Bi-Gaussian analysis reveals distinct education-related alterations in spherical equivalent and axial length-results from the Gutenberg Health Study

PURPOSE

The aim of this study is to investigate the distribution of spherical equivalent and axial length in the general population and to analyze the influence of education on spherical equivalent with a focus on ocular biometric parameters.

METHODS

The Gutenberg Health Study is a population-based cohort study in Mainz, Germany. Participants underwent comprehensive ophthalmologic examinations as part of the 5-year follow-up examination in 2012-2017 including genotyping. The spherical equivalent and axial length distributions were modeled with gaussian mixture models. Regression analysis (on person-individual level) was performed to analyze associations between biometric parameters and educational factors. Mendelian randomization analysis explored the causal effect between spherical equivalent, axial length, and education. Additionally, effect mediation analysis examined the link between spherical equivalent and education.

RESULTS

A total of 8532 study participants were included (median age: 57 years, 49% female). The distribution of spherical equivalent and axial length follows a bi-Gaussian function, partially explained by the length of education (i.e., < 11 years education vs. 11-20 years). Mendelian randomization indicated an effect of education on refractive error using a genetic risk score of education as an instrument variable (- 0.35 diopters per SD increase in the instrument, 95% CI, - 0.64-0.05, p = 0.02) and an effect of education on axial length (0.63 mm per SD increase in the instrument, 95% CI, 0.22-1.04, p = 0.003). Spherical equivalent, axial length and anterior chamber depth were associated with length of education in regression analyses. Mediation analysis revealed that the association between spherical equivalent and education is mainly driven (70%) by alteration in axial length.

CONCLUSIONS

The distribution of axial length and spherical equivalent is represented by subgroups of the population (bi-Gaussian). This distribution can be partially explained by length of education. The impact of education on spherical equivalent is mainly driven by alteration in axial length.

Paul Glaucoma Implant following Congenital Cataract Surgery in a Pediatric Cohort

Background: The aim of this study was to evaluate the short-term efficacy and safety of the Paul Glaucoma Implant (PGI) in pediatric eyes diagnosed with glaucoma following congenital cataract surgery (GFCS). Methods: A retrospective, single-center, descriptive study was conducted on consecutive children diagnosed with GFCS who underwent PGI implantation between July 2022 and November 2023 at the University Medical Center Mainz. The primary outcome measure was the reduction in IOP at the last follow-up visit. Results: Ten eyes of nine children were included in the study. The mean follow-up time was 7.70 ± 4.22 months (4.68-10.72 months). At the end of the study follow-up, the mean (95% CI) reduction in IOP was -14.8 ± 8.73 mmHg (-8.56 to -21.04 mmHg, p < 0.001). At the last follow-up, 30.0% (3/10) of patients achieved an IOP (intraocular pressure) of ≥6 and ≤21 mmHg with a reduction in IOP of ≥25% without treatment, while 90.0% (9/10) achieved this target IOP regardless of glaucoma medication treatment. The mean number of antiglaucoma medications was significantly reduced from 3.50 (IQR = 1) to 2.0 (IQR = 2, p = 0.01), and the visual acuity logMAR improved from 1.26 ± 0.62 to 1.03 ± 0.48 (p = 0.04). Only one eye experienced numerical hypotony (4 mmHg) without choroidal detachment or anterior chamber shallowing within the first 24 h. No other adverse events were observed during the follow-up period. Conclusions: PGI implantation significantly lowered IOP and the number of antiglaucoma eye drops with a favorable safety profile in children diagnosed with GFCS, thereby achieving a high rate of qualified surgical success in the short term.

Iatrogenic Keratectasia after Refractive Surgery - Causes, Prophylaxis, Therapy

Iatrogenic keratectasia is induced thinning and protrusion of the cornea after laser refractive surgery. Known risk factors include an excessively thin postoperative residual stromal bed, a thicker flap, or preoperatively undetected evidence of preexisting subclinical keratoconus. The rate of post-refractive ectasia in eyes without identifiable preoperative risk factors is 20 per 100 000 eyes for photorefractive keratectomy, 90 per 100 000 eyes for laser in situ keratomileusis, and 11 per 100 000 eyes for small incision lenticule extraction. Traditional screening tools for preoperative risk include the ectasia risk score system and percentage of tissue alteration. More recent methods include corneal elastography and epithelial mapping, in addition to Artificial Intelligence methods for data analysis. Therapy includes contact lenses, cross-linking, implantation of intracorneal ring segments, penetrating or lamellar keratoplasty, and, in early studies, implantation of corneal lenticules.

Current practice in the treatment of epithelial and melanocytic tumors with Interferon-alpha 2b: a survey among tertiary eye centers in Germany

Purpose: To evaluate the standard of care, in particular the use of topical or subconjunctival Interferon-α2b, in treating ocular surface squamous neoplasia or melanocytic tumors among tertiary eye centers in Germany. Methods: A survey containing 14 questions was sent to 43 tertiary eye centers in Germany. The questions addressed the surgical and medical management of ocular surface squamous neoplasia and melanocytic tumors (primary acquired melanosis and malignant melanoma) as well as the clinical experiences and difficulties in prescribing off-label Interferon-α2b eye drops and subconjunctival injections. Results: Twenty-four tertiary eye centers responded to the survey. Eighty-three percent of centers have used Interferon-α2b in their clinical practice and 25% prescribed it as the first-line cytostatic agent following surgical excision of ocular surface squamous neoplasia, while 10% would do so for melanocytic tumors. Correspondingly, the majority of respondents selected Mitomycin C as their first-line agent. Side effects were uncommon with topical Interferon-α2b eye drops, but were more frequently reported after subconjunctival Interferon-α2b injections. In total, eight centers had experience with Interferon-α2b injections. The most significant obstacles perceived by ophthalmologists when prescribing Interferon-α2b were its high cost and the reimbursement thereof. Conclusion: Off-label Mitomycin C was the preferred adjuvant therapy for epithelial and melanocytic tumors, with Interferon-α2b being the standard second-line option. Interferon-α2b has predominantly been used to treat ocular surface squamous neoplasia and, to a lesser extent, melanocytic tumors at German tertiary eye centers. Following its market withdrawal, supply shortages of Interferon-α2b are likely to have a profound impact on patient care and their quality of life. Ziel: Evaluation des Therapiestandards, insbesondere der Verwendung von topischem oder subkonjunktivalem Interferon-α2b, bei der Behandlung von Neoplasien der plattenepithelialen, okulären Oberfläche oder melanozytären Tumoren der Augenoberfläche in tertiären Augenzentren in Deutschland. Methoden: Eine Umfrage mit 14 Fragen wurde an 43 tertiäre Augenzentren in Deutschland verschickt. Die Fragen befassten sich mit der chirurgischen und medizinischen Behandlung von Neoplasien der plattenepithelialen, okulären Oberfläche und melanozytären Tumoren (primär erworbene Melanose und malignes Melanom) sowie den klinischen Erfahrungen und Schwierigkeiten bei der Verschreibung von Off-Label Interferon-α2b Augentropfen und subkonjunktivalen Injektionen. Ergebnisse: 24 tertiäre Augenzentren nahmen an der Umfrage teil. 83% der Zentren hatten Interferon-α2b eingesetzt und 25 % verschrieben es als First-Line-Therapie nach chirurgischer Entfernung von Neoplasien der plattenepithelialen, okulären Oberfläche, wohingegen 10 % dies bei melanozytären Tumoren angewendet hätten. Dementsprechend wählte die Mehrheit der Befragten Mitomycin C als Mittel der ersten Wahl aus. Nebenwirkungen waren bei topischen Interferon-α2b Augentropfen selten, wurden aber häufiger nach subkonjunktivalen Interferon-α2b-Injektionen gemeldet. Insgesamt hatten acht Zentren Erfahrungen mit Interferon-α2b-Injektionen. Die größten Hürden, die Augenärzte bei der Verschreibung von Interferon-α2b hinderten waren die hohen Kosten und deren Übernahme durch die Krankenkassen. Schlussfolgerung: Off-label Mitomycin C war die bevorzugte adjuvante Therapie für epitheliale und melanozytäre Tumoren, während Interferon-α2b Standardoption für eine Zweitlinientherapie war. Interferon-α2b wurde in deutschen, tertiären Augenzentren vorwiegend zur Behandlung von Neoplasien der plattenepithelialen, okulären Oberfläche und in geringerem Maße von melanozytären Tumoren eingesetzt. Nach der Marktrücknahme von Interferon-α2b werden Lieferengpässe wahrscheinlich beträchtliche Auswirkungen auf die Patientenversorgung und ihre Lebensqualität haben.

Long-term success after trabeculectomy in open-angle glaucoma: results of a retrospective cohort study

OBJECTIVE

To evaluate the long-term outcomes of trabeculectomy (TE) surgery in a large cohort with a minimum follow-up of 3 years.

DESIGN

Retrospective cohort study.

SETTING

University Eye Hospital, Germany.

PARTICIPANTS

Three hundred and seventy-nine patients with open-angle glaucoma underwent TE with mitomycin C (MMC) between January 2013 and February 2017 with a minimal follow-up of 3 years. Eligible patients were identified via an electronic surgical case register.

INTERVENTIONS

All patients had undergone TE with MMC following a set surgical protocol. To assess the influence of cataract surgery following TE, eyes which underwent cataract surgery at least 6 months after TE were matched 1:3 by sex and age to eyes who did not undergo cataract surgery during the follow-up period.

MAIN OUTCOME MEASURES

Primary outcome was the proportion of surgical success based on intraocular pressure (IOP), surgical complications, the need for revision surgery, loss of light perception and the need for additional pressure-lowering medication.

RESULTS

The mean follow-up time was 6 (±0.8, IQR: 5.4-6.5) years. Seventy-three per cent of eyes achieved qualified surgical success at the last follow-up (IOP≥5 mm Hg and ≤18 mm Hg, without surgical complications or complete loss of vision) but necessitated additional medical therapy, complete surgical success with no additional medical therapy was achieved in 69% of eyes. There was no significant difference in the success probability between eyes that had undergone cataract surgery after TE and those that had not (p=0.45).

CONCLUSIONS

The results demonstrate a high and stable success rate of TE after a mean follow-up time of approximately 6 years, that is, not affected by later cataract surgery.

Methods to measure blood flow and vascular reactivity in the retina

Disturbances of retinal perfusion are involved in the onset and maintenance of several ocular diseases, including diabetic retinopathy, glaucoma, and retinal vascular occlusion. Hence, knowledge on ocular vascular anatomy and function is highly relevant for basic research studies and for clinical judgment and treatment. The retinal vasculature is composed of the superficial, intermediate, and deep vascular layer. Detection of changes in blood flow and vascular diameter especially in smaller vessels is essential to understand and to analyze vascular diseases. Several methods to evaluate blood flow regulation in the retina have been described so far, but no gold standard has been established. For highly reliable assessment of retinal blood flow, exact determination of vessel diameter is necessary. Several measurement methods have already been reported in humans. But for further analysis of retinal vascular diseases, studies in laboratory animals, including genetically modified mice, are important. As for mice, the small vessel size is challenging requiring devices with high optic resolution. In this review, we recapitulate different methods for retinal blood flow and vessel diameter measurement. Moreover, studies in humans and in experimental animals are described.

Publisher Correction: Groundwater Throughflow and Seawater Intrusion in High Quality Coastal Aquifers

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Peripapillary Retinal Nerve Fiber Layer Profile in Relation to Refractive Error and Axial Length: Results From the Gutenberg Health Study

Purpose

To investigate the retinal nerve fiber layer profile measured by optical coherence tomography and its relation to refractive error and axial length.

Methods

The Gutenberg Health Study is a population-based study in Mainz, Germany. At the five-year follow-up examination, participants underwent optical coherence tomography, objective refraction and biometry. Peripapillary retinal nerve fiber layer (pRNFL) was segmented using proprietary software. The pRNFL profiles were compared between different refraction groups and the angle between the maxima, i.e., the peaks of pRNFL thickness in the upper and lower hemisphere (angle between the maxima of pRNFL thickness [AMR]) was computed. Multivariable linear regression analysis was carried out to determine associations of pRNFL profile (AMR) including age, sex, optic disc size, and axial length in model 1 and spherical equivalent in model 2.

Results

A total of 5387 participants were included. AMR was 145.3° ± 23.4° in right eyes and 151.8° ± 26.7° in left eyes and the pRNFL profile was significant different in the upper hemisphere. The AMR decreased with increasing axial length by −5.86°/mm (95% confidence interval [CI]: [−6.44; −5.29], P < 0.001), female sex (−7.61°; 95% CI: [−8.71; −6.51], P < 0.001) and increased with higher age (0.08°/year; 95% CI: [0.03; 0.14], P = 0.002) and larger optic disc size (2.29°/mm²; 95% CI: [1.18; 3.41], P < 0.001). In phakic eyes, AMR increased with hyperopic refractive error by 2.60°/diopters (dpt) (95% CI: [2.33; 2.88], P < 0.001).

Conclusions

The pRNFL profiles are related to individual ocular and systemic parameters.

Translational Relevance

Biometric parameters should be considered when pRNFL profiles are interpreted in diagnostics, i.e., in glaucoma.

Groundwater Throughflow and Seawater Intrusion in High Quality Coastal Aquifers

High quality coastal aquifer systems provide vast quantities of potable groundwater for millions of people worldwide. Managing this setting has economic and environmental consequences. Specific knowledge of the dynamic relationship between fresh terrestrial groundwater discharging to the ocean and seawater intrusion is necessary. We present multi- disciplinary research that assesses the relationships between groundwater throughflow and seawater intrusion. This combines numerical simulation, geophysics, and analysis of more than 30 years of data from a seawater intrusion monitoring site. The monitoring wells are set in a shallow karstic aquifer system located along the southwest coast of Western Australia, where hundreds of gigalitres of fresh groundwater flow into the ocean annually. There is clear evidence for seawater intrusion along this coastal margin. We demonstrate how hydraulic anisotropy will impact on the landward extent of seawater for a given groundwater throughflow. Our examples show how the distance between the ocean and the seawater interface toe can shrink by over 100% after increasing the rotation angle of hydraulic conductivity anisotropy when compared to a homogeneous aquifer. We observe extreme variability in the properties of the shallow aquifer from ground penetrating radar, hand samples, and hydraulic parameters estimated from field measurements. This motived us to complete numerical experiments with sets of spatially correlated random hydraulic conductivity fields, representative of karstic aquifers. The hydraulic conductivity proximal to the zone of submarine groundwater discharge is shown to be significant in determining the overall geometry and landward extent of the seawater interface. Electrical resistivity imaging (ERI) data was acquired and assessed for its ability to recover the seawater interface. Imaging outcomes from field ERI data are compared with simulated ERI outcomes derived from transport modelling with a range of hydraulic conductivity distributions. This process allows for interpretation of the approximate geometry of the seawater interface, however recovery of an accurate resistivity distribution across the wedge and mixing zone remains challenging. We reveal extremes in groundwater velocity, particularly where fresh terrestrial groundwater discharges to the ocean, and across the seawater recirculation cell. An overarching conclusion is that conventional seawater intrusion monitoring wells may not be suitable to constrain numerical simulation of the seawater intrusion. Based on these lessons, we present future options for groundwater monitoring that are specifically designed to quantify the distribution of; (i) high vertical and horizontal pressure gradients, (ii) sharp variations in subsurface flow velocity, (iii) extremes in hydraulic properties, and (iv) rapid changes in groundwater chemistry. These extremes in parameter distribution are common in karstic aquifer systems at the transition from land to ocean. Our research provides new insights into the behaviour of groundwater in dynamic, densely populated, and ecologically sensitive coastal environments found worldwide.

Efficacy and safety of XEN®-Implantation vs. trabeculectomy: Data of a "real-world" setting

Objective

To compare surgical success, postoperative intraocular pressure and complication rates between trabeculectomy and XEN gelstent surgery in a cohort of glaucoma patients in a typical clinical setting.

Methods

A retrospective cohort study of consecutive patients with refractory open-angle glaucoma including patients who underwent either stand-alone XEN gelstent insertion with Mitomycin C or trabeculectomy with Mitomycin C between 2016 and 2018 at the University Eye Hospital Mainz, Germany. Primary outcome measure was the proportion of surgical success 1 year after surgery. Patients with an IOP ≤18mmHg, an intraocular pressure reduction of >20% and in no need of revision surgery or topical medication were considered a complete surgical success. If topical therapy was necessary, they were considered a qualified success. Multivariable logistic regression analysis was carried out for the primary outcome including gender, age, preoperative intraocular pressure and number of medication classes used preoperatively as adjustment variables.

Results

171 eyes of 144 patients were included, including 82 eyes of 58 patients in the XEN group and 89 eyes of 86 patients in the trabeculectomy group. The primary outcome defined as the proportion of surgical success after 1 year (mean 11.1 months ± 2.2) was similar for both groups. The complete success proportion was 65.5% (95%-CI: 55.6–75.9%) in the trabeculectomy group, and 58.5% (95%-CI: 47.6–69.4%) in the XEN group and not statistically different in our analysis model (crude OR = 0.61; 95%-CI: 0.31–1.22; adjusted OR = 0.66; 95%-CI: 0.32–1.37). The intraocular pressure reduction, as secondary outcome measure, was higher in the trabeculectomy group (10.5 mmHg) compared to the XEN group (7.2 mmHg; p = 0.003) at the 12-month follow-up.

Conclusion

Both XEN gelstent implantation and trabeculectomy show similar proportions of surgical success and of complications and are therefore both recommendable for clinical routine. However, trabeculectomy seems to be more effective in lowering intraocular pressure than the XEN implantation. A prospective randomized clinical trial is necessary to evaluate differences in the long-term clinical outcome.

The effectiveness of the high-LET radiations from the boron neutron capture [10B(n,α) 7Li] reaction determined for induction of chromosome aberrations and apoptosis in lymphocytes of human blood samples

Provided that a selective accumulation of (10)B-containing compounds is introduced in tumor cells, following irradiation by thermal neutrons produces high-LET alpha-particles ((4)He) and recoiling lithium-7 ((7)Li) nuclei emitted during the capture of thermalized neutrons (0.025 eV) from (10)B. To estimate the biological effectiveness of this boron neutron capture [(10)B(n,α)(7)Li] reaction, the chromosome aberration assay and the flow cytometry apoptosis assay were applied. At the presence of the clinically used compounds BSH (sodium borocaptate) and BPA (p-boronophenylalanine), human lymphocytes were irradiated by sub-thermal neutrons. For analyzing chromosome aberrations, human lymphocytes were exposed to thermally equivalent neutron fluences of 1.82 × 10(11) cm(-2) or 7.30 × 10(11) cm(-2) (corresponding to thermal neutron doses of 0.062 and 0.248 Gy, respectively) in the presence of 0, 10, 20, and 30 ppm of BSH or BPA. Since the kerma coefficient of blood increased by 0.864 × 10(-12) Gy cm(2) per 10 ppm of (10)B, the kerma coefficients in blood increase from 0.34 × 10(-12) cm(2) (blood without BSH or BPA) up to 2.93 × 10(-12) Gy cm(2) in the presence of 30 ppm of (10)B. For the (10)B(n, α)(7)Li reaction, linear dose-response relations for dicentrics with coefficients α = 0.0546 ± 0.0081 Gy(-1) for BSH and α = 0.0654 ± 0.0075 Gy(-1) for BPA were obtained at 0.062 Gy as well as α = 0.0985 ± 0.0284 Gy(-1) for BSH and α = 0.1293 ± 0.0419 Gy(-1) for BPA at 0.248 Gy. At both doses, the corresponding (10)B(n, α)(7)Li reactions from BSH and BPA are not significantly different. A linear dose-response relation for dicentrics also was obtained for the induction of apoptosis by the (10)B(n, α)(7)Li reaction at 0.248 Gy. The linear coefficients α = 0.0249 ± 0.0119 Gy(-1) for BSH and α = 0.0334 ± 0.0064 Gy(-1) for BPA are not significantly different. Independently of the applied thermal neutron doses of 0.062 Gy or 0.248 Gy, the (10)B(n, α)(7)Li reaction from 30 ppm BSH or BPA induced an apparent RBE of about 2.2 for the production of dicentrics as compared to exposure to thermal neutrons alone. Since the apparent RBE value is defined as the product of the RBE of a thermal neutron dose alone times a boron localization factor which depends on the concentration of a (10)B-containing compound, this localization factor determines the biological effectiveness of the (10)B(n, α)(7)Li reaction.

Experimental determination of the antineutrino spectrum of the fission products of U238

An experiment was performed at the scientific neutron source FRM II in Garching to determine the cumulative antineutrino spectrum of the fission products of U238. Target foils of natural uranium were irradiated with a thermal and a fast neutron beam and the emitted β spectra were recorded with a γ-suppressing electron telescope. The obtained β spectrum of the fission products of U235 was normalized to the data of the magnetic spectrometer BILL. This method strongly reduces systematic errors in the U238 measurement. The β spectrum of U238 was converted into the corresponding ν¯e spectrum. The final ν¯e spectrum is given in 250 keV bins in the range from 2.875 to 7.625 MeV with an energy-dependent error of 3.5% at 3 MeV, 7.6% at 6 MeV, and ≳14% at energies ≳7  MeV (68% confidence level). Furthermore, an energy-independent uncertainty of ∼3.3% due to the absolute normalization is added. Compared to the generally used summation calculations, the obtained spectrum reveals a spectral distortion of ∼10% but returns the same value for the mean cross section per fission for the inverse beta decay.

RBE of thermal neutrons for induction of chromosome aberrations in human lymphocytes

The induction of chromosome aberrations in human lymphocytes irradiated in vitro with slow neutrons was examined to assess the maximum low-dose RBE (RBE(M)) relative to (60)Co γ-rays. For the blood irradiations, cold neutron beam available at the prompt gamma activation analysis facility at the Munich research reactor FRM II was used. The given flux of cold neutrons can be converted into a thermally equivalent one. Since blood was taken from the same donor whose blood had been used for previous irradiation experiments using widely varying neutron energies, the greatest possible accuracy was available for such an estimation of the RBE(M) avoiding the inter-individual variations or differences in methodology usually associated with inter-laboratory comparisons. The magnitude of the coefficient α of the linear dose-response relationship (α = 0.400 ± 0.018 Gy(-1)) and the derived RBE(M) of 36.4 ± 13.3 obtained for the production of dicentrics by thermal neutrons confirm our earlier observations of a strong decrease in α and RBE(M) with decreasing neutron energy lower than 0.385 MeV (RBE(M) = 94.4 ± 38.9). The magnitude of the presently estimated RBE(M) of thermal neutrons is-with some restrictions-not significantly different to previously reported RBE(M) values of two laboratories.

Minimally invasive resection of a right atrial mass in a cardiac transplant recipient: a case report

Intracardiac thrombus formation usually occurs in the left-sided cavities of the heart, most frequently in the presence of atrial fibrillation or cardiomyopathy. We report the case of an initially unclear mass developing in the right atrium (RA) of a heart transplant recipient, which was subsequently resected via a minimally invasive surgical approach. Access via right anterior minithoracotomy using videoscopic assistance allowed for uncomplicated RA thrombectomy in the presented case, avoiding reentry sternotomy with the potential risk of cardiac injury and without aortic cross-clamping or cardioplegic arrest. The patient is doing fine with excellent graft function at the latest follow-up 4 months after minimally invasive thrombectomy and 30 months after cardiac transplantation. To the best of our knowledge, this is the first report describing minimally invasive resection of a right atrial thrombus in a heart transplant recipient.

Dose-response relationship of dicentric chromosomes in human lymphocytes obtained for the fission neutron therapy facility MEDAPP at the research reactor FRM II

The biological effectiveness of neutrons from the neutron therapy facility MEDAPP (mean neutron energy 1.9 MeV) at the new research reactor FRM II at Garching, Germany, has been analyzed, at different depths in a polyethylene phantom. Whole blood samples were exposed to the MEDAPP beam in special irradiation chambers to total doses of 0.14-3.52 Gy at 2-cm depth, and 0.18-3.04 Gy at 6-cm depth of the phantom. The neutron and gamma-ray absorbed dose rates were measured to be 0.55 Gy min(-1) and 0.27 Gy min(-1) at 2-cm depth, while they were 0.28 and 0.25 Gy min(-1) at 6-cm depth. Although the irradiation conditions at the MEDAPP beam and the RENT beam of the former FRM I research reactor were not identical, neutrons from both facilities gave a similar linear-quadratic dose-response relationship for dicentric chromosomes at a depth of 2 cm. Different dose-response curves for dicentrics were obtained for the MEDAPP beam at 2 and 6 cm depth, suggesting a significantly lower biological effectiveness of the radiation with increasing depth. No obvious differences in the dose-response curves for dicentric chromosomes estimated under interactive or additive prediction between neutrons or gamma-rays and the experimentally obtained dose-response curves could be determined. Relative to (60)Co gamma-rays, the values for the relative biological effectiveness at the MEDAPP beam decrease from 5.9 at 0.14 Gy to 1.6 at 3.52 Gy at 2-cm depth, and from 4.1 at 0.18 Gy to 1.5 at 3.04 Gy at 6-cm depth. Using the best possible conditions of consistency, i.e., using blood samples from the same donor and the same measurement techniques for about two decades, avoiding the inter-individual variations in sensitivity or the differences in methodology usually associated with inter-laboratory comparisons, a linear-quadratic dose-response relationship for the mixed neutron and gamma-ray MEDAPP field as well as for its fission neutron part was obtained. Therefore, the debate on whether the fission-neutron induced yield of dicentric chromosomes increases linearly with dose remains open.

Heart transplantation in a patient with multiple sclerosis and mitoxantrone-induced cardiomyopathy

We describe a 30-year-old man with end-stage heart failure after therapy with mitoxantrone for multiple sclerosis. A successful orthotopic heart transplantation was performed when intensified medical therapy failed to improve the patient's hemodynamics. In spite of the severe underlying disease he did well on dual immunosuppression with methylprednisone and cyclosporine. Neurologic symptoms remained stable throughout the procedure and, after 2 months, he resumed preoperative ambulatory status. Eight years after the operation, the patient is now in New York Heart Association (NYHA) Class I status. Using canes, he is able to walk short distances. Repeated urinary tract infections caused by Escherichia coli became a problem, but have been controlled by long-term oral antibiotic prophylaxis with trimethoprim.

Young Investigator's Prizewinner 2001. Direct visualization of the influence of normothermic as opposed to hypothermic cardiopulmonary bypass on the systemic microcirculation in neonatal piglets

The direct visualization of systemic microcirculation using intravitalmicroscopy permits the classification of proinflammatory and ischemic microvascular alterations during normothermic and hypothermic cardiopulmonary bypass in neonates. We used seven newborn piglets, on average aged 9 days, and weighing 3200g, as a control group. In addition, we studied nine piglets subjected to 60 minutes of constant nonpulsatile flow using hypothermic extracorporeal circulation at 28 degrees C, and five piglets using normothermic conditions at 37 degrees C. The microvascular network of the greater omentum and the subcutaneous tissue was directly visualized using intravitalmicroscopy. We analysed interactions between leukocytes and endothelial cells, microvascular morphology, and microrheological conditions, focussing on signs of ischemic and proinflammatory alterations. During normothermic cardiopulmonary bypass, the numbers of activated leukocytes were elevated compared to hypothermic cardiopulmonary bypass (p > 0.05). Arteriolar diameter decreased during hypothermia. Capillaries were markedly dilated during normothermia. Patterns of microvascular perfusion, for both types of cardiopulmonary bypass, showed signs of ischemic damage, revealed by a reduced functional capillary density. Perfusion dependent levels of lactate were higher during normothermic cardiopulmonary bypass (p > 0.05). This new experimental approach revealed that non-pulsatile cardiopulmonary bypass, independent of temperature, induces a proinflammatory and ischemic response compared to an unaltered control group. The markedly elevated numbers of activated adherent leukocytes, the reduced capillary density, and the high lactate levels in those undergoing bypass in normothermic conditions indicate a more pronounced inflammatory stimulus and tissue hypoperfusion compared to the possible protective effect of hypothermia for children undergoing cardiopulmonary bypass.

New telemetric system for daily pulmonary function surveillance of lung transplant recipients

BACKGROUND

Following lung transplantation, prompt diagnosis and therapy of acute pulmonary rejection and infection episodes relies primarily upon changes in pulmonary function and determines long-term outcome. We tested a new system that allows daily monitoring of the patient's pulmonary status even after discharge from the hospital.

METHODS

Seven lung transplant recipients from our center were equipped with a telemetric monitoring device consisting of a portable flowmeter and a special modem unit. The flowmeter measures forced vital capacity (FVC), forced expiratory volume per second (FEV1), and mid expiratory flows (MEFs), encodes information like fever, cough, and dyspnea in a binary code form, and stores all values in a 32 kB memory unit. After its use, the patient positions the flowmeter onto the modem unit which automatically connects to a central computer at our center to transfer all saved data. The whole set can be used via any regular phone jack. The patient's file in the computer can be checked every day.

RESULTS

All patients learned to use the unit during their postoperative stay or during later follow-up, and were able to apply the system at home. In a mean follow-up period of 10.3+/-2.2 months, 15 episodes of significant deterioration in home pulmonary function tests (PFTs) (>10%) were registered in 6 patients, which were all confirmed by in-hospital body plethysmography. They resulted in diagnoses of 4 episodes of acute rejection, 6 cases of beginning bacterial pneumonia, and 5 cases of, most likely, viral tracheobronchitis. Only 1 patient had to be admitted to the hospital. All patients PFTs returned to previous values after treatment.

CONCLUSIONS

Telemetric monitoring of graft function in lung transplant recipients allows reliable early diagnosis and treatment of infection or rejection, which might help to prevent exacerbation of the pathology and reduce quantity of amounting graft dysfunction.

Port Access surgery for congenital heart disease

OBJECTIVES

Minimally invasive surgical techniques have been introduced into cardiac surgery in order to avoid median sternotomy related complications. Surgical trauma to the patient can be significantly reduced without compromising the safety. In addition, a small lateral chest incision results in improved cosmesis, especially in female patients.

METHODS

Thirteen patients (median age 39 +/- 14 years, ranged from 17-61 years) with atrial septal defect were treated with a minimally invasive surgical method using a modified Port Access technique. In all patients access to the heart was achieved via a small (4-8 cm) right lateral chest incision in the 4th intercostal space. In these patients the selection of the Port Access system was used for cardiopulmonary bypass via the femoral vessel and for the application of cardioplegic solution.

RESULTS

No deaths or intraoperative complications were observed in any of the patients. The postoperative course was uneventful and only minor complications were observed postoperatively. The median hospital stay was 8.0 +/- 1 days (median +/- SEM).

CONCLUSION

This minimally invasive surgical technique for the treatment of atrial septal defects represent a safe alternative to conventional treatment of ASD using median sternotomy and standard cardiopulmonary bypass. The exposure of the right atrium via the 4th intercostal space is ideal and can be performed with excellent cosmetic results.

The Dresden approach for complete multivessel revascularization

BACKGROUND

In a prospective clinical trial, a group of patients receiving less invasive surgical procedure, including minithoracotomy in combination with cardiopulmonary bypass (group 1), was compared to a group of patients receiving conventional bypass surgery (group 2) for the treatment of coronary artery disease.

METHODS

Group 1 included 85 patients (71 men, 14 women, aged 39 to 82 years, median 61.1 +/- 9.0 years); group 2 included 53 patients (38 men, 15 women, aged 51 to 79 years, median 62.0 +/- 6.1 years).

RESULTS

There were no perioperative deaths in the whole series of patients. Time of operation was 256 +/- 43 minutes in group 1 and 150.0 +/- 53.6 minutes in group 2. Hospitalization was 6.0 +/- 1.4 days and intensive care unit stay 1 day for both groups. Back pain assessment on postoperative day 3 showed less pain in group 1. Three-month follow-up revealed ischemia in stress electrocardiogram in 2 patients (2.5%) in group 1 and in 2 patients (4.1%) in group 2. Coronary angiograms confirmed the stress-electrocardiogram findings.

CONCLUSIONS

Surgical results are equal for both techniques. Even though time of operation is longer in patients receiving less invasive procedures, intensive care unit stay and hospital stays are the same length. Early postoperative back pain is less in group 1 and combined with faster convalescence.

Oxygen tension in transplanted mouse osteosarcomas during fractionated high-LET- and low-LET radiotherapy--predictive aspects for choosing beam quality?

PURPOSE

The lower OER of high-LET radiations, compared to conventional (low-LET) radiations, has often been put forward as an argument for using high-LET radiotherapy in the management of hypoxic tumours. Among the different neutron beams used in therapy, the reactor fission neutrons have the lowest OER. The aim of the present study is to follow the variations of tumour oxygenation status during fractionated irradiation with different radiation qualities. Little information is available so far after fractionated high-LET irradiation. In addition, the RBE of reactor fission neutrons for effects on tumours and on normal tissues are compared.

MATERIAL AND METHODS

Murine OTS 64-osteosarcomas were transplanted in 102 balb-C mice and irradiated by 36 Gy of photons in fractions of 3 Gy five times a week (group P-36/3) or by 12 Gy of reactor fission neutrons in fractions of 2 Gy two times a week (group N-12/2). Irradiations started at a tumor volume of 500 to 600 mm3. A third group received no radiotherapy, but all investigations (group CG). Tumor volume and tumor oxygenation were measured once a week under therapy and during three weeks after therapy. For in vivo-evaluation of oxygen status a computerized polarographic needle electrode system (KIMOC pO2 histograph, Eppendorf) was used. The median pO2 and the hypoxic fraction (pO2 values < 5 mm Hg) of single tumors and of total groups were calculated from pooled histograms and from row data as well.

RESULTS

In correlation with the increase of tumor volume, from day 1 to day 42 of follow-up the median pO2 decreased from 20 mm to 8 mm Hg and the hypoxic fraction increased from 7% to 31%. After fractionated photon therapy a growth delay of three weeks was observed. Six weeks after beginning of the irradiation the median tumor volume had been doubled again. After fission neutron therapy growth delay continued until the end of the follow-up period. In both of the irradiated groups a significant decrease of median pO2 values and an increase of the hypoxic fraction were observed under radiotherapy. Hypoxia was more intensive after neutrons with a decrease of the median pO2 from 20 mm Hg to 1 mm Hg vs. 10 mm Hg after photon therapy and with an increase of the hypoxic fraction from 7% to 78% vs. 36% respectively. Two weeks after the end of therapy the median pO2 and the hypoxic fraction of both treated groups reached the levels prior to irradiation indicating a complete reoxygenation.

CONCLUSION

During fractionated irradiation of murine osteosarcomas with photons and reactor fission neutrons, a marked hypoxia was observed for both radiation qualities, but hypoxia was more intense during fractionated neutron irradiation. After irradiation, a complete reoxygenation occurred in both groups independently of the degree of hypoxia observed during the treatment. The RBE of reactor fission neutrons, after fractionated irradiation, was much higher for effects on murine osteosarcomas compared to their RBE observed for normal tissues in previous experiments. Present data are in agreement with our clinical observations on more than 300 patients treated with reactor fission neutrons for advanced and hypoxic tumours with various histologies.

New minimally invasive surgical technique using arterial T-grafts for treatment of double-vessel coronary artery disease: experimental study

Minimally invasive surgery has been used successfully in patients with single-vessel coronary artery disease (CAD), but there are no clinical reports of surgical techniques for the treatment of multivessel disease in this field using both internal mammary arteries (IMAs). Therefore a canine model has been established to demonstrate the feasibility of a minimally invasive surgical treatment of coronary artery double-vessel disease using both IMAs. Ten mongrel dogs underwent bilateral thoracoscopic preparation of both internal mammary arteries through small left lateral chest ports. Using the Port Access endovascular cardiopulmonary bypass system the right IMA (RIMA) was anastomosed as a free graft end-to-side to the left IMA (LIMA) as a T-graft. After induction of cardioplegic arrest the RIMA was anastomosed to the circumflex artery and the LIMA to the left anterior descending artery. All animals were weaned from cardiopulmonary bypass without inotropic support. The electrocardiogram showed sinus rhythm with no signs of ischemia. Intraoperative coronary angiography demonstrated patency of all anastomoses. The minimally invasive surgical treatment of double-vessel CAD using arterial T-grafts of both IMAs is thus feasible. Surgical trauma can be further reduced by harvesting the RIMA transmediastinally through the left lateral chest.

Clinical experience with minimally invasive coronary artery and mitral valve surgery with the advantage of cardiopulmonary bypass and cardioplegic arrest using the Port Access technique

To minimize surgical trauma, the use of Port Access cardiac surgery was initiated in patients (pts) with coronary artery disease (CAD) (42 pts) or mitral valve disease (MVD) (24 pts) in March 1996 at our institution. Altogether 42 pts (36 men, 6 women; age 31-75 years, median 59.0 years) with isolated lesions of the left anterior descending (LAD) artery underwent Port Access coronary artery surgery (PACAS). A small (5-9 cm) incision was done parasternally on top on the fourth rib. The left internal mammary artery (LIMA) was dissected through the minithoracotomy or by using an additional thoracoscopic approach. A total of 24 pts (12 men, 12 women; age 30-75 years, median 62 years) underwent Port Access mitral valve surgery (PAMVS). In these pts the procedure was performed through a small right thoracotomy (6-8 cm). In all cases, endovascular cardiopulmonary bypass (CPB) was instituted through femoral cannulation, and an additional endoaortic balloon catheter was introduced into the ascending aorta for aortic occlusion. In pts with PACAS the survival was 98% (41/42) and in the PAMVS group 100%. All pts but one survived the PACAS and are well today. There were no deaths in the PAMVS group. The hospital stay was reduced by 1 day on average after PACAS and 3 days after PAMVS. Thus in well selected patients Port Access cardiac surgery represents a safe and feasible minimally invasive surgical approach that avoids the potential complications of a sternotomy while offering the advantages and safety of CPB and cardioplegic arrest. This minimally invasive approach offers a shortened hospital stay and earlier rehabilitation.