[Feasibility of intraoperative diagnosis with a mobile computed tomography scanner]

AIMS

The possibility of performing intraoperative computed tomography may add to the safety and efficiency of some maxillofacial procedures. It would be preferable for intraoperative image data acquisition to be available to a surgeon on demand for immediate control of therapy results.

METHODS

In a pilot study, the use of a mobile computed tomographic scanner (Philips Tomoscan M, Philips Medical Systems, Eindhoven, Netherlands) was evaluated in our unit. The scanner is equipped with wheels, draws power from wall outlets in combination with batteries, and has a translating gantry.

RESULTS

Experience to date with six patients has confirmed the feasibility of intraoperative CT. All patients operated on were treated for craniofacial trauma. The CT images showed good spatial resolution. In all cases, visualization of the correct fragment position was excellent without causing significant delay of the operative procedure.

CONCLUSIONS

Intraoperative computed tomography could be the new state-of-the-art method for direct control of treatment results in maxillofacial traumatology. Nevertheless, the high expenses for installation of such technical infrastructure has to be pointed out; therefore, the routine use of this technique might be questioned.

[Intraoperative computer tomography control within the scope of maxillofacial traumatology using a mobile scanner]

Advances in intra-operative imaging and the development of new minimally invasive techniques are having an ever greater impact on modern surgery. Mobile CT scanners in the operating room is a new technique that permits image-guided surgery, and helps minimize postoperative complications. We report on our initial experience with intraoperative CT scanning during surgery on patients suffering lateral midface trauma. A mobile CT unit, the Tomoscan M (Philips, Utrecht, Netherlands) set up in the operating room, was evaluated in 6 patients with zygomatic bone fractures. The patients were placed on the CT scanner table, which is detachable from the gantry. The unit is powered by batteries charged from an ordinary ring mains supply via a conventional plug. The CT images obtained were of good quality in all cases. No technical problems were observed during surgery. Using repeat CT scans, the procedure also permits accurate intraoperative monitoring of the anatomical repositioning of the bone fragments, and accurate implantation. No intraoperative or early postoperative complications were observed. This new technical aid ensures highly accurate reduction of the bone fragments, and minimizes the need for reoperation. High-quality intraoperative imaging with surgical navigation increase surgical outcome, and expand the spectrum of minimally invasive surgery.

[Cystic neck lymph node metastases as an indication of occult tonsillar carcinoma]

BACKGROUND

Cystic carcinomas of the neck without evidence of a primary tumor are diagnostically challenging lesions. Differentiation between a cystic lymph node metastasis of an occult primary tumor and a carcinoma arising in a branchiogenic cyst is frequently not possible even with histological examination. In order to clarify the diagnosis, an intensive search for a primary lesion in the upper aerodigestive tract must be carried out.

DIAGNOSIS

An occult carcinoma might be situated in Waldeyer's ring, especially in the tonsillar crypts. These tumors tend to produce cystic metastases in the jugulodigastric region. Therefore, multiple biopsies have to be taken from the tissue of Waldeyer's ring. In the case of a positive histological result, adequate therapy of both the primary and the metastasis can be carried out. The diagnosis of a malignant branchiogenic cyst is only permissible after a primary lesion has been thoroughly excluded.

[Current aspects of hepatotoxicity in occupational medicine]

A large number of chemical agents encountered occupationally are known as potential hepatotoxins. The practical relevance of these results should be considered critically for the individual case and under usual work layout. In this paper the current state of knowledge for hepatotoxicity in occupational medicine is described. Different diagnostical methods and criteria for suspected chemical-induced liver injury are shown. The paper focuses on the potential hepatotoxic effects of chronic exposures to solvents, since these substances are used in a large variety of modern places of work. On the basis of field studies in occupationally exposed workers the potential hepatotoxical effects of mixtures of solvents are discussed. Recommendations for medical surveillance places of work are proposed.

[Value of panendoscopic examinations within the scope of diagnosing the extent of carcinoma of the mouth cavity]

BACKGROUND

In our department panendoscopic examinations of the tracheobronchial system, the epi-, meso,- and hypopharynx, and the upper gastrointestinal tract are obligatory with regard to the staging of oral squamous cell carcinomas, the main interest being the exclusion of synchronous secondary carcinomas. The aim of this study was to present the pathological findings in 160 panendoscopies of patients with previously untreated oral squamous cell carcinomas.

STUDY

A total of 17 synchronous carcinomas were found in 13 (8.2%) of all cases studied. They were situated in the esophagus (n = 9), the stomach (n = 1), the duodenum (n = 1), the hypopharynx (n = 1), the trachea (n = 1), and the lung (n = 4). Multiple carcinomas were found in three patients. The survival time of patients with a secondary carcinoma proved to be significantly worse than that of the other patients. The abuse of alcohol and tobacco causes a high amount of inflammatory changes in the aerodigestive system. In 27 cases (17%) ulcers of the stomach or duodenum were found, although the majority of the patients had large inflammatory mucosal alterations. In 49 cases (34.5%) a chronic tracheobronchitis could be found.

DISCUSSION

In our opinion there is an absolute indication for panendoscopic examinations of patients with oral squamous cell carcinomas. In cases with dysplastic mucosal findings these endoscopies have to be repeated on a regular basis.

Insulin-like growth factor-1 and transforming growth factor-beta1 accelerates osteotomy healing using polylactide-coated implants as a delivery system: a biomechanical and histological study in minipigs

Stimulation of bone healing and bone formation through local application of growth factors from implants may improve the clinical outcome in fracture treatment. Previous studies demonstrated a high mechanical stability of a thin poly(D,L-lactide) (PDLLA) coating on metallic implants that can withstand the process of intramedullary insertion. Following an initial peak, 80% of incorporated insulin-like growth factor-1 (IGF-1) and transforming growth factor-beta1 (TGF-beta1) were released continuously, within 42 days. The goal of the present study is evaluation of the coated implants on fracture healing in a large animal model. A midshaft osteotomy (1 mm gap) of the right tibia of Yucatan minipigs was stabilized with uncoated vs. coated titanium interlocking nails (5 mm). X-ray examinations and blood analyses (including IGF-1 and IGF-binding proteins) were performed, and body weight and body temperature were taken throughout the experiment. After 28 days, both tibiae were dissected for mechanical torsional testing and histomorphometric analyses. No differences were found in the blood analyses, body weight, or temperature due to the coating or the incorporated growth factors between the groups. X-ray examinations revealed a faster consolidation of the osteotomy in the growth factor-treated group. Biomechanical testing showed a significantly higher torsional stiffness and maximum load. Progressive remodeling was observed in the histological and histomorphometric analyses with a larger callus volume in the growth factor group compared with the control groups. We conclude that local application of growth factors from a biodegradable PDLLA coating of intramedullary implants accelerates bone healing in a large animal model without systemic side effects.

Biotransformation of trichloroethene by pure bacterial cultures

From natural samples 11 isolates able to remove trichloroethene (CCl2CHCl) from an aqueous environment were obtained which were capable of cometabolic degradation of CCl2CHCl by an enzyme system for phenol degradation. At an initial CCl2CHCl concentration of 1 mg/L, the resting cells of particular cultures degraded 33-94% CCl2CHCl during 1 d and their transformation capacity ranged from 0.3 to 3.1 mg CCl2CHCl per g organic fraction. An analysis of a mixed phenol-fed culture with an excellent trichloroethene-degrading ability found a markedly minority isolate represented in the consortium to be responsible for this property. This culture degraded CCl2CHCl even at a low inoculum concentration and attained a transformation capacity of 14.7 mg CCl2CHCl per g. The increase in chloride concentration after degradation was quantitative when compared with the decrease in organically bound chlorine. The degree of CCl2CHCl degradation was affected by Me2S2; this substance can significantly reduce the degrading ability of some tested cultures (> 60%); however, it does not cause this inhibition with others.

TNFalpha and oxLDL reduce protein S-nitrosylation in endothelial cells

Nitric oxide (NO) plays an important role in the regulation of the functional integrity of the endothelium. The intracellular reaction of NO with reactive cysteine groups leads to the formation of S-nitrosothiols. To investigate the regulation of S-nitrosothiols in endothelial cells, we first analyzed the composition of the S-nitrosylated molecules in endothelial cells. Gel filtration revealed that more than 95% of the detected S-nitrosothiols had a molecular mass of more than 5000 Da. Moreover, inhibition of de novo synthesis of glutathione using N-butyl-sulfoximine did not diminish the overall cellular S-NO content suggesting that S-nitrosylated glutathione quantitatively plays only a minor role in endothelial cells. Having demonstrated that most of the S-nitrosothiols are proteins, we determined the regulation of the S-nitrosylation by pro-inflammatory and pro-atherogenic factors, such as TNFalpha and mildly oxidized low density lipoprotein (oxLDL). TNFalpha and oxLDL induced denitrosylation of various proteins as assessed by Saville-Griess assay, by immunostaining with an anti-S-nitrosocysteine antibody, and by a Western blot approach. Furthermore, the caspase-3 p17 subunit, which has previously been shown to be S-nitrosylated and thereby inhibited, was denitrosylated by TNFalpha treatment suggesting that S-nitrosylation and denitrosylation are important regulatory mechanisms in endothelial cells contributing to the integrity of the endothelial cell monolayer.

Vitamin C inhibits endothelial cell apoptosis in congestive heart failure

BACKGROUND

Proinflammatory cytokines like tumor necrosis factor-alpha and oxidative stress induce apoptotic cell death in endothelial cells (ECs). Systemic inflammation and increased oxidative stress in congestive heart failure (CHF) coincide with enhanced EC apoptosis and the development of endothelial dysfunction. Therefore, we investigated the effects of antioxidative vitamin C therapy on EC apoptosis in CHF patients.

METHODS AND RESULTS

Vitamin C dose dependently suppressed the induction of EC apoptosis by tumor necrosis factor-alpha and angiotensin II in vitro as assessed by DNA fragmentation, DAPI nuclear staining, and MTT viability assay. The antiapoptotic effect of vitamin C was associated with reduced cytochrome C release from mitochondria and the inhibition of caspase-9 activity. To assess EC protection by vitamin C in CHF patients, we prospectively randomized CHF patients in a double-blind trial to vitamin C treatment versus placebo. Vitamin C administration to CHF patients markedly reduced plasma levels of circulating apoptotic microparticles to 32+/-8% of baseline levels, whereas placebo had no effect (87+/-14%, P<0.005). In addition, vitamin C administration suppressed the proapoptotic activity on EC of the serum of CHF patients (P<0.001).

CONCLUSIONS

Administration of vitamin C to CHF patients suppresses EC apoptosis in vivo, which might contribute to the established functional benefit of vitamin C supplementation on endothelial function.

Aging enhances the sensitivity of endothelial cells toward apoptotic stimuli: important role of nitric oxide

Advanced aging leads to impaired endothelial NO synthesis and enhanced endothelial cell apoptosis; therefore, we investigated the sensitivity of aged endothelial cells toward apoptotic stimuli and determined the role of NO. Human umbilical vein endothelial cells (HUVECs) were cultured until 14th passage. In aged cells, oxLDL and tumor necrosis factor-alpha-induced apoptosis and caspase-3-like activity were significantly enhanced more than 3-fold compared with young cells (passage 3). Because NO contributes to protection against endothelial cell death via S-nitrosylation of caspases, we determined endothelial NO synthase (eNOS) protein expression and the content of S-nitrosylated proteins. Aged HUVECs showed significantly reduced eNOS expression (35+/-10%) and a decrease in the overall S-NO content (33+/-3%), suggesting that eNOS downregulation may be involved in age-dependent increase of apoptosis sensitivity. Indeed, eNOS knockout endothelial cells showed a significantly enhanced apoptosis induction. Exogenous NO donors abolished increased apoptosis and caspase-3-like activity. In contrast, the application of shear stress, which exerts a profound apoptosis inhibitory effect via upregulation of NO synthesis in young cells, failed to inhibit apoptosis in aged cells. Moreover, no upregulation of eNOS protein expression and S-NO content in response to shear stress was detected in aged cells. Overexpression of wild-type eNOS completely restored the antiapoptotic effect of shear stress, whereas only a partial inhibitory effect was detected under steady conditions. Strikingly, transfection of constitutively active phosphomimetic eNOS (S1177D) further abrogated apoptosis in aged HUVECs. Thus, aging of endothelial cells is associated with decreased NO synthesis and concomitantly increased sensitivity of apoptosis, which may contribute to functional impairment of the endothelial monolayer.

Wooden foreign bodies in facial injury: a radiological pitfall

Foreign bodies can present a diagnostic challenge to the maxillofacial surgeon. Three patients, who suffered from a penetrating injury with a wooden foreign body, were examined and treated. Their preoperative CT and MRI scans were evaluated. In an acute case, the penetrating wooden body mimicked air bubbles. In the other two patients, the wood was retained for several months and appeared with a much higher density on CT. In MRI the wooden foreign bodies gave a low signal intensity. In all injuries removal of the foreign body was delayed, because it was initially radiologically missed or misdiagnosed. In the appropriate trauma setting a penetrating wooden body must always be considered. Its attenuation value increases with time as water is absorbed from the surrounding tissues. Although the radiological appearance may show a great variety, CT imaging is the basic diagnostic technique. MRI is the method of second choice.

Subcellular distribution of epothilones in human tumor cells

Epothilones are a new class of natural and potent antineoplastic agents that stabilize microtubules. Although 12,13-epoxide derivatives are potent antiproliferative agents, the activities of the corresponding 12,13-olefin analogs are significantly decreased. These data were confirmed for two new analogs, 6-propyl-EpoB (pEB) and 6-propyl-EpoD (pED), in comparison with the natural compounds EpoB/EpoD, by using human A431, MCF7, and MDR1-overexpressing NCI/Adr cells. By using tritiated pEB/pED, compound uptake, release, and nuclear accumulation were investigated in A431 and NCI/Adr cells. In these cells, epothilones can principally be recognized and exported by Verapamil-sensitive efflux pumps, which are not identical to MDR1. The degree of export depends on the structure, olefin vs. epoxide-analog, and also on the intracellular drug concentration. The accumulation of pED used at 3.5 or 70 nM, respectively, was increased in the presence of 10 microM Verapamil in both cell lines 2- to 8-fold. In contrast, the intracellular levels of pEB were affected by Verapamil only at 3.5 nM pEB in NCI/Adr (2-fold) and not in A431 cells. In addition, strong nuclear accumulation was observed for pEB (40-50%) but not paclitaxel or pED (5-15%) in both cell lines. Our study suggests that differences in growth inhibitory efficacy between epoxide and olefin analogs may be based on different mechanisms of drug accumulation and subcellular distribution.

The FF Planning System: Fast Plan Generation Through Heuristic Search

We describe and evaluate the algorithmic techniques that are used in the FF planning system. Like the HSP system, FF relies on forward state space search, using a heuristic that estimates goal distances by ignoring delete lists. Unlike HSP's heuristic, our method does not assume facts to be independent. We introduce a novel search strategy that combines hill-climbing with systematic search, and we show how other powerful heuristic information can be extracted and used to prune the search space. FF was the most successful automatic planner at the recent AIPS-2000 planning competition. We review the results of the competition, give data for other benchmark domains, and investigate the reasons for the runtime performance of FF compared to HSP.

Prognostic value of heart rate variability analysis in patients with carcinoid syndrome

BACKGROUND/AIMS

Recently, a decrease in heart rate variability measures was found in patients with carcinoid syndrome suffering from carcinoid heart disease compared to those without cardiac involvement of carcinoid syndrome. The prognostic relevance of this finding, however, was not clear.

PATIENTS AND METHODS

Therefore, 35 patients with carcinoid syndrome (21 men, age 56 +/- 11 years), all of them suffering from metastatic carcinoid tumors, were followed prospectively at our institution. Digital 24-hour Holter monitoring, echocardiography, and serum serotonin and urine 5-hydroxyindole acetic acid (5-HIAA) samplings were performed in all study patients at baseline. Indices of time domain heart rate variability obtained from Holter recordings included the standard deviation of all normal RR intervals (SDNN) representing overall variability, the square root of the mean of the squared differences between adjacent normal RR intervals (rMSSD), and the percentage of the number of pairs of adjacent normal RR intervals differing by >50 ms (pNN50), both indices reflecting predominantly vagal influences on heart rate.

RESULTS

During a mean follow-up of 18 +/- 7 months, 15 of 35 patients with carcinoid syndrome (43%) died. Patients with cardiac manifestation of the carcinoid syndrome showed a tendency towards an increased mortality in comparison to patients without cardiac involvement (p = 0.09). Patients with the combination of decreased heart rate variability (SDNN <100 ms) and presence of carcinoid heart disease had a significant worse prognosis (p = 0.04) compared to patients without carcinoid heart disease and preserved heart rate variability (SDNN > or =100 ms).

CONCLUSIONS

The presence of carcinoid heart disease in combination with decreased heart rate variability is associated with the most adverse prognosis in the setting of carcinoid syndrome.

Pharmacodynamics and safety of lefradafiban, an oral platelet glycoprotein IIb/IIIa receptor antagonist, in patients with stable coronary artery disease undergoing elective angioplasty

OBJECTIVE

Lefradafiban is the orally active prodrug of fradafiban, a glycoprotein IIb/IIIa receptor antagonist. The present phase II study aimed to determine the dose of lefradafiban that provides 80% blockade of the glycoprotein IIb/IIIa receptors by fradafiban, and to study the pharmacodynamics and safety of different doses in patients with stable angina undergoing angioplasty.

DESIGN

A double blind, placebo controlled, dose finding study.

SETTING

Four academic and community hospitals in the Netherlands.

PATIENTS

64 patients with stable coronary artery disease undergoing elective percutaneous transluminal coronary angioplasty.

INTERVENTIONS

30 mg, 45 mg, and 60 mg of lefradafiban three times daily or placebo was given for 48 hours.

MAIN OUTCOME MEASURES

The primary safety end point was the occurrence of bleeding, classified as major, minor, or insignificant according to the thrombolysis in myocardial infarction (TIMI) criteria. Efficacy indices included per cent fibrinogen receptor occupancy (FRO), ex vivo platelet aggregation, and plasma concentrations of fradafiban.

RESULTS

Administration of lefradafiban 30, 45, and 60 mg three times daily resulted in a dose dependent increase in median FRO levels of 71%, 85%, and 88%, respectively. Inhibition of platelet aggregation was closely related to FRO. There were no major bleeding events. The 60 mg lefradafiban group had a high (71%) incidence of minor and insignificant bleeding. The incidence of bleeding was 44% in the 30 mg and 45 mg groups, compared with 9% in placebo patients. Puncture site bleeding was the most common event. The odds of bleeding increased by 3% for every 1% increase in FRO.

CONCLUSIONS

Lefradafiban is an effective oral glycoprotein IIb/IIIa receptor blocker. The clinical effectiveness of doses up to 45 mg three times daily should be investigated.