Livin and Bcl-2 expression in high-grade osteosarcoma

AIMS

The evaluation of prognosis in patients with osteosarcoma is limited to clinical parameters. Although numerous molecular markers have been studied, none are currently in routine clinical use. The aim of this study was to determine if Livin and Bcl-2, acting as antiapoptotic proteins through different mechanisms, are expressed in osteosarcoma, and whether they can be used as prognostic markers in human osteosarcoma.

METHODS

Tumor specimens of 29 patients with high-grade central osteosarcoma, with complete clinical follow-up for a minimum of 5 years, were studied. The localization and distribution of Livin and Bcl-2 were investigated using immunohistochemistry. Results were correlated with the histological response to chemotherapy, 5-year disease-free and 5-year overall survival.

RESULTS

Bcl-2 was expressed only in the cytoplasm of 16/29 cases and there was no statistically significant correlation between expression and any of the studied parameters. Livin was detected in 17/29 cases, in the cytoplasm of all 17 and in the nucleus of only 3 cases. Nuclear expression was significantly correlated with a decreased overall survival (P < 0.0002) compared with those patients without nuclear expression.

CONCLUSIONS

The results of this study indicate that Bc1-2 and Livin are highly expressed in osteosarcoma cells and that possibly, the evaluation of nuclear Livin expression might be a useful prognostic marker in osteosarcoma.

Death in correctional facilities: opportunities for automated external defibrillation

BACKGROUND

Death due to cardiovascular disease occurs more frequently in prisons than the national average. Due to close surveillance 24 h/day, the ability to reach the patient within 3 min and time consuming access for the EMS crews, it was hypothesised that the deployment of automated external defibrillators (AEDs) might make improvements regarding Call-to-the-First-AED-Prompt (CTP) interval and formed the aim of this study.

METHODS

Our investigation was analysed on an intention to treat basis and conducted in a prospective, open and observational design. As the primary outcome, the CTP-intervals were compared to the arrival intervals of the EMS. As a secondary outcome, an analysis of all deceased inmates was described.

RESULTS

The average daily population of inmates in Austrian correctional facilities is 7714. During a period of 13 months, 10 instances in which an AED was activated and electrodes attached to a collapsed inmate, were reported. The CTP-interval (median+/-S.D.) was 2.3+/-1.6 S.D. min. It took the EMS 10.0+/-4.3 S.D. min. to arrive at the patient's side. Four out of 10 cases of cardiac arrest occurred due to myocardial infarction. Of 39 deceased inmates, a post mortem examination was completed in 34 cases. In 13 cases, cardiovascular disease was the cause of death.

DISCUSSION

The main finding was a four-fold reduction of the CTP-interval. This fact indicates the potential improvements which could be achieved with the deployment of AEDs. Our secondary objective revealed that death due to cardiovascular disease was found in a high proportion and could be considered to be a strong incentive to initiate programmes to counter cardiovascular death in prison.

[Management of upper limb deformities. Treatment concepts through the years]

The provision of aids and prostheses for patients with upper limb deficiencies has to be based on comprehensive knowledge in the field of orthopaedic technology. Taking into account the patient's complete background, evaluation of the possible functional benefit is mandatory in order to achieve good acceptance of a prosthesis in the long term. The extent of extremity "loss" and the remaining function of the deficient limb have an impact on the success of prosthetic fitting. Furthermore, there is a trend towards myoelectric prostheses, which seem to improve prosthetic acceptance. Bilateral congenital deficiency of the upper limbs cannot be equated with amputations. Most people affected do not push for a prosthesis, but should be provided with one, if the need arises. Decades of overuse of the deficient limbs often take their toll in terms of decreasing function as degenerative changes occur. As a consequence, artificial upper limbs may be obligatory to prevent loss of independence.

[Significance of microbial colonisation in materials for orthopaedic technology. New insights]

A great problem in the treatment of diabetes are infections of diabetic feet. A likely reservoir of microorganisms are contaminated orthopaedic materials. Insoles from 70 patients were examined for potential microbial colonisation. Commonly employed materials were contaminated in vitro under standardised conditions using known microorganisms. After treating with an alcoholic skin disinfectant, the organisms were counted semiquantitatively. In addition to pathogens, the surfaces showed mainly microorganisms present in the normal skin flora. In all materials tested, disinfection reduced the number of organisms by 4-5 log orders. It could be shown that simple disinfection (wiping) reduces the microorganisms present on orthopaedic materials to an acceptable number. Further studies are needed to determine whether this also reduces the incidence of diabetic skin and soft tissue infection.

Nitric oxide modulates the interaction of pressure-induced wall mechanics and myogenic response of rat intramural coronary arterioles

Interactions between the biomechanical characteristics and pressure-induced active response of coronary microvessels are still not well known. We tested the hypothesis that pressure-dependent biomechanical characteristics of the coronary vascular wall are modulated by the active myogenic response and local vasodilators. We have utilized data obtained previously in isolated rat intramural coronary arterioles (approximately 100 microm in diameter), in which the diameter was investigated as a function of intraluminal pressure (Szekeres et al.: J. Cardiovasc. Pharmacol., 43, 242-249, 2004). To characterize the magnitude of myogenic response, diameter was expressed as percent of passive diameter as a function of pressure (normalized diameter; ND). In addition, circumferential wall stress (WS) and incremental distensibility (ID) were calculated. In control conditions, after an initial increase between 0-30 mm Hg, ND decreased substantially as pressure increased from 30 to 150 mm Hg. Correspondingly, WS gradually increased as a function of pressure (from 0.3 +/- 0.03 to 34.7 +/- 4.4 kPa) exhibiting a plateau phase between 40-80 mm Hg. In contrast, ID decreased and reached negative values (min: -104.9 +/- 21.9 10(-6) m2/N at 50 mm Hg). Inhibition of nitric oxide (NO) synthase by L-NNA decreased basal diameter (approximately 35% at 2 mm Hg), eliminated pressure-induced changes in ND, reduced the slope of pressure-WS curve, and decreased ID at lower pressures. Simultaneous administration of L-NNA and adenosine (which restored initial diameter, i.e. length of smooth muscle) restored--in part--the pressure-induced reduction in ND, reversed the pressure-induced behavior of WS to control, but not that of ID. These results not only confirm that in coronary arterioles wall stress is regulated by the myogenic response, but also suggest that there is interplay between the mechanical behavior of the wall and the myogenic response. Furthermore, the presence of NO seems to be necessary for maintaining a higher distensibility of intramural coronary arterioles allowing increases in diameter to lower pressures, which then activate the myogenic mechanism resulting in constrictions and full development of myogenic tone, as indicated by the presence of negative slope of pressure-diameter curve in the presence of NO.

Decrease in eccentric hamstring strength in runners in the Tirol Speed Marathon

BACKGROUND

The local muscular endurance of knee flexors, during eccentric work in particular, is important in preventing or delaying kinematic changes associated with fatigue during treadmill running. This result, however, may not be transferable to overground running.

OBJECTIVE

To test the hypothesis that overground running is associated with eccentric hamstring fatigue.

METHODS

Thirteen runners (12 male and one female) performed an isokinetic muscle test three to four days before and 18 hours after a marathon. Both legs were tested. The testing protocol consisted of concentric and eccentric quadriceps and hamstring contractions.

RESULTS

There were no significant differences between peak torque before and after the race, except that eccentric peak hamstring torque (both thighs) was reduced.

CONCLUSION

Overground running (running a marathon) is associated with eccentric hamstring fatigue. Eccentric hamstring fatigue may be a potential risk factor for knee and soft tissue injuries during running. Eccentric hamstring training should therefore be introduced as an integral part of the training programme of runners.

[Reconstructive foot surgery in cases of diabetic-neuropathic osteoarthropathy]

QUESTION

Neurogenic osteoarthropathy often results in a debilitating deformity of the foot which can not be handled conservatively. Indications for surgery are recurrent ulcers, deep tissue infection and decompensated statics with progressing deformity. External fixation as a possible method of correction has to show its efficiency and methods.

METHODS

Between 1997 and 2003, 65 feet which could be examined retrospectively, were operated for neuroarthropathy in 21 women and 43 men. A diabetic polyneuropathy was present in 56 patients. In 59 cases, an external fixation was used while in nine cases Steinmann pins were used. Follow-up treatment consisted of mobilisation in a ankle-foot-orthosis (AFO) for up to a year.

RESULTS

For diabetics, the mean duration of illness was 24.8 years (Type 1) and 13.7 years (Type 2). All feet were Levin stage 3 or 4 and for the classification types II-V. In five cases there was only luxation, another nine had a combination of luxation and osseous changes. Surgical revision was necessary in seven cases, sometimes more than once. Additional operations as the illness progressed were necessary 13 times, in six cases due to loss of correction. The application of a prosthesis was necessary in three cases following amputations in two patients after an average of 752 days. Pin infections and disturbances in healing wound were common but could be successfully treated conservatively and were independent of previous ulceration or infection. Within the first year after operation, 13.9% of the feet developed an ulcer. All of the patients could be mobilised with the help of an orthosis (47 cases) or orthopedic shoes (15 cases)

CONCLUSIONS

External fixation is a suitable and variable method for correcting malalignment of the foot in cases of neuroarthropathy. It has a low complication rate and can be used for rapidly developing as well as non-progressing osteoarthropathies. In general, a fibrous ankylosis is the result of treatment, which allows pain free mobilisation under full weight bearing. In suitable cases, with a good alignment of the foot and good patient cooperation, the use of the AFO can be changed to orthopedic shoes after about 12 months.

Verringerung des plantaren Spitzendrucks beim Diabetiker durch Verk�rzung der Schrittl�nge

Plantar peak pressure is a diagnostically significant parameter for the evaluation of the risk of foot ulceration in patients with diabetic neuropathy. The prophylaxis and therapy of the diabetic foot therefore is to a large extent oriented on peak pressure, and is aimed at an extensive reduction in this parameter. This is mainly accomplished with protective footwear including shoe modifications and cushioning. In comparison, other approaches affecting the loading and motion pattern of the patient are of minor importance--as for example control of gait pattern. In this study we examined shortening of stride length as a possible measure in reducing plantar peak pressure during gait. In 17 diabetic patients without acute foot ulcerations, stride length was reduced to 33% of leg length using an elastic hobble. This led to a reduction in stride length of 23%. At the same time, the walking speed was significantly reduced by 27% and the cadence by 5.7%. As a consequence, the peak pressure was reduced in nearly all regions of the foot--except the small toes. In the metatarsal region peak pressure is reduced by 14.5%. Thus, a reduction in stride length offers the possibility of reducing plantar peak pressure as a supplementary measure in addition to orthopaedic footwear. However, at present clinical feasibility has not yet been established.

Die fu�entlastende Unterschenkelorthese und ihre klinische Anwendung bei Patienten mit diabetisch-neuropathischer Osteoarthropathie

In the daily routine of treating patients with diabetic neuropathic osteoarthropathy (DNOAP), their history often reveals a prolonged course of therapy caused in part by incorrect diagnosis but also by inadequate provision of orthopedic devices. A "classic" case is that of undetected osteoarthropathy, which is erroneously interpreted as osteomyelitis. Thus, subsequent to frustrating attempts at therapy and persistence of the clinical symptoms, patients are not infrequently "offered" the option of amputation, which is performed quite proximal to the osseous lesion to "ensure treatment success." The fact that major amputations lead to a statistically significant decrease of the patient's life span is usually not taken into consideration during the decision making process for amputation. Orthopedic surgical procedures to preserve the leg should be given precedence for the sake of maintaining quality of life just as orthopedic devices and orthopedic shoes should be preferred to retain mobility before amputation is indicated in patients with DNOAP. The cases reports presented here should encourage others to implement treatment concepts with the aim of avoiding unnecessary amputations.

Radiologische und klinische Aspekte der diabetisch-neuropathischen Osteoarthropathie

AIMS

The clinical and radiological observation of patients with neuroarthropathy was carried out with the aim of determining the most significant factors and risk factors involved.

METHODS AND MATERIALS

From January 1998 to December 2000, 53 patients between 29 and 79 years of age were treated in the Clinic for Technical Orthopedics for diabetic-neuropathic osteoarthropathy (DNOAP) of the foot. A comparison was made between the retrospective data for conservative and surgical treatments.

RESULTS

Almost 90% of the effected patients were of working age, which is an indication of the socioeconomic consequences of DNOAP. The mean age of the diabetics was 30.3 years for diabetes mellitus type 1 and 14.6 years for type 2. Overweight was a possible risk factor for the development of orthoarthropathic lesions, in particular at the rear of the foot. An additional risk factor was the presence of claw toes. Taking the radiological data into consideration, DNOAP of the foot can be seen as a dynamic illness that is not adequately dealt with in the commonly used Sanders' classification. In the case of proximal lesions, the number of additional DNOAP changes on the same foot was more than for distal lesions. A possible explanation is the microtrauma of neighbouring bones due to changes in the statics and biomechanics of the foot. Our results indicate that type 1 diabetes plays a particularly important role. Contrary to the other forms of DNOAP, Sanders type 1 is associated with atrophic-destructive changes to the bone. In our cohort, pAVK and ulcers were common with Sanders type 1 diabetes, and overweight appeared to be insignificant.

CONCLUSIONS

Our results are a plea for an early, consequent and stage specific treatment of DNOAP in order to prevent the advance of bone destruction. The clinical and radiological course show that a lasting clearance of ulcers, the removal of necrosis and the repositioning of luxations by suitable stabilisation promote healing in DNOAP.

Do dose area product meter measurements reflect radiation doses absorbed by health care workers?

This study determined the correlation between radiation doses absorbed by health care workers and dose area product meter (DAP) measurements at Universitas Hospital, Bloemfontein. The DAP is an instrument which accurately measures the radiation emitted from the source. The study included the interventional radiologists, radiographers and nurses associated with radiological intervention procedures during the period 1 August 2003 - 31 August 2003. The amount of radiation produced during every procedure was measured by a dose area product meter (DAP) and routinely recorded. The absorbed doses received by health care workers were measured using a thermoluminescent dose meter (TLD). The TLDs were analysed and recorded at the end of each week. Health care workers wore TLDs on the following areas: forehead, thyroid (attached under thyroid guard), and abdomen (worn under lead jacket). A strong positive correlation (r = 0.9, p = 0.0374) was found between the radiographers’ head TLD and DAP meter readings. All other correlations between TLD and DAP readings were not statistically significant. Strong positive correlations were found between the TLD readings of the radiologists’ and nurses’ bodies, the nurses’ and radiographers’ bodies and the radiologists’ and the radiographers’ bodies, all of which were statistically significant.

Physical and Physiological Factors Associated with Success in Professional Alpine Skiing

Scientific data on the physiological profile of world class skiers are sparse. During the last decade the Austria Ski Team was the most successful in the world. It was the objective of this study to describe the physical and physiological characteristics of World Cup (WC) skiers. Twenty female and 28 male members of the Austrian WC Ski Team were examined pre- and post-seasonally from 1997 to 2000. Physical parameters such as age, height, body mass, body mass index, percent body fat and thigh circumference were recorded from each athlete. The physiological variables investigated consisted in the aerobic power and in the muscle strength of the lower limbs. Racing performance was defined by the WC ranking position. The athlete's aerobic performance capacity was assessed by maximal exercise testing on a bicycle ergometer, and the isokinetic muscle strength of the knee extensor and flexor muscles by the use of a computer-interfaced dynamometer. From 1997 to 2000 about half (48 %; n = 106) of all alpine WC racing events (n = 221) were won by the athletes investigated. The typical world class skier is in the mid-twenties (25.2 y [female]; 27.6 y [male]). The mean values for height were 1.66 m (female) vs. 1.81 m (male), for body mass 65.1 kg (female) vs. 87 kg (male) and for the percentage of body fat 24.5 % (female) vs. 15.8 % (male). The maximum power output was 4.3 +/- 0.4 (female ) and 4.7 +/- 0.4 W/kg (male), the corresponding values for VO(2)max were 55 +/- 3.5 (female) and 60 +/- 4.7 ml/kg/min (male). The maximal values for peak torque and work for knee extension amounted to 206 +/- 21 (female) and 334 +/- 43 Nm (male), and 2690 +/- 364 (female) and 4414 +/- 629 J (male), respectively. In both sexes there were neither significant laterality nor dysbalance. The hamstring/quadriceps ratios were between 0.57 - 0.60. Among all physical and physiological variables, only the aerobic power in males was found to be strongly correlated (r = 0.947; p = 0.001 for W (max); r = 0.964; p < 0.001 for VO(2)max) to racing performance. The study proves the practical experience that success in professional alpine skiing is not related to single physiological variables. Two main factors, however, are crucial, i. e. high levels of aerobic power and muscle strength.

[Brunner's technique for open wedge resection]

The interaction of different risk factors exposes the feet of diabetics to a very high risk of infection. Therapeutic measures that are often implemented too late or are inappropriate result in major amputation. A retrospective analysis was performed to assess whether surgical reconstruction with an open wedge resection could also be achieved in cases of serious infections. An open wedge resection was performed between 1996 and 2001 on ten patients who had been suffering from diabetes mellitus for an average of 14 years. After V-shaped excision of necrotic tissue and metatarsal osteotomy close to the base, the wound was treated with wet compresses. The patients were mobilized with interim shoes or orthotics. None of the patients with an average age of 45 years experienced a recurrent ulcer or infection during the average follow-up period of 19 months. Eight patients were fitted with made-to-measure orthopedic shoes while modified standard shoes sufficed for two patients. Brunner's technique for open wedge resection is adequately radical to repair deep forefoot defects and simultaneously appropriate to avoid major amputation. The afflicted patients thus retain the highest measure of mobility and quality of life.

[The MRSA patient in technical orthopaedics and rehabilitation]

Colonisation and infection of humans by methicillin-resistant Staphylococcus aureus (MRSA) was examined retrospectively at the Clinic of Technical Orthopedics and Rehabilitation of the University Clinic at Münster (Germany). The cohort consisted of 28 patients who over the period were microbiologically shown to harbour MRSA from January 1997 to June 2000. Out of these, only 16 patients were colonised and only 12 patients developed MRSA infection. The inpatient stay was longer for MRSA subjects than for non-MRSA subjects. All patients had chronic wound healing disorders of the lower extremities which were due to peripheral neuropathies, diabetes mellitus and/or obstructive disease of the arteries. All patients were at risk for colonisation with MRSA.

[The MRSA patient in technical orthopaedics and rehabilitation. Part 2: Hygiene management]

One of the multiresistant pathogens is methicillin-resistant Staphylococcus aureus (MRSA),which was increasingly found in the 1980's. In the USA, the ratio of MRSA rose from 2% in 1975 to 29% in 1991. A similarly steep rise was seen in Germany, with the Paul Ehrlich Society for Chemotherapy reporting a rise from 1.7% in 1990 to 15.7% in 1998. In order to control MRSA, the Clinic and Polyclinic of Technical Orthopaedics and Rehabilitation at the University Clinic Münster, Germany,has set up a comprehensive hygiene management programme for early detection and treatment of nosocomial infections. In addition to addressing the usual problems of MRSA carriers (e.g., higher mortality, longer hospital stays, stigmatisation), these preventive measures are also aimed at combating MRSA-caused cost increases.

[Link-Witzel operation for diabetics]

The inner Chopart's amputation for tuberculosis of the tarsal as performed by Link and Witzel at the end of the nineteenth century laid the groundwork for a foot-saving surgical procedure in cases of neuropathic osteoarthropathy with concomitant infection. The question was posed whether such an inner amputation can represent an alternative to the classic hindfoot amputation. Six patients with neuropathic osteoarthropathy, five of whom had diabetes mellitus,who had been operated between 1989 and 2002 were analyzed retrospectively. In all of the cases, surgery had been indicated by chronic osteomyelitis of the tarsal with concomitant, extensive, mainly plantar ulcerations. During the average follow-up period of 55 weeks, no recurrence of an ulcer or infection occurred and therefore no further proximal amputation was necessary. In addition to being provided with orthotics, the remaining five patients could be fitted with made-to-measure orthopedic shoes. In selected cases, the inner Chopart's amputation can represent a solution even in such problematic cases that cannot be solved by a typical hindfoot amputation. The surgical procedure according to Link and Witzel should thus not only be considered as an alternative to Chopart's amputation, but also as a further method to spare diabetics major amputations.

Time empty and ketone body status in the early postpartum period of dairy cows

This study aimed to assess the effect of ketone body status early postpartum on time empty in 74 multiparous dairy cows under field conditions. Animals were equally distributed across eight farms and were controlled by the same herd-fertility-monitoring programme. Cows were visited twice antepartum and six times postpartum at weekly intervals between 0530 and 0830 a.m. On these occasions, body condition scores and milk yields were measured, blood and milk samples were taken, cows were gynaecologically examined, and parameters of reproduction were recorded. Cows with a time empty of less or more than 80 days were classified as early and late conceiving cows (EC and LC, respectively). A time empty of 80 days results in calving-to-calving intervals of 1 year and classification based on this threshold value resulted in groups of equal size and equal distribution of EC and LC within farms. Ketone bodies measured were beta-hydroxybutyrate in blood and acetoacetate and acetone in blood and milk. Blood and milk ketone body concentrations, as well as the ratios of acetoacetate and acetone to beta-hydroxybutyrate, over the first 6 weeks postpartum were higher in LC than in EC, whereas plasma glucose and non-esterified fatty acids and milk fat, protein and urea concentrations did not exhibit clear differences between groups. Ketone body concentrations were as good predictors of time empty as ketone body ratios and might have practical impact in herd-fertility-monitoring programmes.

A new X-ray calibration/reconstruction system for 3D clinical assessment of spinal deformities

The main objective of this study was to develop a 3D X-ray reconstruction system of the spine and rib cage for an accurate clinical assessment of spinal deformities. The proposed system uses an explicit calibration technique and a new calibration object composed of: (1) a set of radiopaque markers embedded in a jacket worn by the patient during the X-ray exposures; (2) six control markers to define a reference vertical plane. Computer simulations were performed to evaluate the accuracy of the 3D reconstruction procedure when different kind of displacements were applied on a reference model. Clinical indices computed from the 3D X-ray reconstruction of the spine for 24 scoliotic subjects were compared to those obtained with the DLT method. The results of the evaluation study showed that the new system allows the patient to adopt a normal attitude without any constraint, compensating for its displacement between exposures.

Study of patient positioning on a dynamic frame for scoliosis surgery

The goal of this clinical trial was to measure patient geometry on a dynamic positioning frame in various prone positions. Fourteen subjects (2 males and 12 females) were recruited from the scoliosis clinic at Ste-Justine Hospital on a volunteer basis. The subjects were AIS patients who were potential candidates for surgery. The Cobb angle, averaged 50 degrees (32 degrees-64 degrees). The mean age was 14.1 years (11-17). A Polaris system (Northern Digital inc, Canada) with 10 passive reflective markers was used to measure various indices of the patient's trunk geometry. Acquisitions were made while the unanaesthetized patient was in five different prone positions: I similar to the standard positioning on a Relton-Hall frame; II addition of a force applied to the ribcage at the apex of the curve; III application of a force at the apex of the curve in the lumbar region; IV, the shoulder pads were elevated to increase the patient's kyphosis; V adjustment of each pad and the application of thoracic and lumbar forces to obtain an optimal correction. The measurements of trunk geometry at each position were compared using position I as a base. A paired student t-test determined a significant difference between positions. When comparing position I to position II there was a significant difference and correction of the rib hump. There was also a significant change in shoulder angle that resulted in over correction. Position III had a significantly negative change in the rib hump. During position IV, there was a measurable increase in kyphosis. During the optimal correction, position V, a significant increase in spine length was observed as well as a significant correction in rib hump and shoulder angle. Patient trunk geometry can be improved by the application of different forces on a dynamic positioning frame. Caution is necessary as over correction and unintended negative effects were observed. The optimal patient position has not yet been found and future studies are directed at determining this.

Evaluation of the efficiency of patient stabilization devices for 3D X-ray reconstruction of the spine and rib cage

Four devices designed to stabilize the patient's position and/or posture between X-ray exposures were investigated in order to obtain accurate 3-D reconstruction of their spine: a pelvis support, two elbow supports with handlebars, a back neck contact system and a device with three divergent laser beams pointing on subject body targets. Stability and the bearing of natural posture on a group of 10 adults without scoliosis was evaluated for the different devices using a statistical experimental design (Plackett-Burman plan of resolution IV). Small displacements of subjects were obtained by an Optotrak system with 11 infrared diodes placed on the subject's back. Results showed that the elbow supports with handlebars and pelvis support improved the subject's stability while the pelvis support was the device that produces more changes in the subject's natural posture. The elbow and back neck supports were retained for further evaluation.

Effect of estrogen on flow-induced dilation in NO deficiency: role of prostaglandins and EDHF

To investigate the role of estrogen in flow-induced dilation (FiD) in nitric oxide (NO) deficiency, FiD was examined in isolated gracilis arterioles of ovariectomized (OVX) and OVX rats with estrogen replacement (OVE). Both groups of rats were treated chronically with N(omega)-nitro-L-arginine methyl ester. Plasma concentration of NO(2)/NO(3) was reduced in both groups. Plasma concentration of estradiol was lower in OVX than in OVE rats. FiD was similar in vessels of the two groups; calculated wall shear stress and basal tone were significantly greater in OVX vs. OVE rats. Indomethacin did not affect FiD in vessels from OVE rats but abolished dilation in vessels from OVX rats. Valeryl salicylate or NS-398 inhibited FiD by approximately 50%, whereas their simultaneous administration eliminated the response in arterioles from OVX rats. In vessels from OVE rats, miconazole or charybdotoxin eliminated FiD. Thus, in NO deficiency, prostaglandins derived from both cyclooxygenase isoforms mediate FiD in gracilis arterioles of OVX rats. Estrogen replacement switches the mediation, showing dependence on endothelium-derived hyperpolarizing factor in the arterioles of OVE rats.

Pharmacologic inhomogeneity between the reactivity of intramural coronary arteries and arterioles

We hypothesized that because of their size, anatomic location, and hemodynamic function, coronary arteries and arterioles would respond differently to vasoactive substances. Intramural arteries (281.7 +/- 23.1 microm) and arterioles (77.3 +/- 6.6 microm) of the left anterior descending coronary of rats were isolated and cannulated. Spontaneous tone was lower in arteries than in arterioles (81.1 +/- 5.7 vs. 53.0 +/- 3.9% of passive diameter, p < 0.05 at 60 mm Hg intraluminal pressure). Arterial tone was adjusted by the thromboxane receptor agonist U46619 (5 x 10(-8) M ) to reach an active tone close to that of arterioles. Bradykinin elicited dilations in both types of vessels. Acetylcholine (10(-6) - 10(-5) M ) dilated arteries (by 42.6 +/- 11.5 microm) but constricted arterioles (by 16.4 +/- 9.3 microm). Sodium nitroprusside and adenosine elicited significantly greater dilations in arterioles than in arteries (by 7.9 and 11.9%, respectively, p < 0.05), whereas dilations to norepinephrine were similar. Inhibition of nitric oxide synthesis caused a significantly smaller constriction in arteries (10.2 +/- 3.31%) than in arterioles (31.6 +/- 6.9%) and completely blocked bradykinin-and acetylcholine-induced dilations, whereas it did not affect dilations to sodium nitroprusside, adenosine, and norepinephrine. Compared with arteries, arterioles have a greater spontaneous tone and enhanced nitric oxide modulation of basal tone and exhibit greater responsiveness to nitric oxide and adenosine. In addition, nitric oxide synthase is activated differently by pharmacologic stimuli in these segments. The qualitative and quantitative differences among vasoactive responses of coronary arteries and arterioles demonstrated in this study suggest segment-specific roles for endothelial and metabolic factors in regulation of coronary vascular resistance.

Creatine kinase, myosin heavy chains and magnetic resonance imaging after eccentric exercise

The aim of this study was to examine the relationship between myosin heavy chain (MHC) release as a specific marker of slow-twitch muscle fibre breakdown and magnetic resonance imaging (MRI) of skeletal muscle injury after eccentric exercise. The effects of a single series of 70 high-intensity eccentric contractions of the quadriceps femoris muscle group (single leg) on plasma concentrations of creatine kinase and MHC fragments were assessed in 10 young male sport education trainees before and 1 and 4 days after exercise. To visualize muscle injury, MRI of the loaded thigh was performed before and 4 days after the eccentric exercise. All participants recorded an increase (P < 0.05) in creatine kinase after exercise. In five participants, T2 signal intensity was unchanged post-exercise compared with pre-exercise and MHC plasma concentration was normal; however, they showed an increase (P < 0.05) in creatine kinase after exercise. For the remaining five participants, there was an increase in T2 signal intensity of the loaded vastus intermedius and vastus lateralis. These changes in MRI were accompanied by an increase in MHC plasma concentration (P< 0.01) as well as an increase in creatine kinase (P < 0.01). We suggest that changes in MRI T, signal intensity after muscle damage induced by eccentric exercise are closely related to damage to structurally bound contractile filaments of some muscle fibres. Additionally, MHC plasma release indicates that this damage affects not only fast-twitch fibres but also some slow-twitch fibres.

Role of endothelial [Ca2+]i in activation of eNOS in pressurized arterioles by agonists and wall shear stress

In cultured endothelial cells, Ca2+-dependent and -independent activation of nitric oxide (NO) synthesis to agonists and flow/wall shear stress (WSS) has been demonstrated. However, the presence and function of these pathways are less well known in microvessels that can be exposed to a high level of WSS. We hypothesized that the role of changes in endothelial intracellular calcium concentration ([Ca2+]i) is different in agonist- and WSS-induced release of NO. Thus changes in endothelial [Ca2+]i and diameter of intact pressurized (approximately 100 microm at 80 mmHg) gracilis skeletal muscle arterioles of rats were measured by fluorescent videomicroscopy. Acetylcholine (ACh) and increases in WSS (by increasing intraluminal flow) elicited dilations (maximum 91 +/- 2% and 34 +/- 4%) that could be inhibited by N(omega)-nitro-L-arginine methyl ester (L-NAME), a NO synthase blocker. In diameter-clamped arterioles, ACh caused substantial increases in the endothelial calcium fluorescence ratio (ER(Ca), maximum 43 +/- 5%), which was significantly greater than changes in ER(Ca) (maximum approximately 10%) to increases in WSS. The Ca(2+) ionophore A-23187 also substantially increased ER(Ca) (maximum 38 +/- 5%) and elicited significant L-NAME-sensitive arteriolar dilations (maximum 45 +/- 7%). Intraluminal administration of the tyrosine kinase inhibitor genistein had no effect on dilations induced by ACh or the NO donor sodium nitroprusside, whereas it eliminated WSS-induced dilations. Collectively, our data suggest that, in endothelium of skeletal muscle arterioles, NO synthesis is activated by shear stress without a substantial increase in [Ca2+]i, most likely by activation of tyrosine kinase pathways, whereas NO release by ACh and A-23187 is associated with substantial increases in [Ca2+]i.

Mediation of EDHF-induced reduction of smooth muscle [Ca(2+)](i) and arteriolar dilation by K(+) channels, 5,6-EET, and gap junctions

OBJECTIVE

To characterize the role of K(+) channels, the cytochrome P-450 (CYP) metabolite 5,6-EET, and gap junctions in modulation of arteriolar myogenic tone by a non-nitric oxide nonprostaglandin mediator, termed "endothelium-dependent hyperpolarizing factor" (EDHF), released to acetylcholine (ACh) in skeletal muscle arterioles.

METHODS

In isolated rat gracilis arterioles, simultaneous changes in smooth muscle (aSM) [Ca(2+)](i) (assessed by changes in fura-2 ratiometric signal, R(Ca)) and diameter were measured in response to ACh in the presence of indomethacin and L-NAME.

RESULTS

ACh, the K(ATP) channel opener pinacidil, and the Ca(2+) channel inhibitor verapamil elicited comparable decreases in aSM [Ca(2+)](i) (max.: -32 +/- 3%, 29 +/- 3%, and -30 +/- 3%, respectively) and arteriolar dilations (max.: 90 +/- 4%, 96 +/- 2%, and 95 +/- 2%, respectively). ACh-induced responses were inhibited by KCl-depolarization, K(Ca) channel blockers (TEA, charybdotoxin), or gap junction inhibitors (18alpha-glycyrrhetinic acid, hyperosmolar sucrose). The K(ATP) channel inhibitor glibenclamide, the K(IR) channel inhibitor barium chloride, or the CYP inhibitor 17-octadecynoic acid (ODYA) were without effect. The putative EDHF analogue 5,6-EET elicited constrictions in the presence of the endothelium that could be prevented by indomethacin or a TxA(2) receptor antagonist, whereas in the absence of the endothelium, EDHF elicited only small, charybdotoxin-insensitive decreases in aSM R(Ca) and dilations (max.: -8 +/- 2% and 27 +/- 4%, respectively).

CONCLUSIONS

In skeletal muscle arterioles, EDHF 1) substantially and rapidly reduces myogenic tone by decreasing aSM [Ca(2+)](i) via opening K(Ca) channels, 2) it is unlikely to be 5,6-EET or other CYP metabolites, but 3) requires functional gap junctions.

[Methicillin-resistant Staphylococcus aureus (MRSA). Current status and significance of preventing infection in technical orthopedics]

Many patients of the Clinic for Technical Orthopedics and Rehabilitation of the Munster University are facing several risk factors at the same time, which have to be considered for infection registration and therapy accordingly. The interaction of the known late consequences of diabetes mellitus creates the prerequisites which give way for infections of the soft parts and bones. Very often, patients are only being transferred to special university clinics after long-lasting pre-treatments as day-patients or inpatients. The integrity of patients physiological barriers is often broken through by the already existing morphological damages, and the function of the immune systems defence possibly is affected by already existing basic diseases. Parallel to the increasing importance of Staphylococcus aureus (S. aureus) being the pathogen for nosocomial infections, the resistance situation towards a lot of antibiotics has significantly and increasingly deteriorated. The methicillin resistance of S. aureus, i.e. the resistance of the pathogen towards so-called staphylococcus-effective penicillinase-resistant penicillins (isoxazolylpenicillins), is presently creating the especially for the clinical practice problematic resistance mechanisms. The methicillin (oxacillin)-resistant S. aureus (MRSA, ORSA) stems usually present the phenomenon of multiresistance, i.e. the resistance towards substances of several classes of antibiotics, and, therefore, are not only resistant to all beta-lactamantibiotics (penicillins, cephalosporins, carbapenems). Thus, MRSA infections become a significant risk factor for the respective patients. In many cases there are only a very few options left for an antibiotic therapy. The increasing and often unquestioned use of "reserve substances" is leading to a selection of pathogens creating resistances to the corresponding substances. This results in a resistance spiral which makes an antibiotic therapy more and more difficult.

Selected contribution: NO released to flow reduces myogenic tone of skeletal muscle arterioles by decreasing smooth muscle Ca(2+) sensitivity

To clarify the contribution of intracellular Ca(2+) concentration ([Ca(2+)](i))-dependent and -independent signaling mechanisms in arteriolar smooth muscle (aSM) to modulation of arteriolar myogenic tone by nitric oxide (NO), released in response to increases in intraluminal flow from the endothelium, changes in aSM [Ca(2+)](i) and diameter of isolated rat gracilis muscle arterioles (pretreated with indomethacin) were studied by fluorescent videomicroscopy. At an intraluminal pressure of 80 mmHg, [Ca(2+)](i) significantly increased and myogenic tone developed in response to elevations of extracellular Ca(2+) concentration. The Ca(2+) channel inhibitor nimodipine substantially decreased [Ca(2+)](i) and completely inhibited myogenic tone. Dilations to intraluminal flow (that were inhibited by N(omega)-nitro-L-arginine methyl ester) or dilations to the NO donor S-nitroso-N-acetyl-DL-penicillamine (that were inhibited by the guanylate cyclase inhibitor 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one) were not accompanied by substantial decreases in aSM [Ca(2+)](i). 8-Bromoguanosine cGMP and the cGMP-specific phosphodiesterase inhibitor zaprinast significantly dilated arterioles yet elicited only minimal decreases in [Ca(2+)](i). Thus flow-induced endothelial release of NO elicits relaxation of arteriolar smooth muscle by a cGMP-dependent decrease of the Ca(2+) sensitivity of the contractile apparatus without substantial changes in the pressure-induced level of [Ca(2+)](i).

EDHF mediates flow-induced dilation in skeletal muscle arterioles of female eNOS-KO mice

Vasodilation to increases in flow was studied in isolated gracilis muscle arterioles of female endothelial nitric oxide synthase (eNOS)-knockout (KO) and female wild-type (WT) mice. Dilation to flow (0-10 microl/min) was similar in the two groups, yet calculated wall shear stress was significantly greater in arterioles of eNOS-KO than in arterioles of WT mice. Indomethacin, which inhibited flow-induced dilation in vessels of WT mice by approximately 40%, did not affect the responses of eNOS-KO mice, whereas miconazole and 6-(2-proparglyoxyphenyl)hexanoic acid (PPOH) abolished the responses. Basal release of epoxyeicosatrienonic acids from arterioles was inhibited by PPOH. Iberiotoxin eliminated flow-induced dilation in arterioles of eNOS-KO mice but had no effect on arterioles of WT mice. In WT mice, neither N(omega)-nitro-L-arginine methyl ester nor miconazole alone affected flow-induced dilation. Combination of both inhibitors inhibited the responses by approximately 50%. 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ) alone inhibited flow-induced dilation by approximately 49%. ODQ + indomethacin eliminated the responses. Thus, in arterioles of female WT mice, nitric oxide and prostaglandins mediate flow-induced dilation. When eNOS is inhibited, endothelium-derived hyperpolarizing factor substitutes for nitric oxide. In female eNOS-KO mice, metabolites of cytochrome P-450, via activation of large-conductance Ca2+-activated K+ channels of smooth muscle, mediate entirely the arteriolar dilation to flow.

Gender-specific compensation for the lack of NO in the mediation of flow-induced arteriolar dilation

Flow-induced dilation of gracilis muscle arterioles was examined in both genders of control rats and rats chronically treated with N ω-nitro-l-arginine methyl ester (l-NAME). After l-NAME treatment (4 wk), systolic blood pressure was significantly increased compared with control, whereas the plasma concentration of nitrate/nitrite was significantly reduced. Isolated and pressurized arterioles dilated significantly in response to increases in flow (0–25 μl/min). Flow-induced dilation was comparable in arterioles of control andl-NAME-treated rats but was significantly greater in female than in male rats. l-NAME + indomethacin, which abolished flow-induced dilation in arterioles of male control rats, inhibited the dilation by only ∼75% in female control rats. The residual portion of the response was eliminated by additional administration of miconazole, an inhibitor of cytochrome P-450. Indomethacin did not affect the dilation in femalel-NAME-treated rats but completely inhibited the response in male l-NAME-treated rats. The indomethacin-insensitive, flow-induced dilation in female l-NAME-treated arterioles was abolished by miconazole, 6-(2-proparglyoxyphenyl)hexanoic acid, or charybdotoxin. Thus an augmented release of endothelial prostaglandins accounts for the preserved flow-induced dilation in arterioles of male rats, whereas a metabolite of cytochrome P-450 is responsible for the maintenance of flow-induced dilation in female rats, suggesting important differences in the adaptation of the endothelium of arterioles from male and female rats to the lack of nitric oxide (NO) synthesis.

Homocysteine reduces smooth muscle [Ca2+]i and constrictor responses of isolated arterioles

Chronic elevation of plasma homocysteine concentration has been shown to be associated with impaired vascular function. The acute direct effect of homocysteine on the tone and vasoactive responses of arterioles and the possible underlying mechanisms, however, have not yet been elucidated. Thus arterioles were isolated from gracilis muscle of rats (d: approximately 130 microm) and their diameter was measured by videomicroscopy. Homocysteine (10(-6)-10(-4) M) elicited dose-dependent dilation of arterioles (maximum: 44+/-6% at 10(-4) M). The dilation was not affected by the presence of the nitric oxide synthase inhibitor Nomega-nitro-L-arginine methyl ester or by removal of the endothelium, or the free radical scavenger catalase and superoxide dismutase, or the K+ channel inhibitors glibenclamide, 4-aminopyridine, or tetraethyl ammonium. Incubation of vessels with homocysteine (10(-4) M, 20 min) did not affect dilations to acetylcholine or sodium nitroprusside, whereas it significantly decreased constrictions to norepinephrine (at 10(-6) M; control: 57+/-7%, homocysteine: 21+/-5%) and to the thromboxane A2 analogue U46619 (at 10(-8) M: control: 44+/-3%, homocysteine: 20+/-4%). Homocysteine (10(-4) M), similar to the voltage-operated Ca2+ channel inhibitor nitrendipine (10(-8) M), significantly decreased the arteriolar smooth muscle [Ca2+]i as assessed by changes in the fura-2 ratiometric signal (R(Ca), -6+/-1% and -24+/-3%, respectively). These data suggest that in isolated arterioles homocysteine decreases pressure-induced tone and responses to vasoconstrictor agents, likely by altering Ca2+ signaling of arteriolar smooth muscle.

Endothelial microtubule disruption blocks flow-dependent dilation of arterioles

The cytoskeleton is believed to have an important role in the structural and functional integrity of endothelial cells. The role of the endothelial cytoskeleton, specifically microtubules, in the mediation of flow-induced dilation of arterioles has not yet been studied. Thus the aim of our study was to investigate the role of microtubules in the endothelial mechanotransduction of flow-induced dilation of isolated gracilis arterioles of the rat. The active diameter of arterioles at a constant perfusion pressure (80 mmHg) was approximately 63 microm, whereas their passive diameter (Ca(2+)-free solution) was approximately 119 microm. At a constant pressure, increases in flow of the perfusate solution (from 0 to 10 and from 10 to 20 microl/min) elicited increases in diameter up to approximately 95 microm (approximately a 53% increase). Intraluminal administration of nocodazole at concentrations of 5 x 10(-9) and 5 x 10(-8) M had no discernible effects on the structure of endothelial microtubules or on flow-induced dilation, whereas it disassembled microtubules and eliminated flow-induced dilation at a concentration of 5 x 10(-7) M. At this higher concentration, however, the basal diameter and dilations to acetylcholine (10(-8) M), sodium nitroprusside (10(-7) M), arachidonic acid (5 x 10(-6) M), and prostaglandin E2 (10(-8) M) were unaffected. Colchicine (5 x 10(-7) M) also disassembled microtubules and eliminated flow-induced dilation. We concluded that, in isolated arterioles, the integrity of the endothelial cytoskeleton is essential for the transduction of the shear stress signal that results in the release of endothelial factors evoking dilation.

Reestablishment of foot-stability with external fixation in cases of neurogenic osteoarthropathy

The localization of neurogenic osteopathy in the hindfoot often results in deformities which cannot be corrected by conservative methods. Indications for operation are recurring ulcers, deep infection, and reduced stability with progressive deformity. The aim of this study was to ascertain whether external fixation enables reestablishment of foot stability even when the osteoarthropathic processes have not entirely ceased. A bilaterally mounted Hoffman 2 fixator was used for open repositioning and restabilization on 14 patients with osteoarthropathy of the hindfoot: 12 had diabetes mellitus and 13 had florid processes. Revision with axial correction was necessary in 2 patients. One underwent amputation according to Syme and received a prosthesis. Thirteen were completely remobilized: ten were fitted with an orthosis and three with a rigid orthopedic shoe. Complicated deformities of the hindfoot from neurogenic arthropathy can be satisfactorily restabilized in the edematous and demineralizing stages by surgery and the application of external fixation.

Holt-Oram syndrome. Three case reports and their physiotherapeutic, ergotherapeutic, and technical orthopedic treatment

The combination of organ and skeletal malformation as well as the fact that Holt-Oram syndrome appears in many forms with related functional disturbances and makes it mandatory that the therapy for these patients be determined on an individual basis. Supportive statomotoric therapy of young patients plays a particularly central role, as do development-synchronized treatment aids. Physiotherapy, ergotherapy, and technical orthopedic support oriented toward functionality are all part of the therapeutic concept.

Regular exercise enhances blood pressure lowering effect of acetylcholine by increased contribution of nitric oxide

This study is aimed to test the hypothesis, that short-term daily bouts of exercise alter the endothelial regulation of peripheral vascular resistance by nitric oxide. Rats ran on a treadmill once a day, 5 days a week, for an average of three weeks with gradually increasing intensity (EX), while a control group remained sedentary (SED). Dose dependent reductions in mean arterial blood pressure (resting MABP; SED: 120.0 +/- 3.4 and EX: 127.8 +/- 4.0 mm Hg) of pentobarbital anesthetized rats to intravenous endothelium independent dilator sodium nitropmsside (SNP; 0.6-3.0 microg/kg) were not different in EX and SED animals. In contrast, dose dependent reductions in MABP to endothelium dependent dilator acetylcholine (ACh) were significantly enhanced in EX compared to those in SED rats (at 0.5 and 1.0 microg/kg ACh: 60.3 +/- 2.4 and 66.5 +/- 1.8 vs 52.8 +/- 2.0 and 59.8 +/- 1.7 mmHg, respectively, p<0.01). There was no significant difference in the heart rate (HR) response to ACh and SNP in the two groups of rats. Intravenous administration of 20 mg/kg Nomega-nitro-L-arginine (L-NNA, a nitric oxide synthase inhibitor) elicited a similar increase (approximately 30%) in the MABP in the two groups and eliminated the difference between ACh-induced blood pressure lowering responses in EX and SED rats (at 0.5 and 1.0 microg/kg ACh: 44.6 +/- 4.7 and 56.3 +/- 4.4 vs 50.9 +/- 4.5 and 59.4 +/- 3.6 mm Hg, respectively). Thus, we suggest that the enhanced acetylcholine-induced decrease in systemic blood pressure following regular daily exercise is primarily due to the augmented synthesis of nitric oxide in the endothelium of peripheral vasculature. This change in the function of endothelium could be important in the adaptation of circulation to exercise training.

[Syme amputation in heel defects]

The main advantage of Syme's amputation is the end-bearing stump. A defective heel pad often leads to below-knee amputation. The question of interest is whether an atypical cutaneous flap also provides a covering for the stump adaptable to weight-bearing. Thirteen patients with heel pad ulcers or tumors who could not be attended to with a classic Syme's amputation were operated on in a modified fashion. Skin from the dorsum of the foot or a medial flap was used for covering the stump. Two patients underwent transtibial amputation. The remaining 11 patients received a covering for the end of the stump composed of tissue thick and bulky enough for weight-bearing in a prosthesis typical for a Syme stump. The results show that a transtibial amputation can be prevented by atypical soft-tissue coverage of a Syme stump with satisfactory results regarding function and cosmetics.

[Incidence and detection of nosocomial infections in technical orthopedics]

The significance of nosocomial infections is increasing. The reasons for this are a higher concentration of problematic patients in hospitals due to the increasing number of outpatient surgeries, the increase of invasive therapeutic and diagnostic procedures, the growing share of immunodeficient patients as well as the increase in antibiotic-resistant and multiresistant pathogenic organisms. Basic changes in the medical system call for a systematic discussion about directed quality management. Surveillance, i.e., the systematic registration and evaluation of occurred diseases as well as the feedback to the personnel in charge is very important in this context, particularly when complemented by comprehensive hygienic measures. The growing significance of hospital infections increasingly triggered by multiresistant pathogenic organisms emphasizes the importance of general prevention. Each hospital has to determine which surveillance methods for the registration of nosocomial infections and multiresistant pathogenic organisms are the most appropriate under their respective conditions. To get a first idea of possible problem areas, prevalence studies are very suitable for the start before moving on to well-directed incidence studies in certain wards and for certain kinds of infection.

Endothelial K(ca) channels mediate flow-dependent dilation of arterioles of skeletal muscle and mesentery

The role of Ca(2+)-activated potassium channels (K(Ca)) in flow-initiated intracellular events in microvessels is not known. We hypothesized that K(Ca) channels in the arteriolar endothelium are responsible for the mechanotransduction of flow/shear stress-induced arteriolar dilation in skeletal muscle and mesentery of rats. The active diameter of arterioles isolated from gracilis (80 mm Hg) and cremaster (60 mm Hg) muscles and mesentery (80 mm Hg) at a constant intraluminal pressure was 53 +/- 3, 77 +/- 5, and 72 +/- 6 microm, respectively. Their passive diameter (in Ca(2+)-free solution) was 113 +/- 3, 152 +/- 12, and 121 +/- 7 microm, respectively. At a constant intraluminal pressure stepwise increases in perfusate flow (25, 40, and 14 microL/min in 5, 10, and 2 microL/min steps) elicited a gradual increase in diameter of all three groups of arterioles up to 93 +/- 5, 137 +/- 11, and 102 +/- 7 microm, respectively. Flow-induced dilations of arterioles were eliminated by intraluminal administration of iberiotoxin (ibTX 10(-9) M), an inhibitor of high conductance K(Ca) channels (BK(Ca)). In contrast, arteriolar dilations to acetylcholine and sodium nitroprusside were not altered by this agent, indicating that BK(Ca) channels are not involved in the receptor-mediated endothelial synthesis of nitric oxide (NO) and that the inhibitor did not affect the action of NO on smooth muscle. Abluminal application of ibTX (10(-8) M) did not affect flow-dependent dilation. We conclude that in arterioles of several tissues activation of endothelial BK(Ca) channels is an obligatory step in the transduction of the signal initiated by changes in intraluminal flow/shear stress, leading to the release of endothelial factors evoking dilation.

Import of peroxisomal matrix and membrane proteins

This review summarizes the progress made in our understanding of peroxisome biogenesis in the last few years, during which the functional roles of many of the 23 peroxins (proteins involved in peroxisomal protein import and peroxisome biogenesis) have become clearer. Previous reviews in the field have focussed on the metabolic functions of peroxisomes, aspects of import/biogenesis the role of peroxins in human disease, and involvement of the endoplasmic reticulum in peroxisome membrane biogenesis as well as the degradation of this organelle. This review refers to some of the earlier work for the sake of introduction and continuity but deals primarily with the more recent progress. The principal areas of progress are the identification of new peroxins, definition of protein-protein interactions among peroxins leading to the recognition of complexes involved in peroxisomal protein import, insight into the biogenesis of peroxisomal membrane proteins, and, of most importance, the elucidation of the role of many conserved peroxins in human disease. Given the rapid progress in the field, this review also highlights some of the unanswered questions that remain to be tackled.

Flow-induced constriction in arterioles of hyperhomocysteinemic rats is due to impaired nitric oxide and enhanced thromboxane A(2) mediation

Hyperhomocysteinemia (HHcy) is thought to promote arteriosclerosis and peripheral arterial disease, in part by impairing the function of endothelium. Because flow-induced dilation is mediated by the endothelium, we hypothesized that HHcy alters this response by interfering with the synthesis/action of NO and prostaglandins. Thus, changes in the diameter of isolated, pressurized (at 80 mm Hg) gracilis skeletal muscle arterioles (diameter approximately 170 microm) from control and methionine diet-induced HHcy rats were investigated with videomicroscopy. Increases in intraluminal flow (from 0 to 25 microL/min) resulted in dilations of control arterioles (maximum, 34+/-4 microm). In contrast, increases in flow elicited constrictions of HHcy arterioles (-36+/-3 microm). In control arterioles, the NO synthase inhibitor N:(omega)-nitro-L-arginine-methyl ester significantly attenuated (approximately 50%) dilation, whereas the additional administration of indomethacin, an inhibitor of cyclooxygenase, eliminated flow-induced dilation. In the arterioles of HHcy rats, flow-induced constriction was not affected by N:(omega)-nitro-L-arginine-methyl ester, whereas it was abolished by indomethacin or the prostaglandin H(2)/thromboxane A(2) (TXA(2)) receptor antagonist SQ 29,548 or the TXA(2) synthase inhibitor CGS 13,080. Thus, in HHcy, increases in intraluminal flow elicit constrictions of skeletal muscle arterioles due to the impaired NO and enhanced TXA(2) mediation of the response, alterations that likely contribute to the development of peripheral arterial disease.

Release of muscle proteins after downhill running in male and female subjects

The release of muscle proteins after downhill running, which mainly includes eccentric muscle action, was compared in females (F; n=9) and males (M; n=9). They performed 20 min of downhill treadmill running with 16% decline with a target heart rate of 70% of the individual VO2peak, which was determined two weeks before. Blood samples were drawn before, 6 and 24 h after exercise to measure plasma levels of skeletal troponin I (sTnI), myosin heavy chain fragments (MHC), creatine kinase (CK), and myoglobin (Mb). Baseline levels before exercise were significantly higher in males compared to females for the cytoplasmic proteins CK and Mb, but the difference for MHC and sTnI was not significant. Both groups displayed marked and significant early (6 h) increases (P<0.05) for sTnI (median: F: 8.2 microg/L; M: 22.0 microg/L), Mb (median: F: 86.8 microg/L; M: 407 microg/L), and CK (median: F: 162 U/L; M: 339 U/L). A significant (P<0.05) but delayed (24 h) increase was found for MHC (median: F: 482 microU/L; M: 651 microU/L). The absolute values for all four parameters were significantly (P<0.05) higher in males compared to females; however, no difference was found for the relative increases and the time course of all parameters between females and males. We conclude 1) that there were no significant differences in the basal concentrations of predominantly bound proteins, and 2) that there were no differences in the relative muscle protein release between females and males before and after one bout of high-intensive eccentric exercise. The higher plasma concentrations of all measured muscle proteins in males are probably caused by the higher muscle mass compared to females.

Nitric oxide-mediated arteriolar dilation after endothelial deformation

Previously, we frequently observed dilation of arterioles after agonist-induced constrictions. We hypothesized that deformation of the endothelium during decreases in diameter of isolated arterioles elicits the release of nitric oxide (NO). In isolated arterioles of rat mesentery, phenylephrine (PE, 10(-7) M)-, U-46619 (10(-7) M)-, and KCl (50 mM)-induced constrictions were followed by potent dilations. Inhibition of NO synthase with N(omega)-nitro-L-arginine (L-NNA, 2 x 10(-4) M) or removal of the endothelium significantly enhanced constriction and reduced the postconstriction dilation. In the presence of 80 mmHg of intraluminal pressure, an increase in extraluminal pressure (P(e)) to 75 mmHg for 20 s and 1 and 2 min decreased vessel diameter. After release of P(e), arterioles dilated as a function of the duration of diameter reduction by P(e). Removal of the endothelium or administration of L-NNA significantly diminished the post-P(e) dilations. In cultured mesenteric arteriolar endothelial cells (EC), PE, U-46619, or KCl did not increase, whereas ACh did increase, the production of NO, as measured by a fluorometric assay for nitrite. Furthermore, when EC, cultured on a stretched silicone membrane, were subjected to deformation by shortening the membrane to 50% of its original length, NO release increased significantly. Based on all of the above, we propose that deformation of EC per se elicits release of NO, a mechanism that modulates arteriolar constriction.

Hyperosmolality dilates rat skeletal muscle arterioles: role of endothelial K(ATP) channels and daily exercise

The purpose of this study was to investigate the mechanism underlying arteriolar responses to hyperosmolality and to determine the effects of daily exercise on this response. Dilator responses were measured in isolated, cannulated, and pressurized skeletal muscle arterioles. Osmolality was increased from approximately 290 to 330 mosmol/kgH(2)O by adding glucose, sucrose, or mannitol to the superfusion solution. All three compounds elicited similar changes in vessel diameter, suggesting that this response was due to changes in osmolality. Responses to glucose were abolished by endothelium removal but were not altered in endothelium-intact vessels by superfusion with the nitric oxide synthase inhibitor N(omega)-nitro-L-arginine or the cyclooxygenase inhibitor indomethacin. In endothelium-intact arterioles, responses to glucose superfusion with the ATP-sensitive potassium (K(ATP)) channel inhibitor glibenclamide; however, intraluminal perfusion with glibenclamide nearly abolished the responses to glucose and mannitol. Intraluminal administration of glucose elicited a significantly greater dilation than extraluminal glucose. The response to intraluminal glucose was also inhibited by intraluminal glibenclamide. Four weeks of daily exercise did not significantly alter the responses to hyperosmolality in gracilis or soleus muscle arterioles. These data demonstrate that physiological increases in intraluminal osmolality dilate rat skeletal muscle arterioles via activation of endothelial K(ATP) channels; however, this endothelium-dependent response is not augmented by daily exercise.