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Biomedical subjects

A Falk

Publications and source records attributed to A Falk.

At least 19 recordsLinked to original sources
PubMed2006

Obstructive jaundice due to isolated tuberculosis of the pancreas: endoscopic treatment instead of surgery?

The optimal treatment for relieving biliary obstruction due to isolated pancreatic tuberculosis has not so far been defined, and most previously reported patients were treated surgically. We describe a 17-year-old, immunocompetent girl who was admitted with obstructive jaundice caused by a tuberculous mass in the head of the pancreas. Antituberculous therapy alone failed to alleviate the jaundice, and she was therefore treated by stent insertion and, subsequently, balloon dilation of the common bile duct stricture. At follow-up 5 years later, magnetic resonance cholangiopancreatography showed no evidence of stricture in the common bile duct.

Adolescent↗
PubMed2005

Conversion of temporary hemodialysis catheters to tunneled hemodialysis catheters.

PURPOSE: To determine the feasibility and clinical outcomes of conversion of temporary to tunneled hemodialysis catheters using the same venous insertion site. METHODS: Data from 42 patients with existing temporary hemodialysis catheters referred for placement of tunneled hemodialysis catheters were retrospectively reviewed. In these patients, the temporary catheter was exchanged for a peel-away sheath, and a tunneled catheter was inserted using the existing venous access site. Technical success, procedural complications, and clinical outcomes were evaluated. Hemodialysis records were reviewed to assess catheter patency during a 30-day follow-up period. RESULTS: The study group consisted of 20 males and 22 females (mean age: 58 years). All 42 temporary catheters were successfully converted to tunneled hemodialysis catheters without immediate procedure-related complications. Follow-up data were available for 32 patients (total: 3038; median 71 catheter days). Nine catheters were removed for infection, yielding a catheter infection rate of 0.30/100 catheter days; three catheters were removed for blood flow <200 ml/min. 13 patients had catheters removed when catheters were no longer needed. Three patients died with working catheters. The patency rate was 72% at 30 days, with four catheters functioning at the end of the study period. CONCLUSION: Conversion of a temporary hemodialysis catheter to a tunneled hemodialysis catheter using the same venous insertion site is a safe procedure that avoids complications associated with venotomy and allows conservation of other central venous access sites. Patency and infection rates in these catheters are comparable to several studies of catheter exchange and de novo placement of tunneled hemodialysis catheters.

Adolescent↗
PubMed2004

Efficacy of reteplase in poorly functioning hemodialysis catheters.

AIM: This is a retrospective study of reteplase efficacy for restoration of flow in occluded and poorly functioning hemodialysis catheters. PATIENTS AND METHODS: From May 1, 2001 to December 31, 2001, all hemodialysis patients seen at our university dialysis center with occluded or poorly functioning (< 200 ml/min blood flow) catheters treated with reteplase were included in the study. All catheters had been in place for more than 48 hours. Reteplase 0.4 U was instilled into each port; dwell time was 30 minutes. If aspiration had not been possible, reteplase had remained in the catheter for an additional 30 minutes. If flow was established (> 200 ml/min), the catheter was used for dialysis. If flow was not adequately established after 1 hour, the patient was referred for catheter exchange. RESULTS: Reteplase (0.4 U) was used in 50 instances to restore or improve blood flow rates in a total of 23 catheters in 19 patients. Reteplase was effective in establishing adequate blood flow rates during the current and next dialysis session in 44/50 (88%) cases; 6 cases required 1-hour dwell time. Six cases (in 5 patients) required catheter exchange; in these, an anatomic or pathologic complication was responsible for catheter malfunction. No adverse events were related to reteplase instillation during the study. CONCLUSION: Data suggest that reteplase is safe and effective in restoring flow to malfunctioning hemodialysis catheters. Results are comparable to those achieved with alteplase.

Adolescent↗
PubMed2003

Recurrent pancreatitis as a late complication of endoscopic sphincterotomy for common bile duct stones: diagnosis and therapy.

Although long-term complications of endoscopic sphincterotomy (ES) have often been reported, the possible effects of the procedure on the pancreatic duct orifice remain virtually unknown. Three women patients are described who developed attacks of recurrent pancreatitis at 2, 7, and 27 months after ES for bile duct stones. The attacks were apparently caused by a partial stenosis of the pancreatic orifice, arising from post-procedure fibrosis and scarring. The patients were evaluated and treated endoscopically. All three patients benefited from endoscopic therapy; two became symptom-free and one improved. Symptoms recurred in the three patients, after 26, 41, and 23 months. In one patient, re-stenosis was documented and repeat sphincterotomy resulted in complete relief of symptoms during the ensuing 5 months. In the remaining two patients, the symptoms were mild and no further intervention was needed. Concerning complications, one patient suffered a moderately severe pancreatitis without sequelae. Recurrent pancreatitis may emerge as a late complication after ES for common bile duct stones. It is probably causally related to stenosis of the pancreatic orifice brought about by fibrosis and scarring, which may exceptionally develop after the procedure. Endoscopic therapy should probably be considered in the first instance, but the optimal treatment for this condition remains to be determined.

Aged↗
PubMed2003

Treatment of "swing point stenoses" in hemodialysis arteriovenous fistulae.

AIM: This is a retrospective study of percutaneous transluminal balloon angioplasty (PTA) efficacy for treatment of surgical vein mobilization site ("swing point") stenoses in hemodialysis arteriovenous fistulae (AVF) that fail to mature or are poorly functioning. METHOD: Between February 1, 1999, and February 28, 2001, 65 non-maturing or poorly functioning AVF were studied in 63 consecutive hemodialysis patients (30 male, 33 female, aged 26-92 years). All AVF underwent contrast angiography to study the inflow artery, AVF, outflow and central veins. PTA of stenotic sites was performed to initiate or restore AVF function. RESULTS: Seventy-eight venous and 2 arterial stenoses were found and treated with PTA in the 65 AVF. All PTA were technically successful. A total of 55 stenoses were identified in the vein at the site of surgical mobilization ("swing point"). Additionally, 19 cephalic and 4 central venous stenoses were found. During the study, 13 AVF underwent repeat PTA at the "swing point". Of the 65 AVF treated, 50 were being successfully used as an access site, 4 AVF were lost during follow-up (34-688 days; mean: 258 days) and 8 patients died within the study period. The duration of functional patency of the treated AVF was 39-660 days (mean: 280 days). CONCLUSION: Non-maturing or poorly functioning AVF frequently have stenoses in the outflow vein at the original site of surgical vein mobilization. These "swing point stenoses" are amenable to PTA, which is a safe and effective treatment for prolonging AVF patency and function.

Adult↗
PubMed2003

One-week esomeprazole treatment: an effective confirmatory test in patients with suspected gastroesophageal reflux disease.

BACKGROUND: Symptomatic response to acid inhibition can be used as a guide in diagnosing patients with reflux symptoms. The proton-pump inhibitor (PPI) omeprazole has been used as such a diagnostic tool. Intragastric acid control with esomeprazole is more effective than other PPIs and has the potential to offer an advance in the diagnostic use of PPIs. METHODS: Patients experiencing heartburn (for > or = 6 months) were studied in this randomized, double-blind, multicenter study. Following a 3-day placebo run-in, 440 patients were randomized to 14 days' treatment with esomeprazole 40 mg once daily (o.d.), esomeprazole 20 mg twice daily (b.i.d.) or placebo. Heartburn symptoms were recorded daily. Endoscopy and 24-h esophageal pH-monitoring were performed to determine the presence of gastroesophageal reflux disease (GERD). The esomeprazole treatment test was considered positive if patients' symptoms improved during the treatment period compared with symptoms recorded on Day 0. RESULTS: 63 patients were excluded from the analysis due to lack of symptoms on Day 0 or failure to complete pH-monitoring. The sensitivity of an esomeprazole treatment test in confirming GERD increased during the first days of treatment and stabilized between 79% and 86% after 5 days (both esomeprazole arms). The corresponding figure for the placebo arm was 36%. Specificity was variable (24%-65%) for both active treatment and placebo. CONCLUSION: A treatment test with esomeprazole 40 mg has a high sensitivity in confirming GERD. Furthermore, the data indicate that 1-week treatment with a once-daily dosage is sufficient to ensure adequate diagnosis.

Adult↗
PubMed2002

Obese and non-obese hemodialysis patients have a similar prevalence of functioning arteriovenous fistula using pre-operative vein mapping.

AIMS: The arteriovenous fistula (AVF) is the preferred hemodialysis access. Subset analyses of both the HEMO and DOPPS studies have shown that obese hemodialysis patients have a lower prevalence of functioning AVF. Doppler ultrasound may increase the prevalence of functioning AVF in obese subjects. PATIENTS AND METHODS: The effect of pre-operative vein mapping employed between 10/01/98 and 12/08/00 on the prevalence of functioning AVF in a single university hemodialysis program was studied. Preoperative ultrasound was performed to study venous and arterial systems on both arms. RESULTS: There were 50 obese patients, defined as bodymass index (BMI) > or = 27 kg/m2, and 130 patients with a lower BMI. The groups were similar in mean age and diabetes prevalence. The obese group had statistically significantly more females 34/50 versus 61/130 with p = 0.01. There was no statistically significant difference between the vein mapping parameters studied in the two BMI groups, including mean mid-forearm cephalic vein diameter, distal radial artery peak systolic velocity and subclavian vein patency. No obese patient required venography. There was no significant difference between the number of functioning AVF in both groups (22/50 obese, 48/130 lower BMI, p = 0.24). CONCLUSIONS: Pre-operative vein mapping is associated with a similar prevalence of functioning AVF in obese and lower BMI patients. Pre-operative ultrasound screening is a useful tool to promote AVF placement in obese patients.

Adult↗
PubMed2001

Reteplase in the treatment of thrombosed hemodialysis grafts.

PURPOSE: To prospectively evaluate the efficacy and safety of reteplase with percutaneous transluminal angioplasty (PTA) in the treatment of thrombosed polytetrafluoroethylene hemodialysis arteriovenous grafts (AVGs). MATERIALS AND METHODS: Forty-two patients were entered into the study. Sixty-two procedures in 43 grafts were performed. One unit of reteplase and 4,000 units of heparin were administered into the AVGs. Routine venography and percutaneous transluminal angioplasty (PTA) was then performed. Patients were transferred for hemodialysis immediately after the procedure. RESULTS: Technical success was achieved in 92% of the cases. Four cases involved intentional repeat thrombosis because of poor outflow and/or need for a new graft site. Minor complications occurred in 6.5% of the cases. No major complications occurred. The mean procedure time for experienced versus less-experienced interventionalists was significantly shorter (P <.001). Primary patency rates were 50%, 34%, and 34% at 30, 90, and 180 days, respectively. CONCLUSION: Reteplase in conjunction with heparin and PTA is a safe and effective means of thrombolysis of AVGs. Its efficacy is comparable to that of other available thrombolytic drugs.

Adult↗
PubMed2001

Aortic intimal dehiscence: a complication of percutaneous balloon fenestration for aortic dissection.

A patient with acute type B dissection and a tube configuration of the intimal flap presented with signs of advanced mesenteric and renal ischemia as well as decreased pulses in the lower extremities. The patient was referred for emergency percutaneous fenestration of the abdominal aorta as a salvage procedure and a possible bridge to later surgery. After fenestration, femoral pulses became transiently stronger and then disappeared. The patient died after exploratory laparotomy. Postmortem examination demonstrated dehiscence of the infrarenal abdominal aortic intima with occlusion of the aortic bifurcation.

Acute Disease↗
PubMed2001

Thrombolysis of clotted hemodialysis grafts with tissue-type plasminogen activator.

PURPOSE: To evaluate prospectively the efficacy of treating thrombosed hemodialysis arteriovenous polytetrafluoroethylene (PTFE) grafts using tissue-type plasminogen activator (tPA) and percutaneous transluminal angioplasty (PTA). MATERIALS AND METHODS: Forty-two sequential thrombosed PTFE dialysis grafts in 33 patients presented for declotting. All 42 grafts were treated with a modified lysis and PTA technique with use of 2 mg tPA and 3,000-5,000 U heparin in a total volume of 5 mL, administered into the graft via an angiocatheter. The elapsed time from tPA injection until completion was recorded. Prospective data collection included demographic information, technical details of the procedure, immediate outcomes, complications, and patency rates. RESULTS: Technical success, defined as complete graft recanalization with a palpable thrill after treatment plus successful hemodialysis, was achieved in all cases, except five. These five cases were deliberate graft closures due to inadequacy of the outflow veins to support an arteriovenous graft after successful lysis. Mean lysis time was 40.8 minutes and mean room procedure time after the lysis period was 65.4 minutes. Eight procedure-related complications occurred (two major and six minor). The follow-up period was 4-241 days, with an estimated mean of 157 days. The 30-day and 90-day primary patency rates were 57% and 50%, respectively. CONCLUSIONS: Treatment of thrombosed PTFE dialysis grafts with use of 2 mg tPA and 3,000 U of heparin is safe and effective. Use of this modified lysis and PTA technique allows an expeditious procedure in the angiography suite. However, this technique precludes imaging of the outflow veins before treatment, so that grafts entering diffusely diseased veins may need to be closed after successful lysis.

Angioplasty, Balloon↗
PubMed2001

Hemodialysis access placement with preoperative noninvasive vascular mapping: comparison between patients with and without diabetes.

We retrospectively analyzed data on preoperative vascular mapping in 195 consecutive patients to investigate the common belief that patients with diabetes are poor candidates to have an arteriovenous fistula placed as dialysis access because they lack suitable blood vessels. There was no difference in venous diameter, arterial diameter, and arterial peak systolic velocity measurements between patients with and without diabetes. Patients with diabetes had a greater prevalence of vascular calcifications and greater cuff measurements of systolic segmental arterial pressure. In 140 of 195 patients, subsequent vascular access surgery had been performed in our institution, and 127 of these patients were on hemodialysis therapy at the end of the study period. There was no difference in the prevalence of fistula placement (66% versus 60%; chi-square = 2.6; df = 2; P = 0.28, not significant [NS]) and percentage of functioning fistulae between patients with and without diabetes (67% versus 62%; chi-square = 0.27; df = 1; P = 0.61, NS). The percentage of patients dialyzed through a temporary catheter was equal in patients with and without diabetes (18%). In summary, patients with diabetes seem to be as good candidates for arteriovenous fistula placement as patients without diabetes. Additional studies are required to determine the long-term outcome of fistulae in patients with diabetes.

Arteries↗
PubMed2001

[Word generation in bilinguals--fMRI study with implications for language and memory processes].

For over a century the cerebral representation of language functions is a matter of debate. In Neuroscience language is regarded as one of the most lateralized cognitive functions. Thus, while the language which is acquired first in most cases is processed by the left hemisphere some studies in brain damaged but also experimental investigations propose a pivotal role of the right hemisphere in second language processing. By the advent of modern neuroimaging it is now possible to study language lateralization and bilinguality also in healthy subjects. We studied first and second language abilities in a group of bilingual, healthy individuals by means of functional magnetic resonance imaging (fMRI) with a word-fluency paradigm. While we found a predominantly left prefrontal activity during both first and also second language processing an additional right prefrontal activation was registered during the use of second language. Our findings are discussed on the basis of an interaction between language and memory processes.

Adult↗
PubMed2000

[Pure titanium as bone substitute. Geometric and substance-specific aspects of computer-assisted fabrication and follow-up imaging].

Computer-assisted prefabricated skull implants of pure titanium as a bone replacement material have been used in 22 departments since 1994. Our experience with 104 implants includes clinical aspects (indication; tissue quality; surgical technique; patient guidance), but also geometric and material-specific parameters (acquisition, transfer, and evaluation of CT data; construction; manufacturing; cleaning; postoperative use of radiologic techniques). While the clinical aspects are responsibly defined by the respective surgeon, the geometric and material-specific parameters of individual implants have to comply with the laws on medical products. Therefore, the prospective documentation for each implant includes: helical CT acquisition parameters; geometric data of the computer-based skull model and implant; the cleaning procedure; and the individual marking. Medically specified pure titanium is processed by milling only so that neither purity nor structure is impaired. A specially developed milling technique guarantees the fabrication of all constructed elements down to fine details of 50 microns. Considering the necessary radiologic follow-up of defects after tumor surgery, all patients in our hospital undergo postoperative MRI examination, partly with preoperative documentation as an intraindividual control. Such comprehensive documentation and quality assurance is essential for techniques of prefabricated bone substitution. Hand in hand with scientific research and clinical application, these formal criteria have to be elaborated and fulfilled for the respective techniques. The successful determination of specifically adapted MRI sequences goes even one step further: spin-echo sequences minimize inhomogeneities of the magnetic field induced by the titanium implants and enable accurate postoperative documentation and diagnostics especially in the follow-up after tumor surgery.

Bone Substitutes↗
PubMed2000

Endovascular grafts in the treatment of thoracic aortic aneurysms and pseudoaneurysms.

The purpose of this study was to describe our experience with balloon and self-expanding endovascular grafts for the management of thoracic aortic lesions. Between February 1997 and June 1998, 20 endovascular grafts were implanted in 14 patients for the treatment of thoracic aortic aneurysms and pseudoaneurysms. Endovascular procedures were performed using one of four different devices: (1) Dacron-covered balloon-expandable Palmaztrade mark stent, (2) balloon-expandable Palmaz stent-PTFE graft prosthesis (BE-PS), (3) self-expanding internally supported Nitinol Dacron prosthesis (Vanguardtrade mark SE-V), and (4) self-expanding externally supported Nitinol PTFE prosthesis (Excludertrade mark SE-E). The results show that endovascular grafting represents a potentially important alternative therapy to open repair of the thoracic aorta. Self-expanding devices were, in our experience, easier to use and more accurately deployed.

Adult↗
PubMed2000

[CT perfusion imaging in acute ischemic cerebral infarct: comparison of cerebral perfusion maps and conventional CT findings].

PURPOSE: To evaluate the findings of acute brain ischemia on different functional maps of cerebral perfusion CT in stroke patients and to compare the results with early ischemic changes on conventional CT. METHODS: The baseline CT scans of 45 acute stroke patients were retrospectively evaluated with respect to early CT findings. For each patient the extent of cerebral ischemia as shown on the maps of cerebral blood flow (CBF), cerebral blood volume (CBV), and "time to peak" (TP) was compared and the severity of ischemia was assigned to one of three levels based on the findings of the CBF image. RESULTS: In 75% of all patients conventional CT was performed within 2 hours from symptom onset. 29 of 45 patients showed early signs of ischemia on conventional CT, whereas perfusion CT revealed cerebral ischemia in all patients. Severe ischemia was found in approximately the same rate of incidence in patients with early CT changes (55.2%) and in those with normal findings (43.8%). If the perfusion impairment was judged as mild or moderate the extent of the hypoperfused area was significantly larger on the CBF and TP images than on the CBV map. This was significantly different in patients with severe hypoperfusion where a complete correspondence of the affected area between the three functional maps was found. DISCUSSION: The use of conventional CT for the assessment of stroke in the hyperacute phase is limited. Perfusion CT yields excellent information regarding the severity and extent of ischemia. The use of various perfusion maps helps to differentiate the core of infarction from the ischemic penumbra zone.

Acute Disease↗
PubMed1999

EDS1, an essential component of R gene-mediated disease resistance in Arabidopsis has homology to eukaryotic lipases.

A major class of plant disease resistance (R) genes encodes leucine-rich-repeat proteins that possess a nucleotide binding site and amino-terminal similarity to the cytoplasmic domains of the Drosophila Toll and human IL-1 receptors. In Arabidopsis thaliana, EDS1 is indispensable for the function of these R genes. The EDS1 gene was cloned by targeted transposon tagging and found to encode a protein that has similarity in its amino-terminal portion to the catalytic site of eukaryotic lipases. Thus, hydrolase activity, possibly on a lipid-based substrate, is anticipated to be central to EDS1 function. The predicted EDS1 carboxyl terminus has no significant sequence homologies, although analysis of eight defective eds1 alleles reveals it to be essential for EDS1 function. Two plant defense pathways have been defined previously that depend on salicylic acid, a phenolic compound, or jasmonic acid, a lipid-derived molecule. We examined the expression of EDS1 mRNA and marker mRNAs (PR1 and PDF1.2, respectively) for these two pathways in wild-type and eds1 mutant plants after different challenges. The results suggest that EDS1 functions upstream of salicylic acid-dependent PR1 mRNA accumulation and is not required for jasmonic acid-induced PDF1.2 mRNA expression.

Amino Acid Sequence↗