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Biomedical subjects

R Maas

Publications and source records attributed to R Maas.

At least 91 records · Page 5Linked to original sources
PubMed1992

[Legg-Calvé-Perthes disease. The value of MRT in its early diagnosis and the assessment of its course].

We report on the value of MRT in diagnosis and follow-up of Perthes' disease. 38 children who were clinically suspect of suffering from Perthes' disease were examined by conventional x-ray and MRT. 25 children were proven to have Perthes' disease, 12 of them in an early stage. During the onset of the disease MRT showed a higher sensitivity (58% vs 50%) and accuracy (74% vs 71%) than conventional x-ray while specificity was equal (83% for both). Additionally, MRT in combination with the still obligatory x-ray gave no false-positive results. In some cases, the diagnosis may be found up to 6 weeks earlier using MRT. Conservative therapeutic regimens obviously will not profit from this. Although excluding other diseases is certainly helpful, the value of MRT as a primary diagnostic procedure is limited. During follow-up, MRT helps to reduce the number of x-ray examinations since it can easily assess the containment of the hip and the bone marrow revitalisation. Scintigraphy, another valuable method to judge revitalisation, should remain limited to selected cases, as it requires significant amounts of radiation.

Adolescent↗
PubMed1992

[Radiologic diagnosis of the recurrence of soft tissue sarcomas].

We report about the diagnosis of recurrent soft tissue tumors in more than 350 patients using magnetic resonance tomography (MRT) and computed tomography (CT) during the last 5-6 years. MRT turned out to be the method of choice having a sensitivity of about 85% and a specificity of 60-70%, provided that a high resolution technique is used and a paramagnetic contrast agent (gadolinium-DTPA (Gd)) is applied. By performing "dynamic Gd-sequences" a quantification and of the perfusion of a recurrent tumor is possible. Even MRT does not produce a definite tumor-specificity. The alterations of imaging concerning surgical treatment or therapeutic irradiation are extensively discussed. Practical suggestions for the daily routine diagnostic in case of uncertain clinic or symptoms are given.

Adolescent↗
PubMed1992

[Results of CT-controlled puncture of the thorax].

Results of 56 CT-guided biopsies in 45 patients are presented. Aspiration biopsies (n = 23) had a usable result in 75% of the cases; cutting biopsies (n = 33) in 80%. The main complication was the pneumothorax with 9%; in one patient the procedure caused a haemoptoe.

Humans↗
PubMed1991

Ultrasound diagnosis of fetal abnormalities and cytogenetic evaluation.

Over a 6 1/2 year period, in 288 pregnancies a variety of fetal malformations were detected by ultrasound. Two hundred and ten fetuses (73 per cent) were karyotyped. Gestational age at detection ranged from 11 to 38 weeks. The incidence of an abnormal karyotype in the total series was 14 per cent and 14.7 per cent in the 210 pregnancies in which a karyotype was performed. Single structural anomalies were found in 149 cytogenetically investigated fetuses, of which 25 had a chromosomal abnormality (17 per cent). Multiple structural malformations were present in 61 fetuses, of which 16 had an abnormal karyotype (26 per cent). Trisomy 18 was the most frequent finding. The most constant ultrasound finding in cases of an abnormal karyotype was polyhydramnios and severe IUGR in combination with structural defects. There is a need for extensive detailed ultrasound examination in high-risk pregnancies.

Chromosomes, Human, Pair 13↗
PubMed1991

Isolation and properties of the RepA1 protein of the IncFII replicon, RepFIC.

The initiator protein RepA1 of the IncFII replicon RepFIC derived from the enterotoxin plasmid EntP307 has been cloned under the control of the lambda PL promoter. This has enabled us to overproduce this protein and study its properties. Here we show that RepA1 is a soluble basic protein with an experimentally determined molecular weight of 40,000. Deletion analysis indicates that the overproduced protein originates from the open reading frame which we previously designated as coding for RepA1. We have also shown that the replication function of the replicon RepFIC depends on the intact RepA1 coding frame.

Amino Acid Sequence↗
PubMed1991

Control of type-I diabetes mellitus in pregnancy.

Type-I diabetes mellitus is a serious risk factor in pregnancy. To reduce the chance of congenital defects, macrosomia, intrauterine death and neonatal morbidity, tight control of glucose has to be achieved before and during pregnancy. Disadvantage of this tight regimen is an increase of retinopathy of the mother in good controlled cases of diabetes mellitus. Waiting for spontaneous labour is possible in combination with fetal surveillance by cardiotocography.

Blood Glucose↗
PubMed1991

[Initial experiences with the use of gadolinium DTPA in infants and children under 2 years of age].

The use of Gadolinium-DTPA as a paramagnetic contrast agent in MRI with adults and juveniles concerning brain and spinal cord pathology is well proven since years. Tolerance and safety were excellent. In the FRG it is only introduced for children over two years of age. Therefore this report deals with the experience in four infants and small children under the age of two, who received gadolinium-DTPA for diagnostic purposes in pre- or post-operative circumstances. They all were suffering from neurological tumors and got additional diagnostic information in three cases. Clinical side-effects like urticaria, vomiting or convulsions had not been observed nor had pathologic changes of the biochemical parameters been noticed.

Central Nervous System Neoplasms↗
PubMed1990

[The diagnostic value of MR tomography following gadolinium-DTPA compared to computed tomography in bladder tumors].

In a prospective study, 58 patients with carcinomas of the bladder were examined by CT and MRI; in 48, gadolinium-DTPA was administered intravenously. MRI provided exact staging in 89%, compared with 80% with CT. There was 13% over-staging with CT and 11% with MRI. MRI, unlike CT did not result in any under-staging. In 36 patients a quotient could be calculated from the signal intensity of the tumour and surrounding soft tissues both before and after the intravenous contrast medium and the increased quotient after contrast administration could be estimated. There was a significant increase in the tumour/muscle quotient with a mean of 72 +/- 22% (minimum 43%, maximum 153%), corresponding to a marked increase of the signal from the tumour when compared with the pre-contrast images. This had the following advantages compared with CT: accurate differentiation between superficial and intramural spread. MRI was better than CT at demonstrating tumours in the roof of the bladder and at the trigone.

Adult↗
PubMed1990

[MRT of acute soft tissue hematomas at 1.5 T: animal experimental results].

In 16 Göttingen minipigs 31 soft-tissue haematomas of different location were produced by reinjection of freshly drawn arterial and venous blood. Immediately after the injection, MRI of the haematomas was performed and continued for 2-3 h. The MRI appearance of the haematomas depended on the site of the injection. Intramuscular haematomas demonstrated on T2-weighted gradient-echo images a decrease in signal intensity within a few minutes after injection. With the same scan parameters, subcutaneous haematomas had a high signal intensity still at 3 h after injection. When section of the cadaver was performed, the subcutaneous haematomas consisted of compact clot, whereas with intramuscular injection diffuse infiltration of the muscle was present.

Acute Disease↗
PubMed1990

[The lateral thoracic radiograph in the intensive care unit using digital luminescence radiography].

The digital luminescence radiography (DLR) technique is being used increasingly for clinical diagnosis, particularly in intensive care . Since the installation of a DLR unit, we have carried out more than 20,000 examinations of the chest on patients in intensive care. 12.1% of these were lateral radiographs. In this way, the diagnosis can be made of the extent of a pleural effusion, the presence of a ventral pneumothorax or of atelectasis. Using DLR, these examinations can be carried out at the bedside and have improved the radiological investigation of patients in intensive care.

Humans↗
PubMed1989

Properties and incompatibility behavior of miniplasmids derived from the bireplicon plasmid pCG86.

Many plasmids belonging to the F incompatibility groups contain more than one basic replicon. The chimeric plasmid pCG86 is an example of such a multireplicon plasmid. The two basic replicons of pCG86, RepFIIA/FIC and RepFIB have been cloned and re-ligated, the copy numbers of the clones have been determined, and the incompatibility behavior of plasmids containing the ligated replicons and the individual replicons has been studied. The bireplicon plasmids are not expected to be incompatible as recipients with monoreplicon RepFIB or RepFIIA/RepFIC plasmids, since when one replicon is challenged by an incoming replicon, the other should be able to handle the plasmid's replication. In our studies, we found that challenge with either monoreplicon plasmid resulted in incompatibility. This incompatibility was increased in bireplicon plasmids in which RepFIB was duplicated. We conclude that in the bireplicon plasmids, challenging the replication control of one replicon by an incompatible plasmid can interfere with the replication originating from the second replicon.

Cloning, Molecular↗
PubMed1989

Radiological diagnosis of cervical trauma at the level C7/T1.

After a car accident a 23-year-old man was found to have rotational luxation of the cervical spine at the level C7/T1. The diagnosis was suspected from indirect signs on the ap X-ray and subsequently confirmed by conventional lateral tomography. Neurological symptoms were not present. Magnetic resonance imaging demonstrated dorsal protrusion of the intervertebral disc.

Adult↗
PubMed1989

Advantages of diagnosing bacterial spondylitis with magnetic resonance imaging.

We report on 16 cases of suspected spondylitis in which we used magnetic resonance (MR) imaging to confirm or exclude the diagnosis. MR has several advantages, one of which is to permit diagnosis of this disease in the early stages without major risks. In addition, MR permits recognition of complications such as paravertebral or intraspinal abscess formation with a high security and accuracy. Moreover, it is possible to show spondylitic alterations in three different planes. To differentiate this disease from metastatic or tumorous lesions the technique with T1- and T2-weighted images is helpful. As a result, MR imaging can shorten the time between onset and diagnosis of spondylitis.

Bacterial Infections↗
PubMed1989

[Quantitative volumetric determinations on MR tomograms in communicating hydrocephalus].

For patients with communicating hydrocephalus the implantation of a cardioventricular shunt is mostly an approved therapy. However, indications are frequently problematic and therefore a shunt operation will not be always successful. The proof of periventricular oedemas in addition to clinical signs seems to be a criterion for an indication for implantation and for the selection of a special valve. With the aid of a newly developed computer programme volume estimation of the ventricular system and the periventricular oedemas has been effected for six patients on T2-weighted MR-tomograms (1.5 tesla). Quotients of the different volumes are correlated with cerebrospinal fluid (CSF) pressure obtained during shunt implantation or lumbar measurement. Distinct indications have been found for a correlation between the volume of the periventricular oedemas and the pressure measurements.

Brain Edema↗