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J Scharf

Publications and source records attributed to J Scharf.

At least 37 records · Page 2Linked to original sources
PubMed1996

A comparison of magnetization prepared 3D gradient-echo (MP-RAGE) sequences for imaging of intracranial lesions.

In a pilot study including 64 patients with different types of brain tumors we investigated four types of MP-RAGE sequences. The sequences differ in the length of the recovery period and the data acquisition mode (sequential vs. centric phase-encoding). The sequence with sequential encoding and a short recovery period provided images that reached the quality and reliability of spin-echo images. The other MP-RAGE sequences failed in providing equivalent information. In particular, a considerable number of small lesions identified in spin-echo images were not detected in MP-RAGE images. The impact of the evolving magnetization on the point spread function was analyzed by performing simulation calculations. It was found that lesions with short T1 times are rendered with low spatial resolution when sequence parameters are not set appropriately. The low overall quality of images obtained by sequences applying centric encoding may be explained by eddy current effects as reported in other recently published studies.

Brain Neoplasms↗
PubMed1996

Cerebral arteriovenous malformations: improved nidus demarcation by means of dynamic tagging MR-angiography.

Our purpose was to further improve the target volume definition for radiosurgical treatment of cerebral arteriovenous malformations (AVMs) by means of dynamic MRA (dMRA) using a blood bolus tagging sequence. We therefore compare this technique with 3D-TOF-MRA and transfemoral high resolution angiography in plain film technique. Twenty patients with angiographically proven cerebral AVMs were investigated by dMRA, TOF-MRA, and conventional angiography during the MR-assisted radiosurgical planning protocol. The patient's head was fixed in an MR-compatible stereotactic device. The different angiography techniques were evaluated by consensus of two radiologists. AVMs were characterized by the number and origin of feeding arteries, the maximum diameter of the AVM nidus, and the venous drainage pattern. Dynamic MRA was able to demonstrate the complete AVM characteristics and hemodynamics in 12 out of 20 patients. In three patients with an AVM nidus smaller than 1 cm in diameter the technique could not reliably depict the malformation. Technical problems due to steel screws and pins in the initially used stereotactic frame occurred in five patients. Due to reduced vessel overlap and the lack of disturbances caused by formations with short T1 time, dMRA was superior to TOF-MRA in the detection and the exact localization of the AVM nidus in four patients. We conclude that dMRA is able to demonstrate reliably AVM characteristics and hemodynamics in AVMs with a nidus larger than 1 cm in diameter. Because of the improved demarcation of the AVM nidus, this technique may be a valuable adjunct to radiosurgery planning of cerebral AVMs.

Adult↗
PubMed1996

Synthesis of insulinlike growth factor binding proteins and of the acid-labile subunit in primary cultures of rat hepatocytes, of Kupffer cells, and in cocultures: regulation by insulin, insulinlike growth factor, and growth hormone.

The adult liver is the main source of circulating insulinlike growth factors (IGFs) and their serum binding proteins (IGFBPs) including the acid-labile subunit (ALS), a component of the ternary binding protein complex. Within the liver, the biosynthesis of individual proteins has been attributed to different cell populations, e.g., that of ALS to hepatocytes and that of IGFBP-3 to nonparenchymal cells. Ligand and immunoblotting as well as Northern blotting analyses were used to study synthesis of IGFBPs and their hormonal regulation in cultured adult rat hepatocytes, Kupffer cells (KCs), and cocultures. In hepatocytes, synthesis of IGFBP-1, -2, and -4 was observed; insulin and IGF-I decreased that of IGFBP-1, and -2 while increasing that of IGFBP-4. KCs synthesized IGFBP-2, and -3, insulin and IGF-I showing no effect. In cocultures, however, synthesis of IGFBP-3 was stimulated by insulin and IGF-I. By immunocytochemistry IGFBP-3 biosynthesis was localized to KCs exclusively. When pore membranes were used for separation of hepatocytes and KCs in coculture, this insulin-stimulatory action on IGFBP-3 synthesis was preserved. Growth hormone (GH) did not affect biosynthesis of IGFBPs. Expression of ALS was localized in hepatocytes only. Insulin, IGF-I, and GH increased ALS expression. It can be concluded that biosynthesis of individual IGFBPs and of ALS are compartmentalized in adult rat liver and are distinctly regulated by insulin, IGF-I, and GH. The insulin-dependent stimulation of IGFBP-3 synthesis in KCs appears to require a diffusable mediator derived from hepatocytes.

Animals↗
PubMed1995

Influence of 17 beta-estradiol and progesterone on rat ocular lens.

The effect of 17 beta-estradiol and progesterone on ocular lens in rats and untreated controls was studied. In the treated lenses, the activity of hexokinase and glucose-6-phosphate dehydrogenase remained unchanged. The activity of aldolase was increased in 18- and 20-month-old lenses as compared to controls. Aldose reductase activity was decreased at the age of 20 months (p < 0.001). Structural lens proteins studies by SDS polyacrylamide gel electrophoresis and immunodecoration with specific antibodies for crystallines alpha A + alpha B and beta + gamma suggest some protective effect in treated animals.

Aldehyde Reductase↗
PubMed1994

Significance of haemorrhagic lacunes on MRI in patients with hypertensive cerebrovascular disease and intracerebral haemorrhage.

Our purpose was to determine the frequency and significance of haemorrhagic lacunes (HL) on MRI in patients with a history of, or at risk for intracerebral haemorrhage. We examined 72 patients with old spontaneous intracerebral haemorrhage (ICH) using T1- and T2-weighted spin-echo sequences. MRI studies of 137 consecutive patients with cerebrovascular disease but no known ICH were also reviewed. Both groups showed about the same degree of age-related white matter change and nonhaemorrhagic lacunar infarcts, whereas the ICH group had a higher frequency of HL (12/72 patients) than the non-ICH group (6/131 patients, p < 0.01). These results correlate well with reported pathological findings. We conclude that haemorrhagic lacunes found on MRI studies of patients with cerebrovascular disease may suggest a higher risk of intracerebral haemorrhage.

Adult↗
PubMed1994

Estimation of cardiac index by means of the arterial and the mixed venous oxygen content and pulmonary oxygen uptake determination in the early post-operative period following surgery of congenital heart disease.

OBJECTIVE: To assess the reliability of estimation of cardiac index based on the mixed venous oxygen saturation and methods of improving the estimation of cardiac index. SETTING: PICU in an university hospital. DESIGN: In the post-operative period following complete repair of congenital heart disease we carried out 55 measurements of blood gases in 25 infants and children (mean age 16.1 months, mean body surface 0.43 m2) from a systemic artery (arterial) and the pulmonary artery (mixed venous). We also determined the pulmonary oxygen uptake and calculated the cardiac index (CI) using Fick's principle. In the analysis we compared the CI with the mixed venous oxygen saturation (SvO2) and with the quotient of the arterial oxygen content (CaO2) and the oxygen extraction (Ca-vDO2). This quotient is equal to arterial oxygen delivery (DO2) divided by the oxygen consumption (VO2). RESULTS: Pearson's correlation coefficient was 0.77 when SvO2 was compared to CI in a linear regression model. Assuming an inverse relationship between SvO2 and CI the correlation was much better (r = 0.90). However, the best estimation of CI provides the quotient CaO2/Ca-vDO2 (r = 0.93). CONCLUSIONS: CaO2/Ca-vDO2 correlates much better with CI than the SvO2, therefore CI could be better estimated based on CaO2/Ca-vDO2. Furthermore CaO2/Ca-vDO2 provides good information about the oxygen supply situation of the body.

Arteries↗
PubMed1994

Improved target volume definition for precision radiotherapy planning of meningiomas by correlation of CT and dynamic, Gd-DTPA-enhanced FLASH MR imaging.

In this methodological paper the authors report a fast, T1-weighted gradient-echo sequence (FLASH) for dynamic, Gd-DTPA-enhanced magnetic resonance (MR) imaging of meningiomas and its application in precision radiotherapy planning. Indications for radiotherapy included unresected tumors, tumor remaining after surgery, and recurrences. The patient's head was fixed in a stereotactic localization system which is usable at the CT, MR and the linear accelerator installations. By phantom measurements different materials (steel, aluminum, titanium, plastic, wood, ceramics) used for the stereotactic system were tested for mechanical stability and geometric MR image distortion. All metallic stereotactic rings (closed rings made of massive metal) led to a more or less dramatic geometric distortion and signal cancellation in the MR images. The best properties--nearly no distortion and high mechanic stability--are provided by a ceramic ring. If necessary, the remaining geometric MR image distortion can be 'corrected' (reducing displacements to the size of a pixel) by calculations based on modeling the distortion as a fourth order two-dimensional polynomial. The target volume was defined in dynamic, T1-weighted FLASH MR images, which were measured before, during, and after the controlled intravenous infusion of 0.1 mmol/kg body weight Gd-DTPA. The stereotactic localization technique allows the precise transfer of the target volume information from MR onto CT data to provide a map of the radiation attenuation coefficient for dose calculation. In genera, the superior soft tissue contrast of MR showed an excellent tumor delineation, especially in regions, such as the base of the skull, where the target often was obscured in CT images.(ABSTRACT TRUNCATED AT 250 WORDS)

Adipose Tissue↗
PubMed1994

A prospective, randomized, double-blind comparison of epidural and intravenous sufentanil infusions.

BACKGROUND: The site of action (spinal vs. central) of epidurally administered lipid-soluble opioids has been the subject of controversy. We compared the efficacy, plasma concentration and side effects of epidural and intravenously administered sufentanil for postoperative pain relief. METHODS: Using a double-blind, prospective design, 50 patients scheduled for intraabdominal operations during combined epidural-general anesthesia were randomized into one of two groups. Patients in group 1 (n = 24) received a 1-microgram/ml sufentanil infusion epidurally at 0.2 microgram.kg-1.h-1 and a saline infusion intravenously at the same rate. Patients in group 2 (n = 26) received a 1-microgram/ml sufentanil infusion intravenously at 0.2 microgram.kg-1.h-1 and a saline infusion epidurally at the same rate. Intravenous morphine sulfate was available in 2-mg increments to all patients in the postanesthesia care unit until visual analogue scale (0-100 mm) pain score was < or = 30. Then, a patient-controlled intravenous pump providing morphine on demand (1 mg with a 10-min lockout) was begun. Blood samples were drawn for sufentanil plasma levels and patients were assessed for pain, sedation and nausea for the 48 h after commencement of the infusions. RESULTS: Similar visual analogue pain, sedation, and nausea scores were found between the patients in the two groups. No differences were found in supplemental morphine requirements and plasma sufentanil concentrations between the patients in the two groups. A higher incidence of excessive sedation requiring infusion decrease was infusion decrease was found in the intravenous group (six vs. one, P < 0.05). CONCLUSIONS: Many clinical similarities were found when epidural and intravenous sufentanil infusions were compared. The higher incidence of excessive sedation in the patients receiving intravenous sufentanil could not be explained on the basis of plasma sufentanil concentrations alone. This study indicates that little clinical difference exists between epidural and intravenous administration of sufentanil.

Aged↗
PubMed1994

Frequency of stress lesions of the upper gastrointestinal tract in paediatric patients after cardiac surgery: effects of prophylaxis.

BACKGROUND: Stress lesions of the upper gastrointestinal tract are well recognised in adult patients in intensive care. There are no controlled studies of the incidence of these lesions and the effects or side effects of prophylactic treatment in high risk paediatric patients. METHODS: 79 paediatric patients in intensive care were studied prospectively after operation for congenital heart disease. All patients had at least one endoscopic examination. The first 36 patients were not given prophylactic medication: later 43 children were treated randomly either with pirenzepine (n = 21) or with famotidine (n = 22). Gastric and tracheal secretions were taken daily for culture in those patients given prophylactic medication. RESULTS: Severe inflammation or ulceration of the upper gastrointestinal tract was less common in those patients who were given prophylactic medication (18% v 44%). Prophylactic treatment did not, however, reduce the total incidence of postoperative stress lesions: it shifted the severity of these changes towards mild lesions and reduced the incidence of ulcerations from 25% to 2%. None of the patients developed a pneumonia caused by an organism previously isolated from the stomach. CONCLUSIONS: The incidence of stress lesions in children after cardiac surgery resembles that in high risk adult patients. Children in intensive care after cardiac surgery should be treated prophylactically with famotidine or pirenzepine until they can be fed by mouth.

Adolescent↗
PubMed1994

[Total cavopulmonary anastomosis: risk factors and results in patients under 4 years of age].

In recent years, an increasing number of modified Fontan-operations has been performed in children younger than 4 years of age. The purpose of this study was to identify preoperative risk factors in this age group. From February 1990 until February 1993, we performed in our center a modified Fontan-operation using the technique of total cavopulmonary anastomosis (TCPA) in 37 consecutive patients (17 pts. < 4 years = group I, 20 pts. > 4 years = group II). Early postoperative mortality occurred in patients of group I only (n = 3 pts.). All of these patients had additional preoperative risk factors. Pulmonary vascular resistance (PVRI) > 2 U x m2 was a significant risk factor for the younger patients while pulmonary artery size alone (expressed as the McGoon-ratio or Nakata-index) could not be identified as a separate risk factor. Using two additional indices (McGoon-ratio/PVRI and Nakata-index/PVRI), we were able to identify patients with unfavorable postoperative hemodynamics as high-risk patients. In our experience, TCPA can be performed in patients younger than 4 years of age with a low mortality, if there are no additional preoperative risk factors. For high-risk patients we recommend either a bidirectional Glenn-anastomosis as a first step procedure or a TCPA with fenestration of the intraatrial tunnel-patch.

Adolescent↗
PubMed1994

[Color Doppler controlled compression therapy of puncture aneurysms--a noninvasive therapy concept].

After transfemoral catheterization, pseudoaneurysms can occur in about 0.1-0.05% of cases, especially after the use of large instruments and a faulty puncture technique. Today, pseudoaneurysms can be easily and accurately diagnosed with the help of duplex and color Doppler ultrasound. Apart from its diagnostic application, color Doppler ultrasound also offers a noninvasive and cheap alternative therapy mode as compared to surgical repair. The purpose of our study was to evaluate the therapeutic efficiency of an ultrasound-guided compression technique for postpunctional pseudoaneurysms. Over a 12-month period, nine patients were sonographically diagnosed with postpunctional pseudoaneurysm of the femoral superficial artery. The compression therapy was only applied if no contraindications (e.g. rupture, retroperitoneal site of the lesion, infection, large haematoma with suspected ischaemia, and necrosis) were present. Two of the nine patients were primarily excluded from therapy because of a high risk of rupture or a large haematoma. Five patients of the remaining seven have been successfully treated. In one of the unsuccessfully treated patients, only a partial thrombosis of the aneurysm was obtained, followed by complete spontaneous thrombosis 4 days later. The second compression failed because of the 4-month time interval between angiography and compression therapy. A successful therapy clearly depended on the time interval between puncture and compression. We could not find any significant correlation between the aneurysm volume and the duration of compression. Color Doppler ultrasound-guided therapy is a noninvasive easily applicable, and cheap alternative to surgical repair of postpunctional pseudoaneurysms.

Adult↗
PubMed1994

Influence of systemic diseases and environmental factors on age at appearance, location and type of acquired cataract.

We studied 257 patients scheduled for cataract surgery for possible correlation with systemic diseases, blood chemistry, and environmental exposure. We found that posterior subcapsular cataract appeared in patients 10 years younger on average than those with other types of cataract. Nuclear cataract patients had higher blood levels of uric acid and creatinine and lower blood levels of calcium. We suggest capsular insult as a possible pathophysiological explanation for cataract formation in young age groups (as well as diabetes) and a toxic effect of blood metabolites in patients with renal failure, resulting in earlier and more prevalent sclerosis of lens fibers. No effect of smoking or of exposure to sunlight on the distribution of various types of cataracts was noted.

Age Factors↗
PubMed1994

Presurgical prosthetic management of the periodontal patient--a modern adhesive approach.

The comprehensive management of the periodontal prosthetic patient requires that treatment be provided in a logical sequence; initial therapy, presurgical prosthetic management, surgical management of hard and soft tissue lesions, post-surgical prosthetics, followed by maintenance therapy. This article focuses on some of the most perplexing challenges encountered during the presurgical prosthetic management phase of periodontal diagnosis and therapy, including the stabilization of mobile teeth, the immediate replacement of teeth that require removal due to advanced attachment loss, and the correction of visual defects created by soft tissue loss. A number of creative treatment modalities are described that utilize silane-treated etched-glass fiber ropes and tapes (GlasSpan, GlasSpan, Inc.) for the internal reinforcement of periodontal splints and for the attachment of composite and natural tooth pontics as transitional tooth replacements. Gingival-colored composite (Gingiblend, Jeneric Pentron) and its importance as a diagnostic aid during the early stages of periodontal therapy and as an esthetic permanent restorative material are also examined.

Adult↗
PubMed1993

DL-propranolol inhibits lens hexokinase activity and affects lens optics.

A clinico-biochemical study indicated that the beta-blocker DL-propranolol may affect human lens epithelial hexokinase (HK) activity. In that study five key enzymes were analysed in 192 freshly excised human lens epithelia obtained during cataract surgery. In a large number of patients the epithelial HK was found to be inactive. Medical records of these patients showed widespread use of the drug DL-propranolol. In vitro experiments demonstrated a direct inhibitory effect of the drug on human lens HK activity. Lens refractive function was monitored during long term bovine lens culture experiments in which the potential cataractogenic agent was added to the culture media. DL-propranolol in a concentration of 0.1 mM reduced HK activity in bovine lens epithelium after 72 hr in organ culture and disrupted lens light focusing ability after 250 hr of incubation. Kinetic studies of HK inhibition suggested a competitive inhibitory effect of the drug on the enzyme.

Animals↗
PubMed1993

Total cavopulmonary anastomosis: selection criteria related to postoperative results.

In this study we review our experience with total cavopulmonary anastomosis (modified Fontan procedure) which was performed in 31 patients. One patient died from postoperative cardiac low-output syndrome, the other died from a neurological complication (early mortality 6.5%). During a mean follow-up period of 15 months there was no late mortality. Preoperative assessment showed that one, two, or three of the Choussat criteria (defining the ideal Fontan candidate) were not fulfilled by 39%, 16% and 6% of our patients. In the 2 patients who died 2 and 3 of those criteria were not fulfilled. Poor outcome could not be predicted based on assessment of the pulmonary artery size (expressed as the McGoon-ratio or the Nakata-index) alone. In order to assess the relationship of pulmonary artery size and pulmonary arteriolar resistance (PVR) as a predictor of outcome, we introduced two new indices (McGoon-ratio/PVR and Nakata-index/PVR). The patient who died from poor postoperative hemodynamics had the lowest values of all patients. Among the 29 survivors we did not observe significant acquired postoperative arrhythmias. In our experience the total cavopulmonary anastomosis can be performed with a low mortality and good postoperative results. Patients who do not fulfill at least 8 of the Choussat criteria and children with a low ratio of pulmonary artery size to PVR are high-risk patients. In these children we recommend either a bidirectional Glenn anastomosis as a first-step procedure or a total cavopulmonary anastomosis with a fenestration of the intraatrial tunnel.

Adolescent↗
PubMed1993

[Follow-up of hormonal and metabolic parameters after heart operations in childhood].

UNLABELLED: FORMULATION OF QUESTION: Determination of extent and duration of stress metabolism in children after cardiac surgery. METHODS: Before and 5 days following cardiac surgery glucose, cortisol, glucagon, insulin, human growth hormone, lactate, urea, free fatty acids, triglycerides, total-T3, total-T4, TSH and thyroxine-binding globulin were determined in 20 infants and children (1/3-12 3/4 years). RESULTS: In the first postoperative hours we found increased values for glucose, cortisol, lactate and free fatty acids, decreasing values for glucagon, human growth hormone and thyroid hormones including TSH. Around the 3rd postoperative day blood glucose normalized, glucagon, insulin, human growth hormone and thyroid hormones increased. Patients with preoperative cyanosis (n = 11) showed a slightly more protracted course than patients without (n = 9). CONCLUSIONS: During the postoperative period the pattern of stress metabolism predominated with compromised utilisation of glucose and elevated oxygenation of endogenous lipid depots. The postoperatively decreased thyroid hormones were interpreted as a measure to lower the basic metabolic rate. Round about the 3rd postoperative day normalized glucose levels and rising glucagon, insulin, human growth hormone and thyroid hormones/signaled the change to an anabolic metabolism.

Blood Glucose↗