The distribution of iron in the brain: a phylogenetic analysis using iron histochemistry.

Histochemical procedures can be used to detect the cellular distribution of iron in the brain. The objective of the present study was to determine if the cellular distribution of iron enrichment is conserved between animals on different branches of the phylogenetic tree. This information can facilitate our understanding of the role of iron enrichment in cells of the brain. The animals studied were the mouse, rat, chicken, frog, fish and fly. In order to optimize the detection of iron, two histochemical staining methods and three fixatives per staining method were examined for each species. The results indicated that there was no single cell type that displayed iron enrichment in each of the species examined. In three out of five species in the phylum chordata, iron was enriched in oligodendrocytes; the exceptions to this were the fish and frog, which had iron enrichment in neurons but not oligodendrocytes. Iron was enriched in ependymal cells and endothelial cells in four out of the five species in the phylum chordata with the fish and the mouse being the respective exceptions. Myelin was stained in the mouse and rat, and microglia were occasionally observed in the rat and chicken. Astrocyte staining was not observed in any of the species examined. In the fly third instar larvae, iron enrichment was found in border glia and in neuropil. The absence of a conserved staining pattern between species suggests that iron enrichment probably does not play a role in the main functions that have been attributed to those cells that were stained. These findings, taken together with previously published data on the distribution of ferritin and transferrin, suggests that iron-enriched cells serve as stores of iron for the brain.

Induced components in the spontaneous ovulatory cycle of the Djungarian hamster (Phodopus campbelli).

Although Djungarian hamsters, Phodopus campbelli, show regular, 4-day spontaneous estrous cycles when tested for behavioral receptivity, this study shows that over 50% of 624 virgin females paired with males show their first behavioral estrous on the third day after pairing. The observed pattern is compared against predictions of estrous synchrony and/or estrous cycle suppression models. They fail to explain the high incidence of mating on the third day, and are incompatible with our current understanding of the natural history of the species. An alternative hypothesis, that Djungarian hamsters fail to cycle in the absence of a male, but are rapidly induced into a succession of 4-day cycles by his presence, appears to explain both the pattern of matings and earlier observations that estrous cycles could not be monitored by vaginal smear or lavage, only by interactions with a male. These analyses, thus, conclude that Djungarian hamster females may require a signal from a male to initiate and maintain successive 4-day estrous cycles.

Accuracy of gamma-variate fits to concentration-time curves from dynamic susceptibility-contrast enhanced MRI: influence of time resolution, maximal signal drop and signal-to-noise.

Concentration-time curves derived from dynamic susceptibility-contrast enhanced magnetic resonance imaging are widely used to calculate cerebrovascular parameters. To exclude effects of recirculation, a non-linear regression method is used to fit a gamma-variate function to the concentration-time course. In previous studies the errors arising from the fitting procedure have not been quantified. In a computer simulation we investigate the uncertainties of parameters calculated from the fitted gamma-variate function, exploring the dependencies on signal-to-noise (SNR), time resolution (delta t), and maximal signal drop (MSD). Our study was performed to give a framework on how to design MR-sequences and choose contrast media and their application in order to yield concentration-time curves which allow a reliable performance of the gamma-variate fitting procedure. We recorded 396 concentration-time curves from regions of interest of 40 patients. The gamma-variate fitting procedure was applied to these curves resulting in 396 parameter sets. Ideal concentration-time curves as gamma-variate functions were generated from these sets with a given delta t, MSD, and SNR. Recirculation effect was simulated. Then the gamma-variate fitting was performed again. From ideal and simulated gamma-variate function the area and the normalized first moment were calculated. The uncertainties of the values calculated from the simulated curve relating to the values of the original one were determined. Increase of SNR decreases the involved errors. With SNR values of 100 and more there is only minor influence of delta t and MSD and the fitted curve approximates the original data very well. Smaller values of SNR lead to a stronger influence of delta t and MSD and a higher number of fitting failures. With increasing delta t the uncertainties also increase. Intermediate values of MSD (30% to 70%) yield the smallest errors while increasing or decreasing MSD yields an increase of uncertainty. To achieve low uncertainties in the calculation of cerebrovascular parameters from gamma-variate fits, delta t of the imaging sequence and MSD must be considered. This is more important the lower SNR is. The shown dependencies should be taken into account when choosing MR sequence parameters and application of contrast media.

[MRI in chronic inflammatory bowel disease]. / MRT chronisch entzündlicher Darmerkrankungen.

Chronic inflammatory bowel disease is diagnosed and monitored by the combination of colonoscopy and small bowel enteroklysis. Magnetic resonance imaging has become the gold standard for the imaging of perirectal and pelvic fistulas. With the advent of ultrafast MRI small and large bowel imaging has become highly attractive and is being advocated more and more in the diagnostic work up of inflammatory bowel disease. Imaging protocols include fast T1-weighted gradient echo and T2-weighted TSE sequences and oral or rectal bowel distension. Furthermore, dedicated imaging protocols are based on breath-hold imaging under pharmacological bowel paralysis and gastrointestinal MR contrast agents (Hydro-MRI). High diagnostic accuracy can be achieved in Crohn's disease with special reference to the pattern of disease, depth of inflammation, mesenteric reaction, sinus tract depiction and formation of abscess. In ulcerative colitis, the mucosa-related inflammation causes significantly less bowel wall thickening compared to Crohn's disease. Therefore with MRI, the extent of inflammatory changes is always underestimated compared to colonoscopy. According to our experience in more than 200 patients as well as the results in other centers, Hydro-MRI possesses the potential to replace enteroklysis in the diagnosis of chronic inflammatory bowel disease and most of the follow-up colonoscopies in Crohn's disease. Further technical improvements in 3D imaging will allow interactive postprocessing of the MR data.

[Studies on contrast medium dosage in perfusion-weighted MR imaging]. / Untersuchungen zur Kontrastmitteldosierung bei der perfusionsgewichteten MRT.

PURPOSE: In this study we investigated, whether increasing the dosage of a paramagnetic contrast agent results in a stronger signal decrease in T2*-weighted perfusion sequences and therefore more meaningful parameter maps. MATERIAL AND METHODS: In a prospective study bolus injection of gadolinium-DTPA was performed at dosages of 0.1, 0.2, and 0.3 mmol/kg body weight (BW) in 10 patients each. Before, during and after bolus injection 40 T2*-weighted images of a reference brain slice were acquired within 65.6 seconds on a 1.0 T clinical scanner and perfusion parameters were calculated. RESULTS: Due to the limited signal decrease during bolus passage and the resulting low signal-difference-to-noise ratio (delta S/N) no reliable differentiation of gray and white matter was possible at a contrast agent dosage of 0.1 mmol/kg BW. Only at higher dosages, both, signal decrease and delta S/N were strong enough to allow differentiation of gray and white matter and to yield reliable parameter maps. CONCLUSION: For meaningful MR perfusion imaging at 1.0 T and with the given sequence a contrast agent dosage of at least 0.2 mmol/kg BW is necessary, if a 0.5-molar contrast agent is used.

Effects of lorazepam on brain activity pattern during an anxiety symptom provocation challenge.

Human models of anxiety are useful to develop new effective anxiolytics. The objective of this study was to use functional magnetic resonance imaging (fMRI) to test the hypothesis that a single dose of lorazepam modifies brain activation during an anxiety challenge. Eighteen healthy male subjects underwent fMRI associated with a challenge based on the anticipation of aversive electrical stimulations after pretreatment, either with placebo or with 1.0 mg of oral lorazepam. Anxiety was rated before fMRI and after, referring to the threat condition periods, using State Trait Anxiety Inventory (STAI) and Hamilton scales. The conditioning procedure induced anxiety, as indicated by clinical rating score changes. Lorazepam did not modify anxiety rating as compared to placebo. Lorazepam reduced cerebral activity in superior frontal gyrus, anterior insula/inferior frontal gyrus and cingulate gyrus. The current finding provides the first evidence of the modulatory effects of an established anxiolytic agent on brain activation related to anticipatory anxiety.

Toward improved grading of malignancy in oligodendrogliomas using metabolomics.

In spite of having been the object of considerable attention, the histopathological grading of oligodendrogliomas is still controversial. The determination of reliable biomarkers capable of improving the malignancy grading remains an essential step in working toward better therapeutic management of patients. Therefore the metabolome of 34 human brain biopsies, histopathologically classified as low-grade (LGO, N = 10) and high-grade (HGO, N = 24) oligodendrogliomas, was studied using high-resolution magic angle spinning nuclear magnetic resonance spectroscopy (HRMAS NMR) and multivariate statistical analysis. The classification model obtained afforded a clear distinction between LGOs and HGOs and provided some useful insights into the different metabolic pathways that underlie malignancy grading. The analysis of the most discriminant metabolites in the model revealed the presence of tumoral hypoxia in HGOs. The statistical model was then used to study biopsy samples that were classified as intermediate oligodendrogliomas (N = 6) and glioblastomas (GBMs) (N = 30) by histopathology. The results revealed a gradient of tumoral hypoxia increasing in the following direction: LGOs, intermediate oligodendrogliomas, HGOs, and GBMs. Moreover upon analysis of the clinical evolution of the patients, the metabolic classification seems to provide a closer correlation with the actual patient evolution than the histopathological analysis.

Restless legs syndrome and low brain iron levels in patients with haemochromatosis.

Regional brain iron levels of two patients with haemochromatosis and severe restless legs syndrome (RLS) were assessed using R2' magnetic resonance imaging (MRI) sequences in both patients and in nine healthy controls. R2' relaxation rates in the patients were decreased in the substantia nigra, red nucleus, and pallidum when compared with the controls. These results indicate that local brain iron deficiency may occur in patients with haemochromatosis and suggest a role for brain iron metabolism in the pathophysiology of RLS.

Expression of myosin heavy and light chains changes during pregnancy in the rat uterus.

We investigated the in vivo expression of myosin heavy chains (MHC) and myosin light chains (MLC) in the rat uterus during pregnancy and post partum (p. p.). According to their antigenic reactivity, we observed two smooth-muscle-specific MHC (SM-MHC) of 204 kDa and 200 kDa (SM1 and SM2 respectively) and one non-muscle-specific MHC band of 198 kDa (NM-MHC). Adult virgin female rats expressed SM1 and NM-MHC (65/35) but no SM2. During the first pregnancy NM-MHC expression decreased in favour of the SM1 form, the SM1/NM-MHC ratio being 82/12 after 20 days of pregnancy. SM2 is newly expressed in the first p. p. state, the SM1/SM2/NM-MHC ratio being 58/28/14 between 3 and 33 days p. p. During the second pregnancy, starting 34 days p. p., both SM2 and NM-MHC expression decreased, the SM1/SM2/NM-MHC ratio being 85/0/15 after 20 days of pregnancy. Two protein bands of approximately 154 kDa and 145 kDa (sodium dodecylsulphate electrophoresis), designated SMP1 and SMP2 respectively, with the same immunoreactivity as the SM-MHC were observed in vivo in the pregnant but not in the non-pregnant uterus. In addition, a Ca(2+)-independent protease, which uses MHC as substrate, is expressed in the pregnant but not in the non-pregnant rat uterus. Two isoforms of the 17-kDa MLC (LC17a and LC17b) exist in the rat uterus. Expression of the LC17a isoform increased during the first pregnancy from 46% in virgin rats to 65% in uteri of rats 20 days pregnant.(ABSTRACT TRUNCATED AT 250 WORDS)

Preimplantation endocrinology in the Djungarian hamster (Phodopus campbelli): progesterone, estrogen, corpora lutea, and embryonic development. G.

This study reports the results of a detailed investigation of pregnancy in the Djungarian hamster, Phodopus campbelli, with a 2-h time resolution from 2000 h on proestrus (Day 0) through 0600 h on Day 5. Comparisons of the serum levels of progesterone (P4) and estradiol-17 beta (E2), along with the extractable content of each in the corpora lutea and the nonluteal portion of the right ovary, were used to assess the sources and circulating levels of these steroids throughout preimplantation pregnancy. Simultaneous investigation of embryonic development and location within the reproductive tract permitted accurate staging of development. The time course for development and implantation was similar to that in other short-cycle rodents, with transit into the uterus on the evening of Day 3 and implantation beginning early on Day 5 of pregnancy. In three different circumstances, tissue accumulations of steroids were not associated with concurrent increases in serum levels. The first, late on proestrus to early Day 1 of pregnancy, was a significant accumulation of P4 in the nonluteal ovary while serum levels remained basal. The second, throughout Day 2 of pregnancy, was an accumulation of P4 in the corpora lutea that paralleled the pattern of serum P4 during a normal estrous cycle, but which, in these pregnant females, was not seen as elevated serum P4 levels. This response is likely to be coitally induced and thus advances the first maternal steroid response to pregnancy by 24 h relative to other short-cycle rodents studied.(ABSTRACT TRUNCATED AT 250 WORDS)

Prolactin, follicle-stimulating hormone, and luteinizing hormone levels during preimplantation in the Djungarian hamster (Phodopus campbelli).

The reproductive physiology of female Djungarian hamsters (Phodopus campbelli) varies in several ways from that of more conventional laboratory models. In this study we investigated serum and pituitary levels of prolactin (PRL), LH, and FSH during preimplantation pregnancy. Data were collected from independent females every 2 h from 2200 h on proestrus through 0600 h on Day 5. PRL levels in serum showed a distinct, biphasic, nocturnal surge pattern. Levels during the light phase were low, with variable PRL during Day 2, when both estrogen and progesterone are at low levels in serum. FSH and LH levels in serum were determined twice daily. Elevated FSH and LH levels were found on Day 0 (proestrus). FSH then remained at a basal level while LH began to increase, with evidence for a daily rhythm in serum LH levels. Both FSH and LH accumulated in the pituitary over the first 4 days of pregnancy, although patterns were difficult to interpret. Data were consistent with a hypothesis that ovarian follicular development and preparation for a possible ovulation occur during preimplantation.

Dynamic contrast-enhanced T2*-weighted MRI in patients with cerebrovascular disease.

Our purpose was to investigate the potential of dynamic susceptibility contrast-enhanced MRI in assessing regional haemodynamics in patients with cerebrovascular disease. T2*-weighted FLASH sequences were performed on a control group of 10 healthy subjects, 13 patients with unilateral stenosis or occlusion of the internal carotid artery and 6 patients with acute onset of neurological symptoms, the observed signal intensities being converted into concentration-time curves. A gamma-variate function was fitted to the measured concentration-time curves to eliminate effects of tracer recirculation. In each patient the two cerebral hemispheres were compared and the difference between the mean transit times and the percental change of the regional cerebral blood volume, calculated for each side. Patients with haemodynamically significant unilateral carotid obstruction can be divided into two subgroups: those with good and those with poor collateral supply. Patients with good collateral supply had a slight but not statistically significant increase in mean transit time and cerebral blood volume on the diseased side, whereas those with poor collaterals had a significant increase compared with the control group. In patients with acute onset of neurological symptoms perfusion maps clearly demonstrated the disturbed perfusion at a time when T2-weighted images were still normal. Perfusion imaging is a reliable and noninvasive method of assessing changes in cerebral perfusion in patients with unilateral carotid stenosis. This MR technique permits monitoring of haemodynamic changes during therapy and thus may become an alternative to SPECT and PET scanning. In patients with acute occlusion of a cerebral artery, perfusion imaging reveals the entire, perfusion deficit before conventional MRI and thus allows early intervention.

[Follow up of Crohn's disease under therapy with hydro-MRI]. / Hydro-MRT in der Verlaufsbeobachtung des Morbus Crohn unter Therapie.

PURPOSE: Evaluation of typical MRI-findings in patients with Crohn's disease receiving therapy. Correlation with the course of disease. PATIENTS AND METHODS: 81 follow-up MRI-studies in 25 patients conducted within a period of 3 weeks to 4 years were evaluated retrospectively. Therapy consisted in various combinations of antibiotics and immunosuppressive agents and if necessary operation. The findings of the MRI-studies were correlated with clinical data (e.g.operation of Crohn's complications) and the subjective perception during therapy. RESULTS: The morphological substrate of Crohn's disease in the Hydro-MRI images is reliably detected. Especially in a delineation of extraluminal changes MRI is superior to endoscopy and enteroclysis. Independent from clinical symptoms short- and mid-term follow-up showed inflammatory changes of the intestinal wall in all 25 patients. In 24/81 studies there was persistence or even progression of Crohn's disease in the MRI-studies, although patients were free of symptoms by the time of image acquisition. CONCLUSION: Hydro-MRI is a modality for the evaluation of inflammatory changes in patients with Crohn's disease. Independent from clinical symptoms persistence of Crohn's disease is detectable.

Endocrinology of the pregnant Djungarian hamster Phodopus campbelli.

Factors regulating maternal serum progesterone concentrations during pregnancy in the Djungarian hamster Phodopus campbelli were investigated through changes in (1) concentrations of progesterone and oestradiol in the serum and extracted corpus luteum, non-luteal ovary, and placenta during late pregnancy, (2) prolactin concentrations in the serum, and (3) mass of the fetus, placenta, corpus luteum and non-luteal ovary. Early pregnancy (days 1-4) was characterized by surges of prolactin, corpus luteum growth and increased corpus luteum activity as indicated by increases in luteal mass, progesterone content and serum progesterone concentration. During mid-pregnancy (days 8-11) there was a loss of prolactin surges and a halt in the growth of the corpus luteum, as indicated by stable luteal mass, progesterone content and serum progesterone concentrations that were comparable with those of day 4 of pregnancy. At the same time, the non-luteal ovary began to secrete oestradiol and, on day 12, preovulatory follicles of unknown function were found. During late pregnancy (days 14-17), the prolactin surge pattern was re-established, the non-luteal ovary and corpus luteum contained oestradiol, luteal cell growth caused an increase in corpus luteum size and mass, and serum progesterone concentrations doubled. As late-term pregnancies failed to survive bilateral ovariectomy and the placenta contained little extractable progesterone, it appears that the progesterone of Djungarian hamster pregnancy is synthesized by the corpus luteum throughout gestation.

Alternative splicing and cycling kinetics of myosin change during hypertrophy of human smooth muscle cells.

We investigated in vivo expression of myosin heavy chain (MHC) isoforms, 17 kDa myosin light chain (MLC17), and phosphorylation of the 20 kDa MLC (MLC20) as well as mechanical performance of chemically skinned fibers of normal and hypertrophied smooth muscle (SM) of human myometrium. According to their immunological reactivity, we identified three MHC isoenzymes in the human myometrium: two SM-MHC (SM1 with 204 kDa and SM2 with 200 kDa), and one non-muscle specific MHC (NM with 196 kDa). No cross-reactivity was detected with an antibody raised against a peptide corresponding to a seven amino acid insert at the 25K/50K junction of the myosin head (a-25K/50K) in both normal and hypertrophied myometrium. In contrast, SM-MHC of human myomatous tissue strongly reacted with a-25K/50K. Expression of SM1/SM2/NM (%) in normal myometrium was 31.7/34.7/33.6 and 35.1/40.9/24 in hypertrophied myometrium. The increased SM2 and decreased NM expression in the hypertrophied state was statistically significant (P < 0.05). MHC isoform distribution in myomatous tissue was similar to normal myometrium (36.3/35.3/29.4). In vivo expression of MLC17a increased from 25.5% in normal to 44.2% in hypertrophied (P < 0.001) myometrium. Phosphorylation levels of MLC20 upon maximal Ca(2+)-calmodulin activation of skinned myometrial fibers were the same in normal and hypertrophied myometrial fibers. Maximal force of isometric contraction of skinned fibers (pCa 4.5, slack-length) was 2.85 mN/mm2 and 5.6 mN/mm2 in the normal and hypertrophied state, respectively (P < 0.001). Apparent maximal shortening velocity (Vmax(appt), extrapolated from the force-velocity relation) of myometrium rose from 0.13 muscle length s-1 (ML/s) in normal to 0.24 ML/s in hypertrophied fibers (P < 0.001).

Cerebral MR perfusion imaging: first clinical application of a 1 M gadolinium chelate (Gadovist 1.0) in a double-blinded randomized dose-finding study.

The purpose of this study was to evaluate efficacy and safety of the 1 M gadolinium chelate Gadovist 1.0 for assessment of cerebral hemodynamics with dynamic susceptibility contrast-enhanced magnetic resonance (MR) imaging. Eighty-nine patients with carotid artery stenosis or cerebral infarcts were included in this multicenter, double-blinded study using five dose groups from 0.1 to 0.5 mmol/kg. Imaging was performed with 1-T scanners using a T2*-weighted fast low-angle shot (FLASH) sequence. Dose-dependent changes in quantitative and qualitative parameters describing signal-time curves and relative regional cerebral blood volume maps were investigated. For safety evaluation, vital signs, clinical and laboratory tests, and adverse events were assessed. The quantitative measurements revealed an optimal dose of 0.4 mmol/kg. The qualitative evaluation revealed that the required qualitative assessment for clinical purposes was already reached at a dose of 0. 3 mmol/kg. No significant changes in vital signs and laboratory tests were found. No serious adverse events were observed. The combined results revealed the dose of 0.3 mmol/kg as the diagnostically adequate dose given the gradient-echo sequence and field strength used. Gadovist 1.0 has been shown to be a safe and well-tolerated contrast agent. J. Magn. Reson. Imaging 2000;12:371-380.