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Biomedical subjects

P D Hansen

Publications and source records attributed to P D Hansen.

At least 37 records · Page 2Linked to original sources
PubMed2001

A new monoclonal antibody against vitellogenin from rainbow trout (Oncorhynchus mykiss).

Monoclonal antibodies were developed against vitellogenin (vtg) of rainbow trout. This protein is used as a biochemical response to the exposure with estrogenic compounds. Several mice were immunized with purified vtg and the spleen cells of these mice were fused with myeloma cells. The resulting hybridoma cells were screened with an enzyme immunoassay for the production of specific anti-vtg antibodies. Twelve positive cell lines were detected. The hybridoma cell line B8D8 was adjusted to serum free medium; it produced monoclonal antibodies with a high selectivity and sensitivity. A detection limit of 5 microg/l vtg was achieved with a competitive enzyme immunoassay applying a preincubation step and a streptavidin-biotin amplification system (ABC system). Cross-reactivity with vtg of other species was detected with roach (Rutilus rutilus), flounder (Platichthys flesus) and dab (Limanda limanda). The assay was applied to rainbow trout (Oncorhynchus mykiss), which were exposed for six months to defined concentrations of effluents (10%, 20%, 30% and 40%) and surface water. Increased vtg levels in male fish are correlated with the increasing levels of effluent. The effluent levels in the exposure experiments are relevant for effluent loadings of the Berlin waterways during the seasons of the year.

Animals↗
PubMed2001

Evaluation of estrogenic effects of municipal effluents to the freshwater mussel Elliptio complanata.

Municipal effluents are an important source of estrogens to the aquatic environment. The purpose of this study was to examine the estrogenicity of municipal effluents to the indigenous freshwater mussel, Elliptio complanata. First, estradiol-binding sites in gonad homogenates were characterized to determine the binding affinity and specificity of estrogens. Mussels were exposed to increasing concentrations of a municipal effluent for 96 h at 15 degrees C. In another experiment, mussels were placed in cages and submerged for 62 days at 1.5 km upstream and 5 km downstream of a municipal effluent plume in the St. Lawrence River. Mussels were harvested for assessment of vitellogenin-like proteins in the hemolymph and determination of total lipid, carbohydrate and protein in the gonad. The presence of specific estrogen-binding sites was found in both male and female gonads. Binding of estradiol to cytosol proteins reached saturation, yielding a dissociation constant of 0.4 nM. Vitellogenin (Vg) levels increased significantly in both the hemolymph and the gonad after exposure to the effluent. Moreover, females appeared to be more sensitive than males to producing Vg. Mussels exposed in situ to contaminated surface waters had higher levels of Vg at the downstream site, again, females had higher levels of Vg than did males. On the other hand, lipid and sugar levels in male gonads were significantly increased at the downstream site. Moreover, mussels at the downstream site had decreased shell growth length and increased total and soft tissue weights. We conclude that municipal effluents contain bio-available xenoestrogens at levels sufficient to elicit effects in freshwater mussels.

Animals↗
PubMed2001

The continuous monitoring of field water samples with a novel multi-channel two-stage mini-bioreactor system.

Toxicity monitoring of field water samples was performed using a novel multi-channel two-stage mini-bioreactor system and genetically engineered bioluminescent bacteria for the continuous monitoring and classification of the toxicity present in the samples. The toxicity of various samples spiked with known endocrine disrupting chemicals and phenol was also investigated for system characterization. The field samples used in this study were obtained from two different sites on a monthly basis--from a drinking water treatment plant, referred to as site N, and from a stream near a dam which is currently being constructed, referred to as site T. These samples were either pumped or injected into the second mini-bioreactors to initiate the toxicity test. Most of the samples did not show any specific toxicity. However, one sample showed to have, based upon the detection results, and was deemed toxic. The samples spiked with phenol showed possible responses in the DPD2540 and TV1061 channels, indicating the occurrence of both membrane and protein damage due to phenol. In the tests using an endocrine disrupting chemical, bisphenol A, DNA damage was detected in the DPD2794 channel with a concentration of 2 ppm. Finally, a simple but novel early warning protocol that can be used in a drinking water reservoir and a suspected place where effluents of toxic materials enter the water sourse was suggested with a schematic diagram. In conclusion, this system showed good feasibility for use as a toxicity monitoring system in the field and as an early warning system, indicating if effluents are toxic.

Bacteria↗
PubMed2000

Effect of an esophageal bougie on the incidence of dysphagia following nissen fundoplication: a prospective, blinded, randomized clinical trial.

HYPOTHESIS: Based on retrospective, uncontrolled studies, it has been claimed that Nissen fundoplication should be performed over an esophageal bougie to minimize postoperative dysphagia. We hypothesized that a surgeon experienced in laparoscopic fundoplication will have similar rates of postoperative dysphagia whether or not an esophageal bougie is used. DESIGN: A patient and observer blinded, randomized, prospective clinical trial to assess the effect of intraoperative bougie use. SETTING: A tertiary care teaching hospital that is a regional referral source for complex laparoscopic foregut surgical procedures. PATIENTS: Three hundred thirty-six consecutive patients referred for laparoscopic fundoplication between March 1, 1996, and July 31, 1998, were evaluated for eligibility based on inclusion criteria and, if applicable, were offered randomization for fundoplication with or without a 56F bougie. One hundred seventy-one patients were enrolled in this study. INTERVENTIONS: All patients underwent laparoscopic Nissen fundoplication, 81 with a bougie (hereafter referred to as the bougie group) and 90 without a bougie (hereafter referred to as the no bougie group). MAIN OUTCOME MEASURES: Dysphagia severity and frequency were assessed by a blinded observer using a standardized scoring system. Incidence of complications related to the use or absence of a bougie, operative times, and postsurgical recovery was also assessed. RESULTS: The mean operating time was 148 minutes (range, 65-295 minutes). The overall operative morbidity was 9% (7. 4% in the bougie group and 11% in the no bougie group, P=.41). One esophageal injury (1.2%) occurred in the bougie group. The 30-day mortality was 0. Long-term dysphagia assessment was completed in 90% of patients, with a mean follow-up of 11 months. Overall, long-term postoperative dysphagia was present in 13 patients (17%) in the bougie group and 24 patients(31%) in the no bougie group (P=.047). Severe dysphagia occurred in 5% of patients in the bougie group and 14% in the no bougie group. CONCLUSION: This study confirms the dogma that use of a large-caliber stent during the creation of a fundoplication decreases the long-term incidence of dysphagia; albeit at the risk of injury from the introduction of a bougie.

Adult↗
PubMed2000

Blood donation.

Explore the source record for details and available documents.

Blood Donors↗
PubMed2000

Laparoscopic placement of a continuous hepatic artery infusion pump.

Regional liver infusion chemotherapy has been used for several decades in the treatment of isolated hepatic metastases from colorectal cancer. Although implantation of infusion pumps has traditionally required a laparotomy, minimally invasive techniques have been used recently in an attempt to reduce the morbidity resulting from pump placement. This report describes a technique for laparoscopic pump placement and presents the investigators' results with this technique.

Antineoplastic Agents↗
PubMed1999

Radiofrequency ablation lesions in a pig liver model.

BACKGROUND: Radiofrequency (RF) ablation has been reported as a means of liver tumor destruction. This study evaluates the use of ultrasound monitoring of radiofrequency lesion creation and describes the morphology, histologic characteristics, and vascular effects of radiofrequency ablations in a pig liver model. MATERIALS AND METHODS: Hemodynamic monitoring was established and laparotomies were performed in 50-kg pigs. Under ultrasound guidance, radiofrequency needle probes were placed in the liver at predetermined locations. Radiofrequency energy was applied over 15 min to generate lesions 3 cm in diameter. Eighty lesions were generated in 10 animals. At the completion of the experiment, the lesions were examined with ultrasound and then excised for CT, gross, and histologic examination. RESULTS: There were no adverse systemic effects. Ultrasound imaging demonstrated the size, shape, and position of the lesions. Gross examination demonstrated a core of ablated tissue with a surrounding 1- to 2-mm hemorrhagic perimeter. Lesion volumes averaged 12.8 cc(3) (range 5-34 cc(3)). Final lesion shape and size were frequently altered by the cooling effect of local blood flow. Histologic stains demonstrated microvascular thrombosis and coagulative necrosis within the lesions. There appeared to be 100% cellular destruction within the lesion by cytochemical staining. CONCLUSIONS: We demonstrated that RF ablation is capable of killing large volumes of normal liver tissue; however, local vasculature plays a significant a role in defining the ultimate size and shape of the lesion created. This may interfere with the utility of radiofrequency ablation as a modality for local tumor control.

Animals↗
PubMed1999

Factors predictive of dysphagia after laparoscopic Nissen fundoplication.

BACKGROUND: Persistent postoperative dysphagia occurs in up to 24% of patients who undergo a laparoscopic Nissen fundoplication for reflux disease [7]. We hypothesized that patient history, pH testing, and esophageal manometry could be used to preoperatively identify patients at risk for this complication. METHODS: Of 156 laparoscopic Nissen fundoplications performed over a 27-month period, we identified 19 patients (12%) who suffered from postoperative dysphagia longer than 3 months. The presenting complaint of preoperative swallowing difficulty was noted as was the presence of a known esophageal stricture. Preoperative pH testing and esophageal manometry were performed for all subjects. We compared the following parameters to an age and gender-matched control group: history of esophageal stricture, presence of preoperative dysphagia, DeMeester reflux score, upper esophageal sphincter pressure and relaxation, esophageal body motility, location of respiratory inversion point, and lower esophageal sphincter length, resting pressure, and relaxation. Data were compared via t-test and Fisher's exact test. RESULTS: Patients who presented before surgery with complaints of difficulty swallowing were more likely to suffer from postoperative dysphagia (p = 0.029). Incidence of stricture, DeMeester score, and manometric measurements did not differ between the dysphagia and control groups (p > 0.05 for all parameters). CONCLUSIONS: Although preoperative studies are not helpful in identifying patients at risk for persistent dysphagia after laparoscopic Nissen fundoplication, patients presenting with the preoperative complaint of difficulty swallowing are at increased risk for this complication.

Deglutition Disorders↗
PubMed1999

Clinical short-term results of radiofrequency ablation in primary and secondary liver tumors.

BACKGROUND: Radiofrequency ablation (RFA) is emerging as a new therapeutic method for management of solid tumors. We report here our experience in the use of this technique for management of primary and secondary unresectable liver cancers. METHODS: Thirty-five patients with liver cancers were considered not suitable for curative resection at presentation: 8 with primary hepatocellular carcinoma ([HCC] 6 HCC and 2 fibrolamellar); 27 with metastatic liver cancer (17 colorectal carcinoma and 10 others). They were treated either with radiofrequency heat ablation (Radionics Europe N.V., Wettdren, Belgium) alone percutaneously and/or intraoperatively or in conjunction with surgical resections. The quality of RFA was based on the subjective feeling of whether the tumor was completely destroyed or not. The effectiveness of RFA was assessed according to clinical findings, radiographic images, and tumor markers at follow-up. RESULTS: In 8 primary liver cases, 4 patients with a high level of alpha fetoprotein (AFP) benefited from the RFA with a 83.3% to 99.7% reduction of AFP. One with fibrolamellar hepatocellular carcinoma died 2 months after an incomplete percutaneous RFA from recurrence. The rest all had stable disease at the time of follow-up (mean 10.4 months). In patients with colorectal liver metastases, there were 4 deaths: 1 patient died postoperatively on the 30th day from a severe chest infection having shown a considerable reduction of carcinoembryonic antigen level (CEA, 8 versus 36 microg/L); 3 died from local and systemic disease, 1 at 12 months and 2 at 1 month, having had an incomplete RFA. The others had stable disease at follow-up (mean 7.6 months). Five patients underwent liver resections successfully with the application of RFA for residual lesions in the remaining contralateral lobe. In 10 patients with other liver tumors, 7 patients had stable disease at follow-up (mean 13.4 months); 1 patient had evidence of local and systemic recurrence 10 months after surgical resections with the intraoperative RFA and 2 patients died of systemic recurrence of disease 3 and 6 months after RFA alone. Two patients had liver resections in conjunction with the intraoperative RFA. The mean follow-up in our series was 8.5 months. CONCLUSION: Radiofrequency heat ablation is useful as a primary treatment for unresectable liver cancers. The procedure can be used to treat the small residual tumor load in the contralateral lobe following liver resection in those considered unresectable at the first presentation. This new therapeutic strategy seems to increase surgical resectability in patients judged unresectable.

Carcinoembryonic Antigen↗
PubMed1999

Duodenal leiomyosarcoma.

Malignant stromal tumours of the duodenum are rare. The efficacy of surgical resection for duodenal leiomyosarcoma was assessed in 5 patients treated over an 11-year period, probably the largest series treated by a single surgeon. There were 3 women and 2 men with an age range of 27-52 years. Tumours were large (8.5-21 cm diameter) and partly cystic (4 cases). They arose from the second (2), third (2) and fourth parts of the duodenum. Resection was a major undertaking and comprised either partial duodenectomy (n = 4) or Whipple resection. Two patients required a right hemicolectomy in addition. Two patients with positive resection margins had adjuvant radiotherapy. Operative time ranged from 4.0 to 6.25 h and blood loss from 1.8 to 4.5 litres. Two patients developed complications: a transient low-output biliary fistula and an infected haematoma requiring percutaneous drainage. The 2 patients with incomplete resection died of recurrent disease at 3 and 15 months. The 3 survivors are free of disease at 24, 60 and 66 months. The results support a policy of aggressive resection despite the technical difficulties posed by these large and vascular tumours.

Adult↗
PubMed1997

New biosensors for environmental analysis.

Environmental analysis requires fast and reliable measurement results. Biosensors, which facilitate integral monitoring as well as single substance analysis, achieve high sensitivities in a minimum of measuring time. Four new on-line biosensors, which cover a wide range of environmentally relevant substances, are introduced: A water-quality monitoring bacteria electrode, whose gradual development is described as an example, a heavy-metal screening urease inhibition sensor, a genotoxic potential as well as a immunotoxic potential indicating sensor. Future prospects are given.

Biosensing Techniques↗
PubMed1997

Evaluation of laparoscopic Toupet fundoplication as a primary repair for all patients with medically resistant gastroesophageal reflux.

BACKGROUND: This prospective study assesses the outcome results in 100 consecutive patients with gastroesophageal reflux disease (GERD) treated with a laparoscopic Toupet fundoplication. METHODS: GERD was confirmed by 24-h pH study and/or esophagogastroduodenoscopy (EGD). Pre- and postoperative symptoms, operative times, and perioperative complications were recorded on standardized data forms. Early follow-up was at 3 months and late follow-up, including 24-h pH, manometry, and EGD was at 22 months. RESULTS: Preoperative symptoms included heartburn (92%), regurgitation (58%), water brash (39%), and dysphagia (39%). Mean operative time was 3.2 hours. There were no conversions to celiotomy and there were no mortalities. The perioperative complication rate was 14%; 6% (5/83) of patients reported heartburn at 3 months and 20% (15/74) at 22 months. Early and late dysphagia was 20% (17/83) and 9% (7/74), respectively; 24-h pH testing was abnormal in 90% of symptomatic patients (9/10), 39% of asymptomatic patients (12/31), and 51% overall. CONCLUSIONS: Despite early improvement in reflux symptoms following laparoscopic Toupet fundoplications, there is a high incidence of recurrent GERD. Symptomatic follow-up underestimates the true incidence of 24-h pH-documented reflux. Based on these results we cannot recommend the laparoscopic Toupet repair for GERD patients with normal esophageal motility.

Adult↗
PubMed1997

Laparoscopic thermal ablation of hepatic neuroendocrine tumor metastases.

BACKGROUND: Neuroendocrine tumor metastases to the liver are generally slow growing, but patients suffer from hormone hypersecretion despite aggressive multimodality therapy. A minimally invasive method of tumor ablation affords symptomatic improvement with minimal morbidity. METHODS: Radiofrequency electrical energy is delivered to tissues via a 4-prong catheter resulting in tissue heating to 60 to 70 degrees C and cell death. Porcine studies were conducted to define appropriate parameters for energy delivery and then applied to patients using laparoscopic techniques. RESULTS: In the porcine model 3.5 to 4 cm lesions were reproducibly created in 15 minutes using 30 to 50 W of power. The ablation process was monitored via temperature feedback from thermocouples in the catheter tips and by a hyperechoic blush noted on ultrasonography. Laparoscopic thermal ablation of 13 tumors in six patients with carcinoid (two patients), gastrinoma, insulinoma, nonsecreting islet cell cancer, or medullary thyroid cancer was performed. There were no intraoperative complications, and all patients were discharged the next day. Successful ablation was confirmed by spiral-computed tomography and by symptomatic improvement in patients with secreting tumors. CONCLUSIONS: Laparoscopic thermal ablation of hepatic tumors is a novel, minimally invasive method of providing effective cytoreduction of neuroendocrine tumors metastatic to the liver.

Aged↗
PubMed1997

Age-related differences in performance of stereotype arm movements: movement and posture interaction.

Postural destabilizations in response to cyclic pull-and-push arm movements were compared in young and elderly subjects, with the goal of determining how age-related differences in postural stability influence strategies of cyclic arm movements made at different speeds, against different loads and while standing on support surfaces of different compliances. The results show that elderly subjects performed the experimental task more slowly with a lower mean movement frequency and a smaller amplitude. Despite of this fact, the elderly's upright posture was destabilized by this movement to a greater extent than in young subjects. The older adults exhibited lower damping of the disturbing torques produced by arm movements as evidenced by a higher amplitude of the center of foot pressure excursions. The results document close reciprocal motor and posture interaction and indicate that parameters of the voluntary movement task such as cyclic arm movements might be used as a sensitive measure of postural stability.

Adult↗
PubMed1996

Effectiveness of water exercise on postural mobility in the well elderly: an experimental study on balance enhancement.

BACKGROUND: The fear of falling may cause elderly people to limit their movement. As movement errors are known to facilitate the acquisition of motor skills, the elderly may inadvertently cause the loss of postural skills by constraining their movements, and hence avoid potential movement errors. It was hypothesized that by having elderly individuals exercise in a risk-free environment-water was utilized in this experiment-their postural capabilities would improve. METHODS: Four groups of elderly subjects (80 +/- 5.8 years old) were placed into four groups: Water Exercisers; Land Exercisers; Water Sitters; and Land Sitters. Each group met twice per week for 45 minutes for 5 weeks of simple exercises or socializing in the designated medium. The distance each individual could reach (Functional Reach, FR) was measured at the end of each week. RESULTS: Initially, each group was at risk (FR < 10 inches) for falling Statistical testing showed that the Water Exercisers (WE) increased their FR almost every week; the Land Exercisers (LE) increased only during the first week; and the Water Sitters (WS) and Land Sitters (LS) did not increase at all. The FRs after 5 weeks were 13.4 +/- 1.6 (WE), 11.3 +/- 1.5 (LE), 9.6 +/- 1.3 (WS), and 9.3 +/- 0.71 (LS) inches for each group, respectively. CONCLUSIONS: The data showed that the postural capabilities in these elderly people, as measured by the FR, were enhanced by the production of movement errors that was facilitated in a water environment (in the case of the Water groups) or the initiation of a novel exercise program (Land Exercisers). Alternative explanations, and implication of these results, are discussed.

Accidental Falls↗
PubMed1995

Decreased incidence of scoliosis in hearing-impaired children. Implications for a neurologic basis for idiopathic scoliosis.

STUDY DESIGN: A retrospective survey of the incidence of positive scoliosis screenings in schools for the hearing impaired was performed. OBJECTIVES: The incidence rate of scoliosis in a population with a high incidence of vestibular dysfunction was compared with the national normative incidence rate. The comparison was done to investigate the contribution of the vestibular system to scoliosis. SUMMARY OF BACKGROUND DATA: Several reports have emphasized a possible neural etiology to idiopathic scoliosis. Based on the experimental hypothesis that an altered vestibular processing is critical for the production of scoliosis, 100 schools for the hearing impaired were surveyed to determine their incidence of positive screenings for scoliosis. Because it is known that hearing-impaired children have a high incidence of vestibular dysfunction, it was hypothesized that their screening incidence would change if the vestibular system contributed to idiopathic scoliosis. METHODS: Surveys were sent to 100 schools for the hearing impaired asking for their most recent scoliosis screening data. RESULTS: Of the 40 surveys returned, 28 schools for the hearing impaired conducted routine scoliosis screenings, of which 17 had demographics representative of the national norms. Of the 3127 students screened at these 17 schools, 1.2% of the students screened positive for scoliosis. This is significantly less than national incidence rate of 4%-10%. CONCLUSION: The results suggested that hearing-impaired students may be a population that is protected from idiopathic scoliosis by a neural dysfunction. These data strongly suggest that idiopathic scoliosis has a neural etiology.

Adolescent↗