The geometry of photopolymerized topography influences neurite pathfinding by directing growth cone morphology and migration

Objective. Cochlear implants provide auditory perception to those with severe to profound sensorineural hearing loss: however, the quality of sound perceived by users does not approximate natural hearing. This limitation is due in part to the large physical gap between the stimulating electrodes and their target neurons. Therefore, directing the controlled outgrowth of processes from spiral ganglion neurons (SGNs) into close proximity to the electrode array could provide significantly increased hearing function.Approach.For this objective to be properly designed and implemented, the ability and limits of SGN neurites to be guided must first be determined. In this work, we engineer precise topographical microfeatures with angle turn challenges of various geometries to study SGN pathfinding and use live imaging to better understand how neurite growth is guided by these cues.Main Results.We find that the geometry of the angled microfeatures determines the ability of neurites to navigate the angled microfeature turns. SGN neurite pathfinding fidelity is increased by 20%-70% through minor increases in microfeature amplitude (depth) and by 25% if the angle of the patterned turn is made obtuse. Further, we see that dorsal root ganglion neuron growth cones change their morphology and migration to become more elongated within microfeatures. Our observations also indicate complexities in studying neurite turning. First, as the growth cone pathfinds in response to the various cues, the associated neurite often reorients across the angle topographical microfeatures. Additionally, neurite branching is observed in response to topographical guidance cues, most frequently when turning decisions are most uncertain.Significance.Overall, the multi-angle channel micropatterned substrate is a versatile and efficient system to assess neurite turning and pathfinding in response to topographical cues. These findings represent fundamental principles of neurite pathfinding that will be essential to consider for the design of 3D systems aiming to guide neurite growthin vivo.

The geometry of photopolymerized topography influences neurite pathfinding by directing growth cone morphology and migration

Cochlear implants (CIs) provide auditory perception to those with profound sensorineural hearing loss: however, the quality of sound perceived by a CI user does not approximate natural hearing. This limitation is due in part to the large physical gap between the stimulating electrodes and their target neurons. Therefore, directing the controlled outgrowth of processes from spiral ganglion neurons (SGNs) into close proximity to the electrode array could provide significantly increased hearing function. For this objective to be properly designed and implemented, the ability and limits of SGN neurites to be guided must first be determined. In this work, we engineered precise topographical microfeatures with angle turn challenges of various geometries to study SGN pathfinding. Additionally, we analyze sensory neurite growth in response to topographically patterned substrates and use live imaging to better understand how neurite growth is guided by these cues. In assessing the ability of neurites to sense and turn in response to topographical cues, we find that the geometry of the angled microfeatures determines the ability of neurites to navigate the angled microfeature turns. SGN neurite pathfinding fidelity can be increased by 20-70% through minor increases in microfeature amplitude (depth) and by 25% if the angle of the patterned turn is made more obtuse. Further, by using engineered topographies and live imaging of dorsal root ganglion neurons (DRGNs), we see that DRGN growth cones change their morphology and migration to become more elongated within microfeatures. However, our observations also indicate complexities in studying neurite turning. First, as the growth cone pathfinds in response to the various cues, the associated neurite often reorients across the angle topographical microfeatures. This reorientation is likely related to the tension the neurite shaft experiences when the growth cone elongates in the microfeature around a turn. Additionally, neurite branching is observed in response to topographical guidance cues, most frequently when turning decisions are most uncertain. Overall, the multi-angle channel micropatterned substrate is a versatile and efficient system to assess SGN neurite turning and pathfinding in response to topographical cues. These findings represent fundamental principles of neurite pathfinding that will be essential to consider for the design of 3D systems aiming to guide neurite growth in vivo.

Sensitivity of CNN image analysis to multifaceted measurements of neurite growth

Quantitative analysis of neurite growth and morphology is essential for understanding the determinants of neural development and regeneration, however, it is complicated by the labor-intensive process of measuring diverse parameters of neurite outgrowth. Consequently, automated approaches have been developed to study neurite morphology in a high-throughput and comprehensive manner. These approaches include computer-automated algorithms known as 'convolutional neural networks' (CNNs)-powerful models capable of learning complex tasks without the biases of hand-crafted models. Nevertheless, their complexity often relegates them to functioning as 'black boxes.' Therefore, research in the field of explainable AI is imperative to comprehend the relationship between CNN image analysis output and predefined morphological parameters of neurite growth in order to assess the applicability of these machine learning approaches. In this study, drawing inspiration from the field of automated feature selection, we investigate the correlation between quantified metrics of neurite morphology and the image analysis results from NeuriteNet-a CNN developed to analyze neurite growth. NeuriteNet accurately distinguishes images of neurite growth based on different treatment groups within two separate experimental systems. These systems differentiate between neurons cultured on different substrate conditions and neurons subjected to drug treatment inhibiting neurite outgrowth. By examining the model's function and patterns of activation underlying its classification decisions, we discover that NeuriteNet focuses on aspects of neuron morphology that represent quantifiable metrics distinguishing these groups. Additionally, it incorporates factors that are not encompassed by neuron morphology tracing analyses. NeuriteNet presents a novel tool ideally suited for screening morphological differences in heterogeneous neuron groups while also providing impetus for targeted follow-up studies.

Metabolic risk factors in formerly obese women--effects of a pronounced weight loss by gastric band operation compared with weight loss by diet alone

AIM

The aim of the present study was to evaluate differences in the metabolic risk profile in formerly obese women, in whom a significant weight loss was obtained by Swedish adjustable gastric band (SAGB) operation or by diet alone.

METHODS

A total of 40 patients (24 after SAGB and 16 after diet) participated in the study. Clinical data, including body mass index (BMI), waist-to-hip ratio, body fat content and blood pressure values, as well as laboratory results [fasting glucose, insulin, homeostasis model assessment (HOMA) index, leptin, lipid values and markers of subclinical inflammation] were evaluated before a planned abdominoplastic operation.

RESULTS

Patients in the SABG group had lost a significantly greater amount of weight (52.7 +/- 10.0 kg) compared with the diet group (20.0 +/- 11.5 kg; p < 0.001), and the percent excess weight loss was 69.1 +/- 11.4 in the SAGB group and 54.5 +/- 17.7 (p < 0.040) in the diet group. Before the abdominoplastic operation neither the mean BMI nor the percentage of fat mass revealed a significant difference between the groups. Fasting insulin (6.1 +/- 3.0 microU/ml) and the HOMA index (1.4 +/- 0.7) as a measure of insulin resistance were significantly lower in the SAGB than in the diet group (fasting insulin: 8.2 +/- 3.8 microU/ml; p < 0.048; HOMA index: 2.0 +/- 1.0; p < 0.031). Swedish adjustable gastric band patients showed significantly lower plasma leptin levels (9.4 +/- 10.8 ng/ml) than the dietary-treated patients (13.9 +/- 9.6 ng/ml; p < 0.014), while tumour necrosis factor-alpha serum levels were increased in the SAGB group (17.6 +/- 7.3 pg/ml) compared with the diet group (11.9 +/- 0.49 pg/l; p < 0.048).

CONCLUSIONS

The extensive weight loss in formerly obese women after SAGB operation was paralleled by a favourable metabolic profile indicating a higher degree of insulin sensitivity than in women after a successful, but less pronounced weight loss by diet alone.

Decompression without anterior transposition: an effective minimally invasive technique for cubital tunnel syndrome

Cubital tunnel syndrome represents the second most common compression neuropathy in the upper limb. There are three main surgical procedures to deal with this issue, namely simple decompression, medial epicondylectomy and anterior transposition. Nevertheless, optimal surgical treatment is still open to question. In the past three years we performed decompression of the nerve with or without external neurolysis and epineuriotomy on 52 patients (55 extremities). Preoperative diagnostic procedures included functional hand status, neurophysiological evaluation, X-ray of the elbow and neurosonography. Patients were then divided into three groups according to the staging criteria of Dellon. After an average follow-up of 13 months, the outcome was evaluated by complete examination of hand function, electrophysiological studies and interview with the patients. Postoperatively, two-point discrimination as well as strength improved significantly. Postoperative grip was 28.78 kg (79.8 % of the other hand), compared to 20.31 kg (58 % of the other hand) preoperatively (p = 0.000). Evaluation of each stage individually showed that the best functional outcome was achieved by the minimum-staged group with improvements in strength and sensory in all patients and total relief in two-thirds. In the severe-staged group, improvement could still be found in 75 % of the patients. Evaluation of conduction velocities showed highly significant improvements for both motor and sensory conduction velocities. In summary, simple decompression, if necessary modified with external neurolysis and epineuriotomy, showed high success rates in all stages. Decompression is a minimally invasive procedure, but very effective for mild as well as for severe cases and therefore the optimal treatment in cubital tunnel syndrome.

[Plastic reconstructive operations after weight loss through gastric banding]

The number of patients who desire reconstructive surgery after a huge weight loss through gastric banding is increasing. From 1999 to 2001, 40 reconstructive operations were performed on 25 patients after an average decrease in weight of 58 kg. Six months later, a follow-up examination was done. A questionnaire was handed out and the aesthetic results were judged by five independent plastic surgeons. The department of psychology judged the patient's attitude towards their body, the presentation of their body for attractiveness, satisfaction with life, anxiety and depression, and changes in experience and behavior. The results showed a discrepancy between the subjective satisfaction of the patients and the judgment of the plastic surgeons; the preference for long scars instead of remaining surplus tissue, the necessity of a strict indication for transplantation of one's own tissue, the importance of detailed preoperative information using pictures, advantages and disadvantages of simultaneous operations in different anatomical regions, the need for exact planning and postoperative care as well as the importance of interdisciplinary teamwork. These results will influence the indication for a reconstructive operation in the future.

Dupuytren's disease in children-differential diagnosis

BACKGROUND/PURPOSE

Dupuytren's disease in children is uncommon; only a few histologically confirmed diagnoses are found in literature. In its early, proliferative phase with many fibroblasts, it can resemble the early stadium of an epitheloid sarcoma, which also is a rare tumor. The purpose of this report is to show pediatric surgeons and pathologists the importance of differential diagnosis of nodules and fibrotic bands in children's hands, especially to exclude a malignancy.

METHODS

Between 1998 and 2000, 3 children at ages of 2(1/2) years, 9 years, and 10 years, respectively, presented with the clinical signs of Dupuytren's disease of the hand. Each of them had fibrous bands with a flexion contracture of the fingers. All of them underwent fasciectomy.

RESULTS

In patient 1, a 10 degrees extension lag of the index finger resulted after 3 operations. Histology findings showed the typical features of Dupuytren's disease. In patient 2, histology findings showed a recurring digital fibroma of childhood. After consultation with the pathologist and reevaluation of the slides, the histologic diagnosis was corrected to Dupuytren's disease. Full extension and thumb abduction has been achieved. In patient 3, histology of the first and second operation was misdiagnosed as Dupuytren's disease. In the third operation 2(1/2) years later, the histologic diagnosis of epitheloid sarcoma was made. Amputation of the forearm was necessary.

CONCLUSIONS

Exact anamnesis, location of the lesion, and suspicious diagnosis must be mentioned to the pathologist in the case of biopsy or excision of Dupuytrenlike lesions in children's hands. Awareness of the possibility of the epitheloid sarcoma may help prevent misdiagnosis.

Pitfalls in diagnosing carpal tunnel syndrome

The aim of this paper is to point out the differential diagnosis be-tween a thumb hypoplasia type 1/11 and a carpal tunnel syndrome. Both syndromes have symptoms in common. Two children and an adult with hypoplastic thumbs were sent to our department with the diagnosis carpal tunnel syndrome. In both children, the diagnosis was changed after an exact history and examination, and in one child an opponensplasty was done. The adult patient had already been operated unsuccessfully for a carpal tunnel syndrome elsewhere and again at our department. The exact diagnosis was only made after the second operation,when an extended questioning was done. This shows how important a careful history taking, an exact clinical examination, X-ray examinations of both hands, knowledge of type 1/11 hypoplasia, and finally electroneurography and sonography are important for a correct diagnosis.

[Pedicled flap plasty in closure of defects after recurrence of tumors of the back]

Resection of recurrent tumors of the back often results in large transmural defects. Sometimes, radiation therapy is applied after the first operation, leading to indurated, badly vascularized skin and surrounding tissue, often complicated by infection. For this reason, it is necessary to remove not only the tumor but also the surrounding tissue. To reconstruct such wide defects, we use large axial pattern flaps with extension through a fasciocutaneous flap. This leads to safe reconstruction of a complex defect with well-vascularized tissue. We report on two patients with recurrent tumors of the back, reconstructed with combined, extended axial pattern flaps.

[Extra-abdominal fibromatosis--extra-abdominal desmoid. Review and personal experiences]

Extraabdominal desmoids represent one group of deep fibromatoses. These aggressive nonmetastasizing tumorlike lesions have a strong tendency to local infiltration, with a recurrence rate of about 40%. Trauma, hormones and heredity have been implicated as etiologic factors. Shoulder, chest wall, back and thigh are favored sites. By combination of different diagnostic procedures the number of differential diagnoses can be reduced to only a few. While in former times surgery was thought to be the only kind of therapy, nowadays adjuvant procedures like radiation, hormonal therapy and also chemotherapy are becoming more and more important. Amputation or other mutilating procedures should be done only if the tumor recurs repeatedly.

Gastrocnemius myotendinous flap for patellar or quadriceps tendon repair, or both

The authors' experience with simultaneous reconstruction of the quadriceps femoris or patellar tendon or both and soft tissue defect using a musculotendinous unit of the gastrocnemius muscle is presented. Five patients with a partial or complete defect of the quadriceps or patellar tendon or both and additional large soft tissue defects underwent reconstruction applying this technique as a one-stage surgical procedure in different variations. In cases with a partial defect of the tendon or loss of tendon thickness, the thick aponeurosis from the deeper aspect of the gastrocnemius was dissected and transferred as a pedicled tendon flap to reconstruct the tendon defect. In cases with a complete defect of the tendon, the superficial layer of the Achilles tendon together with the deep aponeurotic layer of the gastrocnemius muscle served to reconstruct the tendon. In both procedures the gastrocnemius muscle belly provided soft tissue coverage and was covered with a split thickness skin graft. One patient had a marginal deep necrosis develop that had to be covered with the other gastrocnemius muscle in a second operation. One patient with chronic polyarthritis and infection of his knee prosthesis declined additional reconstruction surgery and had the leg amputated. The average followup was 3.5 years. All patients achieved good results in active extension of the knee with an extension deficit of only 5 degrees to 15 degrees. The range of flexion was at least 90 degrees. The surgical technique described in this report provides functional tendon reconstruction and adequate soft tissue repair simultaneously.

[Streptococcal toxic shock-like syndrome with necrotizing myositis]

Streptococcal toxic shocklike syndrome is caused by group A streptococci and characterized by multiorgan failure and soft-tissue necrosis, often in young patients with a bland history and at most a minor trauma. Diagnosis is reached through the clinical presentation, imaging methods and positive bacterial verification. The course is fulminant and in the case of muscle involvement, mortality reaches 80-100%. Therapy consists of immediate fasciotomy and often of debridement of affected soft tissues with high-dose antibiotics in intensive care. Sometimes an unconfirmed diagnosis must be sufficient to operate. We report the case of a 29-year-old man without an exceptional history who was forced to undergo thigh amputation, multiple soft-tissue debridements, and after a total of 240 erythrocyte concentrates, finally hip joint enucleation.

[Iatrogenic lesion of the accessory nerve in cervical lymph node biopsy]

The majority of lesions of the spinal accessory nerve occur as an iatrogenic injury after lymph node biopsy in the posterior cervical triangle (trigonum colli laterale). In most cases the accessory nerve palsy is not recognised immediately after the injury. Therefore surgical repair is often performed too late to regain sufficient function of the paralytic trapezius muscle. Later than 6 months after the injury, reconstruction seems to be hopeless. However, "timely" reconstructions often have poor results. Exact knowledge of anatomy, postoperative check of the trapezius muscle and, if an accessory nerve injury has occurred, early reconstructive procedures (neurolysis, reconstruction of nerve continuity) may on the one hand prevent iatrogenic lesions of the nerve and on the other hand improve the reconstructive result. A series of 6 patients with an injury of the spinal accessory nerve after lymph node biopsy is reported. In 2 cases primary coaptation, in 3 cases interpositional nerve grafting and in 1 case neurotization was performed. Clinical recovery was achieved in 3 of the 6 cases.

[Correlation of histology of the primary tumor with liver metastases in colorectal carcinoma]

The histology of colorectal tumors was correlated with the presence of liver metastases in a retrospective study performed on 179 patients who were autopsied between 1975 and 1990. For the analysis of metastatic patterns, 116 cases with at least one distant metastatic site were selected. A distinct relationship between mucin expression of colorectal tumors and liver involvement was found. Pure adenocarcinomas and their papillary variants showed the highest affinity to the hepatic tissue regarding the frequency as well as extent of involvement. A subtotal replacement of the liver by metastases was restricted to these two variants. An extracellular mucin component was associated with a lower frequency of liver involvement and a tendency to solitary or oligotopic metastases. Ten cases of signet ring cell carcinomas had no metastases in the liver. The results described here for colorectal cancers are similar to those previously reported for gastric cancer. The therapeutic implications were discussed. A detailed link between these clinical findings and the results found at the level of molecular biology is yet to be determined.

Assessment of endothelial preservation in human cell cultures

BACKGROUND

Impairment of microcirculation due to endothelial cell damage must be considered a limiting factor in organ preservation. The present study aims at a quantitative assessment of preservation-induced injury in cultured human endothelial cells.

METHODS

Monolayer cultures of human umbilical vein endothelial cells were exposed to cold (40 degrees C) hypoxic storage in University of Wisconsin solution, histidine-tryptophane-ketoglutarate solution, Euro-Collins solution, and saline solution. Cellular integrity was evaluated by viable cell count, ultrastructural analysis, and prostacyclin release after 24, 48, and 72 hours of storage and subsequent 6 hours of reincubation in culture medium at 37 degrees C. Expression of intercellular adhesion molecule-1 was investigated after 6, 12, and 24 hours of cold preservation and after 6 hours of rewarming.

RESULTS

Cellular viability was best maintained with University of Wisconsin and histidine-tryptophane-ketoglutarate solutions with no significant reduction of cell count up to 72 hours; Euro-Collins solution and saline solution caused a significant decline in cell numbers after 24 hours (p < 0.05). Morphology was best preserved by University of Wisconsin solution. Prostacyclin values were elevated after 24 hours in Euro-Collins solution and saline solution, after 48 hours in histidine-tryptophane-ketoglutarate, Euro-Collins, and saline solutions, and after 72 hours in Euro-Collins solution (p < 0.05, compared with University of Wisconsin solution). ICAM expression was weak after cold storage (24 hours) in University of Wisconsin solution, moderate after incubation in histidine-tryptophane-ketoglutarate and Euro-Collins solutions and intensive after storage in saline solution. In contrast, rewarming caused intensive expression of intercellular adhesion molecule-1 in all experimental groups as compared with controls, which showed baseline expression at any time.

CONCLUSIONS

From our results we conclude that in this model cellular integrity is best protected by University of Wisconsin solution, increased prostacyclin release is consistent with morphologic alterations and intercellular adhesion molecule-1 expression is clearly up-regulated in endothelial cells under reperfusion conditions after cold hypoxic storage.