[Phacoemulsification of human lens nucleus with a water jet]. / Zerkleinerung humaner Linsenkerne mittels Waterjet.

BACKGROUND: Today, phacoemulsification with ultrasound represents the gold standard in cataract surgery. Nevertheless, new technologies for this operation are being developed to reduce the loss of endothelial cells, the heating of the tissue, and the size of the accesses. In addition to bimanual phacoemulsification, laser phacoemulsification, and mechanic phacolysis, the waterjet is discussed as an alternative. MATERIALS AND METHODS: Human soft and hard nuclei of the lens obtained by extracapsular cataract extraction (ECCE) were divided in the water bath with the waterjet, whereby the parameter pressure was varied and the time needed for fragmentation was recorded. RESULTS: In spite of different consistencies, all nuclei could be divided under the direct force of the waterjet. For the emulsification of hard nuclei of the lens, a pressure of no less than 10 bar was necessary. This value was obviously higher than a lens capsule can tolerate. For the fragmentation of soft nuclei of the lens with lower acceptable pressures of 5 bar, comparatively long operating times (in some cases over 5 min) were measured. This means that also in these cases a pressure of 10 bar was required. CONCLUSION: Intraocular use of the waterjet with direct effect of the stream with these pressures is not justifiable. Instruments for waterjet phacoemulsification should be developed which pose no danger to the corneal endothelium and lens capsule.

The use of human hematopoietic growth factors (rhGM-CSF and rhEPO) as a supportive therapy for FIV-infected cats.

Recombinant human GM-CSF (rhGM-CSF) and erythropoietin (rhEPO) were tested on chronically FIV-infected laboratory cats and uninfected specific-pathogen-free (SPF) cats. In Study 1, a total of eight cats (four cats per group of either infected or uninfected cats) received subcutaneous injection (twice a day) for 2 weeks with 5 microg/kg of rhGM-CSF, while seven cats (three SPF and four FIV-infected cats) served as the placebo-treated control cats. Four of eight rhGM-CSF-treated cats (two cats each from infected and uninfected groups) developed elevated WBC counts which peaked at Days 5-8 of treatment when compared to placebo-treated cats. The elevated WBC counts were attributed to the increase in either neutrophils, lymphocytes, eosinophils, monocytes, or their combinations. The RBC counts, platelet counts, and blood chemistry were not significantly affected by the treatment. Anti-rhGM-CSF antibodies were detected in six of eight rhGM-CSF-treated cats by Day 35 post-first treatment. All rhGM-CSF-treated infected cats but no placebo-treated infected cats had 1-2 log increase in FIV load in the PBMC during the treatment. In vitro studies suggest that rhGM-CSF has an effect on FIV replication in T cells but not in alveolar macrophages. Five of eight rhGM-CSF-treated cats had low-grade fever at 3-6 days of treatment. In Study 2, four cats per group of either infected or uninfected cats were treated (subcutaneously once a day) three times a week for 2 weeks with 100U/kg of rhEPO and monitored as before, while seven cats (three SPF and four FIV-infected cats) served as the placebo-treated control cats. All rhEPO-treated cats had a gradual increase in RBC, Hgb, and PCV counts which peaked at 2-4 weeks post-first rhEPO treatment, whereas none of the placebo-treated cats had significant increase in these parameters. The rhEPO-treated cats also developed elevated WBC counts consisting of either elevated neutrophils, lymphocytes, or their combination by 4 weeks post-first treatment but there was no statistical difference between rhEPO-treated and placebo-treated groups. None of the cats developed anti-rhEPO antibodies and no remarkable changes in blood chemistry, clinical signs, and FIV loads or FIV antibody titers were observed. Overall, rhEPO can be used safely on FIV-infected cats but the use of rhGM-CSF on FIV-infected cats should be performed with discretion.

[Examination of resistance of the lens capsule against the waterjet]. / Untersuchungen zur Belastung der Linsenkapsel durch den Waterjet.

BACKGROUND: Although cataract surgery is highly developed today, there are still problems such as secondary cataract. In polishing the posterior capsule lens, epithelial cells often remain, causing secondary cataracts. Additionally, there are the problems of tissue heating and endothelial cell loss during phacoemulsification by ultrasound. This could be another field for improvement of cataract surgery by using the waterjet. METHODS: After removing the cornea of freshly enucleated porcine bulbs, we used the water jet from 4 to 12 bar. The hit angel on the capsule varied between 45 degrees and 90 degrees. RESULTS: Rupture of the posterior capsule occurred at a mean of 8.5 bar using the jet at 45 degrees and a mean of 8.6 bar using the jet at 90 degrees. CONCLUSION: The waterjet pressure should not be over 4 bar during polishing of the posterior capsule.

[Potential of the water jet in cataract surgery]. / Was kann der Wasserstrahl in der Kataraktchirurgie?

UNLABELLED: Though cataract surgery is highly developed today, there are still problems such as endothelial cell loss after surgery and the occurrence of aftercataract. To reduce these complications we looked for techniques with a high degree of safety and precision. We found the water jet, an instrument already well established in liver surgery. We tested the possibility of improving the results of cataract surgery using the water jet method. METHODS: We performed cataract surgery--phacoemulsifikation and polishing of the capsule--on freshly enucleated porcine bulbs using water jet and by conventional procedures. By scanning electron microscope examination we compared the results. Additionally we emulsified human lens nuclei obtained by extracapsular cataract extraction using the water jet. RESULTS: The epithelial cells and lens fragments on the capsule were considerably reduced after the water jet procedure. CONCLUSION: The results show the possibility of improvement of cataract surgery by using the water jet. Further studies are necessary to adapt this technique to routine surgery in humans.

Computer model generated density correction factors for gamma spectroscopy counting.

Using the calibration curve of a single reference source to infer activity levels in samples of different bulk density and/or elemental composition may yield inaccurate results by a gamma spectroscopy system. These inaccuracies are magnified when counting low energy photons, which interact primarily through the photoelectric effect. There have been numerous methods described to empirically derive density correction factors for various samples. An alternate solution is to theoretically derive density correction factors using a computer model. The computer model generated density correction factors for material such as sand, ilmenite, and polyester are in close agreement with published empirically derived density correction factors for these same materials.