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Biomedical subjects

P Gerhardt

Publications and source records attributed to P Gerhardt.

At least 19 recordsLinked to original sources
PubMed2001

Options for investigative postsurgical therapy for gastric cancer, and case report of using the option for combined immunotherapy and chemotherapy.

The investigative therapy for a senior patient after radical subtotal gastroesophagectomy for regional lymph node and proximal esophagus metastasized adenocarcinoma (stage IIIA, T3, N 1 M0) of the cardioesophageal junction is reported. The case has several unusual features: (1) the patient is the author and is not a physician; (2) in the absence of codified postsurgical treatment, he used his academic biomedical background, commercial associations, and international contacts to find and prioritize six clinically tested options for investigative postsurgical therapy; (3) after unsuccessful efforts to append ongoing clinical trials of new immunotherapies for breast adenocarcinoma (the first two therapy options), an innovative protocol was designed and gained allowance by the U.S. Food and Drug Administration for his use of combined nonspecific immunotherapy and chemotherapy based on extensive trials in South Korea that showed the synergistic effect of the two postsurgical therapies used together. A potent, new, nonspecific immunostimulant (DetoxPC) was injected subcutaneously in 10 diminishing doses during 105 weeks. Two standard chemotherapeutic drugs (5-fluorouracil and mitomycin-C) were injected intravenously in six equal doses during three weeks. Five years after the surgery, the patient enjoys good health without signs or symptoms of recurrence or metastasis. He discusses his perspectives on future clinical trials and on a patient actively pursuing investigative postsurgical therapy for a malignancy when otherwise poor survival is indicated.

Adenocarcinoma↗
PubMed2000

[Functional MR-pancreatography with secretin. A comparison of imaging quality and diagnostic value].

PURPOSE: The aim of the present study was to assess imaging improvement and diagnostic value of secretin stimulated MR-pancreatography (MRP) compared to conventional MRP. MATERIALS AND METHODS: 50 patients were studied with a 1.0 T system using a single-shot-TSE sequence (RARE). Imaging quality and diameter of the different parts of the pancreatic tract and diagnoses were monitored before and after secretin. RESULTS: The visualization of the normal main pancreatic duct (MPD) was improved significantly in head, body and tail. Side branches were not depicted at all. Even in chronic pancreatitis a significant improvement of imaging quality could be observed, but only in patients without duct dilation before secretin. In advanced disease with duct dilation, secretin stimulation provided no further diagnostic improvement. CONCLUSIONS: In conclusion, secretin increases the diagnostic value of MRP especially in patients with normal or non-dilated native MPD and may help to avoid unnecessary invasive procedures such as ERCP.

Adolescent↗
PubMed2000

Endoscopic ultrasound criteria for vascular invasion in the staging of cancer of the head of the pancreas: a blind reevaluation of videotapes.

BACKGROUND: It has been claimed in several prospective studies that endoscopic ultrasonography (EUS) is highly accurate in the locoregional staging of pancreatic cancer. However, the value of the EUS criteria for the diagnosis of vascular involvement is less well established. To totally exclude potential bias introduced by the availability of prior information, a completely blinded analysis of videotapes of patients with cancer of the pancreatic head was therefore conducted. METHODS: Videotape sequences of 75 patients with cancer of the head of the pancreas with surgical confirmation or unequivocally positive angiography demonstrating vascular invasion were reevaluated without any clinical data or information from other imaging studies. Involvement of the vascular system (portal vein with confluence, superior mesenteric vein, celiac axis) was assessed on EUS with special emphasis on EUS parameters of the tumor-vessel relationship. RESULTS: The overall sensitivity and specificity of EUS in the diagnosis of venous invasion were 43% and 91%, respectively, when using predetermined parameters (visualization of tumor in the lumen, complete obstruction, or collateral vessels). If the parameter "irregular tumor-vessel relationship" had been added to these criteria, the sensitivity would have risen to 62%, but the specificity would have fallen to 79%. The only vascular system that could be properly visualized by EUS was the portal vein/confluence area. The positive and negative predictive values for the single parameters chosen to diagnose portal venous involvement were as follows: 42% and 33% for irregular tumor-vessel relationship, 36% and 34% for visualization of tumor in the vascular lumen, 80% and 28% for complete vascular obstruction, and 88% and 18% for collateral vessels. CONCLUSIONS: In a completely blinded evaluation of the EUS diagnosis of vascular invasion by cancer of the head of the pancreas it was not possible to find suitable morphologic parameters with clinically useful sensitivity and specificity values (over 80%).

Adult↗
PubMed2000

Modern imaging methods versus clinical assessment in the evaluation of hospital in-patients with suspected pancreatic disease.

OBJECTIVE: Various modern imaging procedures such as endoscopic retrograde cholangiopancreatography (ERCP), computed tomography (CT), and endoscopic ultrasonography (EUS) have been shown to be highly accurate in the diagnosis of specific disorders of the pancreas. However, prior information often causes bias in the interpretation of these results. Little information is available concerning the value of these examinations in the primary and differential diagnosis of suspected pancreatic disease-particularly in comparison with clinical evaluation, including laboratory tests and transabdominal ultrasound (TUS). METHODS: Clinical and imaging information (EUS, ERCP, and CT) was collected for 184 inpatients who were referred over a 5-yr period for evaluation of suspected pancreatic disease. On the basis of patient history, laboratory tests, and the results of routine TUS, one gastroenterologist, who was unaware of any of the other procedures or the final diagnosis, made a presumptive clinical diagnosis. CT and ERCP images and EUS videotapes were then analyzed by three different and independent examiners, who had the same clinical information except for the TUS results, but were completely blinded to the results of the other examinations and the patients' diagnoses. The final diagnoses were obtained by surgery, histology, and cytology, plus a follow-up of at least 1 yr (mean 35 months) in all noncancer cases. RESULTS: The final diagnoses were: normal pancreas (n = 36), chronic pancreatitis without a focal inflammatory mass (n = 53) or with a focal inflammatory mass (n = 18), and pancreatic malignancy (n = 77). Clinical evaluation, including ultrasonography, achieved a sensitivity for pancreatic disease of 94% but a specificity of only 35%. The figures for the sensitivity and specificity of the three imaging procedures were 93% and 94%, respectively, for EUS; 89% and 92% for ERCP; and 91% and 78% for CT (p < 0.05 for the specificity of clinical assessment vs all three imaging tests, p > 0.05 for comparison of the three imaging procedures). In the differential diagnosis between cancer and chronic pancreatitis as well as between malignant and inflammatory tumors, there was no difference among clinical assessment and the three imaging tests. CONCLUSIONS: In a group of patients with a high suspicion of pancreatic disease, little additional sensitivity in the diagnosis of pancreatic disease is provided by sophisticated imaging procedures such as EUS, ERCP, and CT, in comparison with clinical assessment including laboratory values and TUS. However, the specificity can be substantially improved. To confirm the diagnosis, one of the three examinations is needed, depending on the suspected disease and local expertise. The imaging procedures should be performed in a stepwise fashion for specific purposes, such as exclusion of pancreatic disease and the planning of treatment in chronic pancreatitis and pancreatic cancer.

Adolescent↗
PubMed1999

[Obstructive sleep apnea syndrome caused by occupational exposure to solvents].

HISTORY AND ADMISSION FINDINGS: A 52-year-old man working in a chemical laboratory was referred with the possible diagnosis of toxic encephalopathy. For 17 years he had been exposed to high concentrations of perchlorethylene and n-butanol vapours which every day had caused acute symptoms of organic solvent intoxication. Current complaints were autonomic nervous system symptoms, loss of concentration and memory, and fatigue in the second half of the day. The patient was obese but in good general condition. INVESTIGATIONS: Neuropsychiatric examination confirmed the reported loss of concentration and planning ability at work. The polysomnogram indicated an increased number of largely obstructive apnoea attacks. DIAGNOSIS, TREATMENT AND COURSE: As the patients had an obstructive type of sleep apnoea treatment consisted of positive pressure ventilation at night and weight reduction. The occupational exposure to organic solvents was the likely cause. CONCLUSIONS: As the symptoms of encephalopathy and sleep apnoea syndrome overlap, the latter should be considered before an encephalopathy is diagnosed. Because a rare cause of the sleep apnoea syndrome is prolonged and marked occupational exposure to organic solvents this should be asked about in taking the history. If indeed there has been occupational exposure, it should cease at once and be reported.

1-Butanol↗
PubMed1999

Results of a prospective multicenter study for evaluation of the diagnostic quality of an open whole-body low-field MRI unit. A comparison with high-field MRI measured by the applicable gold standard.

OBJECTIVE: To evaluate the diagnostic quality of an open whole-body low-field MRI scanner compared to high-field scanners. MATERIALS AND METHODS: Over a period of 3 months, 401 patients with diseases of the kidney (n = 78), the shoulder (n = 122), the spine (n = 105) and the cerebrum (n = 96) were prospectively evaluated in four participating centers. They all underwent clinical evaluation, low-field and high-field MRI examination and surgical or follow-up confirmation of diagnosis. Clinical, histopathologic, high-field and low-field MRI diagnoses were recorded in standardized questionnaires that were centrally evaluated. Statistical evaluation comprised two parts: ROC analysis assessed accuracy of MRI and clinical diagnoses; furthermore rates of concordance of high- and low-field MRI diagnosis were calculated. RESULTS: We found no statistically relevant difference in high-field MRI diagnosis compared to low-field MRI diagnostic accuracy measured by clinical or surgical gold standard in three of the four regions examined; in cerebral examinations there was a small yet significant advantage for the high-field systems (P = 0.01). CONCLUSION: We conclude that the open low-field scanner we evaluated using clinical and surgical gold standard as reference is able to achieve comparable diagnostic accuracy compared to high-field scanners at lower costs and greater patient comfort. Limitations due to field strength (signal-to-noise ratio, resolution, scan time) seem to be relevant only in a very small number of cases that warrant high-field examination.

Adult↗
PubMed1998

Modulation of memory, reinforcement and anxiety parameters by intra-amygdala injection of cholecystokinin-fragments Boc-CCK-4 and CCK-8s.

This series of experiments examined the effects of the cholecystokinin (CCK) fragments Boc-CCK-4 and CCK-8s on memory, reinforcement and anxiety following unilateral injection into the central nucleus of the amygdala (CeA). In experiment 1, rats with chronically implanted cannulae were injected with CCK-8s or Boc-CCK-4 and were tested on a one-trial uphill avoidance task. Post-trial injection of 20 ng Boc-CCK-4 or 1 ng CCK-8s was found to improve the retention performance, whereas lower and higher doses had no effect. The hypermnestic effects of Boc-CCK-4 and CCK-8s were no longer evident when injection was performed 5 h, rather than immediately, after the learning trial. In experiment 2, the elevated plus-maze was used to gauge anxiogenous properties of intra-amygdala injections of Boc-CCK-4 and CCK-8s in memory-enhancing doses. The treatment with 20 ng Boc-CCK-4 and 1 ng CCK-8s did not influence the number of entries into and time spent on the open and enclosed arms of the maze as well as other anxiety-related behaviors. In experiment 3, possible reinforcing effects of the CCK-fragments were examined. After intra-amygdala injection of Boc-CCK-4 or CCK-8s in memory-enhancing doses the rats were placed into one of four restricted quadrants of a circular open field (closed corral) for a single conditioning trial. Subsequent tests for conditioned corral preference revealed no evidence for reinforcing or aversive effects of the CCK-fragments. In sum, these findings indicate that Boc-CCK-4 and CCK-8s facilitate memory processing upon injection into the CeA without exerting reinforcing or anxiogenous effects.

Amygdala↗
PubMed1998

Concepts of a Web-based open distributed textbook for the multimodal diagnostics of gastrointestinal tumours with MRI, CT and video-endoscopy addressing students of medicine and students of medical informatics as two different target groups.

Multimodal diagnostics of gastrointestinal tumours with MRI, CT and video-endoscopy is a rapidly changing domain. The education at our universities should overcome the obstacles of traditional learning based on paper media and oral lectures with retention rates of 10-30% only. The paper presents the objectives and the results of the design phase of the project ODITEB1-Open Distributed TExt Book, for Computer-Assisted Instruction in the domain mentioned above. The main objective is to produce an electronic interactive textbook in order to shift education to more efficient learning settings with higher retention rates. The main concepts are 1) three-layer architecture (dynamic case layer, intermediate query layer, static instruction layer) 2) case pool distribution 3) active learners experience (interactive exploration of original image data).

Computer-Assisted Instruction↗
PubMed1998

[Progress in diagnostic imaging in the area of the pancreas (CT, MRI, MR-angio, hydro-CT, MR cholangiopancreatography)].

Advances in diagnostic pancreas imaging concern the MRCP and SCT. Both methods must be performed with the best possible strategy. For MRCP, this means the oral application of a superparamagnetic contrast medium and the i.v. injection of SekretolinR. The SCT requires a two-phase technique with sufficient contrast medium and flow after bolus tracking. It is to be expected that MRCP will replace diagnostic ERCP. Although the results of MRI are similar to SCT, it still cannot replace this method due to the considerable costs and long examination times. The diagnostical procedure has to be applied prior to possible stent implantation to avoid artifacts caused by the manipulation.

Cholangiography↗
PubMed1996

MRI of peripheral joints with a low-field dedicated system: a reliable and cost-effective alternative to high-field units?

In the age of health care cost containment new imaging technology has to meet diagnostic requirements as well as economic limitations. In the MR sector new dedicated systems promise reliable diagnostic information at considerably lower costs than whole-body imagers. Within the past 18 months we have examined 2200 patients with acute and chronic lesions of peripheral joints (knee, ankle, foot, elbow, wrist, hand) in a 0.2T dedicated MR system (ARTOSCAN, Esaote Biomedica, Genoa, Italy). We report our experience with this system focusing on its special features, cost-effectiveness and on diagnostic accuracy of low-field MR studies of the knee in correlation with arthroscopy and in comparison with high-field whole-body imagers.

Acute Disease↗
PubMed1996

[Diagnostic radiology in the cost development spectrum in medicine].

Health care costs have risen considerably since 1970 in all industrialized countries. This has several causes: changes in demographic structure, the large number of physicians, increased personnel needs resulting from generous vacation and special leave privileges, wage increases and--last but not least--medical progress. Advances in medical technology are often regarded as one of the main reasons for spiraling costs in health care. Careful analyses reveal, however, that the high costs of imaging services are due to conventional radiography rather than to high-technology (CT, MR) imaging. The legitimate demands for cost reduction have to be met with improved cost efficiency while optimal quality standards must also be maintained. Relevant suggestions, such as generally accepted examination strategies, should be realized with the help of the scientific societies.

Cost Control↗
PubMed1996

Adenocarcinoma of the gastro-esophageal junction: CT for monitoring during neoadjuvant chemotherapy.

OBJECTIVE: A clinical study was performed to assess the diagnostic value of spiral CT for evaluation of response during neoadjuvant chemotherapy (CTx) in patients with adenocarcinoma of the gastro-esophageal-junction (GEJ). Results were compared to those of endoscopy. METHODS AND MATERIAL: Twenty-five patients with histologically proven adenocarcinoma of the GEJ scheduled to undergo neoadjuvant CTx were studied. Before CT examination, 1200 ml of a vanilla flavoured paraffin emulsion were applied orally to the fasting patients and 40 mg BuscopanR or 2 mg glucagon were injected i.v. for hypotonia. Iodine (100 ml) was injected automatically (3 ml/s) and the CT scan was started 10 s after complete administration of CM. For response evaluation to CTx, four standardized parameters were measured by two experienced, blinded radiologists. The results were categorized according to the WHO classification of 1981 and compared to those of endoscopy. RESULTS: In 24 of 25 patients endoscopic and computed tomographic response evaluation showed a close correlation (r = 0.96). CONCLUSION: Spiral CT with negative oral contrast agent is a suitable technique for monitoring of GEJ masses. In combination with standardized metric parameters it offers a quantitative response evaluation in patients with GEJ masses during neoadjuvant CTx.

Adenocarcinoma↗
PubMed1995

Application of 'nose-poke habituation' validation with post-trial diazepam- and cholecystokinin-induced hypo- and hypermnesia.

The present study describes the use of nose-poke habituation as a memory task and demonstrates that it is sensitive to hypo- and hypermnestic pharmacological treatments administered post-trial. Habituation of nose-poke behavior of rats was defined as a reduction in number of nose-pokes compared to baseline. It was measured using a board with 16 holes, to which animals were exposed on 2 consecutive days (baseline and test) for 10 min, respectively. After the first exposure, rats were injected intraperitoneally (i.p.) immediately or with a delay of 2.5 h with doses of diazepam (0.9-4.5 mg/kg) known to be hypomnestic, or cholecystokinin (CCK-8S; 0.2-25 micrograms/kg), which was reported to have memory facilitating effects. An enhancement of habituation in comparison with vehicle controls was interpreted in terms of a hypermnestic effect of the treatment. Conversely, hypomnestic action of the drug treatment was inferred from a reduced habituation. The results show that when diazepam was injected immediately post-trial, the normal reduction in number of nose-pokes during test was prevented, indicative of a failure to habituate presumably due to an amnesia for the baseline/training trial. In contrast, enhanced habituation (facilitation of memory) was induced when CCK-8S was injected immediately post-trial, as reflected by a decrease in number of nose-pokes during test compared to control animals. The effects were not due to enduring proactive effects of the compounds on performance during test, since post-trial injections of diazepam or CCK-8S with a delay of 2.5 h did not have the effects that immediate post-trial injection had.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

[MRI of the knee joint: first results of a comparison of 0,2-T specialized system and 1,5-T high field strength magnet].

PURPOSE: Diagnostic accuracy and image quality of a specialised system for MR examinations of peripheral joints were evaluated. MATERIALS AND METHODS: 20 patients with acute or chronic injuries of the knee were examined using a low-field MR system (0.2 T). For comparison, all patients were also studied with a 1.5 T high field strength magnet and all diagnoses were correlated with arthroscopic findings. RESULTS: We found compatible diagnostic accuracies (cruciate ligaments 90%, menisci 75-90%) and good image quality ratings for the low field system ("good" and "excellent" image quality in 83% of cases). CONCLUSION: The low-field MR-system offers low-cost MR examinations of peripheral joints with good image quality and reliable diagnostic information.

Adult↗