Buffer gas cooled ice chemistry. I. Buffer gas cell and mm-wave spectrometer.

A new instrument is described that will employ buffer gas cooling with mm-wave rotational spectroscopy (60-90 GHz) to probe molecules desorbed from astrochemical ices prepared in an ultrahigh vacuum environment. Here the design and performance of the buffer gas cell, mm-wave spectrometer and data acquisition system are reported, while application to molecules desorbed from ice surfaces will be described in a future publication. The effective temperature of the neon-cooled buffer gas cell is determined by monitoring a range of rotational lines of propyl cyanide introduced into the cell. Its number density is estimated from comparison to room temperature measurements and the effective collision cross section with neon is estimated by monitoring the free induction decay (FID) lifetimes. The spectrometer and data acquisition system described are capable of acquiring and time-domain averaging the FIDs at 10 Gs/s, 10 bit vertical resolution and 98% duty cycle.

[Pulmonary lymphangioleiomyomatosis (LAM)]. / Pulmonale Lymphangioleiomyomatose (LAM).

Lymphangioleiomyomatosis (LAM) is a rare lung disease that mostly occurs in female patients. A total of 200-400 people are assumed to be infected in Germany. A sporadic form and a form associated with the tuberous sclerosis complex (TSC) can be separated. Mutations of the TSC­1 and TSC­2 genes are relevant. Morphologically, pulmonary multicysts and marginal micronodal proliferations of LAM cells are characteristic. Combinations with renal angiomyolipoma are typical and, in cases with TSC glioma, facial angiofibroma and ungual fibroma are seen. Prognosis is favorable (10-year survival: 80%) and with the use of mTORC1 inhibitors it could be improved. Lung transplantation can be considered in some cases.

[Mesothelial proliferation of the tunica vaginalis testis]. / Mesotheliale Proliferate der Tunica vaginalis testis.

Proliferative changes seen in reactive mesothelial hyperplasia of a hydrocele sac may mimic malignant mesothelioma. There is no immunohistochemical staining that reliably separates benign from malignant mesothelial proliferations. However, the combined analysis of BAP1 by immunohistochemistry and CDKN2A by FISH has been reported to yield both a high specificity and sensitivity in this differential diagnosis. In addition, the evaluation of risk factors such as asbestos exposure or prior traumata may be helpful for the correct diagnosis. Exclusion of stromal invasion, which is diagnostic for malign mesothelioma, is of utmost importance. Therefore, extended histological workup is essential.

[Lung transplantation : Histomorphological diagnosis and clinical aspects]. / Lungentransplantation : Histomorphologische Diagnostik und klinische Aspekte.

The function of pulmonary allografts is regularly impaired by alloimmune reactions with quite variable clinical outcomes, different involved effector cells and molecules, as well as affected anatomical compartments. Acute rejection of grafts after lung transplantation (LuTx) is not only associated with the subsequent development of acute graft dysfunction, but can also contribute - among other immunological and nonimmunological factors - to the development of chronic lung allograft dysfunction (CLAD), which is the main reason for the limited long-term survival after LuTx. In addition to ACR and analogous to other solid organ transplants, the importance of antibody-mediated (humoral) rejection (AMR) in LuTx has also been recognized. There are currently no specific laboratory, radiological, or clinical tests available for either ACR or AMR. Only by the synoptic examination of histopathological changes and interpretation against the background of microbiological, virological, serological, and functional findings, can adequate sensitivity and specificity be achieved in the diagnostics of rejection. In this article, the current criteria for histopathological diagnostics of rejection following LuTx are summarized and the most important differential diagnoses are discussed.

[Postoperative maximum dilated fixed pupil and primary graft insufficiency after penetrating keratoplasty]. / Maximal weite lichtstarre Pupille und primäre Transplantatinsuffizienz nach perforierender Keratoplastik.

Postoperative maximum dilated fixed pupil after penetrating keratoplasty, so-called Urrets-Zavalia syndrome, is rare. Primary insufficiency of the graft can necessitate a repeat keratoplasty. Subsequently, a segmental artificial iris reconstruction might be beneficial.

[Pathology of lung cancer]. / Pathologie des Lungenkarzinoms.

Lung cancer is the leading cause of cancer death in men and the second most frequent cause in women. The pathology of lung tumors is of special relevance concerning therapy and prognosis and current classification systems have to be taken into consideration. The results of molecular tissue subtyping allow further classification and therapeutic options. The histological entities are mainly associated with typical X­ray morphological features.

[PONV after strabismus surgery : Risk adapted prophylaxis?]. / PONV nach Strabismus-OP : Risikoadaptierte Prophylaxe?

BACKGROUND: Following strabismus surgery, patients frequently develop variable degrees of postoperative nausea and vomiting (PONV). These symptoms cause discomfort and result in serious complications such as intramuscular bleeding and subconjunctival hemorrhage. In children long lasting PONV can lead to and electrolyte imbalance and dehydration. A prolonged course of recovery is the consequence. For the hospital, PONV can also involve negative economic impacts because of a damaged public reputation of the institution. There is still an ongoing debate on wether prophylaxis of PONV is necessary and how the prophylaxis of PONV should be performed. On one hand, there are proponents of a liberal prophylaxis. These intend to treat almost all patients regardless of their individual risk for PONV. On the other hand, opponents point out that every medication has to be indicated individually. In their view, risk scores should be the base of a risk-adapted approach. OBJECTIVES: The aim of the study was to reduce the frequency of PONV by using an anesthetic technique adapted to the individual risk for PONV. Until now, all trials studying the efficiency of a score-based antiemetic prophylaxis were performed on adult patients. In this study, a risk-adapted approach was evaluated on children for the first time. PATIENTS AND METHODS: In 92 patients, the incidence of PONV was analyzed after strabismus surgery. Before surgery we evaluated the risk factors for PONV according to the POVOC score in children (n = 45, 49 %) and the Apfel's score in adults (n = 47, 51 %). Patients with 0-2 risk factors received a balanced anesthesia (n = 47, 51 %). Those with 3-4 risk factors were operated in total IV anesthesia (TIVA) with propofol (n = 45, 49 %). In addition, as an antiemetic prophylaxis, 0.15 mg/kg dexamethason and 0.1 mg/kg ondansetron were applied in the latter patients. we documented the symptoms and severity of PONV 2, 6 and 24 h after surgery by means of a standardized questionnaire for PONV (Wengritzky-Score). RESULTS: The incidence of PONV was 17 % (n = 16) in all of the patients. The incidence in low-risk patients receiving a BA without prophylaxis were 21 % in adults and 38 % in children. Of the patients at high risk for PONV receiving the multimodal antiemetic approach 8 % (adults) and 9 % (children) suffered from PONV. The combination of TIVA and antiemetics could reduce the incidence of PONV compared to the predicted values in a clinically relevant manner (OR = 0.26, KI: 0.76-0.87). CONCLUSION: The overall incidence could be reduced to a level below 20 %. Particularly in patients with a high risk of PONV, TIVA could clearly reduce the incidence. However, the incidence in patients with 2 risk factors is still high (30-39 %). Therefore, it is important to reconsider the effort involved with risk screening and individually adapting anesthesia. Risk stratification means a pre- and perioperative effort. Therefore, we advocate a more liberal approach for PONV prophylaxis.

[PKP for Keratoconus - From Hand/Motor Trephine to Excimer Laser and Back to Femtosecond Laser]. / Perforierende Keratoplastik bei fortgeschrittenem Keratokonus - vom Hand-/Motortrepan hinauf zum Excimerlaser und zurück zum Femtosekundenlaser.

For patients with keratoconus, rigid gas-permeable contact lenses are the first line correction method and allow good visual acuity for quite some time. In severe stages of the disease with major cone-shaped protrusion of the cornea, even specially designed keratoconus contact lenses are no longer tolerated. If there are contraindications for intrastromal ring segments, corneal transplantation typically has a very good prognosis. In patients with advanced keratoconus - especially after corneal hydrops due to rupture of Descemet's membrane - penetrating keratoplasty (PKP) is still the first line surgical method. Non-contact excimer laser trephination seems to be especially beneficial for eyes with iatrogenic keratectasia after LASIK and for patients with repeat grafts due to "keratoconus recurrences" due to small grafts with thin host cornea. For donor trephination from the epithelial side, an artificial chamber is used. Wound closure is achieved with a double running cross-stitch suture according to Hoffmann. Graft size is adapted individually, depending on corneal size ("as large as possible - as small as necessary"). Limbal centration is preferred intraoperatively, due to optical displacement of the pupil. During the last 10 years, femtosecond laser trephination has been introduced from the USA as a potentially advantageous approach. Prospective clinical studies have shown that the technique of non-contact excimer laser PKP improves donor and recipient centration, reduces "vertical tilt" and "horizontal torsion" of the graft in the recipient bed, and thus results in significantly less "all-sutures-out" keratometric astigmatism (2.8 vs. 5.7 D), more regular topography (surface regularity index [SRI] 0.80 vs. 1.0) and better visual acuity (0.80 vs. 0.60), in comparison to the motor trephine. The stage of the disease does not influence functional outcome after excimer laser PKP. However, the refractive outcome of femtosecond laser keratoplasty resembles that with motor trephine. In contrast to the undisputed clinical advantages of excimer laser keratoplasty with orientation teeth/notches in keratoconus, the major disadvantage of femtosecond laser application is still the necessity of suction and applanation of the cone during trephination, with intraoperative disadvantages and high postoperative astigmatism.

[Coronary atherosclerosis and progression to unstable plaques : Histomorphological and molecular aspects]. / Arteriosklerose der Koronararterien und Plaque-Progression : Histomorphologische und molekularbiologische Aspekte.

Atherosclerosis causes clinical symptoms through luminal narrowing by stenosis or by precipitating thrombi that obstruct blood flow to the myocardium (coronary artery disease), central nervous system (ischemic stroke) or lower extremities (peripheral vascular disease). The most common of these manifestations of atherosclerosis is coronary artery disease, clinically presenting as either stable angina or acute coronary syndromes. Atherosclerosis is a mainly lipoprotein-driven disease, which is associated with the formation of atherosclerotic plaques at specific sites of the vascular system through inflammation, necrosis, fibrosis and calcification. In most cases, plaque rupture of a so-called thin-cap fibroatheroma leads to contact of the necrotic core material of the underlying atherosclerotic plaque with blood, resulting in the formation of a thrombus with acute occlusion of the affected (coronary) artery. The atherosclerotic lesions that can cause acute coronary syndromes by formation of a thrombotic occlusion encompass (1) thin-cap fibroatheroma, (2) plaque erosion and (3) so-called calcified nodules in calcified and tortuous arteries of aged individuals. The underlying pathomechanisms remain incompletely understood so far. In this review, the mechanisms of atherosclerotic plaque initiation and progression are discussed.

[Infectious pulmonary diseases]. / Infektiöse Lungenerkrankungen.

Infectious pulmonary diseases and pneumonias are important causes of death within the group of infectious diseases in Germany. Most cases are triggered by bacteria. The morphology of the inflammation is often determined by the agent involved but several histopathological types of reaction are possible. Histology alone is only rarely able to identify the causal agent; therefore additional microbiological diagnostics are necessary in most cases. Clinically cases are classified as community acquired and nosocomial pneumonia, pneumonia under immunosuppression and mycobacterial infections. Histologically, alveolar and interstitial as well as lobar and focal pneumonia can be differentiated.

[Keratoplasty in children--still a dilemma]. / Die perforierende Keratoplastik im Kindesalter--das ewige Dilemma.

BACKGROUND: Penetrating keratoplasty (PKP) in children is associated with specific age-related problems. In contrast to adults, children can be examined less easily and they are not readily complaining about symptoms. Thus, the rate of intra- and postoperative complications is higher than in adults. In addition, amblyopia is a major issue before the age of seven years potentially resulting in irreversible reduction of visual acuity. PATIENTS AND METHODS: Potential indications for surgery are classified as follows: (i) congenital cloudiness (e.g., congenital hereditary endothelial dystrophy--CHED), (ii) acquired traumatic scars, (iii) acquired non-traumatic scars (e.g., infections, keratoconus) and (iv) irreversible graft failure. Our experience concerning 126 paediatric PKPs between 1980 and 2002 in children under age 16 is reported. Five case reports of PKPs performed in Homburg/Saar from 2006 are added. RESULTS: To minimise the risk of immunological graft rejection and chronic endothelial cell loss, we prefer PTK, lamellar keratoplasty or ipsilateral autologous rotational keratoplasty whenever possible. In cases of sclerocornea we feel that PKP should be avoided in view of the histopathology, in cases of Peters' anomaly an optical sector iridectomy may be considered as a valid alternative to high-risk PKP. In cases of buphthalmos the IOP must be controlled before PKP (e.g., previous trabeculotomy). In cases of central penetrating cornea and lens injuries we advocate simultaneous PKP and IOL implantation in the quiet interval after primary wound closure to achieve quick optical rehabilitation. We prefer smaller grafts and interrupted sutures in children. In addition, early suture removal is attempted, especially in cases of progressive corneal neovascularisation threatening the graft. If in doubt, examinations are performed in general anaesthesia readily. CONCLUSIONS: Corneal grafting in children should be performed as soon as necessary (less amblyopia!), but as late as possible (better cooperation!). In children, critical indication, repeated in-depth counselling of the parents, good cooperation with the anaesthetist and excellent cooperation with the paediatric ophthalmologist are indispensable in order to achieve good morphological and functional results after PKP.

[Treatment of pediatric cataracts. Part 2: IOL implantation, postoperative complications, aphakia management and postoperative development]. / Behandlung der kindlichen Katarakte. Teil 2: IOL-Implantation - postoperative Komplikationen - Aphakiemanagement und postoperative Entwicklung.

There is a lot of uncertainty concerning intraocular lens (IOL) implantation for pediatric cataracts. The appropriate age which ocular abnormalities are contraindications and according to which formula IOL should be calculated are controversial. In addition to the imperative of identifying postoperative complications, such as secondary cataract formation and secondary glaucoma in a sufficiently timely manner, a modern management of aphakia with refractive compensation and occlusion is necessary. Some easy rules can help prevent pitfalls.

[Malformations of the esophagus: diagnosis and therapy]. / Fehlbildungen des Ösophagus: Diagnose und Therapie.

Esophageal malformations are rare and can occur sporadically or as a component of various syndromes. The variations and classifications are manifold. With the available modern operation techniques most malformations can be resolved with good results. However, esophageal malformations are often combined with further malformations which limit the prognosis. The separation of the trachea and esophagus after gastrulation is not yet completely researched. The results so far indicate that the localized expression of various homeodomain transcription factors is essential for normal development of the trachea and esophagus.

[Glandular papilloma of the right main bronchus. Detection of an exon 2 mutation of the KRAS gene (c.35G>A)]. / Glanduläres Papillom des rechten Hauptbronchus. Nachweis einer Exon-2-Mutation des KRAS-Gens (c.35G>A).

Benign epithelial tumors of the tracheobronchial system and the lungs are exceedingly rare. These entities encompass squamous and glandular papillomas (as well as their mixed forms) and adenomas (alveolar adenoma, papillary adenoma, salivary gland-like pleomorphic and mucinous adenomas and mucinous cystadenomas). These tumors are considered to be biologically benign neoplasms; however, they can pose considerable diagnostic difficulties, especially during frozen section evaluation, as they can mimic malignant tumors and in particular they can resemble well differentiated papillary adenocarcinomas. As a result of the extreme rarity of these tumors only a few descriptive diagnostic series exist and a systematic investigation including molecular data does not exist. This article presents the case of a 64-year-old patient with a glandular papilloma of the right main bronchus including the immunohistochemical and molecular work-up as well as a review of the current literature.

[Treatment of cataracts in childhood I: clinical picture und surgical approach]. / Behandlung der kindlichen Katarakte I : Krankheitsbild und operative Versorgung.

Despite progress in microsurgical treatment, pediatric cataracts still imply potential risks for pathological unilateral or bilateral visual and binocular development. Surgical approaches have changed fundamentally over the last 30 years which are directly associated with modifications in the postoperative care. Due to these parallel developments a continuous dynamic process arises between anterior segment surgeons and pediatric ophthalmologists so that only small case series exist which try to combine both subspecialties because until now it was not possible to gather enough experience with a single linear approach. The first article of this two part series will explain the variability of the disease and surgical approaches and the second part will try to convey a linear approach for the postoperative care.