Tom Schroder

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Papers by Tom Schroder

Selective measurement of triacylglycerol lipase activities in pig post-heparin plasma

Biochimica et Biophysica Acta (BBA) - Lipids and Lipid Metabolism, 1979

Immunochemical methods for the selective measurement of pig post-heparin plasma lipoprotein lipas... more Immunochemical methods for the selective measurement of pig post-heparin plasma lipoprotein lipase and hepatic lipase are described and validated. A simple two step pu~fication method for porcine hepatic lipase from hepatic perfusate based on affinity chromato~aphy and gel filtration is reported. The activity of the post-heparin plasma lipoprotein lipase and hepatic lipase in swine is reported. It is demonstrated that fasting decreases the activity of post-heparin plasma lipoprotein lipase activity more than two-fold while it does not affect the hepatic lipase activity significantly.

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Comparison of surgical lasers and conventional methods in skin incisions

Scandinavian Journal of Plastic and Reconstructive Surgery and Hand Surgery, 1989

Steel scalpel, electrocautery, CO2 laser used in a continuous wave mode (CW) and rapid superpulse... more Steel scalpel, electrocautery, CO2 laser used in a continuous wave mode (CW) and rapid superpulse mode (RSP), and contact Nd: YAG laser were tested on pig skin incisions. Speed of incision and histological changes near the wounds were examined. Light microscopical observations were made on postoperative day 0 using standard Van Gieson stain. Width of the scar on postoperative day 14 was also measured. Steel scalpel produced the least pathological changes in the skin, followed by RSP. Electrocautery did not differ significantly from the CO2 lasers in this respect on postoperative day 0. The damage was larger after contact Nd:YAG laser. The situation was essentially similar on postoperative day 14. The width of the scar was narrowest after steel scalpel and widest after contact Nd:YAG laser (p less than 0.01; Nd:YAG vs. other methods). Electrocautery and the two CO2 lasers produced equal scarring. However, electrocautery was significantly faster than any of the lasers (p less than 0.001).

Effect of Local Soil Hydraulic Conductivity Drop Using a Three-Dimensional Root Water Uptake Model

Vadose Zone Journal, 2008

ABSTRACT

Comment on “Root Water Extraction and Limiting Soil Hydraulic Conditions Estimated by Numerical Simulation”

Vadose Zone Journal, 2007

Use of a Three-Dimensional Detailed Modeling Approach for Predicting Root Water Uptake

Vadose Zone Journal, 2008

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Proximal pancreatectomy: A comparison of electrocautery and contact and noncontact Nd:YAG laser techniques in the dog

The American Journal of Surgery, 1987

Pancreatic operations are often associated with technical difficulties due to the anatomic charac... more Pancreatic operations are often associated with technical difficulties due to the anatomic characteristics of the pancreas and its blood supply [I]. Clinical operations are time consuming and blood loss can be considerable . Blood vessels are commonly ligated, and pancreatic tissue incised either with a scalpel or electrocautery . There are only a few reports on the pancreatic tissue effects of the various lasers [2,3].

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Total gastrectomy with esophagojejunostomy

The American Journal of Surgery, 1986

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Surgical treatment of gastric carcinoma

The American Journal of Surgery, 1989

To investigate changes in the resnlts of treatment of jpStl.iC careinama, two IO-year periods bet... more To investigate changes in the resnlts of treatment of jpStl.iC careinama, two IO-year periods between 1963 and 1982 with 641 and 630 patients, respectively, were compared. In the two group% 94 percent and 92 percent of patients were operated on. The operation was considered curative in 200 and 265 patients in Croups 1 and 2, respectively. There was a shift towards move radical operations, with 215 total or snbtotal gastrectomies in Group 2 compaved with 76 in Cronp 1, when distal gastric resettion was considered radicaI enough. Despite the increasing nnmher of cqative operations and more radical surgery in Group 2, no pregress in the 5year snrvivaI rate was noted. Distal and subtotal gaatrectomies gave slightly better resnlts than total gastrectomies, bat the most important single factor contribnting to the long-term survival was cancerens invasion of the serosa. It is concluded that in the past 20 year%, the resnlts of snrgical treatment of gastric carcinoma have not improved, despite the move advanced diagnostic methods and more radical surgery.

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Efficacy and Complications of the ND:YAG Laser in Partial Nephrectomy: Experimental Study in Piglets

Scandinavian Journal of Urology and Nephrology, 1991

Twenty-four partial nephrectomies were performed in 18 piglets using either the combination Nd:YA... more Twenty-four partial nephrectomies were performed in 18 piglets using either the combination Nd:YAG laser technique (contact and noncontact) or a steel scalpel. Additional haemostasis was attempted with ligatures. Blood loss, operation time, and number of ligatures were compared in the two treatment groups. Twelve piglets had a two-week follow-up. The mean blood loss with the laser was 72 +/- 10 g and 83 +/- 13 g with the steel scalpel (no significant difference). The resection time until complete haemostasis was 9.8 +/- 0.9 min with the laser and 14.3 +/- 1.3 min with the steel scalpel (p = 0.0076). The number of ligatures needed for complete haemostasis was 2.8 +/- 0.4 with the laser and 7.5 +/- 1.0 with the steel scalpel (p = 0.0051). Three piglets in the steel scalpel group developed urinomas. There were two perirenal abscesses, one in each group. In the steel scalpel group there was one intussusception. In conclusion, it seems that the combination Nd:YAG laser method offers no definitive advantage over the standard technique for partial nephrectomies in the pig.

Nd:Yag Contact Laser in Partial Nephrectomy: An Experimental Study in Piglets

Scandinavian Journal of Urology and Nephrology, 1991

The Nd: YAG contact laser technique with 12 W power output was used in partial nephrectomies in s... more The Nd: YAG contact laser technique with 12 W power output was used in partial nephrectomies in six piglets. Blood loss, total time and number of ligatures needed for haemostasis were compared in six partial nephrectomies performed with a steel scalpel. Mean blood loss was 53 g with the laser and 108 g with the steel scalpel (p less than 0.04). The mean time needed for haemostasis were 9.5 and 16.2 min respectively (p = 0.2) and the average number of ligatures required 1.5 and 8.8, respectively. The mean temperature rise at 5, 10 and 20 mm distance from the resection line was 5.3, 1.2 and 0.3 degrees C, respectively. The use of laser reduced blood loss and shortened the operation time. Further studies are needed concerning renal function after kidney surgery with a laser.

Contrast-Enhanced Computed Tomography and Microangiography of the Pancreas in Acute Human Hemorrhagic/Necrotizing Pancreatitis

Pancreas, 1988

Five patients with severe acute pancreatitis had a low contrast enhancement (CE) of the pancreas ... more Five patients with severe acute pancreatitis had a low contrast enhancement (CE) of the pancreas in computed tomography (CT) and underwent subtotal pancreatectomy. Microangiography and histologic studies were performed on the resected pancreases, and the findings were related to those of CE. All patients had histologically documented hemorrhagic/necrotizing pancreatitis. The more disturbed the vascular anatomy in microangiography, the more hemorrhages and necroses were found in histology. The microangiographic and histologic findings corresponded closely to the low contrast-enhanced CT of the diseased pancreas in each patient. Thus, in the early phase of severe acute pancreatitis, one can detect by noninvasive means which areas of the gland are necrotic and which edematous by a dynamic study of contrast-enhanced CT of the pancreas.

Lactate dehydrogenase in laser incisions: A comparative analysis of skin wounds made with steel scalpel, electrocautery, superpulse—continuous wave mode carbon-dioxide lasers, and contact Nd:YAG laser

Lasers in Surgery and Medicine, 1989

A histochemical method for demonstrating lactate dehydrogenase activity was used in addition to s... more A histochemical method for demonstrating lactate dehydrogenase activity was used in addition to standard Van Gieson stain to study early alterations near wounds made in pig skin by steel scalpel, electrocautery, two modes of COz laser (the rapid superpulse mode and the continuous wave mode), and contact Nd:YAG laser. The enzyme-free zone near the wounds made using the thermal knives appeared to be twice as wide as the necrotic zone observed with Van Gieson stain. In polarized light, the enzymefree area showed two zones of equal width with respect to birefringence of collagen fibers. The zone lacking birefringence correlated well with that observed with Van Gieson stain. The birefringent zone represented functionally damaged tissue with more or less normal structures by light microscopy. The damage to adjacent tissue caused with the thermal knives seems to be considerably larger than has usually been reported.

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Laser-Induced hyperthermia in the treatment of liver tumors

Lasers in Surgery and Medicine, 1990

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Fatal air embolism as a complication of laser-induced hyperthermia

Lasers in Surgery and Medicine, 1989

Laser-induced hyperthermia is a new treatment modality for malignancies. When large tumors are tr... more Laser-induced hyperthermia is a new treatment modality for malignancies. When large tumors are treated with laser thermia, relatively high laser powers (4-6 W) must be used to accomplish destruction of the cancerous cells. Overheating and burning of the laser fibers and contact tips during laser thermia treatment must be prevented by using coaxial gas or fluid flow. The present report describes a case of fatal air embolism as a complication of laser thermia using coaxial gas. The authors warn all surgeons performing this procedure not to use coaxial air flow for cooling the contact tips because of the potential risk of air embolism.

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Laser-induced hyperthermia: Comparison of two different methods

Lasers in Surgery and Medicine, 1992

The effectiveness of two different techniques of laser-induced hyperthermia was analyzed in healt... more The effectiveness of two different techniques of laser-induced hyperthermia was analyzed in healthy piglet livers. Hyperthermia was produced using a continuous-wave Nd:YAG laser with both a contact sapphire probe and a bare quartz fibre. In both methods the tip was inserted into the liver, and the temperature 1 cm from the tip was raised and held between 42 degrees C and 44 degrees C for 600 seconds. Specimens were taken 0, 7 and 14 days after the treatment. The tissue effects of 36 treatment sites were analysed using standard van Gieson&#39;s method. In addition, a histochemical method for demonstrating lactate dehydrogenase activity was employed to show damage not observable by routine methods. No statistically significant difference in the extent of the treatment sites at d 0 and after 7 days was seen when comparing the two laser methods. After 2 weeks, the diameter of the lesion with the bare fibre was significantly larger (3,7 mm with both analysing methods) than by using the contact probe (2,6 with LDH demonstration; P &lt; 0.01 and 2.1 mm with van Gieson&#39;s staining; P &lt; 0.001). It can be concluded that the simple fibre tip seems more effective in causing tissue necrosis than the sapphire tip.

Effects of different contact laser scalpels on skin and subcutaneous fat

Lasers in Surgery and Medicine, 1988

The tissue effects of different NdYAG contact laser scalpels on pig skin and subcutaneous fat wer... more The tissue effects of different NdYAG contact laser scalpels on pig skin and subcutaneous fat were studied using various power settings. Three different laser scalpels were tested 0.2 mm nonfrosted (LR2), 0.6 mm nonfrosted (LR6), and 1.0 mm frosted (LRPlO), using 3 different power settings (8 W, 14 W, 18 W). The tissue effects of a steel scalpel were used as reference. Incisions on pig loin (4O/pig) were made at randomized sites. Specimens were taken at postoperative days 0 and 14. The depth of tissue damage was measured using a light microscope. The amount of time required for making each incision was recorded.

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An experimental study on the effects of the steel scalpel, electrocautery and various lasers on oral tissue

Lasers in Medical Science, 1989

The tissue effects of the steel scalpel, electrocautery, CO2 laser and contact Nd-YAG laser were ... more The tissue effects of the steel scalpel, electrocautery, CO2 laser and contact Nd-YAG laser were studied on rat tongue. The tip of the tongue (3 ram) was cut offand fixed for histology. The rats (6-10/method/age group) were kept alive for 2, 7 and 14 days, when the remaining tongue was resected. In each postoperative age group the effects to the epithelium and muscular layer were determined separately. Peroperative bleeding was measured and attention was paid to wound contraction and inflammatory cell infiltration.

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Early antibiotic treatment in acute necrotising pancreatitis

The Lancet, 1995

Despite improvements in surgical treatment and intensive care, mortality from severe acute pancre... more Despite improvements in surgical treatment and intensive care, mortality from severe acute pancreatitis remains high. We have carried out a randomised study of 60 consecutive patients with alcohol-induced necrotising pancreatitis to find out whether early antibiotic treatment can improve outcome. 30 patients were assigned cefuroxime (4·5 g/day intravenously) from admission. In the second group, no antibiotic treatment was given until clinical or microbiologically verified infection or after a secondary rise in C-reactive protein. The inclusion criteria were C-reactive protein concentration above 120 mg/L within 48 h of admission and low enhancement (<30 Hounsfield units) on contrast-enhanced computed tomography. There were more infectious complications in the non-antibiotic than in the antibiotic group (mean per patient 1·8 vs 1·0, p=0·01). The most common cause of sepsis was Staphylococcus epidermidis; positive cultures were obtained from pancreatic necrosis or the central venous line in 14 of 18 patients with suspected but blood-culture-negative sepsis. Mortality was higher in the non-antibiotic group (seven vs one in the antibiotic group; p=0·03). Four of the eight patients who died had cultures from pancreatic necrosis positive for Staph epidermidis.

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Long-term ethanol ingestion causes an increase of phospholipase A2 activity in acute experimental pancreatitis in rats

Journal of Surgical Research, 1986

ABSTRACT

Hematoporphyrin derivative uptake and photodynamic therapy in pancreatic carcinoma

Journal of Surgical Oncology, 1988

Little information is currently available concerning the uptake of porphyrins by pancreatic tumor... more Little information is currently available concerning the uptake of porphyrins by pancreatic tumors, or the effect of photodynamic therapy (PDT) on pancreatic cancer. In Syrian golden hamsters (n = 33), the organ distribution of 125I-labeled dihematoporphyrin ether (DHE) was studied in a pancreatic cancer model. In the same animal model the effect of PDT was studied using a gold vapor laser for energy delivery 3 hr after the injection of DHE (n = 7). DHE was 2.4 times more concentrated in the pancreatic tumor than in the nontumorous pancreas at 3 hr. Simultaneously there was a considerable accumulation of DHE in the surrounding gastrointestinal tract, causing perforation of the duodenum and jejunum with resultant death in four (57%) animals after PDT. Photodynamic therapy caused extensive tumor necrosis without any obvious effect on the nontumor-bearing pancreas. Damage to the surrounding tissue in the hamster indicates that precautions should be taken if PDT is to be used clinically in pancreatic cancer. Intratumoral injection of DHE may give higher drug concentrations with greater specificity for tumor treatment.

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