On the reproducibility of extrusion-based bioprinting: round robin study on standardization in the field

The outcome of three-dimensional (3D) bioprinting heavily depends, amongst others, on the interaction between the developed bioink, the printing process, and the printing equipment. However, if this interplay is ensured, bioprinting promises unmatched possibilities in the health care area. To pave the way for comparing newly developed biomaterials, clinical studies, and medical applications (i.e. printed organs, patient-specific tissues), there is a great need for standardization of manufacturing methods in order to enable technology transfers. Despite the importance of such standardization, there is currently a tremendous lack of empirical data that examines the reproducibility and robustness of production in more than one location at a time. In this work, we present data derived from a round robin test for extrusion-based 3D printing performance comprising 12 different academic laboratories throughout Germany and analyze the respective prints using automated image analysis (IA) in three independent academic groups. The fabrication of objects from polymer solutions was standardized as much as currently possible to allow studying the comparability of results from different laboratories. This study has led to the conclusion that current standardization conditions still leave room for the intervention of operators due to missing automation of the equipment. This affects significantly the reproducibility and comparability of bioprinting experiments in multiple laboratories. Nevertheless, automated IA proved to be a suitable methodology for quality assurance as three independently developed workflows achieved similar results. Moreover, the extracted data describing geometric features showed how the function of printers affects the quality of the printed object. A significant step toward standardization of the process was made as an infrastructure for distribution of material and methods, as well as for data transfer and storage was successfully established.

Comparing Attitudes Across Groups: An IRT-Based Item-Fit Statistic for the Analysis of Measurement Invariance

Questionnaires for the assessment of attitudes and other psychological traits are crucial in educational and psychological research, and item response theory (IRT) has become a viable tool for scaling such data. Many international large-scale assessments aim at comparing these constructs across countries, and the invariance of measures across countries is thus required. In its most recent cycle, the Programme for International Student Assessment (PISA 2015) implemented an innovative approach for testing the invariance of IRT-scaled constructs in the context questionnaires administered to students, parents, school principals, and teachers. On the basis of a concurrent calibration with equal item parameters across all groups (i.e., languages within countries), a group-specific item-fit statistic (root mean square deviance [RMSD]) was used as a measure for the invariance of item parameters for individual groups. The present simulation study examines the statistic's distribution under different types and extents of (non)invariance in polytomous items. Responses to five 4-point Likert-type items were generated under the generalized partial credit model (GPCM) for 1,000 simulees in 50 groups each. For one of the five items, either location or discrimination parameters were drawn from a normal distribution. In addition to the type of noninvariance, the extent of noninvariance was varied by manipulating the variation of these distributions. The results indicate that the RMSD statistic is better at detecting noninvariance related to between-group differences in item location than in item discrimination. The study's findings may be used as a starting point to sensitivity analysis aiming to define cutoff values for determining (non)invariance.

Efficacy of Radiation Therapy for the Treatment of Sialocele in Dogs

Background

Sialocele is a collection of saliva that has leaked from a damaged salivary gland or duct and is surrounded by granulation tissue. Surgery is the recognized first‐line treatment. Recurrence rate after surgery is 5–14%. Salivary gland tissue is very sensitive to radiation therapy (RT).

Hypothesis/Objectives

Radiation therapy will be useful for the treatment of sialocele. The aims were to characterize response rate and clinical course of dogs with sialocele treated with RT and to determine a starting dose for clinical use.

Animals

Eleven dogs with sialocele.

Methods

Retrospective study of response and outcome after RT.

Results

All dogs had cervical sialocele. Seven dogs (63.6%) were treated with 3 weekly fractions of 4 Gray (Gy); (total dose, 12 Gy). Three dogs (27.3%) received 4 fractions of 4 Gy (16 Gy) and 1 dog received 5 fractions of 4 Gy (20 Gy) on a Monday‐Wednesday‐Friday schedule. Six dogs (54%) achieved a complete response (CR), and 5 dogs (45%) achieved a partial response (PR). Three dogs had progression of their sialocele 2, 3, and 9 months after RT; all three had received 12 Gy initially and 2 received 2 additional fractions of 4 Gy (cumulative total dose, 20 Gy) and subsequently achieved remission for >2 years.

Conclusions and Clinical Importance

Radiation therapy is useful for the treatment of recurrent sialocele refractory to surgical management and a minimum total dose of 16 or 20 Gy in 4 Gy fractions appears effective.

Effects of Anchoring Vignettes on Comparability and Predictive Validity of Student Self-Reports in 64 Cultures

Anchoring vignettes are item batteries especially designed for correcting responses that might be affected by incomparability. This article investigates the effects of anchoring vignettes on the validity of student self-report data in 64 cultures. Using secondary data analysis from the 2012 Programme for International Student Assessment (PISA), we checked the validity of ratings on vignette questions, and investigated how rescaled item responses of two student scales, Teacher Support and Classroom Management, enhanced comparability and predictive validity. The main findings include that (a) responses to vignette questions represent valid individual and cultural differences; in particular, violations in these responses (i.e., misorderings) are related to low socioeconomic status and low cognitive sophistication; (b) the rescaled responses tend to show higher levels of comparability; and (c) the associations of rescaled Teacher Support and Classroom Management with math achievement, Student-Oriented Instruction, and Teacher-Directed Instruction are slightly different from raw scores of the two target constructs, and the associations with rescaled scores seem to be more in line with the literature. Namely, the associations among all self-report Likert-type scales are weaker with rescaled scores, presumably reducing common method variance, and both rescaled scale scores are more positively related to math achievement. The country ranking also changes substantially; in particular, Asian cultures top the ranking on Teacher Support after rescaling. However, anchoring vignettes are not a cure-all in solving measurement bias in cross-cultural surveys; we discuss the technicality and directions for further research on this technique.

Note: multiplexed multiple-tau auto- and cross-correlators on a single field programmable gate array

We introduce a new multiple-tau hardware correlator design for computing fluorescence correlation functions (CFs) in real time. Use of hardware resources is minimized by scheduling the computation of different segments of the CFs on a single correlator block. Simultaneous calculation of two multiple-tau autocorrelation (ACFs) and two cross-correlation functions (CCFs) is implemented in LabVIEW on a National Instruments field programmable gate array (FPGA) card with a minimal sampling time of 400 ns. Raw data are stored with a time resolution of 50 ns. The design can be easily adapted to other FPGA cards and extended to more inputs.

Primary pulmonary spindle cell tumour (haemangiopericytoma) in a dog

Haemangiopericytoma is a soft tissue sarcoma believed to originate from pericytes. These tumours are commonly located on the skin and subcutaneous tissue of dogs and are most commonly found on the limbs. To the authors' knowledge, primary lung haemangiopericytomas have not been previously described in dogs. This case report describes the diagnostic evaluation and treatment of a primary haemangiopericytoma of the lung in a 10-year-old male, neutered, Siberian husky dog. Staging of the tumour was performed using a computed tomography scan of the thorax and a computed tomography-guided fine-needle aspiration biopsy of the lesion. Treatment was a right caudal lobectomy from a right lateral approach. No regional lymph node changes were noted on computed tomography or intraoperative assessments. Histopathology confirmed a spindle cell tumour that stained positive for vimentin and negative for desmin and S-100.

Identification of proximal 1p36 deletions using array-CGH: a possible new syndrome

Monosomy 1p36 is the most common terminal deletion syndrome with an estimated occurrence of 1:5000 live births. Typically, the deletions span <10 Mb of 1pter-1p36.23 and result in mental retardation, developmental delay, sensorineural hearing loss, seizures, cardiomyopathy and cardiovascular malformations, and distinct facies including large anterior fontanel, deep-set eyes, straight eyebrows, flat nasal bridge, asymmetric ears, and pointed chin. We report five patients with 'atypical' proximal interstitial deletions from 1p36.23-1p36.11 using array-comparative genomic hybridization. Four patients carry large overlapping deletions of approximately 9.38-14.69 Mb in size, and one patient carries a small 2.97 Mb deletion. Interestingly, these patients manifest many clinical characteristics that are different from those seen in 'classical' monosomy 1p36 syndrome. The clinical presentation in our patients included: pre- and post-natal growth deficiency (mostly post-natal), feeding difficulties, seizures, developmental delay, cardiovascular malformations, microcephaly, limb anomalies, and dysmorphic features including frontal and parietal bossing, abnormally shaped and posteriorly rotated ears, hypertelorism, arched eyebrows, and prominent and broad nose. Most children also displayed hirsutism. Based on the analysis of the clinical and molecular data from our patients and those reported in the literature, we suggest that this chromosomal abnormality may constitute yet another deletion syndrome distinct from the classical distal 1p36 deletion syndrome.

Detection of high-energy phosphates in cortical bone as an indicator of bone healing and remodelling: use of a rabbit model

PURPOSE; To study high-energy phosphates in cortical bone through experiments on inbred white New Zealand rabbits.

METHODS

Tibial fractures were induced in 80 rabbits and then stabilised by screw osteosynthesis. After 3 (group A; n=40) or 7 days (groups B; n=40), the defective tissue was covered by local muscle flaps. At increasing intervals (from 1 to 16 weeks), the screws were removed and the animals were euthanised (n=8 per group). The bone was removed and analysed histomorphologically; adenosine triphosphate (ATP) levels were determined by high-performance liquid chromatography.

RESULTS

The mean ATP concentration in healthy cortical bone at 16 weeks was 0.092 (standard error, 0.009) nmol/mg dry mass, which was significantly higher than that in the group with delayed healing: 0.081 (0.011) nmol/mg in group A and 0.005 (0.001) nmol/mg in group B (paired t test, p<0.05). Earlier healing led to lower rates of necrosis (0 vs 38; groups A vs B) and osteomyelitis.

CONCLUSION

Early muscle-flap coverage can revascularise the cortical bone, which is reflected in the higher ATP content in the cortical bone measured by high-performance liquid chromatography. Measuring changes of ATP levels can help investigate the metabolism of the pathological bone.

[Locally recurrent rectal carcinoma]

There is no doubt that surgical treatment with curative intent is warranted in patients with recurrent colorectal cancer. This is also true for locally recurrent rectal cancer. Operative procedures are demanding but may be curative if complete excision can be achieved. Preoperative radiochemotherapy has helped to improve resectability, but operative morbidity is still high. Procedure-related mortality on the other hand is low, at around 3%, and 25% 5-year survival can be expected after complete excision.

Laparoscopic management of hydronephrosis in a woman with rare genitourinary anomalies: unicornous uterus, contralateral agenesis of the kidney, and contralateral ectopic ovary in the groin

A 40-year-old woman had infected right-sided hydronephrosis and rare genitourinary anomalies-a dextroposed unicornous uterus-as the cause of the hydronephrosis, which had to be mobilized laparoscopically by dissecting the scar tissue. Furthermore, the patient had left-sided agenesis of the kidney and a left-sided ectopic ovary with a rudimentary tube in the inner inguinal canal.

Thermodiffusion for the quantification of tissue perfusion in skeletal muscle--clinical evaluation in standardized traumatological procedures with tourniquet and potential application in the diagnosis of compartment syndrome

The quantification of tissue perfusion in different parenchymal organs like liver, kidney, and brain by means of thermodiffusion has recently been validated experimentally and was introduced into clinical practice. Traumatology and plastic surgery deal as well with issues of microcirculation. Therefore, it was the aim of this study to validate thermodiffusion for use in skeletal muscle. Eighteen patients were studied during knee arthroscopic procedures that utilized a tourniquet. A thermodiffusion probe was inserted in the tibialis anterior muscle of the side under treatment. Measurement started before the initiation of limb ischemia (by tourniquet) and continued throughout the procedure until tissue perfusion returned to normal values postoperatively. Furthermore, an example of clinical applicability of this technique is given by monitoring muscle tissue perfusion in 3 patients with imminent compartment syndrome. Preoperative values of muscle tissue perfusion in the patients undergoing arthroscopic procedures were 17.74 +/- 4.27 ml/min 100 g. After initiation of tourniquet perfusion quickly decreased to 3.59 +/- 3.53 ml/min 100 g. Upon reperfusion tissue perfusion increased to values above normal for a few minutes and then returned to preischemic values of 20.86 +/- 7.01 ml/min 100 g. There was no significant difference between pre- and postoperative values (P=0.154) but tissue perfusion during tourniquet was significantly reduced (P=0.0001). In 3 patients presenting with the clinical signs of imminent compartment syndrome, thermodiffusion measurement was applied and showed microcirculatory impairment of different degrees. Fasciotomy was followed by a prompt increase of muscle microcirculation to levels slightly above normal. In summary, valid and stable measurements of tissue perfusion in skeletal muscle by means of thermodiffusion are possible under clinical circumstances. Thermodiffusion allows for on-line monitoring of muscle microcirculation, e.g., in compartment syndrome. The clinical potential of thermodiffusion measurements in trauma surgery needs further prospective evaluation.

Laser doppler flow imaging of open lower leg fractures in an animal experimental model

PURPOSE

Open lower leg fractures are frequently associated with severe soft tissue damage, followed by osteomyelitis. Using an animal experimental model, we investigated the effect of timing of coverage of a tibial fracture with a local muscle flap.

METHODS

80 rabbits had a tibial fracture induced in a standardised fashion, which was stabilised by screw osteosynthesis. After 3 (group A; n=40) and 7 days (group B; n=40), respectively, the tissue defect was covered by a local gastrocnemius flap. In increasing intervals from 1 to 2, 4, 8, and 16 weeks, the rabbits from each group were killed and the bone fracture was analysed histomorphologically. Cortical microcirculation was measured by 2-channel laser doppler flowmetry.

RESULTS

Muscle flaps after 3 days improved perfusion significantly as compared with 7 days (24 Flux [standard error, 5 Flux] versus 10 Flux [3 Flux]; baseline, 1.4 Flux). Group A animals also displayed a lower rate of necrosis (0 versus 38). The incidence of osteomyelitis was higher in group B than in group A (24% versus 0%).

CONCLUSION

Laser doppler flowmetry was proven to be a reliable, minimally invasive means for identifying avital tissue, leading to reduction in the loss of vital bone tissue in experimental settings.

[Angle- and rotation-stable internal fixation of proximal humerus fractures with the humerus fixator plate. Early clinical experience with a newly developed implant]

INTRODUCTION

The Humerus Fixator Plate is presented as a new implant for angle- and rotation-stable internal fixation for the operative treatment of proximal humerus fractures at the surgical neck.

METHODS

In an ongoing two-centre study, 47 patients were treated with the new implant. To date, 31 patients had clinical and radiological postoperative follow-up examinations with a mean interval of 10 months (range: 6-14 months).

RESULTS

In 46 patients (97.9%), complete angle and rotational stability was achieved without limiting the range of motion or requiring immobilization. Good pain relief was obtained in 43 patients (91.5 %), and 3 patients (6.4%) showed moderate pain relief following surgery. There was one implant failure. Utilizing the Constant-Raw score (without any correction factors), a mean result of 82.8 points (range: 46-100 points) was ascertained. The majority of the patients (87.1%) achieved "excellent" or "good" clinical results. X-ray analysis revealed no non-union nor humerus head necrosis. In 4 cases (12.9%), protrusion of a humerus head screw was observed which mandated removal of the implant.

CONCLUSION

The first clinical investigations of the novel Humerus Fixator Plate are encouraging and provide essential advances in the treatment of unstable proximal humerus fractures.

Chronic hypoxia alters prejunctional alpha(2)-receptor function in vascular adrenergic nerves of adult and fetal sheep

The impact of development and chronic high-altitude hypoxia on the function of prejunctional alpha(2)-adrenoceptors was studied by measuring norepinephrine release in vitro from fetal and adult sheep middle cerebral and facial arteries. Blockade of prejunctional alpha(2)-adrenoceptors with idazoxan significantly increased stimulation-evoked norepinephrine release in normoxic arteries. This effect was eliminated after chronic hypoxia in cerebral arteries, with a tendency to decline in fetal facial arteries. After chronic hypoxia, the capacity to release norepinephrine declined in fetal middle cerebral arteries with a similar trend in facial arteries. Norepinephrine release was maintained in adult arteries. During development, stimulation-evoked norepinephrine release from middle cerebral and facial arteries was higher compared with adult arteries. In fetal arteries, adrenergic nerve function declined after chronic hypoxia. However, in adult arteries, adrenergic nerves adapted to chronic hypoxia by maintaining overall function. This differential adaptation of adrenergic nerves in fetal arteries may reflect differences in fetal distribution of blood flow in response to chronic hypoxic stress.

[Psychotropic substances in the area of preclinical intensive care medicine]

The aim of preclinical intensive care is to prevent severe consequences by providing immediate therapeutic aid to emergency patients in a life-threatening condition. We investigated how the abuse of drugs and alcohol influences the frequency and the category of emergency cases as well as the patient outcome. 250 emergency cases were analysed in a prospective study in the area of Heidelberg, Germany, from the summer of 1995 to the spring of 1999. The analysis is based on patient data obtained from the German standardised Emergency Record and on the clinical outcome and influence of drugs and alcohol. A serious level of drugs or alcohol was detected in 17% of the patients (the average level of alcohol was 1.97 promille). 81% of these intoxicated patients were given a NACA (National Advisory Committee for Aeronautics) score of less than 4 (not life-threatening) and therefore were not in need of the a presence of a physician.

[Chronic venous insufficiency after open tibial fracture. An underestimated problem]

There is a wide range of alternatives for primary bone reconstruction in the treatment of open lower leg fractures with soft tissue damage of the type Gustillo II and III. The primary objective should always be the protection of soft tissue damage whether one uses the fixateur externe, or an unreamed nail or primary bone shortening with secondary callus distraction. In recent years, this approach has produced better results and a reduction in the rate of major amputations. The overall effects of the initial treatment can only be analysed after a number of years. Research results indicate long-term soft tissue complications of the lower leg, varying from harmless swelling to venous ulcer. We conducted a clinical investigation which compared 80 patients, who were treated between 1985 and 1994 using the venous-occlusion plethysmography, to 50 healthy individuals. Clinically significant damage of the deep venous system was found in over 50% of cases. There was a direct correlation between the number of years since the initial treatment and the degree of damage found. Based on these findings, we recommend that the initial treatment of this condition and the preventative treatment of the secondary trauma diseases should follow regulated surgical guidelines and be recognised for insurance purposes.

Nitric-oxide synthase-containing nerves facilitate adrenergic transmitter release in sheep middle cerebral arteries

Cerebral blood vessels contain both sympathetic and nitric oxide (NO) synthase (NOS)-containing nerves. NO has been proposed to modulate smooth muscle function and adrenergic nerve activity, and the nature of this modulation is controversial: some data show NO inhibits norepinephrine (NE) release, whereas others suggest that NO augments release. To test the hypothesis that in cerebral arteries NO released by NOS-containing nerves augments stimulation-evoked NE release, we used direct measurement of NE and NO release in isolated sheep middle cerebral arteries. The facial artery, which has not been reported to be innervated with NOS-containing nerves, was used as an artery comparison model. HPLC and redox electrochemical detection was used to measure NE, and NO was measured by chemiluminescence. Stimulation-evoked NE release from the middle cerebral artery significantly declined in the presence of the NOS inhibitor N(omega)-nitro-L-arginine methyl ester (L-NAME). The effect of L-NAME was reversed by the addition of the NO donor S-nitroso-N-acetyl-DL-penicillamine. In contrast, in facial arteries, L-NAME had no effect on stimulation-evoked NE release, whereas S-nitroso-N-acetyl-DL-penicillamine still significantly elevated NE release. Activation of perivascular nerves significantly increased NE release in both the middle cerebral and facial arteries. However, when NO was measured in the same samples, stimulation-evoked release of NO was significantly increased compared with basal release only in middle cerebral arteries. These data support the concept that cerebral arteries in the sheep contain both adrenergic and NOS-containing nerves. Furthermore, this study provides succinct evidence that NO released from NOS nerves augments stimulation-evoked NE release.

Effects of maturation on adrenergic neurotransmission in ovine cerebral arteries

The present studies examine the hypothesis that multiple adrenergic neuroeffector mechanisms are not fully developed in fetal, compared with adult, ovine middle cerebral arteries. In arteries denuded of endothelium and pretreated with 1 microM atropine to block involvement of muscarinic receptors, 10 microM capsaicin to deplete sensory peptidergic neurons, and 10 microM nitro-L-arginine methyl ester (L-NAME) to block possible influences from nitric oxidergic innervation, transmural stimulation at 16 Hz increased contractile tensions to 9.5 +/- 3.7% (n = 6) of the potassium maximum in adult arteries. Corresponding values in fetal arteries, however, were significantly less and averaged only 1.1 +/- 0.6% (n =10). However, postsynaptic sensitivity to norepinephrine (NE) was similar in the two age groups; NE pD(2) values (-log EC(50)) averaged 6.11 +/- 0.12 (n = 6) and 6.33 +/- 0.09 M (n = 9) in fetal and adult arteries, respectively. Similarly, NE content measured via HPLC was also similar in the two age groups and averaged 32.4 +/- 5.0 (n = 17) and 32.5 +/- 3.9 ng/ng wet wt (n = 13) in fetal and adult middle cerebral arteries, respectively. In contrast, stimulation-induced NE release was greater in fetal than in adult arteries, whether calculated as total mass released [883 +/- 184 (n = 17) vs. 416 +/- 106 pg NE/mg wet wt (n = 13)] or as fractional release [51.1 +/- 5.3 (n = 17) vs. 22.8 +/- 3.8 pg/pg NE content per pulse x 10(-6)]. Measured as an index of synaptic density, neuronal cocaine-sensitive NE uptake was similar in fetal and adult arteries [1.55 +/- 0.40 (n = 10) and 1.84 +/- 0.51 pmol/mg wet wt (n = 7), respectively]. Overall, age-related differences in postsynaptic sensitivity to NE, NE release, and NE uptake capacity cannot explain the corresponding age-related differences in response to stimulation. The data thus suggest that total synaptic volume and cleft width, in particular, are probably greater and/or that adrenergic corelease of vasoactive substances other than NE is altered in fetal compared with adult middle cerebral arteries.

Regional metabolic changes in the pedunculopontine nucleus of unilateral 6-hydroxydopamine Parkinson's model rats

The pedunculopontine nucleus (PPN) located in the mesopontine tegmentum is innervated by descending projections from nuclei in the basal ganglia. The present study was performed to determine whether nigrostriatal dopaminergic neuron degeneration is associated with changes in PPN metabolic activity. Unilateral nigrostriatal lesioning was performed by injecting 6-hydroxydopamine (6-OHDA) into the substantia nigra pars compacta in 10 rats. Six of these animals exhibited apomorphine-induced rotations contralateral to the lesion and were included in the experimental group for determination of regional cerebral metabolic rate for glucose (rCMRglucose) along with five sham-lesioned and five normal controls. All studies were performed 13-15 days after lesioning using [14]C-2-deoxyglucose autoradiography. Significant hemispheric differences in metabolic activity were observed only in the 6-OHDA lesioned animals. Increased rCMRglucose was found in the globus pallidus (+63%) ipsilateral to the lesion as compared to the contralateral hemisphere, and reduced rCMRglucose in the primary motor, sensory, and auditory cortex (-7%, -12% and -7%, respectively), and in the subthalamic nucleus (-6%). Metabolic activity within the PPN ipsilateral to the lesion was significantly greater than the contralateral hemisphere (P<0.05; lesion 57+/-8, nonlesion 52+/-5), and significantly greater than the sham-lesioned side of the sham rat (P<0.05; sham lesion 47+/-5). No hemispheric differences were observed in the lateral dorsal tegmental nucleus. These observations offer further support for a role of the PPN in Parkinson's and for the utility of the rodent unilateral 6-OHDA model in defining the pathophysiologic significance of the mesopontine tegmental striatal-motor interfaces in basal ganglia disease.

Impact of development and chronic hypoxia on NE release from adrenergic nerves in sheep arteries

To examine effects of development and chronic high-altitude hypoxia on sympathetic nerve function in sheep, norepinephrine release was measured in vitro from middle cerebral and facial arteries. Capsaicin was used to test the role of capsaicin-sensitive sensory nerves; norepinephrine release was not altered by capsaicin treatment. Nomega-nitro-L-arginine methyl ester (L-NAME), an inhibitor of NO synthase, decreased stimulation-evoked norepinephrine release in middle cerebral arteries from normoxic sheep with no effect in hypoxic arteries or facial arteries. Thus NO-releasing nerves augmented norepinephrine release. Furthermore, the function of NO-releasing nerves declined after chronic hypoxia. Despite loss of the augmenting effects of NO, stimulation-evoked fractional norepinephrine release was unchanged after chronic hypoxia, suggesting that middle cerebral arteries adapt to hypoxia by increasing stimulation-evoked norepinephrine release. In fetal facial arteries, chronic hypoxia resulted in a decline in stimulation-evoked norepinephrine release, but there was an increase in the adult facial artery. In the adult, adaptation to chronic hypoxia is similar in both cerebral and facial arteries. However, differential adaptation in fetal adrenergic nerves may reflect differences in fetal redistribution of blood flow in the face of chronic hypoxia but could also possibly contribute to increased incidence of fetal morbidity.

A comparative study on neurochemistry of cerebrospinal fluid in advanced Parkinson's disease

This study addresses two issues: (1) the comparative neurochemistry of classic tremor type of Parkinson's disease or PD-A and akinetic type of Parkinson's disease or PD-B; and (2) the neurochemistry of levodopa failure syndrome (LDFS). Cerebrospinal fluid from the lateral ventricle was collected from 50 patients with idiopathic Parkinson's disease of PD-A and PD-B. Levels of monoamine neurotransmitters and metabolites were determined using high performance liquid chromatography. We have found that (1) 5-hydroxylindoleacetic acid (5-HIAA) level is significantly lower in PD-B than in PD-A; (2) 5-HIAA level is inversely associated with score of part one of United Parkinson's Disease Rating Score (UPDRS); (3) 5-HIAA level is inversely associated with score of part four of UPDRS; (4) 3-O-methyldopa (3-OMD) level is positively associated with levodopa failure syndrome (LDFS) assessed by part four of UPDRS and inversely associates with 5-HIAA. From these data, it can be inferred that serotonergic activity is decreased in PD-B to a greater extent than in PD-A and that decreased serotonergic activity plays a role in LDFS.

Improved exercise performance following lung volume reduction surgery for emphysema

Lung volume reduction surgery (LVRS) for emphysema has been suggested to improve patient lung function and activity. The short-term impact of LVRS on exercise performance was evaluated using maximal and submaximal steady-state exercise testing in 27 patients with severe hypoxemic chronic obstructive pulmonary disease (COPD), along with measurements of patient function, dyspnea, and quality of life. LVRS significantly improved exercise performance, due to ventilatory improvements associated with increased ventilatory reserve, enhanced tidal volume recruitment, and improved alveolar ventilation. Preoperative measurements of ventilatory reserve and dead space ventilation during exercise testing were closely associated with improved exercise performance. Improvements in patient dyspnea, walk distances, and quality of life also occurred following LVRS and were associated with improvements in exercise performance. Surgical mortality from LVRS was low (4%), but short-term all-cause mortality was increased (19%). Short-term mortality was associated with reduced expiratory muscle strength and markedly elevated dead space ventilation. We conclude that LVRS produces significant improvements in exercise performance, dyspnea, and quality of life in selected patients with COPD. Physiologic prediction of patients most likely to survive for an extended period and have significant benefit following LVRS may also be possible.

Impact of age on modulation of norepinephrine release from sympathetic nerves in the rat superior mesentery artery

There is an age-related increase in stimulation-evoked fractional norepinephrine release in tail arteries of Fischer 344 rats from 6-20 months of age. Previous studies have ruled out changes in the function of uptake and subsequent metabolism mechanisms, or feedback by prejunctional alpha2-adrenoceptors. The tail artery is important in thermoregulation, and there is the possibility that the previously observed increase in sympathetic nerve activity is due to age-related changes in thermoregulation as opposed to a fundamental age-related change in the regulation of sympathetic nerves. Thus, we measured stimulation-evoked norepinephrine release in another blood vessel model, the superior mesentery artery using HPLC with electrochemical detection. In this study fractional norepinephrine release was measured under three separate conditions, drug free Krebs'; in the presence of deoxycorticosterone and cocaine; in the presence of deoxycorticosterone and cocaine and the alpha2-adrenergic receptor antagonist, idazoxan. The most significant finding was that fractional norepinephrine release in mesentery arteries from 20-month-old animals was higher as compared to 6 months regardless of treatment condition. Furthermore, the elevation in norepinephrine release cannot be accounted for by changes in norepinephrine content, uptake and subsequent metabolism mechanisms or changes in basal norepinephrine release. These data from the mesentery artery model confirm and support our previous work in the rat tail artery model. In addition, the data from this study suggest the possibility that there are common mechanisms underlying the age-related increase in peripheral sympathetic nerve activity.

Advancing age alters intracellular calcium buffering in rat adrenergic nerves

There is a marked increase with advancing age of stimulation-evoked neurotransmitter release from vascular adrenergic nerves in the rat, an effect correlated with increased levels of plasma norepinephrine. This increase in norepinephrine release could not be accounted for by an alteration in neuronal and extraneuronal uptake of norepinephrine or a decline in feedback inhibition of release by prejunctional alpha2-adrenergic receptors. Measurement of intracellular calcium in fura-2-labeled superior cervical ganglion cells revealed elevated K+-evoked calcium transients in old compared to young neurons. Blockade of mitochondrial calcium uptake with dinitrophenol resulted in increased calcium transients in old neurons only. Furthermore, following blockade of mitochondrial calcium uptake the rate of return of calcium to resting levels was reduced to a greater degree in old cells as compared to young cells. The effects of dinitrophenol in old cells were attenuated when extracellular calcium was reduced. These findings suggest that older cells are more dependent on mitochondrial calcium buffering, perhaps due to changes in ATP dependent calcium uptake. Increased calcium transients as a result of altered intracellular calcium buffering offer a reasonable explanation for our previous observation of increased stimulation evoked norepinephrine release.

Cerebrospinal fluid from multiple sclerosis patients inactivates neuronal Na+ current

Multiple sclerosis is a common inflammatory disease of the CNS. A great number of immunologically active molecules have been identified in the CSF of these patients (CSF-MS), but the role of these substances in neuronal dysfunction, especially in the origin of transient symptoms, is unclear. Therefore, we investigated the effect of CSF from 13 multiple sclerosis patients on membrane currents of cultured cortical neurons from embryonic rat and compared it with the effect of CSF from 12 patients with non-inflammatory neurological diseases. We found an increase in Na+ current (INa) inactivation by a shift of the hoo curve to more hyperpolarizing potentials by 9.3 mV. This effect was reversible by washing and could be abolished by CSF-MS heat inactivation. The degree of the shift ranged from 4.3 mV to 17.6 mV and correlated with the IgG index, but not with the degree of pleocytosis, protein or albumin content. The maximal amplitude of INa was unchanged. We concluded that diffusible factors are released into the CSF which reduce neuronal excitability and thereby disturb the function of the neuronal network. These factors may well contribute to transient neurological symptoms seen in patients with "active' multiple sclerosis.

Rat tail artery norepinephrine release: age and effect of mitochondrial blockade

An age-related increase in stimulation-evoked fractional norepinephrine release has been demonstrated in tail artery of Fischer-344 rats from 6 to 20 months of age. Previous studies have ruled out alterations in function of uptake mechanisms, metabolism, or feedback via prejunctional alpha-2 adrenoceptors, suggesting that an age-related decline in calcium homeostasis may be responsible. To test this possibility, stimulation-evoked fractional norepinephrine release from perivascular adrenergic nerves of rat tail arteries in the presence of a blocker of mitochondrial calcium uptake, dinitrophenol (100 microM), was measured using HPLC with electrochemical detection. When the mitochondrial proton gradient was dissipated by dinitrophenol, tail arteries from 20-month-old animals showed a marked increase in stimulation-evoked norepinephrine release whereas arteries from 6-month-old animals were not affected. One hypothesis is that the inhibition of mitochondrial calcium uptake in the adrenergic nerves from older animals resulted in an elevated intracellular calcium level. In agreement with this idea, when extracellular calcium was raised from 1.6 to 5 mM, stimulation-evoked norepinephrine release was increased in the 6-month tail arteries in the presence of dinitrophenol. These data suggest that there may be a decline in calcium regulation in older nerves leading to increased norepinephrine release with advancing age.

[Functional healing of compartment syndrome of the tibia. An analysis of follow-up results]

In a retrospective review 78 compartmental syndromes, treated between 1980 and 1988, were analyzed. The mean follow-up was 42 months. 43 patients (53%) suffered an traffic accident. Direct trauma forces predominated (66 patients). The functional results after crush injuries had been worser than after contusion injuries or direct trauma forces. The functional results depended from the posttraumatic interval of decompression. The later the fasciotomy the worser the functional results had been. A wide fascial decompression is necessary. Two cases of rebound compartmental syndromes after unilateral fasciotomy reveal the skin as an important limiting factor in severe cases of compartmental syndrome.

Bacterial endotoxins impair electrophysiological properties of cultured astrocytes but not of cultured neurons

The endotoxins of bacteria are lipopolysaccharides which are released in the central nervous system during bacterial meningitis. Endotoxin titers in cerebrospinal fluid correspond to the appearance of severe neurological symptoms like seizures and coma. The pathogenic mechanism, however, by which endotoxins disturb neuronal function, is unclear. The functional deficit may originate either from direct alteration of neuronal excitability or from indirect effects mediated by glial cells. Therefore, we investigated the effects of lipopolysaccharides on electrophysiological properties of cortical neurons and astrocytes in separate cell cultures. Membrane potential, resistance and membrane currents of neurons were unaffected. By contrast, astrocytes depolarized markedly in a dose dependent manner (concentration range 1.0-10.0 micrograms/ml). The depolarization was Na+ dependent and amiloride sensitive (250 microM), both indicating an activation of an electrogenic sodium dependent transport system like the Na+/Ca2+ exchanger as a source of the depolarization. These results suggest that endotoxin induced neurological deficits are not caused by direct effects on neurons, but may result from an impaired glial cell function.

Age-related changes in the sensitivity of sympathetic nerves to altered extracellular calcium in tail arteries of F-344 rats

There is a significant age-related increase in stimulation evoked norepinephrine release from adrenergic nerves in tail arteries of F-344 rats, that is not accounted for by a change in function of prejunctional alpha 2-adrenergic receptors. To further explore the mechanism of this age-related change in transmitter release, we investigated the effect of altered extracellular calcium. With short stimulation trains the effects of altered extracellular calcium were significantly greater in 20-month-old tail arteries compared to 6 months. At the highest calcium concentration (7.5 mM) when alpha 2-adrenergic receptors were active or blocked, there was a significant decline in fractional norepinephrine release only in arteries of 20-month-old animals. With long stimulation trains the effects of altered extracellular calcium were not as pronounced as with short trains, but the effect of calcium was still significantly greater in 20 month old tail arteries. With alpha 2-adrenergic receptors blocked 6 month tail arteries were insensitive to altered calcium while 20-month tail arteries remained sensitive. One explanation for these findings may be an age-related change in the efficiency of intracellular calcium buffering mechanisms leading to greater calcium transients in the nerves of older animals.

[Muscle power and shoulder joint function after removal of the latissimus dorsi muscle]

Free transplantation of the latissimus dorsi muscle has become the treatment of choice in extensive soft-tissue defects of the lower leg after trauma. However, neither the ability of the remaining muscles of the shoulder to compensate for the lost function nor the long-term effects of latissimus dorsi removal on the function of the shoulder have been objectively measured. Therefore, the postoperative shoulder function in 23 patients was compared after removal of the latissimus dorsi muscle with 23 control subjects. The evaluation included a questionnaire, physical examination, and instrumented muscle-testing (cybex system). No significant statistical differences in the function of the shoulders of all the patients and control subjects could be verified, with the exception that 16 patients exhibited weakness during isokinetic torque during extension of the shoulder in a 55 to 65 degree flexion (4.2 +/- 1.2%). The latissimus dorsi free flap can therefore be recommended as a procedure for soft-tissue coverage of extensive wounds resulting only in negligible loss of function and a slightly altered appearance of the shoulder-girdle.

Tear of the biceps femoris tendon

The clinical and operative findings of an isolated rupture of the biceps femoris tendon are described. The immediate suture and the initial postoperative treatment with a knee brace limiting extension to 20 degrees and flexion to 70 degrees resulted in a free range of motion and full activity of the biceps femoris.

[Conservative or surgical treatment of metacarpal fractures]

A total of 146 patients with 150 closed metacarpal fractures were treated between 1980 and 1981, and 109 patients with 113 metacarpal fractures (75%) were followed up (follow up 7.3 years). After conservative treatment, the functional results were good to excellent in 92.7%, while 5.8% had satisfactory and 1.5% poor functional results. After operative treatment 81.5% had good or excellent functional results, 14.8% satisfactory results and 3.7%, poor functional results. The radiological result did not correspond with the functional result. Angulation of the Ist-IVth metacarpal bones by up to 20 degrees of the Vth metacarpal bone by up to 50 degrees, and even shortening by up to 8 mm had no detrimental influence on the functional results. Axial rotational deviation of the Vth metacarpal bone by up to 15 degrees was tolerated. Joint fractures with a 1 mm step could also be treated by conservatively means.

Postjunctional alpha 2-adrenoceptors in blood vessels: effect of age

To investigate the impact of age on function of vascular postjunctional alpha 2-adrenoceptors in tail arteries of F-344 rats aged 6 and 20 months, vasoconstrictor responses of isolated ring segments were studied. In both 6 and 20 months old animals, norepinephrine concentration response curves were significantly shifted to the right in the presence of the alpha 2-adrenoceptor antagonists idazoxan (300 nM) or rauwolscine (50 nM). Furthermore, in both age groups alpha 2-adrenoceptor agonists UK14304 (300 nM) or BHT920 (25 nM) produced significant enhancements in the vasoconstrictor response to the selective alpha 1-adrenoceptor agonist, methoxamine. Concentration response curves for norepinephrine and methoxamine were not different with age. These data verify the existence of postjunctional alpha 2-adrenoceptors and demonstrate that the function of these receptors does not change with age. This supports the proposition that overall vascular adrenergic function in blood vessels is maintained with advancing age.

[Negative effects of local tibial muscle flap repair on foot function]

Although local muscle flaps of the lower leg are often used, the functional problems that arise after these reconstructive procedures have not yet been adequately studied. Twenty patients who had undergone a local muscle flap of the lower leg 3 years earlier were studied using a isokinetic muscle test. The isokinetic muscle strength profile during flexion of the foot was reduced by up to 21 +/- 16% after transfer of the m. gastrocnemius and by up to 31 +/- 20% after transfer of the m. soleus at a angular velocity of 120 degrees. The isokinetic muscle strength profile during pronation and supination of the foot at an angular velocity of 120 degrees was reduced by up to 89 +/- 32% after transfer of the m. soleus. Statistically, compound tibia fractures without a local flap for soft tissue therapy showed significantly better results. In view of this functional loss, the use of local muscle flaps, particularly the transfer of the m. soleus, should be restricted in younger patients, and alternative techniques (free flaps) should be used.

[Arterial vascular injuries in fractures or dislocations of the lower extremity. Therapeutic concept and results]

Combinations of fractures or dislocations with vascular damage of the leg have a high incidence of amputation or severe functional deficit. With this type of lesion 22 patients were treated at "Bergmannsheil" from 1986 to 1991. Using a pre-, intra- and postoperative protocol, the amputation rate decreased to 18%. More than 80% of the patients had a good function of their leg with only minor joint restrictions.

[Complications after surgical management of scaphoid pseudarthroses]

The Matti-Russe technique yields a 95% success rate in treating scaphoid non-unions diagnosed in the first years after trauma and without osteoarthrosis of the radiocarpal joint. Between October 1981 and December 1989, 215 patients were treated by Matti-Russe procedure at the University Hospital of "Bergmannsheil" Bochum. In ten cases, this operation did not lead to osseous consolidation. The results are presented and discussed.

Influence of age on control of norepinephrine release from the rat tail artery

Stimulation-evoked norepinephrine release from the rat tail artery increases with age; therefore, the sensitivity of prejunctional alpha-2 adrenergic receptors to antagonists and agonists was compared in perfused tail arteries from Fischer-344 rats, aged 6 and 20 months. The increase in endogenous fractional norepinephrine release produced by blockade of alpha-2 adrenergic receptors with submaximal concentrations of either yohimbine or idazoxan was significantly greater in 6-month-old animals as compared to 20 months; however, the effect of a maximal concentration of idazoxan was not significantly different. Inhibition of norepinephrine release by the alpha-2 receptor agonist UK14304 was reduced in 20-month-old animals compared to 6 months. In contrast, there were no age-related differences in inhibition of contractile responses to nerve stimulation by the prejunctionally acting dopamine D2 agonist, N-0923. These data suggest that age-related changes in the sensitivity of prejunctional alpha-2 receptors to agonists and antagonists may not reflect any fundamental alteration in the function of this receptor system, but may be related to competition between alpha-2 agonists or antagonists and increased biophase concentrations of norepinephrine. This conclusion is supported by lack of an age-related change in function of prejunctional dopamine D2 receptors. Persistence of age-related increases in norepinephrine release when alpha-2 adrenergic receptors are fully blocked may reflect an alteration in other fundamental mechanisms that control norepinephrine release.

[Is liver biopsy in gallbladder operations still indicated?]

Biopsy of the liver with the Tru-cut needle was done as a routine diagnostic procedure during gallbladder surgery in 166 cases. The data of history, ultrasonography and laboratory were compared with the microscopic liver findings. Preoperatively in 89% of the cases there was an indication for liver biopsy. In 11% of the cases, where there was no indication for preoperative biopsy, we found severe changes in liver histology. Therefore we recommend liver biopsy during gallbladder surgery as a routine procedure.

Effect of age on prejunctional modulation of norepinephrine release

The effect of age on prejunctional modulation of norepinephrine release was studied in tail arteries isolated from Fischer-344 rats, age 6 to 27 months. Tail arteries were perfused in vitro, and norepinephrine released during adrenergic nerve stimulation was collected and analyzed by high-pressure liquid chromatography with electrochemical detection. There was no progressive change with age in norepinephrine content in the tail artery, although content at 6 months was significantly less than 12 months. The most significant finding was a decline with age in the effect of the alpha-2 adrenergic antagonist yohimbine to increase norepinephrine release, suggesting an age- related fall in the effectiveness of prejunctional alpha-2 adrenoceptor activation. In the absence of drugs there was an age-related increase in fractional norepinephrine release, and an age-related increase in the effect of deoxycorticosterone and cocaine was also seen. The increased effect of deoxycorticosterone and cocaine appears to be related to increased norepinephrine levels in the junctional cleft as opposed to an age-related increase in the activity of catecholamine metabolism and uptake. These results suggest that the age-related increase in fractional norepinephrine release may be due, in part, to a decline in negative feedback mediated by prejunctional alpha-2 adrenergic receptors.

Implantation technique and complications of totally implanted arterial access systems for long-term therapy in patients with occlusive vascular disease

Twenty-six totally implantable catheter systems for intra-arterial infusions were used in patients with peripheral arterial occlusive disease. A total of 606 short-term infusions were administered via the system. The patients were observed up to 22 months. There was an over-all rate of complications in 15.3%. The complications described were: one catheter occlusion, one dislocation, one case of local infection and one case of arterial thrombosis. The latter was successfully treated with local lysis therapy. The system is distinguished from conventional methods of arterial access by its long-term use and the low incidence of complications. The system was extremely well accepted by the patients.