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Biomedical subjects

M Reiser

Publications and source records attributed to M Reiser.

At least 19 recordsLinked to original sources
PubMed1999

Virological efficacy and plasma drug concentrations of nelfinavir plus saquinavir as salvage therapy in HIV-infected patients refractory to standard triple therapy.

Therapeutic options are limited for patients refractory to triple therapy with two reverse transcriptase inhibitors and one protease inhibitor. Preliminary results showing favorable effects of protease inhibitor combination therapy with nelfinavir and saquinavir due to inhibition of metabolism by cytochrome P450 (CYP450) prompted us to study this combination. - Thirteen patients with incomplete suppression of plasma HIV-RNA were enrolled and treatment was started with nelfinavir 750 mg tid and saquinavir 400 mg bid. Saquinavir-dosage was escalated in weekly intervals to 400 mg tid and 600 mg tid, respectively. All doses were given with food, and plasma levels of saquinavir and nelfinavir were assessed 4 hours post-dosing after 1, 2, 3, 4 and 8 weeks. Treatment was considered virologically efficacious if HIV-viral load was reduced by at least 0.5 log10 from baseline. - Double protease inhibitor-treatment with nelfinavir and saquinavir was virologically efficacious in 5/13 (39%) patients after 4 weeks but only in 4/13 (31%) patients after 8 and 1/13 (8%) after 16 and 24 weeks, respectively. No statistical difference in plasma concentrations was observed when saquinavir was administered in increasing doses of 400 mg bid, 400 mg tid or 600 mg tid in combination with nelfinavir. 5/13 (39%) patients developed diarrhea (>4/d), no other serious side-effects were observed. By eight weeks, the mean CD4 count for all patients was significantly higher when compared to baseline. - In patients refractory to standard triple therapy the combination of nelfinavir and saquinavir showed significant elevation of CD4-count, but only short term virological efficacy in a minority of patients. Plasma concentrations of saquinavir could not be increased by weekly dose escalation of the drug from 400 mg bid to 600 mg tid. Saquinavir drug concentrations of 600 mg saquinavir tid and nelfinavir showed rather non-significant lower values when compared to historical controls treated with a double-dose 1200 mg saquinavir tid regimen alone. We conclude that in these patients the combination of nelfinavir plus saquinavir has no advantage in terms of increasing bioavailibility of saquinavir or virological efficacy. During short observation time a beneficial effect on CD4-count was observed.

Adult↗
PubMed1999

Magnetic resonance imaging to detect bone marrow metastases in the initial staging of small cell lung carcinoma and breast carcinoma.

BACKGROUND: Bone marrow is a common site of metastases in patients with small cell lung carcinoma (SCLC) and female breast carcinoma (FBC). Metastatic bone marrow involvement is found in approximately 50% of SCLC patients and up to 85% of FBC patients at autopsy. Initial staging procedures detect malignant bone marrow lesions in only 2-30% of patients with these tumors. This study was performed to assess whether MRI can improve the detection rate of bone marrow metastases in tumors with a high incidence of skeletal involvement. METHODS: Fifty-two patients with histologically verified SCLC (25 with limited stage disease and 27 with extensive stage disease) and 33 women with FBC were entered into a prospective study. The MRI protocol was comprised of coronal slices in the pelvic region and sagittal slices of the whole spine utilizing a T1-weighted spin echo sequence with a field of view of 50 cm. All patients underwent initial routine diagnostic staging procedures including bone scintigraphy, unilateral crest biopsy, and plain film radiography of suspicious skeletal areas. RESULTS: Only in two SCLC patients, MRI was positive in 25 cases. All SCLC patients with bone marrow lesions histologically verified, diagnosed by crest biopsy (six patients) or by bone scan (seven patients) had the correct diagnosis of metastases by MRI. In addition MRI revealed hypointense bone marrow foci in 14 cases. In contrast, 28 of 33 FBC patients examined during the initial staging procedure showed no evidence of bone marrow involvement. MRI was not superior compared with bone scintigraphy in FBC patients. CONCLUSIONS: The staging results obtained in SCLC and FBC patients are different, although both tumors have a high incidence of bone marrow metastases. It may be assumed that the biologic behavior of these tumors is reflected by the initial bone marrow involvement. Because of its superiority compared with biopsy and bone scan, the authors believe MRI should become an integral part of the initial staging procedures in patients with SCLC. When staging patients with FBC, MRI should be applied only in clinically indicated cases.

Bone Marrow Neoplasms↗
PubMed1999

A review and methodologic critique of the literature refuting whiplash syndrome.

The validity of whiplash syndrome has been a source of debate in the medical literature for many years. Some authors have published articles suggesting that whiplash injuries are impossible at certain collision speeds; others have stated that the problem is psychological, or is feigned as a means to obtain secondary financial gain. These articles contradict the majority of the literature, which shows that whiplash injuries and their sequelae are a highly prevalent problem that affects a significant proportion of the population. The authors of the current literature critique reviewed the biomedical and engineering literature relating to whiplash syndrome, searching for articles that refuted the validity of whiplash injuries. Twenty articles containing nine distinct statements refuting the validity of whiplash syndrome were found that fit the inclusion criteria. The methodology described in these articles was evaluated critically to determine if the authors' observations regarding the validity of whiplash syndrome were scientifically sound. The authors of the current critique found that all of the articles contained significant methodologic flaws with regard to their respective authors' statements refuting the validity of whiplash syndrome. The most frequently found flaws were inadequate study size, nonrepresentative study sample, nonrepresentative crash conditions (for crash tests), and inappropriate study design. As a result of the current literature review, it was determined that there is no epidemiologic or scientific basis in the literature for the following statements: whiplash injuries do not lead to chronic pain, rear impact collisions that do not result in vehicle damage are unlikely to cause injury, and whiplash trauma is biomechanically comparable with common movements of daily living.

Accidents, Traffic↗
PubMed1999

[Diagnosis and staging of liver metastases with imaging methods].

Liver metastases are much more common than primary hepatic malignancies and may occur in up to 80% of patients with extrahepatic malignancies. To optimize the patient's management, precise detection or exclusion of liver metastases, as well as assessment of their number and extent, is indispensable. For imaging of liver metastases, ultrasound, computed tomography (CT), magnetic resonance imaging (MRI), scintigraphy, and angiography can be utilized. All these methods have been technically improved with benefits for diagnostic utility. Biphasic contrast-enhanced spiral CT (SCT) and MRI with modern pulse sequences and tissue-specific contrast agents are superior to other imaging modalities in terms of diagnostic efficacy and reproducibility of results. With SCT and MRI sensitivities and specificities in the diagnosis of focal hepatic disease are in the range of 80-95%. Moreover, their non-invasiveness is a strong advantage. The diagnostic strategy in the assessment of liver metastases has to take into account both the strengths and limitations of the respective method. Additionally, the clinical situation of a particular patient has to be considered, and conclusive diagnostic results have to be achieved in a short time in order to ensure a favourable cost-effectiveness relation.

Colorectal Neoplasms↗
PubMed1999

[13-MHc high frequency ultrasound of the lateral ligaments of the ankle joint and the anterior tibia-fibular ligament. Comparison and results of MRI in 64 patients].

PURPOSE: Determination of the value of 13-MHz high-frequency ultrasound in the diagnosis of acute injuries of the lateral ankle ligaments and the anterior tibiofibular ligament by comparison with MRI. METHOD: Sonography was performed prospectively in 64 acutely injured patients using a mechanical 13-MHz sector probe; for diagnosis of the anterior tibiofibular ligament a 15-MHz sector probe was employed during the course of this trial. Using a 0.2-T unit for MRI examination, T1-weighted (TR 580 ms, TE 24 ms) and T2-weighted (TR 3000 ms, TE 80 ms) spin-echo sequences were obtained in various oblique axial imaging planes. RESULTS: In the differentiation of intact and injured ligaments, ultrasound and MRI agreed in 95.3% of cases for the anterior fibulotalar ligament, in 88.3% for the fibulocalcanear ligament and in 85.0% for the anterior tibiofibular ligament. CONCLUSION: Lesions of the anterior talofibular and fibulocalcanear ligament can be accurately demonstrated by ultrasound if a 13-MHz sector scanner is used. The detection of lesions in the anterior tibiofibular ligament is more difficult. With increasing experience and by using a 15-MHz sector scanner, better results can be expected for this ligament.

Ankle Injuries↗
PubMed1999

Assessment of gastric cancer: value of breathhold technique and two-phase spiral CT.

The purpose of this study was to evaluate the capabilities of subsecond spiral CT in detecting and staging of gastric cancer. Our study included 40 patients with endoscopically detected gastric carcinomas. Two-phase spiral CT was performed within one breathhold each. Distension of the stomach was achieved by intravenous application of scopolamine and drinking of 500 ml water. After bolus injection of contrast medium, scanning was performed in the arterial and venous phase. Gastric tumour extention and lymph node involvement was assessed. Gastric cancer was detected in 39 of 40 cases (sensitivity 97.5%). Location of the tumour was correctly assessed in all cases. In 31 of the 39 cases (79.4%) CT staging was accordant with pathological staging. One hundred two (70%) of 145 nodes infiltrated by tumour tissue were detected and 144 (42.8%) of 336 nodes free of metastatic involvement were found. The predictive values of positive and negative results for the detection of lymph node metastases were 67.1 and 75%, respectively. Spiral CT is recommended for staging of gastric cancer.

Adenocarcinoma↗
PubMed1999

Evaluation of spiral CT in staging of colon and rectum carcinoma.

The purpose of our study was to evaluate the capability of a subsecond spiral-CT scanner using two contrast medium phases in staging of colorectal cancer. In our study we included 37 patients with proven rectum or colon carcinoma. Spiral CT was performed following tap-water enema of the colon in the arterial and venous phases of contrast medium enhancement. Our results were compared with the findings of pathological examination after surgery. The tumor's size and extension were evaluated in the arterial and venous phases, the lymph nodes in the venous phase of the CT scan. The tumor was in the rectum (n = 14), sigma (n = 11), descending colon (n = 6), and cecum (n = 6). Two-phase spiral CT had a sensitivity of 97.2% in the arterial phase and 89.1% in the venous phase in detecting the carcinoma. The staging results were in the arterial phase in 30 of 37 cases (81.0%) and in the venous phase in 24 of 37 cases (64.8%) according to pathology. In 27 of 32 patients (84.3%) lymph nodes were detected. The correct classification of the N-stage was possible in 23 of 34 cases (67.6%). The combined use of arterial and venous phases in staging of colorectal cancer can improve the T- and N-stage classification in comparison with using only one contrast medium phase. The arterial phase is superior compared with the venous phase for local tumor staging and the venous phase is used for lymph node assessment.

Adult↗
PubMed1999

Diffuse metastatic infiltration of a carcinoma into skeletal muscle.

Skeletal muscle is one of the most unusual sites of metastasis from any malignancy. We report a patient with rapidly progressive contractures due to metastatic infiltration of a carcinoma of unknown origin into the skeletal muscle. This 61-year-old man presented with a 1-month history of rapidly evolving, painful restriction of mobility of his right arm and his legs. Computed tomography showed diffuse metastatic nodules in all muscles, particularly in the hip abductors. Muscle biopsy revealed extensive infiltration of the muscle with carcinoma cells.

Biopsy↗
PubMed1999

MRI findings of muscle involvement in idiopathic hypereosinophilic syndrome.

A 40-year-old white man presented with fever, muscle pain, skin nodules and persistent hypereosinophilia over a period of 1 year. In addition, he had ventricular arrhythmias with episodes of tachycardia. Besides a lack of response to antiparasitic therapy, laboratory and pathological data excluded the diagnosis of trichinosis or any other parasitic infection. The patient's course of the disease over the previous 1(1)/2 years was compatible with hypereosinophilic syndrome. In a muscle biopsy several eosinophilic perivascular and leucocytic intravascular infiltrates were found, indicative of muscle involvement by the disease. This is a report on the MRI findings of muscle involvement in idiopathic hypereosinophilic syndrome.

Adult↗
PubMed1999

Two cases of toxoplasmic encephalitis in patients with acute T-cell leukaemia and lymphoma.

Two cases of opportunistic cerebral infections in HIV-negative cancer patients due to chemotherapy induced immunosuppression are reported. A 61-year-old patient with low grade lymphoma (immunocytoma as referred to the Kiel classification) developed stereotactical biopsy proven toxoplasmic encephalitis 6 months after initiation of fludarabine treatment. The lymphoma had been diagnosed 8 years earlier and had been treated with several different regimens. In the second case, a 55-year-old patient developed neurological symptoms while in complete remission from acute T-cell leukaemia. The patient had been treated with a multidrug chemotherapy regimen including radiotherapy of the brain and intrathecal chemotherapy. When toxoplasmic encephalitis was bioptically diagnosed the patient was on maintenance chemotherapy with methotrexate and mercaptopurine for 12 months. The patients' characteristics and outcome are reported and the potential pathogenesis is discussed.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1999

Interaction of nitric oxide donors and ascorbic acid on D-[3H] aspartate efflux from rat striatal slices.

There are conflicting reports in the literature concerning the neuroprotective effect of ascorbic acid on excitotoxic processes in which excessive glutamate release and nitric oxide are supposed to be major factors. To study the influence of ascorbate on the nitric oxide modulated glutamate release rat striatal slices, preloaded with the tritiated glutamate analog D-aspartate, were used. The high potassium-induced efflux of D-[3H]aspartate was concentration dependently stimulated by the nitric oxide donors sodium nitroprusside, S-nitroso-N-acetylpenicillamine (SNAP) or 5-amino 3-morpholinyl-1,2,3-oxadiazolium chloride (SIN-1), as well as by solutions of gaseous nitric oxide and, interestingly, by cyanide. Only the stimulation of D-[3H]aspartate release by SNAP and nitroprusside was affected by ascorbate in terms of a highly significant potentiation. Ascorbate was shown to exert its effect primarily by influencing the decomposition of these nitric oxide donors rather than by a direct interaction of ascorbate with nitric monoxide on glutamate release.

Animals↗
PubMed1999

[MRI of plantar fasciitis].

PURPOSE: The purpose of this study was to determine the type and frequency of characteristic bone and soft tissue changes on MRI of patients with a clinical diagnosis of plantar fasciitis. MATERIALS AND METHODS: 28 patients with a clinical diagnosis of plantar fasciitis underwent MR imaging. Besides T1- and T2-weighted sequences, short-tau-inversion-recovery sequences were used routinely. In 27 patients T1-weighted images after intravenous contrast injection were acquired additionally. As a control group the images of 15 patients without clinical signs for plantar fasciitis were evaluated. RESULTS: In 25 of 28 cases (89%) the clinical diagnosis of plantar fasciitis was established by MR imaging. The most common finding was a peritendinous edema at the calcaneal insertion site which was found in all 25 patients. In 19 of 25 cases (76%) a bone marrow edema of the calcaneus was present. In 14 of 25 cases (56%) an intratendinous signal intensity increase of the plantar fascia could be observed which showed contrast enhancement in 12 cases. Compared to the control group (mean thickness 3.3 mm) the plantar fascia showed significant thickening in the 25 MR positive patients (mean thickness 6.72 mm). DISCUSSION: Besides thickening of the plantar fascia and intratendinous signal intensity increase with contrast enhancement to some extent, bone marrow edema of the calcaneus and peritendinous edema close to the plantar fascia are characteristic signs of plantar fasciitis on MRI. Both signs can reliably be seen on STIR sequences only.

Adult↗
PubMed1999

[Assessment of the effective dose for routine protocols in conventional CT, electron beam CT and coronary angiography].

PURPOSE: To compare the effective dose applied by sequential CT (SEQ), spiral CT (SCT), electron beam CT (EBT) and coronary angiography for investigations of the chest, abdomen and the heart. METHODS: The Alderson Phantom was used to compare the effective dose for all modalities. In addition, the effective dose for conventional CT (SEQ and SCT) was estimated with a mathematical phantom. RESULTS: For CT investigation of the chest and abdomen the dose was highest for the EBT (11 mSv and 25 mSv, respectively) and slightly lower for the SEQ (7.8 mSv and 21.5 mSv, respectively), whereas spiral CT required the least dose (5.3 mSv and 8.8 mSv, respectively). For coronary calcium screening (0.8 mSv) and EBT coronary angiography (1.7 mSv) the dose was lower than for coronary catheter angiography (3.3 mSv). For conventional CT the difference between the effective dose derived by the mathematical phantom and by the Alderson phantom was 2% to 20%. CONCLUSIONS: For investigations of the chest and abdomen the effective dose applied by SCT is significantly lower than that with EBT and SEQ. For investigation of the coronary arteries the effective dose applied by EBT is lower than that for coronary catheter angiography.

Body Burden↗
PubMed1999

Comparison of the diagnostic information in relative cerebral blood volume, maximum concentration, and subtraction signal intensity maps based on magnetic resonance imaging of gliomas.

RATIONALE AND OBJECTIVES: The authors investigate the validity of regional relative cerebral blood volume (rCBV) versus maximum concentration and subtraction signal intensity (SI) maps using simple reconstruction modes in patients with gliomas. METHODS: Twenty-five patients were studied using a 1.5 T magnetic resonance imaging scanner. To calculate the rCBV map, the magnetic resonance susceptibility effect SI/time curves were first transformed into concentration/time curves; then a gamma-variate function was fitted and the area under the curve was integrated. From the concentration/time data, the maximum concentration (MAX) maps were calculated pixel per pixel as the maximum peak amplitude of the concentration/time curve. Subtraction (SUB) maps are a result of simple image subtraction of pixelwise baseline SI minus the highest peak of susceptibility change pixel per pixel. Region of interest means SI measurement of the different maps was compared using statistical t test correlation. RESULTS: Normal gray to white matter contrast did not show a significant difference among the rCBV, MAX, and SUB maps. Based on statistical evaluation, the low-grade lesions did not differ significantly in the rCBV, MAX, and SUB maps. The group with high-grade lesions (12 patients) showed no significant difference in standardized rCBV, MAX, and SUB maps. CONCLUSION: Compared to rCBV maps, the simple MAX and SUB maps demonstrated good correlation in both high-grade and low-grade gliomas. This simpler approach could establish first-pass reconstruction in clinical settings because it reduces the need for time-consuming postprocessing.

Adult↗
PubMed1998

Relations between cardiopulmonary exercise testing and quantitative high-resolution computed tomography associated in patients with alpha-1-antitrypsin deficiency.

High-resolution computed tomography (HRCT) can be used to diagnose and quantify emphysema noninvasively, as significant correlations have been found between the histological grade on resected lung specimens and quantified (q) computed tomography (CT). In this study, we performed thin section qHRCT in patients with severe hereditary alpha-1-antitrypsin (AAT) deficiency. AAT deficiency is the most common genetic cause of emphysema in adults, and exercise intolerance is the most disabling, distressing consequence of emphysema for the majority of patients. qHRCT was used to quantify precisely the alterations in the lung parenchyma due to pulmonary emphysema. Up until now, the important relationship between the severity of emphysema and the reduced exercise capacity has received little attention. Therefore the purpose of the study was to investigate the relationship between emphysema as displayed by qHRCT and cardiopulmonary exercise testing (CPX) in patients with severe cardiopulmonary impairment. - qHRCT was performed in 21 patients with homozygous AAT deficiency. CT scans were obtained at three spirometrically standardized levels at the carina and (5 cm above and below the carina). The mean lung density at 50% of vital capacity and a quantitative histogram analysis of the frequencies of CT values were determined. All patients underwent symptom-limited CPX to analyse simultaneously cardiovascular and ventilatory systems responses. - In all patients, qualitative CT assessment demonstrated panlobular emphysema with large and extensive areas of uniform low attenuation, characteristically with a lower-lobe distribution. Mean CT density values of the patients (-845 +/- 6.9 (mean +/- SEM)) were significantly correlated with work capacity (r = 0.55, p <0.01), oxygen-pulse (r = 0.54, p <0.01) and functional dead space ventilation (r = -0.54, p <0.01). Moreover, severe emphysema index (CT values below a threshold value of 950 HU) correlated positively with functional dead space ventilation (r = 0.60, p <0.01) and alveolar-arterial oxygen difference (r = 0.70, p <0.001). - These results clearly demonstrate that CPX parameters, indicating a disturbed pulmonary gas exchange and a ventilation-perfusion-mismatch during exercise, are significantly related to the extent of lung emphysema.

Adult↗
PubMed1998

Hybrid rendering of the cervico-cranial arteries using spiral computed tomography.

PURPOSE: The purpose of this study was to develop a shaded-surface and volume display (hybrid rendering method) of the whole vascular system of the cervico-cranial arteries using spiral computed tomography (SCT). MATERIALS AND METHODS: We examined 12 patients with anatomic abnormalities and pathological conditions of the arterial vascular system. The cervico-cranial arteries were segmented using an interactive threshold interval density volume-growing method and visualized with a color-coded shaded-surface display (SSD) rendering method. The adjacent bone structures were visualized using a transparent volume rendering method. RESULTS: In all cases, the entire volume of the vascular system of the cervico-cranial arteries and the anatomic abnormalities and pathological conditions could be visualized. CONCLUSION: Hybrid rendering of the circulation of the cervico-cranial arteries using image data sets from a subsecond spiral CT scanner is useful for the visualization of anatomical and pathological abnormalities and offer a promising minimally invasive alternative compared with other diagnostic procedures.

Adult↗
PubMed1998

A comparison of digital luminescence mammography and conventional film - screen system: preliminary results of clinical evaluation.

The objective of this study was to determine if digital luminescence mammography can be used as a diagnostic tool. We investigated twenty-two patients with mammographically suspicious findings using a conventional film-screen system and a digital phosphor storage plate in order to compare these two techniques. Four radiologists experienced in mammography reviewed each pair of images. Our results indicate that detectability of microcalcifications and solid masses with digital systems is superior to conventional film-screen mammography due to the increased contrast enhancement associated with digital systems. We did, however, find that characterization of morphological details is inferior with the digital system, presumably due to reduced spatial resolution. In addition, we found no statistically significant difference in the differentiation of benign from malignant lesions with both techniques. The accuracy of mammographic diagnosis was investigated in a receiver operating characteristic study and similar values were found with both techniques. Our results indicate that digital mammography will become an acceptable diagnostic tool although improvement, especially in spatial resolution, is desirable.

Aged↗