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Biomedical subjects

M Smet

Publications and source records attributed to M Smet.

At least 19 recordsLinked to original sources
PubMed2000

Photolabile dendrimers using o-nitrobenzyl ether linkages

[reaction: see text] Benzyl aryl ether dendrimers containing photosensitive, veratryl-based o-nitrobenzyl AB linkages (bold bonds) were prepared to the third generation and shown to undergo site-specific degradation when irradiated with ultraviolet light.

Journal Article↗
PubMed2000

Endocrine consequences of long-term intrathecal administration of opioids.

Intrathecal administration of opioids is a very efficient tool in the long-term control of intractable nonmalignant pain. However, despite the well known role of opioids in endocrine regulation, few data are available about possible effects on hypothalamic-pituitary function during this treatment. Seventy-three patients (29 men and 44 women; mean age, 49.2 +/- 11.7 yr) receiving opioids intrathecally for nonmalignant pain were enrolled for extensive endocrine investigation. At the time of hormonal determination, the mean duration of opioid treatment was 26.6 +/- 16.3 months; the mean daily dose of morphine was 4.8 +/- 3.2 mg. The control group consisted of 20 patients (11 men and 9 women; mean age, 54.2 +/- 14.0 yr) with a comparable pain syndrome but not treated with opioids. Decreased libido or impotency was present in 23 of 24 men receiving opioids. The serum testosterone level was below 9 nmol/L in 25 of 29 men and was significantly lower than that in the control group (P < 0.001). The free androgen index was below normal in 18 of 29 men and was significantly lower than that in the control group (P < 0.001). The serum LH level was less than 2 U/L in 20 of 29 men and was significantly lower than that in the control group (P < 0.001). Serum FSH was comparable in both groups. Decreased libido was present in 22 of 32 women receiving opioids. All 21 premenopausal females developed either amenorrhea or an irregular menstrual cycle, with ovulation in only 1. Serum LH, estradiol, and progesterone levels were lower in the opioid group. In all 18 postmenopausal females significantly decreased serum LH (P < 0.001) and FSH (P = 0.012) levels were found. The 24-h urinary free cortisol excretion was below 20 microg/day in 14 of 71 opioid patients and was significantly lower than that in the control group (P = 0.003). The peak cortisol response to insulin-induced hypoglycemia was below 180 microg/L in 9 of 61 opioid patients and was significantly lower than that in the nonopioid group (P = 0.002). The insulin-like growth factor I SD score was below -2 SD in 12 of 73 opioid patients and was significantly lower than that in the control group (P = 0.002). The peak GH response to hypoglycemia was below 3 microg/L in 9 of 62 subjects and was significantly lower than that in the control group (P = 0.010). Thyroid function tests and PRL levels were considered normal. No metabolic disturbances were recorded, apart from significantly decreased high density lipoprotein cholesterol levels (P = 0.041) and elevated total/high density lipoprotein cholesterol ratio (P = 0.008) in the opioid group compared to the control group. Supplementation with gonadal steroids improved sexual function in most patients. In conclusion, of all patients receiving intrathecal opioids, the large majority of men and all women developed hypogonadotropic hypogonadism, about 15% developed central hypocorticism, and about 15% developed GH deficiency. These findings suggest that further investigations are required to determine the need for systematic endocrine work-up in these patients and the necessity for substitutive therapy.

Adult↗
PubMed1999

N-Confused Calix

Next to the "normal" calix[4]pyrrole 1, the N-confused calix[4]pyrrole 2 is formed in substantial amounts (up to 22 % yield) as side product in the acid-catalyzed condensation reaction of ketones and pyrrole. In some cases, doubly N-confused calix[4]pyrroles are also formed.

Journal Article↗
PubMed1998

Caroli's syndrome.

We report the case of a two-year-old girl presenting with recurrent episodes of fever and hepatomegaly. High resolution ultrasound (US) and computed tomography (CT) of the liver show dilated intrahepatic bile ducts with bridge formation and intraluminal protrusions. The extrahepatic bile duct is normal. The diagnosis of irregular dilated bile ducts with signs of cholangitis and cholangiolitis is proved by liver biopsy. The histologically associated congenital liver fibrosis in our patient enter into the Caroli's syndrome. We illustrate the high resolution US and the CT findings in this case.

Bile Ducts, Intrahepatic↗
PubMed1995

Specific decrease of anti-pseudomonal IgA after anti-pseudomonal therapy in cystic fibrosis.

UNLABELLED: In patients with cystic fibrosis (CF) and chronic colonisation with Pseudomonas aeruginosa, specific anti-pseudomonal IgG and IgA, as well as serum immunoreactive protein C, WBC and differential count, ESR, pulmonary function and chest radiograph score were determined before and after a 2 week intravenous course of anti-pseudomonal antibiotics in 32 cases of acute exacerbation of pulmonary infection. Specific anti-pseudomonal IgA but not specific anti-pseudomonal IgG decreased significantly after treatment. Log of anti-pseudomonal IgA but not log anti-pseudomonal IgG correlated well with disease severity as assessed by the Brasfield chest radiograph score (r 0.57), forced expiratory volume in 1 s (r 0.6) as well as C-reactive protein (r 0.62). CONCLUSION: Specific anti-pseudomonal IgA may be a better parameter than specific IgG in the follow up of lung infection in patients with CF, probably because it more closely reflects ongoing endobronchial infection, the major pathology in CF lungs.

Antibodies, Bacterial↗
PubMed1995

Experimental teleradiology. Novel telematics services using image processing, hypermedia and remote cooperation to improve image-based medical decision making.

We illustrate the possible impact of information technology on digital radiology using two pilot projects. The first aimed to improve the transfer of radiological information and the interaction between radiologist and referring physician, using hypermedia documents and hypermedia electronic mail. During a 12-month evaluation period, approximately 100 hypermedia reports were generated and distributed to hepatologists and neurosurgeons. The second project aimed to improve planning of orthopaedic surgery, using an image processing service for three-dimensional visualization and a conferencing system to support active cooperation. Over two months, 12 routine cases were reconstructed in three dimensions and conferencing was carried out between surgeons and radiologists in hospitals 15 km apart. Initial results were encouraging. Telematics may be valuable in reconciling the growing need for multidisciplinary cooperation with the growing geographical and organizational separation of different experts. We conclude that to benefit from information technology, the focus should not be on a direct translation of traditional working methods, but rather on possibilities that were not available in the film-based environment.

Belgium↗
PubMed1993

Image segmentation: methods and applications in diagnostic radiology and nuclear medicine.

We review and discuss different classes of image segmentation methods. The usefulness of these methods is illustrated by a number of clinical cases. Segmentation is the process of assigning labels to pixels in 2D images or voxels in 3D images. Typically the effect is that the image is split up into segments, also called regions or areas. In medical imaging it is essential for quantification of outlined structures and for 3D visualization of relevant image data. Based on the level of implemented model knowledge we have classified these methods into (1) manual delineation, (2) low-level segmentation, and (3) model-based segmentation. Pure manual delineation of structures in a series of images is time-consuming and user-dependent and should therefore be restricted to quick experiments. Low-level segmentation analyzes the image locally at each pixel in the image and is practically limited to high-contrast images. Model-based segmentation uses knowledge of object structure such as global shape or semantic context. It typically requires an initialization, for example in the form of a rough approximation of the contour to be found. In practice it turns out that the use of high-level knowledge, e.g. anatomical knowledge, in the segmentation algorithm is quite complicated. Generally, the number of clinical applications decreases with the level and extent of prior knowledge needed by the segmentation algorithm. Most problems of segmentation inaccuracies can be overcome by human interaction. Promising segmentation methods for complex images are therefore user-guided and thus semi-automatic. They require manual intervention and guidance and consist of fast and accurate refinement techniques to assist the human operator.

Algorithms↗
PubMed1992

A right lower quadrant mass in cystic fibrosis: a diagnostic challenge.

In a cystic fibrosis (CF) patient a right lower quadrant (RLQ) mass may be a difficult diagnostic problem. Most frequently it is due to a distal intestinal obstruction syndrome also called meconium ileus equivalent, but the possibility of intussusception and appendiceal abscess should also be considered. We describe three CF patients with an appendiceal abscess seen in a 4-year period. All three patients had a palpable RLQ mass. Chronicity and obliteration of the appendiceal lumen with abnormally viscid mucus may lead to concealed perforation and be responsible for the atypical presentation.

Abscess↗
PubMed1992

Unilateral thalamic haemorrhage in the pre-term and full-term newborn.

One full-term and three premature newborns with a unilateral thalamic haemorrhage are reported. The lesion was diagnosed using cranial ultrasonography and confirmed in three using magnetic resonance imaging. Severe perinatal asphyxia occurred in all infants. The neonatal clinical history, subsequent neuro-developmental outcome and neuroimaging findings are discussed. As the prognosis appears to be much better than for infants with bilateral thalamic densities, it is important that this type of lesion is recognised as a separate entity.

Cerebral Hemorrhage↗
PubMed1991

Infantile fibrosarcoma.

Explore the source record for details and available documents.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1990

Cerebrovascular occlusive complications in osteopetrosis major.

We report the case of a 16-year-old patient with osteopetrosis major, complaining of transient sensory and motor disturbances in the left upper limb and dizziness on changing the position of his head. Selective angiography of the cerebral vessels showed severe narrowing of the internal carotid artery within the petrous carotid canal and in its supraclinoid portion. The cervical vertebral arteries showed multiple stenosis within the vertebral canal. These findings are explained by narrowing of the basal foramina by the osteopetrotic bone.

Adolescent↗
PubMed1990

The role of high resolution ultrasound and MRI in the investigation of infants with macrocephaly.

External hydrocephalus was diagnosed using computed tomography in seven children presenting with macrocephaly. The value of different imaging techniques in distinguishing between subdural effusions and external hydrocephalus was investigated. High resolution ultrasonography combined with magnetic resonance imaging appeared to provide enough information to make a distinction between these two conditions. Radionuclide cisternography was still required to assess the flow pattern of the cerebrospinal fluid (CSF) which was important when placement of a lumboperitoneal shunt was considered.

Gestational Age↗
PubMed1990

The role of short latency somatosensory evoked responses in infants with rapidly progressive ventricular dilatation.

The effect of hydrocephalus on somatosensory evoked potentials was studied in nine infants. An increase in N1 latency was found in five infants studied longitudinally during a period of progressive ventricular dilatation. A marked decrease in N1 latency was noted in 7 infants, within one week following shunt insertion and in two infants who showed spontaneous arrest of ventricular growth. A correlation was found between cerebrospinal fluid pressure and the delay in N1 latency, but the number of infants studied is still small. SEPs appear to be a useful additional test when assessing infants with progressive ventricular dilatation. Once a baseline value for N1 has been obtained following shunt insertion, SEPs may subsequently be useful when assessing a child with possible shunt dysfunction.

Cerebral Hemorrhage↗