Tumor model for laparoscopy in pediatric oncology: subperitoneal inoculation of human hepatoblastoma cells in nude rats.

BACKGROUND: Minimally invasive surgery (MIS) for diagnostic or even ablative purposes in pediatric oncology is gradually evolving, but little is known about its biological consequences and surgical complications. Especially for hepatoblastoma (HB), no study on the influence of laparoscopy is available yet. A special tumor model could facilitate a variety of investigations. The present study introduces a laparoscopic technique to create subperitoneal metastases of human HB. METHODS: 7 immuno-incompetent (rnu/rnu) rats (mean weight 198 g) received a stab incision in the lower abdomen to insert a 4 mm scope. Under laparoscopic guidance (CO2 pressure of 1 mmHg, flow of 0.2 l/min) an 18 G needle was introduced, to inject several subperitoneal deposits of the tumor cell suspension (HuH6, 3 x 10 (6) in 1 ml of RPMI-1640 medium). Tumor growth was allowed for 6 - 7 weeks and finally the animals were laparoscopically evaluated for peritoneal metastases. Each suspicious lesion was harvested for histology. RESULTS: One animal was investigated after 6 weeks without evidence of tumor growth. After 7 weeks, in 4 out of 6 animals at least one lesion could be detected. Histology revealed HB in all specimens. CONCLUSION: Subperitoneal inoculation of human HB cells in nude rats achieves intraabdominal tumor growth. The present model allows a variety of laparoscopic strategies and their oncological impact to be studied. Thus it may contribute to the development of distinct oncological concepts for MIS in children with HB.

Fluorescence-guided minimally invasive parathyroidectomy: a novel detection technique for parathyroid glands.

BACKGROUND: Detection of normal and pathologic parathyroid glands often is difficult because of their variability in number and location. The feasibility and efficacy of a fluorescence technique for identifying parathyroids have already been proved in an experimental setting. This is the first report of human fluorescence-guided parathyroidectomy. METHODS: A 72-year-old man with primary hyperparathyroidism underwent minimally invasive videoscopically assisted parathyroidectomy after photosensitization with aminolevulinic acid. Under special fluorescence illumination by the D-light, a unilateral directed neck exploration was performed. RESULTS: The enlarged adenoma and an atrophic parathyroid gland could be identified rapidly and removed because of their intense red fluorescence. Surrounding structures such as thyroid, muscles, and soft tissue remained nonfluorescent and could easily be distinguished from the parathyroid glands. CONCLUSIONS: The aminolevulinic acid-induced fluorescence technique represents a convincing visual detection method for intraoperative identification of parathyroid glands. The technique serves as an additional tool requiring only moderate technical and clinical expenditure for help in guiding dissection down to a preoperatively localized adenoma. When used together with preoperative ultrasonography and sestamibi scan, the fluorescence technique may justify a unilateral, minimally invasive approach for selected patients.

[Carotid-surgery in ultrasound-guided anesthesia of the regio colli lateralis]. / Ultraschallgestützte Blockade der Regio colli lateralis zur Karotis-Chirurgie -- eine Fallserie.

OBJECTIVE: Carotid endarterectomy significantly reduces the risk of stroke in patients with symptomatic and asymptomatic carotid artery stenosis. An increasing number of interventions in carotid surgery are performed under regional anesthesia in conscious patients. Carotid endarterectomy in local anesthesia requires block of the cervical nerves C2-C4, which may be accomplished in different ways. The most frequent method of regional anesthesia in carotid surgery is a combined block of profunda and superficial cervical plexus (by using a nerve stimulator). Ultrasound is frequently used in anesthesia for venous access and peripheral nerve block. By ultrasound, it is possible to visualize puncture needle and spread of local anesthetics at the correct position for block of cervical plexus in carotid surgery. The aim of the case reports was to demonstrate the effectiveness of using ultrasound for regional anesthesia in carotid surgery. METHOD: At the level of carotid bifurcation, scalene muscles were visualized by ultrasound (10-MHz-transducer). At this position, a puncture needle was inserted in the beam of ultrasound. Between the anterior scalene and the sternocleidomastoid muscles the local anesthetics were injected (10 ml prilocaine 1 %, 20 ropivacaine 0.375 %). In addition, superficial cervical plexus was performed by subcutaneous injection (10 ml prilocaine 1 %, 40 ropivacaine 0.375 %). Sedation was performed by application of remifentanil (max. 0.02 microg/kg/min), as needed. RESULTS: Ultrasound guided cervical block was performed in 29 patients. In all cases cervical plexus block was complete. A conversion to general anesthesia during operation was not necessary in any case. CONCLUSION: Ultrasound presents an alternative to cervical block using nerve stimulation, especially in patients with anatomical abnormalities. The method proves to be effective and may improve the approach to profundeal cervical plexus.

Acute respiratory failure after deep cervical plexus block for carotid endarterectomy as a result of bilateral recurrent laryngeal nerve paralysis.

We report about a case of acute respiratory distress (73-year-old female), which occurred minutes after a deep cervical plexus block (40 ml ropivacaine 0.5%) for carotid endarterectomy (CEA) and required immediate endotracheal intubation of the patient's trachea and consecutive mechanical ventilation. Subsequently, CEA was performed under general anaesthesia (TIVA) with continuous monitoring by somatosensory-evoked potentials. After a period of 14 hours, the endotracheal tube could be removed, the patient being in fair respiratory, cardiocirculatory and neurological conditions. Retrospectively, acute respiratory distress was caused by a combination of ipsilateral plexus blockade-induced and pre-existing asymptomatic contralateral recurrent laryngeal nerve (RLN) paralysis confirmed by a postoperative ENT-check and related to previous thyroid surgery more than 50 years ago. RLN paralysis, often being asymptomatic, represents a typical complication of thyroid and other neck surgery with reported incidences of 0.5-3%. Therefore, a thorough preoperative airway check is advisable in all patients scheduled for a cervical plexus block. Particularly in cases with a history of respiratory disorders or previous neck surgery a vocal cord examination is recommended, and the use of a superficial cervical plexus block may lower the risk of respiratory complications. This may prevent a possibly life-threatening coincidence of ipsilateral plexus blockade-induced and pre-existing asymptomatic contralateral RLN paralysis.

Photodynamic therapy for esophageal diseases: a clinical update.

Photodynamic therapy (PDT) is a "drug and device" therapy that combines the use of a photosensitizing agent and a photosensitizer (a drug that selectively accumulates and is preferentially retained in dysplastic or neoplastic cells). When activated by light of a specific wavelength in the presence of oxygen, the photoactive compound produces rapid cell death in the target tissue. While studied in nearly every area of medicine, PDT has been applied most extensively in the treatment of Barrett's mucosa, dysplasia, and early and advanced cancer of the esophagus. This article represents an extensive survey of literature to review the experience gained with PDT and to assess its clinical value in the management of esophageal diseases.

Thoracoscopic fluorescence diagnosis (TFD) of pleural malignancies: experimental studies.

BACKGROUND: Fluorescence diagnosis (FD) using the photosensitiser 5-aminolaevulinic acid (ALA) was experimentally combined with conventional video assisted thoracic surgery (VATS) to improve tumour staging in advanced lung cancer with pleural tumour spread. METHODS: A disseminated pleural carcinosis affecting the entire pleural cavity was induced by inoculation of human adenocarcinoma cells in nude rats. After 5-7 weeks of tumour growth the animals were randomised into six groups with different photosensitisation parameters. Pleural lavage was performed either with 1.5% or 3.0% ALA solution. Photosensitisation times varied were 2, 4, or 6 hours. Conventional white light VATS was first performed to evaluate tumour growth in the pleural cavity. Fluorescence illumination of the light source, the D-light, was then used to examine the site for additional tumours which were previously invisible. The tumour fluorescence intensity was measured spectrometrically and compared with normal tissue. RESULTS: Compared with conventional white light VATS alone, thoracoscopic fluorescence diagnosis (TFD) detected up to 30% additional pleural malignant lesions. The highest diagnostic sensitivity was reached 6 hours after 3.0% ALA pleural lavage. Photosensitiser accumulation in the tumour, measured indirectly by spectrometry, was up to 11 times higher than in normal tissue. CONCLUSIONS: TFD increases sensitivity of VATS for tumour staging. It may prevent unnecessary thoracotomies in cancer patients and facilitate surgical planning.

Fluorescence diagnosis of colorectal neoplasms: a review of clinical applications.

Detection of dysplasia and early-stage carcinoma of the lower gastrointestinal tract is important in the prevention and curative treatment of cancer. Fluorescence-based endoscopic imaging and spectrometry promise a supplemental technique for conventional endoscopy. Fluorescence diagnosis is characterized by the stimulation of exogenous or endogenous fluorophores in malignant or precancerous tumor cells. The emitted fluorescence allows the identification of lesions that are otherwise occult in conventional endoscopy. A review of literature was performed to examine the experience gained with fluorescence diagnosis and to assess its clinical value in the detection of colorectal diseases.

[Photodynamic therapy in the gastrointestinal tract. Possibilities and limits]. / Photodynamische Therapie im Gastrointestinaltrakt. Möglichkeiten und Grenzen.

BACKGROUND: Photodynamic therapy (PDT) is characterized by the extensive selective accumulation of a photoactive agent, the photosensitizer, in malignant or precancerous tumour cells. The photoactive compound is activated by light beam of a specific wavelength and causes cell death. A significant proportion of patients with gastrointestinal malignancies cannot undergo curative treatment, as either the cancer is too advanced or the patient's general constitution is too poor to allow invasive strategies. In such cases, PDT has already proven to be a promising therapeutic modality for selected dysplasias and malignancies in the gastrointestinal tract. MATERIAL AND METHODS: A retrospective review of the literature was performed in order to determine the experience gained with PDT and to assess its clinical value in the curative and palliative management of gastrointestinal neoplasms. RESULTS: PDT seems to be an adequate treatment for selected forms of early cancer and small lesions of the GI tract or for small residual areas after the tumour has been debulked by other techniques (e.g. limited surgical resection, thermal ablation). Especially for patients who refuse or are ineligible for conventional surgery, PDT offers promising results compared to currently accepted clinical approaches. CONCLUSIONS: As a primary or adjuvant mode for either curative or palliative treatment of gastrointestinal neoplasms, PDT is a potentially effective, minimally invasive therapeutic modality. However, further clinical assessment by means of comparative, standardized studies is essential to the definition of its role in oncology.

Predominant mutation of codon 41 of the beta-catenin proto-oncogene in rat colon tumors induced by 1,2-dimethylhydrazine using a complete carcinogenic protocol.

Constitutive activation of the wnt-signaling pathway plays an important role during both human and rat colon carcinogenesis and can be brought through mutations in either the adenomatous polyposis coli or the beta-catenin gene. Mutations found in the beta-catenin gene typically affect one out of four regulatory phosphorylation sites near the N-terminus of the beta-catenin protein. Whereas in human colon cancers, however, the majority of beta-catenin mutations directly alter threonine 41 or serine 45; the beta-catenin mutations found in chemically induced rat colon tumors seemed to cluster around codon 33 instead. Unlike previous studies, that have used relatively short-term (2-5 weeks) treatment with one of the alkylating agents 1,2,-dimethylhydrazine (DMH) or azoxymethane, we have investigated the mutational spectrum of the beta-catenin gene in a panel of rat colon tumors induced by long-term (20 weeks) DMH-treatment. We detected beta-catenin mutations in 12 of 33 (36%) tumors. Interestingly, only one of the beta-catenin mutations found affected the previously implicated codon 33 cluster region (Asp32Asn), whereas 11 of 12 (>90%) mutations represented identical C-->T transitions within codon 41 resulting in the common replacement of threonine by isoleucine. We propose a model in which codon 41 mutations bear higher oncogenic potential but are induced by DMH less frequently than mutations in the codon 33 cluster region. Consequently, only after sustained carcinogenic treatment, as is achieved in the long-term DMH-protocol, codon 41 mutations will be induced frequently enough to be present in all developing malignant lesions and, then, because of their higher oncogenic potential, these are selected for.

Intraoperative fluorescence visualization of the parathyroid gland in rats.

Bilateral neck exploration is the standard procedure of primary hyperparathyroidism. Preoperative localization is not mandatory. Intraoperative visualization methods help to avoid unsuccessful explorations and to reduce morbidity rates. In our study, the application of 5-Aminolevulinic acid (5-ALA), a precursor in the heme biosynthesis pathway, led to Protoporphyrin IX (PpIX) accumulation within the parathyroid gland (PTG). PpIX, a metabolite of 5-ALA, causes red fluorescence (635 nm) when stimulated by light of a defined wavelength. Largely invisible under conventional illumination, all PTGs were fluorescence positive and detectable after PpIX targeting and blue light excitation (380-440 nm). Point spectrometry to measure fluorescence intensities, showed a fluorescence ratio between PTG and surrounding thyroid gland tissue of 5.7:1 (p < 0.001). Fluorescence guided PTG biopsies showed no false positive findings in histology. 5-ALA induced PpIX fluorescence to detect PTGs suggests to be a highly sensitive intraoperative visualization method. Hence, the performance of minimally invasive video-assisted parathyroidectomy will be facilitated by this innovative technique.

Systemic vs local administration of delta-aminolevulinic acid for laparoscopic fluorescence diagnosis of malignant intra-abdominal tumors. Experimental study.

BACKGROUND: Administration of delta-aminolevulinic acid (ALA) either systemically or locally results in tumor-specific accumulation of protoporphyrin IX (PpIX). When excited with light at a defined wavelength and viewed with the appropriate filter cells containing PpIX, have a characteristic red fluorescence. We evaluated both locally (intraperitoneally [i.p.]) and systemically (intravenously [i.v.]) administered ALA to compare its effectiveness for laparoscopic fluorescent visualization of intraperitoneal tumors. METHODS: Peritoneal carcinosis was induced in rats using colon carcinoma cells (CC531). Photosensitization was achieved either by intravenous (i.v. group) or intraperitoneal (i.p. group) application of ALA solution. Staging laparoscopy was performed in both groups, first using conventional white light and subsequently using blue light (380-440 nm) to excite PpIX-induced fluorescence. RESULTS: Conventional white light laparoscopy showed 142 visible intraperitoneal tumor foci in the i.p. group and 116 such foci in the i.v. group. In the i.p. group, all tumors (100%) also were fluorescence positive, whereas in the i.v. group only 32 of the tumors (28%) showed the typical red fluorescence. In the i.p. group, 30 additional tumors were detected by fluorescence excitation (21%), as compared with eight additional tumors in the i.v. group (7%). CONCLUSIONS: Fluorescence laparoscopy after local (i.p.) photosensitization with ALA is a more reliable and effective method than systemic (i.v.) photosensitization for the detection of small or occult i.p. tumors.

Carbon dioxide angiography for endovascular grafting in high-risk patients with infrarenal abdominal aortic aneurysms.

Allergic reactions to contrast media, preexisting renal dysfunction, and hyperthyroidism are relative contraindications for angiography with conventional contrast medium. Carbon dioxide (CO(2)) angiography is an alternative method in high-risk patients because CO(2) is nontoxic, without allergic potential, and not iodic. CO(2)-related complications are extremely rare. Because renal insufficiency often occurs in vascular patients, this method will become increasingly important for endovascular surgery. We report on three consecutive patients with asymptomatic infrarenal aortic aneurysm and concomitant renal dysfunction or allergic reactions to standard contrast media. Aortic stent grafts were deployed under CO(2) angiographic control without complications or worsening of renal function.

Local 5-aminolevulinic acid application for laser light-induced fluorescence diagnosis of early staged colon cancer in rats.

BACKGROUND AND OBJECTIVES: 5-Aminolevulinic acid (ALA) increases the intracellular accumulation of endogenous protoporphyrin IX in colon cancer. Protoporphyrin IX itself is a potential photosensitizer that can be used for laser light-induced fluorescence diagnosis. The aim of this study was to detect cancer in the rat colon before macroscopic visibility. STUDY DESIGN/MATERIALS AND METHODS: Multifocal colon carcinomas were induced by weekly subcutaneous injections of 1,2-dimethylhydrazin-dihydrochloride in male Wistar rats. Local photosensitization was performed with an ALA colon lavage. Red fluorescence (635 nm) was induced by green laser-light irradiation with an Ar-Dye Laser (514 nm) in the colon. Fluorescence was observed by the naked eye with a filter at < 515 nm to eliminate the excitation light. RESULTS: Twenty-five Wistar rats developed 99 macroscopically visible carcinomas and four macroscopically visible dysplasias. The following laser-light-induced fluorescence diagnosis procedure was able to detect 16 additional carcinomas and 41 additional dysplasias. CONCLUSIONS: Local ALA application induces a tumor-specific protoporphyrin IX accumulation in the rat colon and is an efficient method for fluorescence detection of invisible dysplasias and early colon cancer in the rat.

Improving diagnostic staging laparoscopy using intraperitoneal lavage of delta-aminolevulinic acid (ALA) for laparoscopic fluorescence diagnosis.

BACKGROUND: Lymph node metastases and peritoneal carcinosis, occurring as a result of gastrointestinal cancer, reduce the likelihood that conventional therapy will be adequate to remove the cancer. Although diagnostic techniques have greatly improved, it is not always possible to diagnose the entire extent of the metastases. Often, peritoneal micrometastases are not visible and may be missed during laparoscopic or open surgery. METHODS: Peritoneal carcinosis was induced in WAG-Rij rats (n = 6), by laparoscopically implanting 1,2-dimethylhydrazine-induced colon carcinoma tumor cells (CC531, 5 x 10(5)) at multiple sites within the peritoneal cavity. After 12 days of tumor growth, the animals were given delta-aminolevulinic acid (ALA) (5 mL, 3% solution in 0.17 mol/L NaHCO3) by peritoneal lavage. The tumors were visualized laparoscopically using both white and blue light (D-light, Karl Storz, Tuttlingen, Germany). Fluorescence was detected by using a modified CCD camera and a special observation filter incorporated into the laparoscope. RESULTS: Peritoneal carcinoma foci ranging in size from 0.05 to 2.0 cm were clearly visible laparoscopically with conventional white light (n = 142). After blue light excitation, all 142 tumors identified with white light were also identified by fluorescence. There were an additional 30 tumors that could only be identified by blue light-induced fluorescence and were histologically confirmed to be derived from colon carcinoma tumor cells. CONCLUSIONS: Peritoneal colonic carcinoma foci were detected laparoscopically after intraperitoneal lavage with delta-aminolevulinic acid (ALA) and excitation with blue light. These experiments demonstrate that fluorescence laparoscopy is an important technique for the staging of gastrointestinal cancer, including colorectal cancer, because of the enhanced ability to detect small cancerous foci.

Spectrometry supports fluorescence staging laparoscopy after intraperitoneal aminolaevulinic acid lavage for gastrointestinal tumours.

Conventional staging laparoscopy in combination with fluorescence diagnosis has proven to be an effective modality in the detection of macroscopically occult intraperitoneal tumours and metastases. Rats with induced peritoneal carcinosis are photosensibilized by intraperitoneal aminolaevulinic acid (ALA) lavage. After visualization of the tumour foci, the emission from the lesions is measured spectrometrically and the fluorescence analysed quantitatively ('optical biopsy'). There is a considerable accordance between imaging by fluorescence diagnosis laparoscopy and point spectrometry in the detection of peritoneal malignancies. Compared with surrounding healthy peritoneum, tumour-positive areas show significantly higher fluorescence intensities in spectrometry.