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Biomedical subjects

F Martens

Publications and source records attributed to F Martens.

At least 19 recordsLinked to original sources
PubMed2006

Urinary gonadotropin measurements in neonates: a valuable non-invasive method.

BACKGROUND: To measure low neonatal gonadotropin levels, a sensitive non-invasive method is optimal. The aim of the current study was to validate the Architect i2000SR, an automated immunoassay analyser for the measurement of gonadotropins in unextracted neonatal urine samples against serum gonadotropin levels as a gold standard. METHODS: Blood and urine were sampled from 30 approximately six-week-old male and female neonates undergoing elective paediatric surgery. Follicle stimulating hormone (FSH) and luteinizing hormone (LH) were measured and the urine results were corrected for creatinine. RESULTS: The agreement between neonatal serum and urinary FSH was 0.904 (3-5 h between samples) and 0.704 (18-20 h). For LH, the correlation coefficients were 0.785 and 0.507, respectively. CONCLUSION: We conclude that gonadotropins can be reliably measured using the Architect on randomly voided, non-extracted urine samples collected from neonates by an adhesive device. Urinary gonadotropin levels are a proper reflection of the serum levels.

Adult↗
PubMed2004

Basal FSH concentrations as a marker of ovarian ageing are not related to pregnancy outcome in a general population of women over 30 years.

BACKGROUND: Previous studies suggest that elevated basal FSH concentrations are related to aneuploid pregnancies. However, there have been no prospective studies evaluating the incidence of aneuploidies in relation to basal FSH concentrations. Since the majority of aneuploid conceptions end in early pregnancy loss or abortion of a recognized pregnancy, these determinants are appropriate intermediate end-points to study aneuploidy. METHODS: We performed a prospective study in 129 women without a history of subfertility pursuing a spontaneous pregnancy. Basal FSH concentrations were measured during three menstrual cycles. Urinary HCG levels were measured during menstruation for a maximum of six menstrual cycles, to detect early pregnancy loss. We estimated the effect of basal FSH concentrations on pregnancy outcome, taking into account possible confounders. RESULTS: We observed no significant effect of basal FSH concentrations on the incidence of early pregnancy loss or abortion of clinically recognized pregnancies. CONCLUSIONS: We conclude that in a population of women without a history of subfertility, pursuing a spontaneous pregnancy, basal FSH concentrations are not related to the incidence of early pregnancy loss or abortions. This prospective study therefore fails to confirm a relationship between signs of decreased ovarian reserve and aneuploid pregnancies.

Abortion, Spontaneous↗
PubMed2004

Miliaria crystallina in an intensive care setting.

Drop-like, transient blisters of miliaria crystallina may develop with focal intensity of heat within the skin, such as occurs in tropical climates or during febrile episodes. Miliaria crystallina develops due to a transient poral closure of the sweat duct opening, resulting in obstruction of free flow of eccrine sweat and retention in a vesicle below the skin surface. Dual cholinergic and adrenergic sweat gland innervation is influenced by a variety of medications used in intensive care patients. We present two febrile intensive care patients in whom enhanced alpha-adrenergic stimulation of sweat gland myoepithelia may have led to miliaria crystallina.

Adrenergic alpha-Agonists↗
PubMed2002

Basal FSH, estradiol and inhibin B concentrations in women with a previous Down's syndrome affected pregnancy.

BACKGROUND: Two recent studies reported elevated basal FSH concentrations in women with a history of aneuploid conceptions. However, it is not known whether these elevated basal FSH concentrations reflect depletion of the primordial follicle pool, or were caused by an increased secretory drive for FSH. METHODS: Inhibin B and estradiol concentrations were measured as indicators for depletion of the primordial follicle pool in women with a history of a Down's syndrome pregnancy and in controls. RESULTS: In the women with a history of a Down's syndrome pregnancy, there was a significant inverse correlation between basal FSH and inhibin B concentrations (P < 0.0001, 95% CI -0.26 to -0.56). In the control group, this correlation did not reach statistical significance. CONCLUSIONS: Our data indicate that the elevated basal FSH concentrations observed in women with a history of a Down's syndrome pregnancy are likely to reflect early depletion of the primordial follicle pool. Therefore, further research into the ovarian ageing process could provide more insight in the origination of chromosomal abnormalities during pregnancy.

Adult↗
PubMed2002

[Determination of monoester metabolites of butylbenzyl phthalate (BBP) by GC-MS in the urine of exposed workers].

A method of analysis was developed to determine free and glucuronated monobutyl phthalate (BuP) and monobenzyl phthalate (BeP) in urine for the assessment of exposure of man to butylbenzyl phthalate (BBP) in the workplace and in the environment. This method has also been applied in pharmacokinetic studies in experimental animals and the determination in urine of exposed workers. Urine samples are first subjected to enzymatic hydrolysis with beta-glucuronidase to enable the measurement of the total amount of monophthalates excreted. A fraction of the hydrolysate is used for further analysis. Monohexyl phthalate is added as an internal standard and the hydrolysed urine extracted with a n-hexane/dichloromethane mixture after acidification and saturation with salt. The organic fractions are washed, dehydrated and evaporated. The residue is methylated by means of diazomethane dissolved in diethylether, evaporated and further purified by extraction into n-hexane from an alkaline buffer. The organic fractions are evaporated and the residue redissolved in acetonitrile for analysis by ion trap GC-MS equipped with a 50 m apolar WCOT capillary column. TIC mass chromatograms are recorded from which SIM chromatograms can be derived electronically. The m/z values used are 91, 149, and 163 which provide a sufficient sensitive response and which are specific enough to pick up the methylated monophthalates under investigation. The quantitative limit of detection (LOQ) is 60 micrograms/L for BuP and BeP when using the Magnum ion Trap detector and 3 micrograms/L when using the Polaris Q in the splitless mode. The calibration curve in urine is linear from 120 micrograms/L to 50,000 micrograms/L with a coefficient of variation of less than 10%. In case of the Polaris Q linearity started from 10 micrograms/L. The recovery of the method is monitored by the response signal of the internal standard in the ion chromatogram. In the event of insufficient recovery the analysis is repeated. Variations in recovery are compensated by the internal standard of which the molecular structure is very similar to the ones of the monophthalates under investigation.

Animals↗
PubMed2001

[Suspected poisoning. What kind of emergency care?].

Most cases of poisoning are adults attempting suicide by ingesting sedatives. After an initial orientating check of vital functions and rendering any first aid measures that may be necessary, an on-site inspection is carried out (search for remaining tablets or packages, suspicious vessels or odd circumstances). This is followed by a thorough history-taking, where indicated involving friends/relatives, physical examination of the undressed patient and recovery of any suspicious substances (for forensic purposes). The therapeutic measures to be instituted will depend on the certainty of the diagnosis, and are broken down into the preservation or restitution of vital functions and specific measures such as pumping out the stomach, administration of active charcoal or antidotes.

Diagnosis, Differential↗
PubMed2001

Determination of endometrial prolactin in vivo as a marker for endometrial development in spontaneous ovulatory cycles and in vitro fertilization cycles.

Decidual prolactin was directly determined in endometrial tissue in order to assess its potential role in improving the accuracy of the diagnosis of luteal-phase defect (LPD). Endometrial biopsies of 124 women with regular cycles (group 1) and 13 women with controlled ovarian hyperstimulation and progesterone-supported cycles (group 2) were evaluated in the secretory phase. In addition, decidual prolactin was measured in the luteal phase of the in vitro fertilization (IVF) cycles. The biopsies dated on or after day 25 showed a significant increase in the slope of the regression line of the cycle day versus decidual prolactin content (p < 0.05). Delayed endometrium was not characterized by a lower amount of decidual prolactin compared with biopsies with the same histological dating. On day 27 of the cycle, less prolactin was measured in the out-of-phase biopsies (p < 0.05). A large inter-individual variation in endometrial prolactin tissue content was noticed. In group 2 all biopsies but one were in phase. Compared to the in-phase biopsies of group 1, a significantly higher amount of prolactin was found in group 2. Production of endometrial prolactin in vivo is associated with decidualization of the stromal cells. However, because of the large inter-individual variation, determination of prolactin is not of adjuvant diagnostic value for clinical assessment of LPD. Three factors might explain the higher amount of decidual prolactin in group 2 compared to group 1: (1) a higher serum progesterone concentration owing to an increased production by multiple corpora lutea, or because of the administered progesterone; (2) increased estradiol levels and thus progesterone receptors; and (3) direct stimulation of decidualization by gonadotropins.

Adolescent↗
PubMed1999

Bioactivity of luteinizing hormone during normal puberty in girls and boys.

In order to evaluate the in vitro bioactivity of LH during normal puberty compared to LH immunoactivity measured in a highly sensitive immunoassay, blood plasma samples from healthy children were analyzed in a mouse Leydig cell assay (MLCA). Blood samples were obtained from 60 healthy girls and boys during normal pubertal development. Samples were taken on two occasions with a 1-year interval. Three daytime samples and three nighttime samples were analyzed. The correlation of the LH immunoradiometric assay (IRMA) activity with the LH activity in the MLCA varied from 0.60 to 0.96 in the different pubertal stages. During pubertal development, a gradually increase in the activity of LH in both the IRMA and MLCA was found. The ratio of the in vitro bioactivity compared to the immunoreactivity (B/I ratio) did not change significantly during puberty: it was 0.84 (SD 0.58) and 0.66 (SD 0.40) during the first and second sampling period in girls and 0.88 (SD 0.38) and 0.91 (SD 0.46, NS) in the boys. The B/I ratio of LH does not change during puberty. With a high sensitivity and specificity, measurement of LH by IRMA gives representative measurements of the LH in vitro bioactivity in children during pubertal development. Copyrightz1999S. KargerAG,Basel

Adolescent↗
PubMed1994

Stereotactic radiosurgery of vestibular schwannomas with a linear accelerator.

The authors describe their initial experience with stereotactic radiosurgery of 22 cases with vestibular schwannomas using a linear accelerator. 14 of them with a follow-up of at least one year were studied. 6-9 months after treatment 86% had central tumour necrosis, 71% tumour shrinkage and none of them evidence of tumour growth 3 patients developed reversible facial nerve impairment, 2 had permanent facial numbness. Hearing diminished in one case out of three with normal hearing and in two out of three with already diminished hearing. Although there is a general consensus that microsurgery is the treatment of choice for these benign tumours, stereotactic radiosurgery challenges this opinion. Stereotactic radiosurgery not only proves to be a valuable alternative for selected cases not suitable for microsurgery, but it is conceivable that it will become the treatment of choice for small vestibular tumours. Tumour control can be obtained in the majority of treated patients with fewer complications and with a higher rate of cranial nerve sparing. This series indicates that linear accelerators can achieve results similar to the Gamma Unit in the treatment of vestibular schwannomas.

Adult↗
PubMed1993

Stereotactic radiosurgery of cerebral metastases: preliminary results.

The authors have treated 11 solitary cerebral metastases in 9 patients with stereotactic radiosurgery. This relatively new technique of stereotactic single high dose radiotherapy (15-30 Gy to the 70% isodose) is explained. All metastases responded to treatment: six disappeared on CT scan, while the volume of the remaining five diminished significantly. All patients with neurological symptoms had a satisfactory recuperation. There were no complications inherent to the technique. The indications and advantages of this innovative form of "surgical" radiotherapy are discussed.

Adult↗
PubMed1993

Quantitation of paraquat in serum by HPLC.

An HPLC method for the quantitation of paraquat in urine was applied to serum. Sample preparation consisted of ion-pair extraction on disposable cartridges of end-capped octadecyl silica. The paraquat thus extracted, was quantitated by HPLC using 1,1'-diethyl-4,4'-dipyridyl dichloride as an internal standard. Relatively small sample volumes (1 mL serum) were required. Within- and between-assay coefficients of variation for the HPLC technique were 2.9% and 4.0%, respectively, at low paraquat serum concentration (0.4 microgram/mL), and 2.4% and 3.2% at high paraquat serum concentration (4.0 micrograms/mL). The between-assay coefficient of variation for the total procedure, including the extraction, was 5.6% at low concentration (0.4 microgram/mL). Serum concentration levels down to 0.025 microgram/mL could be quantitated. The technique was checked for interference from muscle relaxants (pancuronium bromide and vecuronium bromide) and from anticoagulants (heparin and K2EDTA). No interference was observed.

Chromatography, High Pressure Liquid↗
PubMed1993

Radiosurgery of cerebral arteriovenous malformations with a linear accelerator: preliminary report.

The authors present the results obtained in seven patients with arteriovenous malformations treated with radiosurgery on a linear accelerator. In four patients obliteration of the malformation was obtained after one year. Two of the patients had a transient period of acute brain oedema surrounding the radionecrotic nidus with neurological signs. The present position of radiosurgery in the treatment of arteriovenous malformations is discussed.

Adult↗
PubMed1993

[The stomach speaks: chronicle of a deadly boredom].

The author describes the evolution of the psychotherapy of an 11 year old child: starting with an anonymous depression related to diffuse somatic complaints, it evolved into a playful assertion of a self which seems to depart from the family destiny. The author describes his counter-transferential feelings of tiredness and boredom which were compensated by a constant complicity with his young client. The author suggests that it is this very act of supporting the assertion and formulation of the subject, and disregarding unconditionally the boredom of what is said, which has brought about such a striking and sudden change.

Abdominal Pain↗
PubMed1992

Transventricular endoscopic investigation and treatment of suprasellar arachnoid cysts.

Three children with a suprasellar arachnoid cyst and characteristic neuropathological signs are presented. Through the use of CT scanning and NMR imaging the location, volume and attenuation factors of these cysts can be documented. Stereotactically guided endoscopic exploration of the third ventricle region with visualization and manipulation of the cyst have been performed. This technique should be considered a safe and accurate alternative to craniotomy.

Adolescent↗