Ligament Standard Evaluation Form and the Tegner activity score. A sensitive method of twitch interpolation was used to quantify the VA and to calculate true muscle force. Before operation we found a deficit of VA on both the injured (mean +/- SEM 74.9 +/- 3.5%) and the uninjured side (74.6 +/- 3.0%) in comparison with the control group (91 +/- 0.9%). Two years after reconstruction of the ACL the VA improved significantly on both sides but remained less than that of the controls. Correlation analysis revealed an improvement of the VA in patients who returned to a higher level of activity. The deficit of true muscle force, however, persisted regardless of the clinical outcome and ligament stability.

Adolescent↗
PubMed2001

Pro12Ala polymorphism in the peroxisome proliferator-activated receptor-gamma2 gene is associated with increased antilipolytic insulin sensitivity.

The Pro12Ala polymorphism of the peroxisome proliferator-activated receptor (PPAR)-gamma2 is associated with reduced transcriptional activity in vitro and increased insulin sensitivity in humans in vivo. The mechanism by which this polymorphism influences insulin sensitivity in humans is unclear. PPAR-gamma2 is mainly expressed in adipocytes, and free fatty acids released from adipose tissue are key mediators of peripheral insulin resistance. Therefore, we examined insulin suppression of lipolysis in 51 subjects without (Pro/Pro) and 17 subjects with the polymorphism (X/Ala). Both groups were lean (BMI <27.0 kg/m2) and matched for age, BMI, waist-to-hip ratio, and sex. The isotopically (infusion of d5 glycerol) determined glycerol rate of appearance was used as an index of lipolysis. Insulin sensitivity of lipolysis was expressed as the insulin concentration resulting in half-maximal suppression (EC50). This was directly determined during a three-step hyperinsulinemic-euglycemic clamp (n = 21) or estimated indirectly during a standard hyperinsulinemic-euglycemic clamp (n = 47). The insulin sensitivity index (ISI) of glucose disposal was 0.095+/-0.006 micromol x kg(-1) x min(-1) x pmol(-1) x l(-1) in the control group and 0.129+/-0.008 micromol x kg(-1) x min(-1) x pmol(-1) x l(-1) in the X/Ala group (P = 0.003). The EC50 was 56+/-2 pmol/l in the control group and 44+/-3 pmol/l in the X/Ala group (P = 0.001). The EC50 of lipolysis and ISI was significantly correlated (r = 0.42, P = 0.002). In conclusion, in lean subjects, the Pro12Ala polymorphism is associated with increased insulin sensitivity of glucose disposal and suppression of lipolysis. This result suggests that an altered transcriptional activity of PPAR-gamma2 in X/Ala subjects either causes a more efficient suppression of lipolysis in adipose tissue, which in turn results in improved insulin-stimulated glucose disposal in muscle, or, alternatively, beneficially affects insulin signaling in both tissues independently of one another.

Adult↗
PubMed2001

Phagocytosis and killing of Mycobacterium avium complex by human neutrophils.

Organisms belonging to the Mycobacterium avium complex (MAC) cause life-threatening bacteremia in immunocompromised patients. Monocytes and macrophages are thought to be responsible for ingestion and killing of MAC. However, it has been suggested that neutrophils may play a role in the early immune response to MAC infection. Here, neutrophils in autologous plasma were incubated (at 0 and 37 degrees C) with M. avium labeled with Auramine O, a potent fluorochrome. Neutrophil phagocytosis was measured by flow cytometry. Neutrophils incubated at 37 degrees C showed an increase in fluorescence over time with a maximum at 15 min, whereas neutrophils on ice showed no time-dependent increase in FL1. At 15 min Fl 1 at 37 degrees C was twice as high as FL1 at 0 degrees C. Examination under the fluorescent microscope showed multiple intracellular fluorescent mycobacteria. Results in nine independent experiments showed time-dependent decrease of colony-forming units in neutrophil-associated live M. avium. Significant killing was observed within 30 min and was complete by 120 min. Observation by electron microscopy clearly confirmed the presence of intraphagosomal MAC, both intact and with evidence of degradation. These data demonstrate that MAC is rapidly phagocytized and killed by human neutrophils. The newly established flow cytometry method should be useful in further studies of neutrophil function and of the role of G-CSF and other cytokines in MAC disease.

Adult↗