Neoadjuvant treatment does not influence PD-L1 expression in stage III non-small-cell lung cancer: a retrospective analysis of tumor samples from the trials SAKK 16/96, 16/00, 16/01, and 16/14

BACKGROUND

The inclusion of immune checkpoint inhibitors (ICIs) in the treatment of operable stage III non-small-cell lung cancer is becoming a new standard. Programmed death-ligand 1 (PD-L1) protein expression on tumor cells has emerged as the most important biomarker for sensitivity to ICIs targeting the programmed cell death protein 1 (PD-1)-PD-L1 axis. Little is known about the impact of neoadjuvant treatment on PD-L1 expression.

PATIENTS AND METHODS

We assessed PD-L1 expression by immunohistochemistry (Ventana SP263 assay) on tumor cells in treatment-naive diagnostic tumor samples and matched lung resections from patients with stage III non-small-cell lung cancer included in the Swiss Group for Clinical Cancer Research (SAKK) trials 16/96, 16/00, 16/01, and 16/14. All patients received neoadjuvant chemotherapy (CT) with cisplatin/docetaxel, either as single modality (CT), with sequential radiotherapy [chemoradiation therapy (CRT)] or with the PD-L1 inhibitor durvalumab (CT + ICI).

RESULTS

Overall, 132 paired tumor samples were analyzed from patients with neoadjuvant CT (n = 69), CRT (n = 33) and CT + ICI (n = 30). For CT and CRT, PD-L1 expression before and after neoadjuvant treatment did not differ significantly (Wilcoxon test, P = 0.94). Likewise, no statistically significant difference was observed between CT and CRT for PD-L1 expression after neoadjuvant treatment (P = 0.97). For CT + ICI, PD-L1 expression before and after neoadjuvant treatment also did not differ significantly (Wilcoxon test, P > 0.99). Event-free survival and overall survival for patients with downregulation or upregulation of PD-L1 expression after neoadjuvant treatment were similar.

CONCLUSIONS

In our cohort of patients neoadjuvant treatment did not influence PD-L1 expression, irrespective of the specific neoadjuvant treatment protocol. Dynamic change of PD-L1 expression did not correlate with event-free survival or overall survival.

Early effects of acetazolamide on hemoglobin mass and plasma volume in chronic mountain sickness at 5100 m

INTRODUCTION AND OBJECTIVES

Chronic Mountain Sickness (CMS) syndrome, combining excessive erythrocytosis and clinical symptoms in highlanders, remains a public health concern in high-altitude areas, especially in the Andes, with limited therapeutic approaches. The objectives of this study were to assess in CMS-highlanders permanently living in La Rinconada (5100-5300 m, Peru, the highest city in the world), the early efficacy of acetazolamide (ACZ) and atorvastatin to reduce hematocrit (Hct), as well as the underlying mechanisms focusing on intravascular volumes.

MATERIALS AND METHODS

Forty-one males (46±8 years of age) permanently living in La Rinconada for 15 [10-20] years and suffering from CMS were randomized between ACZ (250 mg once-daily; N = 13), atorvastatin (20 mg once-daily; N = 14) or placebo (N = 14) uptake in a double-blinded parallel study. Hematocrit (primary endpoint) as well as arterial blood gasses, total hemoglobin mass (Hb_mass) and intravascular volumes were assessed at baseline and after a mean (±SD) treatment duration of 19±2 days.

RESULTS

ACZ increased PaO₂ by +13.4% (95% CI: 4.3 to 22.5%) and decreased Hct by -5.2% (95% CI: -8.3 to -2.2%), whereas Hct remained unchanged with placebo or atorvastatin. ACZ tended to decrease Hb_mass (-2.6%, 95% CI: -5.7 to 0.5%), decreased total red blood cell volume (RBCV, -5.3%, 95% CI: -10.3 to -0.3%) and increased plasma volume (PV, +17.6%, 95% CI: 4.9 to 30.3%). Atorvastatin had no effect on intravascular volumes, while Hb_mass and RBCV increased in the placebo group (+6.1%, 95% CI: 4.2 to 7.9% and +7.0%, 95%CI: 2.7 to 11.4%, respectively).

CONCLUSIONS

Short-term ACZ uptake was effective to reduce Hct in CMS-highlanders living at extreme altitude >5,000 m and was associated with both an increase in PV and a reduction in RBCV.

Eryptosis and hemorheological responses to maximal exercise in athletes: Comparison between running and cycling

We compared the effects of cycling and running exercise on hemorheological and hematological properties, as well as eryptosis markers. Seven endurance-trained subjects randomly performed a progressive and maximal exercise test on a cycle ergometer and a treadmill. Blood was sampled at rest and at the end of the exercise to analyze hematological and blood rheological parameters including hematocrit (Hct), red blood cell (RBC) deformability, aggregation, and blood viscosity. Hemoglobin saturation (SpO2), blood lactate, and glucose levels were also monitored. Red blood cell oxidative stress, calcium content, and phosphatidylserine exposure were determined by flow cytometry to assess eryptosis level. Cycling exercise increased blood viscosity and RBC aggregation whereas it had no significant effect on RBC deformability. In contrast, blood viscosity remained unchanged and RBC deformability increased with running. The increase in Hct, lactate, and glucose concentrations and the loss of weight at the end of exercise were not different between running and cycling. Eryptosis markers were not affected by exercise. A significant drop in SpO2 was noted during running but not during cycling. Our study showed that a progressive and maximal exercise test conducted on a cycle ergometer increased blood viscosity while the same test conducted on a treadmill did not change this parameter because of different RBC rheological behavior between the 2 tests. We also demonstrated that a short maximal exercise does not alter RBC physiology in trained athletes. We suspect that exercise-induced hypoxemia occurring during running could be at the origin of the RBC rheological behavior differences with cycling.

Elective neck dissection versus observation in primary parotid carcinoma

OBJECTIVE:

To evaluate the efficacy of elective neck dissection in the clinically negative neck of patients with primary carcinoma of the parotid gland.

STUDY DESIGN AND SETTING:

A retrospective analysis was undertaken at a university Department of Otorhinolaryngology-Head and Neck Surgery on 83 previously untreated patients with primary carcinoma of the parotid gland and a clinically negative neck. The reliability of fine needle aspiration cytology, frozen section, and the clinico-pathologic findings of patients with occult neck metastases were analyzed. The regional recurrence rate and the outcome were compared among 2 groups; one with elective neck dissection (N = 41) and one without elective neck dissection (N = 42).

RESULTS:

The diagnosis of malignancy was known preoperatively in 59 (71%) cases, the exact histologic tumor type in 36 (43%) and the grade in 37 (44%) of 83 cases. Occult metastases were detected in 8 (20%) of 41 cNO patients, in 5 cases associated with a high-grade and in 3 cases with a low-grade carcinoma. Recurrence of disease developed in 5 (12%) patients in the elective neck dissection group and in 11 (26%) patients in the observation group. All of the 7 neck recurrences occurred in the observation group. The 5-year actuarial and disease-free survival rate was 80% and 86% for patients with elective neck dissection and 83% and 69% for patients without neck dissection.

CONCLUSION AND SIGNIFICANCE:

A routine elective neck dissection is suggested in all patients with primary carcinoma of the parotid gland. The efficacy of elective neck dissection, nevertheless, has never been evaluated prospectively.

Imaging appearances of Buerger's disease complications in the upper and lower limbs

Thromboangiitis obliterans (Buerger's disease) is a rare, non-atherosclerotic, segmental, inflammatory vasculitis that most commonly involves small and medium-sized arteries, veins and nerves of the extremities and affects tobacco smokers between the ages of 25 and 45 years. The manifestations of Buerger's disease can be extremely variable and, therefore, awareness of the condition is important for both general and musculoskeletal radiologists. This paper presents the radiological appearance of the sequelae of Buerger's disease involving the upper and lower limbs.

Monostotic fibrous dysplasia of the spine: report of a case involving a cervical vertebra

Monostotic fibrous dysplasia of the spine is a rare entity. Only 26 cases, of which 11 were located in the cervical spine, are to be found in the literature. We report a 56-year-old male patient with cervicobrachialgia of half year's duration. Radiographs showed a diffuse destruction of the vertebral body and the spinous process of C4. A biopsy of the spinous process confirmed histopathologically a fibrous dysplasia. Due to minor symptoms, no surgical treatment was performed or is planned unless in case of increasing pain, an acute instability or neurological symptoms.

Adductor insertion avulsion syndrome, "thigh splints": relevance of radiological follow-up

We present a case of chronic osteomyelitis in a 13-year-old girl which was originally diagnosed as adductor insertion avulsion syndrome ("thigh splints") on the basis of the clinical presentation, patient history, initial radiographs and MRI examination. However, at follow-up with persistent pain and altered radiographic and MRI appearances, surgical biopsy was indicated. Histopathological findings confirmed a bone abscess. This case underlines the necessity of clinical follow-up and imaging in certain patients with apparent thigh splints.

Stewart-Treves syndrome: MR imaging of a postmastectomy upper-limb chronic lymphedema with angiosarcoma

The rare occurrence of angiosarcoma in postmastectomy upper-limb lymphedema with magnetic resonance (MR) imaging is discussed. Unfamiliarity with this aggressive vascular tumor and its harmless appearance often leads to delayed diagnosis. Angiosarcoma complicating chronic lymphedema may be low in signal intensity on T2-weighting and short tau inversion recovery (STIR) imaging reflecting the densely cellular, fibrous stroma, and sparsely vascularized tumor histology. Additional administration of intravenous contrast medium revealed significant enhancement of the tumorous lesions. Awareness of angiosarcoma and its MR imaging appearance in patients with chronic lymphedema may be a key to early diagnosis or allow at least inclusion in the differential diagnosis.

Mycobacterium marinum: MR imaging and clinical course of a rare soft tissue infection

Mycobacterium marinum is a rare cause of soft tissue infections. The imposing MR appearance of the soft tissue involvement is in contrast to the chronic painless clinical manifestation.

Intermediate Outcome and Risk Factor Assessment of Bovine Vascular Heterografts used as AV-Fistulas for Hemodialysis Access

OBJECTIVES

This observational study was set up to prospectively follow all bovine heterograft (ProCol) fistulas implanted for hemodialysis access between 1998 and 2002.

METHODS

ProCol was implanted if autogenous vein was not available or if patients presented with a history of failed, infected or otherwise complicated ePTFE grafts and/or on immunosuppressive therapy. Fistula patency was the primary outcome; secondary outcomes were clinical events and the rate of access revisions.

RESULTS

Sixty-two ProCol grafts were implanted in 56 patients. The mean primary (PP) and secondary patency (SP) was 334 (SEM 57) and 528 (SEM 59) days, respectively. Coronary heart disease was associated with a significantly better SP (OR 0.2, 95% CI 0.1-0.9) whilst diabetes mellitus was associated with a significantly worse SP (OR 0.2, 95% CI 0.1-0.9). Reinterventions were performed at a mean rate of 1.23 (SEM 0.17) per fistula. The relative risk of access revision was significantly higher in patients with diabetes mellitus (OR 9.2, 95% CI 2.3-37.2).

CONCLUSIONS

ProCol grafts, used for AV-fistulas, demonstrate acceptable patency rates in high-risk haemodialysis patients. Diabetes mellitus jeopardizes the patency of these fistulas and is associated with a high revision rate.

Early osteoarthritic changes of human femoral head cartilage subsequent to femoro-acetabular impingement

OBJECTIVE

To use the surgical samples of patients with femoro-acetabular impingement due to a nonspherical head to analyze tissue morphology and early cartilage changes in a mechanical model of hip osteoarthritis (OA).

DESIGN

An aberrant nonspherical shape of the femoral head has been assumed to cause an abutment conflict (impingement mechanism) of the hip with subsequent cartilage lesions of the acetabular rim and surface alterations of the nonspherical portion of the head. In this study, 22 samples of the nonspherical portions of the head have been obtained during hip surgery from young adults (mean 30.4 years, range 19-45 years) with an impingement conflict. The samples were first compared with tissue from the same area obtained from six age-matched deceased persons (control group) with normal hip morphology and second with cartilage from 14 older patients with advanced OA. All samples were characterized histologically and hyaline cartilage was graded according to the Mankin criteria. They were further subjected to examination on a molecular basis by immunohistology for cartilage oligomeric matrix protein (COMP), tenascin-C and a collagenase cleavage product (COL2-3/4C(long)) and by in situ hybridization for collagen type I and collagen type II.

RESULTS

All samples from the patient group revealed hyaline cartilage with degenerative signs. According to the Mankin criteria, the cartilage alterations were significantly different when compared with the control group (p=0.007) but were less distinct when compared with cartilage from patients with advanced OA (p=0.014). Positive staining and distribution pattern for COMP, tenascin-C and COL2-3/4C(long) showed similarities between the samples from the impingement group and osteoarthritic cartilage but they were distinctly different when compared with healthy cartilage. Levels of collagen I and II transcripts were upregulated in 6 and 10, respectively, of the 14 samples with OA and in 9 and 12, respectively, of the 22 samples from the impingement group. None of the samples from the control group showed upregulation of Collagen I and II mRNA.

CONCLUSIONS

The aberrant nonspherical portion of the femoral head in young patients with an impingement conflict consists of hyaline cartilage which shows clear degenerative signs similar to the findings in osteoarthritic cartilage. The tissue alterations are distinctly different when compared with a control group, which substantiates an impingement conflict as an early mechanism for degeneration at the hip joint periphery.

Imaging of chronic recurrent multifocal osteomyelitis of childhood first presenting with isolated primary spinal involvement

OBJECTIVE

Initial presentation with primary spinal involvement in chronic recurrent multifocal osteomyelitis of childhood (CRMO) is rare. Our objective was to review the imaging appearances of three patients who had CRMO who initially presented with isolated primary spinal involvement.

DESIGN AND PATIENTS

The imaging, clinical, laboratory and histology findings of the three patients were retrospectively reviewed. Imaging included seven spinal MR imaging scans, one computed tomography scan, nine bone scans, two tomograms and 16 radiographs. These were reviewed by two musculoskeletal radiologists and a consensus view is reported. All three patients presented with atraumatic spinal pain and had extensive bone spinal pathology. The patients were aged 11, 13 and 12 years. There were two females and one male.

RESULTS AND CONCLUSIONS

The initial patient had thoracic T6 and T8 vertebra plana. Bone scan showed additional vertebral body involvement. Follow-up was available over a 3 year period. The second patient had partial collapse of T9 and, 2 years later, of C6. Subsequently extensive multifocal disease ensued and follow-up was available over 8 years. The third patient initially had L3 inferior partial collapse and 1 year later T8 involvement with multifocal disease. Follow-up was available over 3 years. The imaging findings of the three patients include partial and complete vertebra plana with a subchondral line adjacent to endplates associated with bone marrow MR signal alterations. Awareness of the imaging appearances may help the radiologist to include this entity in the differential diagnosis in children who present with spinal pathology and no history of trauma. Histopathological examination excludes tumor and infection but with typical imaging findings may not always be necessary.

Imaging features of pseudoaneurysms of the hand in children and adults

OBJECTIVE

Our objective was to review the imaging features of pseudoaneurysms of the hand in 25 patients. The patients presented with a mass, peripheral paresthesia, or ischemia. Pseudoaneurysm of the hand is a rare and often clinically unsuspected diagnosis. Correct diagnosis is important because there are risks for distal embolic disease with ischemia or gangrene of the fingers, ulnar or digital nerve dysfunction, rupture, or bone erosion and joint destruction. Scant reports appear in the world literature, and this report is the first review, to our knowledge, of the imaging features. The cause may be a history of a single direct trauma or chronic trauma, as seen in patients with hypothenar or thenar hammer syndrome.

CONCLUSION

Awareness of the specific imaging appearances of pseudoaneurysms of the hand and their complications may improve the accuracy of radiologic diagnosis, advance the preoperative workup, and prevent possible clinical complications such as digital gangrene, nerve dysfunction, and aneurysm rupture.

[Clinico-histologic comparison of allogenic and autologous bone-tendon-bone using one-third of the patellar tendon in reconstruction of the anterior cruciate ligament]

Reconstruction of the ruptured anterior cruciate ligament (ACL) using modern techniques achieves successful long-term results in up to 90% of all cases. Yet the discussion continues as to the suitable implant to replace the ACL in terms of donor morbidity, implant reaction, long-term results, and potenzial risk of carrier concerning the allograft. The clinical and histological results from 2 years experience with the BPTB allograft (Tutoplast) and the BPTB autograft for ACL reconstruction are compared with reference to stability, functionality, rerupture rate, and histological reaction of the remodelling process. A BTB patella tendon allograft was implanted into 132 patients and a BPTB autograft into 136 patients. The patients were randomly allocated to the two groups. The results were recorded by an independent researcher and assessed according to the IKDC and Lysholm score. In the allograft group, a total of 20 patients (2.6%) reruptured within an average period of 11.75 months. In the autograft group, the transplant reruptured in five patients (4.8%) after an average of 17 months. Histological reappraisal indicated delayed incorporation and extended reconstruction in the BPTB allograft. There were clearer and more protracted indications of hypercellularity and hypervascularity, and the collagen matrix had not regularly aligned longitudinally even 1 year later. A detailed analysis of the BPTB allograft group indicated that especially in young and very sporty patients there is increased elongation of the implant and a clearly higher rerupture rate. Hence, according to the data we have collected, it would seem that the use of the BPTB allograft (Tutoplast) is not suitable especially in young patients who frequently practice high-level sports involving high knee stress.

Isolated amelanotic malignant melanoma of the heart

We report a 58-year-old woman presenting with dyspnoea and recurrent pulmonary embolism. Echocardiography revealed pericardial effusion and a tumour located in the atrioventricular groove. Surgical exploration showed tumorous infiltration of the ventricle wall and of parts of the atrium. Curative excision was not possible and the operation was discontinued. Histology revealed an amelanotic malignant melanoma. No other tumour location was detected by scanning procedures. This case represents a very rare manifestation of melanoma exclusively located in the atrioventricular groove of the heart leading to recurrent pulmonary embolism. A review of the literature on cardiac involvement of melanoma is provided.

Peripheral nerve ectopic meningioma at the elbow joint

A rare peripheral ectopic meningioma of the nerve in the elbow region is discussed. The clinical, radiological, surgical and pathological findings are reviewed.

Hibernoma: imaging characteristics of a rare benign soft tissue tumor

Hibernoma is a rare benign soft tissue tumor of brown fat. Awareness of the MR imaging appearances of this lesion may allow for improved preoperative diagnosis or at least inclusion of hibernoma as a possible benign differential diagnosis prior to surgery.

Minimizing aortic manipulation during OPCAB using the symmetry aortic connector system for proximal vein graft anastomoses

BACKGROUND

Since minimal invasive techniques have become increasingly common in coronary artery bypass grafting (CABG), there has been renewed interest in facilitated mechanical anastomoses devices that might have the potential of replacing the standard suturing techniques in vascular anastomoses. We report our initial experience with the successful creation of mechanical proximal vein graft anastomoses in off-pump coronary artery bypass operations.

METHODS

From August to December 2000, we investigated the first 20 consecutive patients who underwent CABG on the beating heart without extracorporeal circulation and who received at least one mechanical proximal vein graft anastomosis with the St. Jude Medical Symmetry aortic connector system without side-clamping of the aorta. We evaluated the different components of the system, the feasibility of such anastomoses, and the intraoperative flow measurements of the grafts using transit time methods.

RESULTS

A total of 32 proximal vein graft anastomoses were performed with the aortic connector system. Hemostasis was instantaneous in all cases except one, in which the connector was removed and the anastomosis was hand-sewn without complications. All other vein grafts were patent at the end of the procedure; intraoperative flow measurements were 39 +/- 25 mL/min for single vein grafts (n = 20) and 69 +/- 25 mL/min for sequential grafts (n = 11).

CONCLUSIONS

The St. Jude Medical Symmetry aortic connector system is a user-friendly, effective, quick, and reliable device for sutureless proximal vein graft anastomosis in CABG. This system allows the construction of uniform and geometrically perfect anastomoses and does not require aortic side-biting. This technology is attractive for all CABG procedures because aortic manipulation is reduced. In off-pump surgical procedures the connector system allows aortic manipulation to be minimized, potentially reducing embolization from aortic wall debris.

Botryoid rhabdomyosarcoma of the nose: pitfalls of pathology

A 2-year-old Swiss boy was referred to our hospital because of an obstructive sleep apnea syndrome with suspected recurrent choanal polyp. During surgery, a polypoid soft mass was found in the right nose and extirpated. The histology of the resected polypoid tumor seemed compatible with a polyp; however, immunohistochemistry revealed a botryoid rhabdomyosarcoma. Rhabdomyosarcomas are rare. The most important differential diagnoses for rhabdomyosarcoma are discussed and methods available for differentiating are included.

Surgical confirmation of ProstaScint abnormalities in two patients with high risk prostate cancer

We describe our initial experience using ProstaScint scanning in addition to conventional imaging modalities for staging of high risk prostate cancer. Using our protocol, ProstaScint images detected abnormalities in pelvic lymph nodes not seen on CT scan or magnetic resonance imaging (MRI) in two patients. Subsequent surgical pelvic lymphadenectomy confirmed these abnormalities. Further patients will be accrued on this study to estimate the sensitivity and specificity of ProstaScint scanning.

Ischaemia/reperfusion contributes to colonic injury following experimental aortic surgery

OBJECTIVES

ischaemia of the colon is an important complication of abdominal aortic aneurysm (AAA) repair. The aim of this animal study was to investigate the effect of sequential ischaemia and reperfusion on sigmoid mucosal pO2 and its association with local ET-1 release.

MATERIAL AND METHODS

twelve pigs underwent colonic ischaemia followed by complete reperfusion. Six other animals were sham controls. A Clark-type microcatheter was used for continuous mucosal pO2 measurements. Serial systemic and inferior mesenteric vein blood samples were obtained for determination of ET-1 concentration. Neutrophil extravasation was assessed by tissue myeloperoxidase (MPO) activity.

RESULTS

arterial occlusion was associated with a gradual decrease of mucosal pO2 and local release of ET-1. After restoration of blood flow, mucosal pO2 returned to near baseline values, whereas ET-1 reached its maximum concentration during the reperfusion period. MPO activity was significantly increased.

CONCLUSIONS

colonic ischaemia and reperfusion causes neutrophil extravasation and local ET-1.

Free nerve endings in the ligamentum capitis femoris

We report the presence of free nerve endings (FNE) in the ligamentum capitis femoris (LCF). Qualitative and quantitative measurements on the incidence of FNE, as assessed by immuno-histochemistry for the S-100 protein, were obtained from 18 patients undergoing hip surgery. We found FNE in all LCF, with no association to age. The presence of FNE in the LCF suggests a role in noci-/proprioception of the hip.

Rare presentation of cardiac hemangiomas

Cardiac hemangiomas are exceptionally rare tumors with an incidence of 1% to 2% of all detected benign heart neoplasms. The clinical appearance of the tumor varies considerably and may mimic other pathological findings of definite heart structures. We report two cases of cardiac hemangiomas presenting with an unusual location and clinical course.

Free nerve endings in the medial and posteromedial capsuloligamentous complexes: occurrence and distribution

Free nerve endings (FNEs) of type IVa play a distinctive role in the articular nociceptive and sensorimotor system of the knee. This study qualitatively and quantitatively analyzed FNEs in the medial and posteromedial capsuloligamentous complexes. Biopsy specimens from ten precisely defined anatomical locations were taken from seven fresh cadaver knee joints. The specimens were fixed with 4% formaldehyde solution and stained with hematoxylin-eosin. The results were examined using immunohistochemistry. The occurrence of FNEs is described in combination with their specific pattern of distribution. A high number of FNEs were found in all investigated elements with a maximum relative density in the insertion of the semimembranosus muscle in the direct attachment on the tibial margin. The number was lowest in the superficial medial collateral ligament. The results were correlated with anatomical and biomechanical functions of the stabilizing effect of the medial capsuloligamentous complex. Our findings indicate that lesions and surgical procedures can alter normal sensory feedback and coordination by modifying the use of muscle fiber during specific movements.

Large thoracic duct cyst - a case report and review of the literature

Large thoracic duct cysts are rare and standard lateral thoracotomy is usually used for resection. In the reported case the combination of an antero-lateral thoracotomy with a partial longitudinal median sternotomy (hemiclamshell approach) allowed an excellent visualization and dissection of a large thoracic duct cyst expanding in the anterior cervico-thoracic junction, and was associated with an uncomplicated recovery.

Mural aortic thrombi: An important cause of peripheral embolization

PURPOSE

Arterial thromboembolism in patients with an unknown source of embolization is still associated with significant morbidity and mortality. The advent of transesophageal echocardiography (TEE) and magnetic resonance imaging (MRI) and the more frequent use of computed tomography (CT) have led to the identification of mural aortic thrombi (MAT) as a source of distal embolization in a much higher proportion of patients than previously appreciated. The incidence, diagnosis, and treatment of patients with MAT is reported.

METHODS

In a prospective study, from January 1996 to December 1998, 89 patients with acute embolic events underwent an extensive diagnostic workup, consisting of TEE, CT, or MRI, to detect the source of embolization. Patients in whom the heart (n = 51), occlusive aortoiliac disease (n = 16), or aortic aneurysms (n = 12) was identified as the source of embolization were excluded.

RESULTS

Five female and three male patients, with a median age of 63 years (range, 35 to 76 years), with bilateral or repetitive embolic events resulting from MAT were identified, representing 9% of all patients with arterial thrombembolism. All patients had several risk factors for atherosclerosis, but only one young patient had a single risk factor that promoted thrombosis. Successful percutaneous catheter aspiration embolectomy was performed in six patients. The remaining two patients underwent surgical thromboembolectomy. A below-knee amputation had to be performed in two patients, thus representing a morbidity of the primary treatment of 25%. MAT of equal value were detected in the ascending (n = 1) and thoracic aorta (n = 3) by means of TEE, CT, or MRI. MAT in the abdominal aorta (n = 4) were identified by means of CT and MRI. Surgical removal of MAT was performed in seven patients by means of graft replacement of the ascending aorta (n = 1), open thrombectomy of the descending aorta (n = 2), and thrombendarterectomy of the abdominal aorta (n = 4), without intraoperative or postoperative complications. No recurrence of MAT occurred during a median follow-up period of 13 months (range, 4 to 24 months).

CONCLUSION

MAT represent an important source of arterial thrombembolism. A diagnostic workup of the aorta, preferably by means of CT or MRI, should be performed in all patients in whom other sources of embolization have been ruled out. The ideal therapeutic approach to these patients still awaits prospective evaluation. However, based on our experience, MAT can be successfully treated with a definitive surgical procedure in selected patients, with low mortality and morbidity.

Primary neuroendocrine tumors of the cystic duct

Primary neuroendocrine tumors of the cystic duct are extremely rare. Only 4 cases have been described to date. We report 2 patients in whom a primary neuroendocrine tumor of the cystic duct was incidentally detected during histological examination following cholecystectomy. With regard to the primary neuroendocrine tumor both patients were asymptomatic at the time of diagnosis. However, histologic examination did not confirm that the neuroendocrine tumors had been completely removed. Both patients underwent a second procedure. They are well after 47 and 49 months, respectively.

[Cryopreserved arterial homografts. A treatment alternative for infected vascular reconstructions]

Deep wound infection or prosthetic vascular graft infection is one of the most challenging complications in vascular surgery with a substantial early and late morbidity and mortality. Surgical treatment usually consists of complete removal of infected vessels or prosthetic vascular grafts followed by extraanatomic bypass procedures. However, this method is associated with significant mortality and amputation rates. Herein, we report two patients with deep wound and prosthetic vascular graft infection who underwent successful in situ reconstruction with cryopreserved arterial homografts. Although the long-term results are missing, this approach may offer a possible treatment alternative for this potentially life-threatening complication.

Risk factor assessment of endoscopically removed malignant colorectal polyps

BACKGROUND

Malignant colorectal polyps are defined as endoscopically removed polyps with cancerous tissue which has invaded the submucosa. Various histological criteria exist for managing these patients.

AIMS

To determine the significance of histological findings of patients with malignant polyps.

METHODS

Five pathologists reviewed the specimens of 85 patients initially diagnosed with malignant polyps. High risk malignant polyps were defined as having one of the following: incomplete polypectomy, a margin not clearly cancer-free, lymphatic or venous invasion, or grade III carcinoma. Adverse outcome was defined as residual cancer in a resection specimen and local or metastatic recurrence in the follow up period (mean 67 months).

RESULTS

Malignant polyps were confirmed in 70 cases. In the 32 low risk malignant polyps, no adverse outcomes occurred; 16 (42%) of the 38 patients with high risk polyps had adverse outcomes (p<0.001). Independent adverse risk factors were incomplete polypectomy and a resected margin not clearly cancer-free; all other risk factors were only associated with adverse outcome when in combination.

CONCLUSION

As no patients with low risk malignant polyps had adverse outcomes, polypectomy alone seems sufficient for these cases. In the high risk group, surgery is recommended when either of the two independent risk factors, incomplete polypectomy or a resection margin not clearly cancer-free, is present or if there is a combination of other risk factors. As lymphatic or venous invasion or grade III cancer did not have an adverse outcome when the sole risk factor, operations in such cases should be individually assessed on the basis of surgical risk.

Mechanism of the long tail-fiber deployment of bacteriophages T-even and its role in adsorption, infection and sedimentation

Models for the tail-fiber deployment of T-even bacteriophages have been experimentally tested by correlating sedimentation constants, adsorption rates, protease inactivation kinetics, and fiber configurations of individual phages observed by electron microscopy. Neither the collective nor the individualistic model, i.e. coordinated fiber retraction and expansion or oscillation of fibers independently of each other, respectively, could satisfactorily account for the results presented. We propose a new intermediary model, in which the base-plate determines a collective behaviour by fixing the hinge angle, around which individual fibers oscillate freely. The bidisperse, so-called dual sedimentation was shown to occur mainly with nascent high-concentration phage stocks in potassium glutamate containing media. Indeed, when mature intracellular phages are released in 0.5 M potassium glutamate--a condition simulating the intracellular environment--only the fast form appears. Upon storage in the cold or release into 0.5 M chloride, both forms appear. Results confirming that the sedimentation constants of the fast and slow form roughly correspond to those of the monodisperse sedimentation, characteristic of the extreme pH values, i.e. 5 and 8, do not allow to conclude that fiber configuration is the only cause of the bidisperse sedimentation.

Occurrence and distribution of free nerve endings in the distal iliotibial tract system of the knee

Free nerve endings (FNE) are nociceptive sensory elements transmitting information on pain and inflammation from the connective tissues to the brain. They form an important part of the proprioceptive sensory system of the knee. We present a qualitative and quantitative analysis of FNEs in the distal iliotibial tract (ITT), documenting their occurrence in this structure as well as their specific distribution pattern. FNEs were found in all elements of the distal ITT, with their maximum density in the fixation sites of the distal ITT to the femur and the tibia. This finding correlates well with anatomical and biomechanical studies and stresses the importance of the deep ITT fibre system for lateral knee stability. The relative number of FNEs in the distal ITT ranges from 5 to 10 per 50 mm2 and is comparable to the frequency found in the synovial sheath of the cruciate ligaments. These findings have clinical implications for surgical procedures on the lateral side of the knee. The distinct anatomy of the distal ITT should be respected in all procedures, since extensive operations in this area may cause pain and loss of range-of-motion due to alterations of proprioceptive function.

Artefacts and morphological changes during chemical fixation

The normally 'condensed' (darkly stained) chromosomes of dinoflagellates decondense by swelling. This occurs in an increasing number of cells when the concentration of added OsO4 is decreased. With different fixatives other types of disintegration can be observed, which vary with the concentration. With cryofixation and freeze-substitution the chromosomes are most 'condensed'. Escherichia coli infected with bacteriophage T4, with or without active lysozyme production, were studied by optical densitometry for partial lysis and by light and electron microscopy for observing swelling. When active lysozyme is present some of the acrolein (2.5%)-glutaraldehyde (2%)-fixed cells swell at 0 degrees C, but do not in the absence of lysozyme nor when fixed at room temperature. If OsO4 is added at concentrations < or = 0.5%, partial lysis occurs when lysozyme is present. The optical density decreases, the cells lose some matter and swell slightly. The corresponding electron micrographs show gap formation by curdling and/or a decreased concentration of the cytoplasm which reveals certain phage-related particles.

Occurrence of free nerve endings in the soft tissue of the knee joint. A histologic investigation

We present a comprehensive histologic study of neurologic structures in 18 static and dynamic knee structures of 8 cadaveric knees. Qualitative and quantitative measurements of the incidence of free nerve endings in the structures were recorded. The highest amounts of afferent nerve fibers type IVa were found in the retinacula, the patellar ligament, the pes anserinus, and in the ligaments of Wrisberg and Humphry; the lowest amount was found in the anterior cruciate ligament. There is a positive correlation between the number of mechanoreceptors per standardized area unit and the clinical presentation of certain knee disorders.

Continuous-flow cultures as in vitro models of the ecology of large intestinal flora

An anaerobic continuous-flow (CF) culture method has been developed which reproduces a number of bacterial interactions that occur in the large intestine of mice. These were determined in the following ways. (i) Bacterial counts in smears stained with 37 specific fluorescent antisera showed that the numeric balance between 37 strict anaerobes isolated from conventional mice was maintained in CF culture of conventional mouse flora in the same manner as in conventional mice. (ii) Mixed populations of various complexity of bacteria isolated from conventional mice were able to suppress Escherichia coli populations to similar levels in gnotobiotic mice and in CF cultures. (iii) Contents of CF cultures when fed to germfree mice were found to redress the germfree abnormalities studied, namely, cecal size and size of the E. coli population. Furthermore, dense layers of bacterial growth formed on the wall of CF cultures of mouse cecal flora, in a manner analogous to the colonization of mouse large intestinal mucosa. In the absence of such bacterial layers, the culture no longer exhibited these interactions. Because of the complexity and diversity of the interactions studied it is highly probable that at least the major underlying ecological control mechanisms operating in the culture model resemble those of the mouse intestine. We speculate that the somewhat surprising similarity between the ecology of the mouse large intestine and that of a CF culture in a glass vessel is due to the fact that both are dominated by thick layers of complex bacterial flora, the composition of which is controlled by their metabolic activities and by their relative ability to adhere to each other.

In vitro studies of the fixation of DNA, nucleoprotamine, nucleohistone and proteins

In view of improving fixation and embedding for thin sections of nuclear material we investigated the crosslinking of selected proteins, nucleic acid and nucleoproteins by observing the eventual gelation of solutions of these substances, which might be produced by current cytological fixatives. For those combinations where gelation occurs, we give thresholds of minimum concentrations required. We discuss the consequences of these findings for the preservation of thin sectioned nuclear structures within cells.