Seafloor primary production in a changing Arctic Ocean

Phytoplankton and sea ice algae are traditionally considered to be the main primary producers in the Arctic Ocean. In this Perspective, we explore the importance of benthic primary producers (BPPs) encompassing microalgae, macroalgae, and seagrasses, which represent a poorly quantified source of Arctic marine primary production. Despite scarce observations, models predict that BPPs are widespread, colonizing ~3 million km2 of the extensive Arctic coastal and shelf seas. Using a synthesis of published data and a novel model, we estimate that BPPs currently contribute ~77 Tg C y-1 of primary production to the Arctic, equivalent to ~20 to 35% of annual phytoplankton production. Macroalgae contribute ~43 Tg C y-1, seagrasses contribute ~23 Tg C y-1, and microalgae-dominated shelf habitats contribute ~11 to 16 Tg C y-1. Since 2003, the Arctic seafloor area exposed to sunlight has increased by ~47,000 km2 y-1, expanding the realm of BPPs in a warming Arctic. Increased macrophyte abundance and productivity is expected along Arctic coastlines with continued ocean warming and sea ice loss. However, microalgal benthic primary production has increased in only a few shelf regions despite substantial sea ice loss over the past 20 y, as higher solar irradiance in the ice-free ocean is counterbalanced by reduced water transparency. This suggests complex impacts of climate change on Arctic light availability and marine primary production. Despite significant knowledge gaps on Arctic BPPs, their widespread presence and obvious contribution to coastal and shelf ecosystem production call for further investigation and for their inclusion in Arctic ecosystem models and carbon budgets.

Visualization of graph products

Graphs are a versatile structure and abstraction for binary relationships between objects. To gain insight into such relationships, their corresponding graph can be visualized. In the past, many classes of graphs have been defined, e.g. trees, planar graphs, directed acyclic graphs, and visualization algorithms were proposed for these classes. Although many graphs may only be classified as "general" graphs, they can contain substructures that belong to a certain class. Archambault proposed the TopoLayout framework: rather than draw any arbitrary graph using one method, split the graph into components that are homogeneous with respect to one graph class and then draw each component with an algorithm best suited for this class. Graph products constitute a class that arises frequently in graph theory, but for which no visualization algorithm has been proposed until now. In this paper, we present an algorithm for drawing graph products and the aesthetic criterion graph product's drawings are subject to. We show that the popular High-Dimensional Embedder approach applied to cartesian products already respects this aestetic criterion, but has disadvantages. We also present how our method is integrated as a new component into the TopoLayout framework. Our implementation is used for further research of graph products in a biological context.

[Maxillary sinus examination after sinus floor elevation combined with autologous onlay osteoplasty]

BACKGROUND

Complication rates after sinus floor augmentation of up to 10% are mentioned in literature, often when heterologous bone implants are used. The aim of our retrospective study was to determine the complication rate involving the maxillary sinus of patients treated with autologous spongiosa.

PATIENTS AND METHODS

In 46 patients with an absolute maxillary atrophy (61% female, 39% male, mean age 49 years), a sinus floor augmentation, if necessary combined with an onlay bone graft of the iliac crest, was performed. Implants (Brånemark) were placed in a two-stage procedure after 3-6 months. Prior to surgery, a panoramic film was made for diagnosis and treatment planning; in addition, a sinus X-ray was taken when disease of the maxillary sinus was suspected. panoramic radiography was routinely taken after surgery. A clinical and radiological follow-up examination was performed after 6-12 months, and the patients answered a questionnaire. This study also included evaluation of operation reports and case histories. Ultrasound as well as magnetic resonance imaging to prevent radiation exposure were performed additionally.

RESULTS

In spite of perforation of the maxillary sinus mucosa in about 25%, removal of the bone graft due to inflammation was not necessary. A transient sinusitis developed in 2%. The implant loss rate (3 out of 154) may be called small.

DISCUSSION

Even though alternative heterologous graft materials exist, maxillary sinus floor elevation with autologous bone graft is still a safe option. Changes of the maxillary sinus are detectable in a small percentage, relatively often due to preexisting unrecognized or subclinical diseases of the maxillary sinus. Magnetic resonance imaging is, in spite of the high financial and technical effort required, a serious alternative to computed tomography. The combination of autologous bone graft with calcium phosphate ceramics, platelet-rich plasma, or synthetic bone growth factors should be tested as an alternative treatment method.

[Aberrant salivary gland tissue in differential diagnosis of branchiogenic neck cyst]

A neck fistula next to the sternocleidomastoid muscle is suspicious of a branchial origin. Here we report on a 29-year-old patient with a discharging cutaneous orifice caused by an ectopic salivary gland. The clinical and histological findings are demonstrated and discussed with reference to the literature. Surgical removal of ectopic salivary gland tissue is the treatment of choice. However, surgery is limited in extent compared to surgical removal of a branchial fistula. Our case demonstrates that an ectopic salivary gland should be considered in the differential diagnosis of a branchial fistula.

Diagnostic evaluation of malignant head and neck cancer by F-18-FDG PET compared to CT/MRI

AIM

Evaluation of F-18-FDG PET in comparison to CT/MRI as diagnostic tool in primary and recurrent head and neck cancer.

METHODS

78 F-18-FDG PET studies were performed in 71 patients with known or suspected primary (n = 48) or recurrent (n = 30) head and neck cancer and compared to CT (n = 75) or MRI investigations (n = 3) concerning detection of the primary or recurrent tumor and detection of regional lymph node metastases in the ipsilateral and contralateral neck sides. Glucose uptake (SUV) of PET findings was correlated to tumor location, grading and dignity of the lesion.

RESULTS

Sensitivity and specificity for PET in detection of primary tumors were 87%* and 67%, respectively (CT/MRI 67%* and 44%) (*p < 0.05), in detection of local recurrence 86% and 75%, respectively (CT/MRI 57% and 92%), in detection of necks affected by lymph node metastases 80% and 92%, respectively (CT/MRI 80% and 84%). Laryngeal, buccal (cheek) and salivary gland tumors had significant lower glucose uptake (SUV) when compared to tumors of the hypopharynx (p < 0.05). G1-tumors (mean SUV 4.26) had significant (p < 0.05) lower glucose uptake when compared to G2- and G3-tumors (mean SUV 7.73 and 8.19, respectively). Mean SUV of malignant PET findings (7.88) was significant (p < 0.05) higher than mean SUV of benign PET findings (5.70). However, a SUV threshold to improve diagnostic accuracy could not be defined.

CONCLUSIONS

F-18-FDG PET is significantly more accurate than CT/MRI for detection of head and neck cancer. Both methods are valuable for detection of cervical lymph node metastases. Glucose uptake shows correlation to histological grading. A quantitative SUV analysis does not improve diagnostic accuracy.

Diagnostic evaluation of malignant head and neck cancer by F-18-FDG PET compared to CT/MRI

AIM

Evaluation of F-18-FDG PET in comparison to CT/MRI as diagnostic tool in primary and recurrent head and neck cancer.

METHODS

78 F-18-FDG PET studies were performed in 71 patients with known or suspected primary (n = 48) or recurrent (n = 30) head and neck cancer and compared to CT (n = 75) or MRI investigations (n = 3) concerning detection of the primary or recurrent tumor and detection of regional lymph node metastases in the ipsilateral and contralateral neck sides. Glucose uptake (SUV) of PET findings was correlated to tumor location, grading and dignity of the lesion.

RESULTS

Sensitivity and specificity for PET in detection of primary tumors were 87%* and 67%, respectively (CT/MRI 67%* and 44%) (*p < 0.05), in detection of local recurrence 86% and 75%, respectively (CT/MRI 57% and 92%), in detection of necks affected by lymph node metastases 80% and 92%, respectively (CT/MRI 80% and 84%). Laryngeal, buccal (cheek) and salivary gland tumors had significant lower glucose uptake (SUV) when compared to tumors of the hypopharynx (p < 0.05). G1-tumors (mean SUV 4.26) had significant (p < 0.05) lower glucose uptake when compared to G2- and G3-tumors (mean SUV 7.73 and 8.19, respectively). Mean SUV of malignant PET findings (7.88) was significant (p < 0.05) higher than mean SUV of benign PET findings (5.70). However, a SUV threshold to improve diagnostic accuracy could not be defined.

CONCLUSIONS

F-18-FDG PET is significantly more accurate than CT/MRI for detection of head and neck cancer. Both methods are valuable for detection of cervical lymph node metastases. Glucose uptake shows correlation to histological grading. A quantitative SUV analysis does not improve diagnostic accuracy.

[Microsurgical anastomosis of the bone transplant as implant site in the maxilla]

A total of 27 vascularized iliac crest segments and four vascularized scapula transplants were transferred to achieve masticatory rehabilitation in 31 patients suffering from extensive maxillary defects; 83 Brånemark implants and 16 IMZ implants were inserted 4-8 months after the bone transplantation. The implants were uncovered 6-8 months after insertion. All patients were provided with a bar-fixed, removable prosthesis. At an average insertion period of 4.5 years, the implant loss rate was 18.8%. The effectiveness of a combination of microsurgical bone transplantation and implantation in treating serious maxillary defects is thus demonstrated.

[Animal experiments for testing a hydroxyapatite ceramic coating under vacuum conditions]

Implants that were coated with hydroxyapatite ceramic (H-A.C.) under atmospheric condition in vivo often showed local areas of delamination. By applying the H-A.C. coating using the vacuum plasma spraying (VPS) technique, the mechanical characteristics of the coating was decidedly improved. We used a standardized rabbit model to compare a coating produced by this new technique with an implant conventionally plasma sprayed under atmospheric condition (APS). Cylindrical implants, 6 x 4 mm in size with a region flattened to a depth of 800 microns, were inserted into distal rabbit femurs underneath the patella. The flattened surfaces were coated with either a 150-micron APS-H-A.C. layer or a 150-micron VPS-H-A.C. layer plasma sprayed on an underlying 50-micron porous titanium layer. The animals were killed after 84 or 365 days. After 84 days histomorphologic evaluation revealed that more than 86% of each surface was covered with mature bone, while the VPS-H-A.C. coating demonstrated an almost two times greater tensile strength than the APS-H-A.C. coating. After 365 days both coatings showed a bony coverage of more than 94%. Again the tensile strength testing revealed much higher values for the VPS-H-A.C. coating. This study demonstrates that after 84 days as well as after 365 days in vivo, the VPS-H-A.C. coating had a significantly greater load capacity than an H-A.C. coating applied under atmospheric condition, and an equal affinity for bone.

Retained pieces of wood in the retromaxillary space: a case report

Detection and operative removal of wood as a foreign body in the cranio-maxillary area has received frequent attention in the literature. However, as a rule, most of the cases described are related to the orbit or the orbito-neurocranial space. Almost no literature exists on the detection and treatment of wooden foreign bodies in the retromaxillary space. The authors present an unusual case of long-term retained wood in this area in a child. The case inspires discussion of the general problem of detecting retained retromaxillary wood, even using modern diagnostic tools in this area and the question of the operative therapy, especially the most favourable surgical access.

A possible inflammatory reaction in a lateral neck cyst (branchial cyst) because of odontogenic infection

We present the case of a woman who suffered from an acutely infected diffuse mass in the right neck. This mass had grown rapidly after difficult extraction of a tooth. Histologic analysis of the excised material revealed a lateral neck cyst with a lymph node that showed signs of an acute inflammation near the cyst. These findings support the theory that a preexisting lateral neck cyst may be "activated" by an intraoral inflammation. The different theories of the origin of lateral neck cysts are presented and discussed in the context of the case description.

[The determination of free and bound methylated nucleobases in food]

The following method was developed for the qualitative and quantitative determination of methylated purine and pyrimidine bases in food; some RNA-rich food was also investigated. The bases were liberated from nucleic acids, nucleotides, and nucleosides by acid hydrolysis with trifluoroacetic and formic acid (1/1, V/V) at 240 degrees C in a pressure-digestion system. Purification and fractionation of hydrolysates were achieved by sorbent extraction with an RP 18 column and a cation exchange column. The major and methylated nucleobases were determined by ion-exchange chromatography and reversed-phase-HPLC.