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Biomedical subjects

R Elsner

Publications and source records attributed to R Elsner.

At least 19 recordsLinked to original sources
PubMed2005

Adenocarcinoma of the rectum in childhood following chemotherapy and radiotherapy for a rhabdomyosarcoma--a case report.

We report a case of rectal adenocarcinoma in a 9-year-old boy, which took the form of a second malignant neoplasm following treatment for an early childhood malignancy. The abdominal complaints were for a long time interpreted as an infectious disease. At the time of diagnosis of the rectal carcinoma, the tumor had already progressed to the stage of metastatic disease. Therapy consisted of deep anterior rectal resection and regional arterial chemotherapy for liver metastases. The child died 18 months after the diagnosis of rectal carcinoma. As survival for childhood tumors improves, rare second malignant neoplasms will become increasingly common in children and adolescents. This phenomenon emphasizes the need for continued clinical surveillance of patients who have been treated with chemotherapy or irradiation for childhood tumors. The increased risk of second malignant neoplasms and an early onset of adult-type tumors has to be considered.

Adenocarcinoma↗
PubMed2002

Diving seals: are they a model for coping with oxidative stress?

The diving lifestyle of seals depends upon cardiovascular adjustments that result in frequent vasoconstriction of numerous organs. With the first post-dive breath, reperfusion allows for eliminating accumulated carbon dioxide (CO(2)) and reloading oxygen (O(2)) stores. Reintroduction of oxygenated blood raises the potential for production of reactive oxygen species (ROS) and the possibility that they may overwhelm the antioxidant defenses. This study addresses the question of possible adaptive responses that allow ringed seal (Phoca hispida) tissues to tolerate repeated cycles of ischemia and reperfusion, and thus protect them from oxidative insult. We obtained samples of ringed seal heart, muscle and kidney through the cooperation of native subsistence hunters at Barrow, Alaska. Samples were subjected to oxidative stress by addition of xanthine oxidase. Production of superoxide radical (O(2)(.-)), lipid peroxidation (as determined by the presence of thiobarbituric acid reactive substances, TBARS) and antioxidant capacity (AOX) were quantified by spectrophotometric analysis. Similarly treated pig tissues were anticipated to be more susceptible to oxidative stress. Contrary to expectations, pig tissues revealed less O(2)(.-) and TBARS compared with ringed seal tissues. These results show that ringed seal muscle, heart and kidney can be induced in vitro to generate ROS, and suggest that the living seal's protective defenses may depend upon O(2)(.-) production, similar to the protective effect of experimental preconditioning, or on enhanced intermediate scavenging, as evidenced by the larger AOX found in ringed seal tissues.

Animals↗
PubMed2001

Muscle capillary supply in harbor seals.

The purpose of this study was to examine muscle capillary supply in harbor seals. Locomotory and nonlocomotory muscles of four harbor seals (mass = 17.5-41 kg) were glutaraldehyde-perfusion fixed and samples processed for electron microscopy and analyzed by morphometry. Capillary-to-fiber number and surface ratios were 0.81 +/- 0.05 and 0.16 +/- 0.01, respectively. Capillary length and surface area per volume of muscle fiber were 1,495 +/- 83 mm/mm(3) and 22.4 +/- 1.6 mm(2)/mm(3), respectively. In the locomotory muscles, we measured capillary length and surface area per volume mitochondria (20.1 +/- 1.7 km/ml and 2,531 +/- 440 cm(2)/ml). All these values are 1.5-3 times lower than in muscles with similar or lower volume densities of mitochondria in dogs of comparable size. Compared with terrestrial mammals, the skeletal muscles of harbor seals do not match their increased aerobic enzyme capacities and mitochondrial volume densities with greater muscle capillary supply. They have a smaller capillary-to-fiber interface and capillary supply per fiber mitochondrial volume than terrestrial mammals of comparable size.

Animals↗
PubMed2000

The Irving-Scholander legacy in polar physiology.

The pioneer arctic and cold environment studies of Laurence Irving and Per Scholander, undertaken during the middle decades of the 20th century, have had a wide ranging and major influence on the direction and character of experimental research on polar species. Their investigations included comparative studies of metabolism, insulation, and acclimatization of mammals and birds in arctic Alaska and the tropics. Freezing, supercooling, and antifreeze research included fishes, insects, and plants. They examined the special problems of cooling in appendages of mammals and birds and the potential for acclimatization of these structures by repeated cold exposure. Studies of cold exposure in human populations considered possible adaptive reactions. Their research on diving mammals opened a vast new area for studies with attention to asphyxial tolerance and temperature regulation. A lesser-known accomplishment was an innovative approach to recovery of ancient atmospheric gases from polar ice fields, an approach that was stimulated by original investigations of frozen insect larvae and gas permeability through ice.

Adaptation, Physiological↗
PubMed2000

Laparoscopic partial adrenalectomy for bilateral pheochromocytomas in a boy with von Hippel-Lindau disease.

OBJECTIVES: In adults, increasing numbers of adrenalectomies for pheochromocytomas are performed laparoscopically. We report for the first time laparoscopic bilateral subtotal adrenalectomy for pheochromocytomas in an 8-year-old boy with von Hippel-Lindau disease. METHODS: In July 1998, an 8-year-old boy with von Hippel-Lindau disease underwent laparoscopic adrenal-sparing surgery for bilateral pheochromocytomas. The boy presented with severe hypertension and two pheochromocytomas on both sides. RESULTS: The child could be solely treated with laparoscopic adrenal-sparing surgery. The procedure was completed as planned. There were absolutely no intraoperative or postoperative complications. Postoperatively, catecholamine levels and hypertension went back to normal. At follow-up no residual tumor could be detected and no steroid replacement therapy was necessary. CONCLUSIONS: In experienced hands, laparoscopic adrenal-sparing surgery for pheochromocytomas is feasible and safe. Moreover, this minimal invasive approach represents an exceptional improvement in life quality, especially in children with von Hippel-Lindau disease since surgery will probably be necessary again and again in their future life.

Adrenal Gland Neoplasms↗
PubMed1999

Preserved adrenocortical function after laparoscopic bilateral adrenal sparing surgery for hereditary pheochromocytoma.

BACKGROUND: Familial pheochromocytoma, increasingly diagnosed in asymptomatic subjects with inherited syndromes such as multiple endocrine neoplasia type 2 and Von Hippel-Lindau disease, is frequently bilateral and multifocal, but very rarely malignant. Therefore, bilateral adrenalectomy and subsequent lifelong steroid replacement, with its attendant side effects, is not desirable. Minimally invasive adrenal sparing surgery by means of laparoscopy was explored for the treatment of bilateral pheochromocytoma. We report on the cure rate and adrenocortical function in a series of patients treated accordingly. PATIENTS AND METHODS: Four patients (three male, one female, ages 9-60 yr) with hereditary bilateral adrenal pheochromocytoma were treated by laparoscopic surgery in an organ sparing fashion. Postoperatively, all patients were reevaluated for complete tumor removal and for adrenocortical function. RESULTS: Two to 24 months after surgery, all patients were normotensive, had normal sodium potassium, glucose, aldosterone, renin, and cortisol serum concentrations, 24-h excretion of norepinephrine, epinephrine, and vanillylmandelic acid. Abdominal magnetic resonance imaging (n = 3) and computed tomographic scan (n = 1) disclosed no remnant or relapsing tumor tissue. ACTH stimulation testing resulted in normal cortisol responses. CONCLUSION: By adrenal sparing laparoscopic surgery not only bilateral pheochromocytoma can be successfully removed, but also adrenocortical function preserved. This may become the treatment of choice for familial pheochromocytoma.

Adrenal Cortex↗
PubMed1998

Diving seals, ischemia-reperfusion and oxygen radicals.

The cardiovascular adaptations of seals that contribute to their ability to tolerate long periods of diving asphyxial hypoxia result in episodic regional ischemia during diving and abrupt reperfusion upon termination of the dive. These conditions might be expected to result in production of oxygen-derived free radicals and other forms of highly reactive oxygen species. Seal organs vary during dives with respect to the degree and persistence of ischemia. Myocardial perfusion is reduced and intermittent; kidney circulation is vigorously vasoconstricted. Heart and kidney tissues from ringed seals (Phoca hispida) and domestic pigs (Sus scrofa) were compared in reactions to experimental ischemia. Resulting production of hypoxanthine, indicative of ATP degradation, was higher in pig than in seal tissues. Activity of superoxide dismutase (SOD), an oxygen radical scavenger, was higher in seal heart. We suggest that these results indicate enhanced protective cellular mechanisms in seals against the potential hazard of highly reactive oxygen forms. SOD activity was unexpectedly higher in pig kidney.

Animals↗
PubMed1998

Heterogeneous cholinergic reactions of ringed seal coronary arteries.

Coronary blood flow of some seal species is unusual in that it is highly variable in both non-diving and diving conditions and shows intermittent fluctuations, especially during dives when it frequently ceases for brief periods. We sought regulatory mechanisms governing these reactions by studying isometric tension recordings of isolated left circumflex (LC) and left anterior descending (LAD) coronary arteries of ringed seals, Phoca hispida, during reactions to a variety of agents for stimulating or blocking autonomic responses of the vascular smooth muscle. Micromolar acetylcholine (ACh) produced constriction of the small diameter segments of the LAD, but relaxation of the LC and larger segments of LAD. Both constrictions and dilations were prevented by atropine. Small vessel constriction by ACh was prevented by micromolar indomethacin and by a thromboxane receptor antagonist. Large vessel ACh dilations were prevented or reduced by rubbing off the endothelium and by the L-arginine analog, L-NG-nitro-arginine, an inhibitor of nitric oxide synthesis. We conclude that cholinergic, muscarinic, dilation of ringed seal large coronary arteries is mediated by endothelial-derived relaxing factor (EDRF), whereas ACh constriction of small arteries is mediated by a prostaglandin.

Acetylcholine↗
PubMed1996

Calcium homeostasis of isolated heart muscle cells exposed to pulsed high-frequency electromagnetic fields.

The intracellular calcium concentration ([Ca(2+)]i) of isolated ventricular cardiac myocytes of the guinea pig was measured during the application of pulsed high-frequency electromagnetic fields. The high-frequency fields were applied in a transverse electromagnetic cell designed to allow microscopic observation of the myocytes during the presence of the high-frequency fields. The [Ca(2+)]i was measured as fura-2 fluorescence by means of digital image analysis. Both the carrier frequency and the square-wave pulse-modulation pattern were varied during the experiments (carrier frequencies: 900, 1,300, and 1,800 MHz pulse modulated at 217Hz with 14 percent duty cycle; pulsation pattern at 900 MHz: continuous wave, 16 Hz, and 50 Hz modulation with 50 percent duty cycle and 30 kHz modulation with 80 percent duty cycle). The mean specific absorption rate (SAR) values in the solution were within one order of magnitude of 1 mW/kg. They varied depending on the applied carrier frequency and pulse pattern. The experiments were designed in three phases: 500 s of sham exposure, followed by 500 s of field exposure, then chemical stimulation without field. The chemical stimulation (K+ -depolarization) indicated the viability of the cells. The K+ depolarization yielded a significant increase in [Ca(2+)]i. Significant differences between sham exposure and high-frequency field exposure were not found except when a very small but statistically significant difference was detected in the case of 900 MHz/50 Hz. However, this small difference was not regarded as a relevant effect of the exposure.

Animals↗
PubMed1996

Cross-linked iron dextran is an efficient oral phosphate binder in the rat.

BACKGROUND: There is a need for alternative oral phosphate binders. In-vitro studies showed that iron(III)oxide-hydroxide-modified cross-linked dextran is a promising, insoluble phosphate-binding agent. The present study was designed to assess its in-vivo efficacy and safety in the rat. STUDY, DESIGN AND METHODS: Iron(III)oxide-hydroxide modified dextran beads were mixed with normal rat feed in a proportion of 8% by weight. With this formula rats were fed for 4 weeks. A control group received the same diet without added phosphate binder. Samples of blood, urine, and faeces were taken from each animal before the phosphate binder was administered, 2 weeks later, and at the end of the examination period (day 29). Phosphate, calcium, iron were analysed in the blood samples. Calcium and phosphate concentrations were determined in the urine, phosphate, calcium, and iron concentrations in the excrements. Stability of the material in the duodenum was also simulated. RESULTS AND CONCLUSIONS: The results demonstrate an excellent phosphate-binding capacity of the material and a good tolerance during the intestinal passage. No significant chemical or enzymatic degradation, histological alterations, or other treatment-related macroscopic findings were recorded. The present efficacy and toxicity study has shown effective phosphate binding with no toxicity and no iron release after ingestion of this novel phosphate binding agent. We propose clinical evaluation studies to assess whether similar efficacy and safety can be shown in humans.

Administration, Oral↗
PubMed1995

Diving patterns of ama divers of Hegura Island, Japan.

Daily diving patterns, especially depth-time profiles, were continuously recorded during the entire work shift in four cachido and four funado divers of Hegura Island, Japan. All Hegura divers (cachido and funado alike) were female and habitually wore wet suits. Cachidos dive free and unassisted from a boat or float, whereas funado divers are assisted by weighted descent and during the ascent by being pulled by a partner into a boat on the water surface. Both funado and cachido divers spent 250-280 min/day on the sea at their diving locations; the actual diving time was 100-120 min. The divers made 90-120 dives/day to a depth of 13-22 m, each dive lasting approximately 60 s, considerably longer and deeper than those observed and recorded previously in ama divers in the Chiba and Miura regions. These dive profiles are similar to those reported by Paulev in which he observed apparent signs of decompression sickness when the subject dived to a depth of 15-20 m 100 times in 5 h. The average bottom time for each dive of Hegura funados was 23.6 s which is approximately 10 s longer than that of Korean female ama. The rate of ascent in the funado divers was 1.5 m/s, which is nearly twice that of the cachido divers (0.8 m/s). The dive frequency of Hegura funados (109 dives/day) was greater than the Chiba male funados (23 dives/day). Accordingly, cumulative bottom time of Hegura funado was 48 min/day, whereas that of Chiba funado was 17 min/day.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Responses of harbor seal and pig heart to progressive and acute hypoxia.

Myocardial oxidative and glycolytic reserves were evaluated in four harbor seals, Phoca vitulina richardsi, and six domestic pigs, Sus scrofa (hematocrits: 58 +/- 5 and 34 +/- 1%., respectively). Progressive hypoxia was induced by lowering arterial hemoglobin-oxygen saturation in 10% decrements, each maintained for 10-min periods, until the onset of heart failure. Myocardial oxygen consumption rate (VO2), lactate release/uptake rate (L), and triple product, an index of myocardial energetic demand, were determined at each saturation level. Onset of L began in pigs at Sao2 = 57 +/- 5% and in seals at Sao2 = 35 +/- 4%. Cumulative oxygen consumption (VO2) during hypoxia, determined from the onset of cardiac lactate release, was 435 ml O2/100 g in seals and 172 ml O2/100 g in pigs. Cumulative lactate release during the same period was 14 mM/100 g in seals and 4.6 mM/100 g in pigs. The pigs' left ventricular contractile response (dP/dtmax) was greater than that of seals throughout the time of lactate release. Total myocardial energetic sources were higher in seals than in pigs, and seals were better able to tolerate myocardial hypoxia than were pigs. In a separate experiment, two seals and six pigs were made acutely hypoxic until cessation of cardiac output (seals, 17.5 min; pigs, 7.4 min) and were then reoxygenated. Both seals recovered promptly to control levels of cardiac mechanical function, whereas none of the pigs recovered. Additionally, five pigs were beta-blocked with 0.10 mg/kg of propranolol and were subjected to acute hypoxia. Tolerance to cardiac hypoxia in beta-blocked pigs was significantly increased compared with that of control animals.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗