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Biomedical subjects

A Steck

Publications and source records attributed to A Steck.

At least 19 recordsLinked to original sources
PubMed1999

Carotenoids from guava (Psidium guajava l.): isolation and structure elucidation.

Sixteen carotenoids were isolated from the flesh of Brazilian red guavas (Psidium guajava L.). Their structures were established by means of UV-visible, 400 and 500 MHz (1)H NMR, 120 and 125 MHz (13)C NMR, mass, and circular dichroism spectra. The carotenoids were identified as phytofluene, (all-E)-, (9Z)-, (13Z)-, and (15Z)-beta-carotene, (all-E)-gamma-carotene, (all-E)-, (9Z)-, (13Z)-, and (15Z)-lycopene, (all-E,3R)-beta-cryptoxanthin, (all-E, 3R)-rubixanthin, (all-E,3S,5R,8S)-cryptoflavin, (all-E,3R,3'R, 6'R)-lutein, (all-E,3S,5R,6R,3'S,5'R,8'R)-, and (all-E,3S,5R,6R,3'S, 5'R,8'S)-neochrome. Thirteen of the carotenoids identified are reported as guava carotenoids for the first time.

Carotenoids↗
PubMed1999

Isolation and structural elucidation of (13Z,13'Z,3R,3'R,6'R)-lutein from marigold flowers, kale, and human plasma.

(13Z,13'Z,3R,3'R,6'R)-Lutein has been isolated and purified from extracts of marigold flowers, fresh raw kale (Brassica oleracea var. Acephala), and human plasma and fully characterized by (1)H and (13)C NMR, UV/vis, and MS. While the concentration of (13Z, 13'Z)-lutein in kale and human plasma compared to (all-E,3R,3'R, 6'R)-lutein was found to be quite low, this compound was readily isolated by fractional crystallization of lutein from marigold extracts. Thus, the mother liquors from two consecutive crystallizations of lutein from a saponified extract of marigold flowers were enriched in (13Z,13'Z)-lutein (8.7% of total carotenoids) and employed for the isolation of this compound by HPLC. The identity of the di-Z-lutein in kale and human plasma has been established by comparison of the HPLC-UV/vis-MS profiles of the purified compounds with those of a fully characterized sample, isolated from marigolds. 3-Hydroxy-beta,epsilon-caroten-3'-one and 3'-epilutein have also been identified in extracts from marigolds.

Brassica↗
PubMed1999

Motor neuropathy in porphobilinogen deaminase-deficient mice imitates the peripheral neuropathy of human acute porphyria.

Acute porphyrias are inherited disorders caused by partial deficiency of specific heme biosynthesis enzymes. Clinically, porphyrias are manifested by a neuropsychiatric syndrome that includes peripheral neuropathy. Although much is known about the porphyrias' enzyme defects and their biochemical consequences, the cause of the neurological manifestations remains unresolved. We have studied porphyric neuropathy in mice with a partial deficiency of porphobilinogen deaminase (PBGD). PBGD-deficient mice (PBGD-/-) imitate acute porphyria through massive induction of hepatic delta-aminolevulinic acid synthase by drugs such as phenobarbital. Here we show that PBGD-/- mice develop impairment of motor coordination and muscle weakness. Histologically femoral nerves of PBGD-/- mice exhibit a marked decrease in large-caliber (>8 microm) axons and ultrastructural changes consistent with primary motor axon degeneration, secondary Schwann cell reactions, and axonal regeneration. These findings resemble those found in studies of affected nerves of patients with acute porphyria and thus provide strong evidence that PBGD deficiency causes degeneration of motor axons without signs of primary demyelination, thereby resolving a long-standing controversy. Interestingly, the neuropathy in PBGD-/- mice developed chronically and progressively and in the presence of normal or only slightly (twofold) increased plasma and urinary levels of the putative neurotoxic heme precursor delta-aminolevulinic acid. These data suggest that heme deficiency and consequent dysfunction of hemeproteins can cause porphyric neuropathy.

Acute Disease↗
PubMed1998

[Intensive monitoring of patients with acute cerebral ischemia within the scope of a coordinated stroke treatment concept: initial experiences].

QUESTIONS UNDER STUDY: It has been shown that the prognosis of patients with stroke can be improved by specialized stroke units. Whether any additional benefit can be achieved by use of intensive care resources is unknown. Therefore, it was the purpose of this study to analyze our first experience of management of patients with acute ischaemic stroke in an intensive care unit, as part of a newly implemented coordinated stroke concept. METHODS: A consecutive series of 88 patients with acute ischemic stroke (age 64.4 +/- 14.2 years, 28% females) hospitalized in a medical intensive care unit according to predefined criteria formed the study population. The goals were to monitor vital functions, to complete diagnostic studies in timely fashion and to prevent and treat complications. RESULTS: The patients were hospitalized in the intensive care unit for a mean period of 34.4 +/- 19.5 hours. Relevant pathologic findings included systolic hypertension > 220 mm Hg in 5% and permanent or intermittent relative systolic hypotension < 150 mm Hg in 25% and 98% of patients respectively. One patient (1%) died during the stay. Additional diagnostic studies were performed more often in patients with progressive or fluctuating symptoms (100% of patients in each group) than in those with improving or stable symptoms (50% of patients in each group). Fourteen percent of patients were treated for hypertension and 30% for hypotension. Antithrombotic therapy with aspirin was started in 34%, prophylaxis for venous thrombosis with low dose heparin in 39% and systemic anticoagulation in 40% of patients respectively. No cardiac or pulmonary complications requiring treatment were observed and no specific therapies for neurologic complications were utilized. At the time of discharge from the intensive care unit, 88% of patients showed improved or stable neurologic findings. CONCLUSIONS: In the present analysis, an unexpectedly high incidence of relative arterial hypotension was observed in patients hospitalized in an intensive care unit for acute ischaemic stroke. Therapeutic measures were restricted mainly to blood pressure control and anticoagulation/antithrombotic treatment. Specific therapies for neurologic complications or interventions requiring the resources of an intensive care unit were not used. Whether defined patient groups with ischaemic stroke will benefit from specific treatment in an intensive care unit needs to be tested by controlled, randomized studies.

Acute Disease↗
PubMed1998

Bioassay-guided isolation of a diastereoisomer of kolavenol from Entada abyssinica active on Trypanosoma brucei rhodesiense.

Bioassay-guided fractionation of the dichloromethane rootbark extract of Entada abyssinica (Leguminosae), a plant used by traditional healers in Uganda for the treatment of sleeping sickness, led to the isolation of a diastereoisomer of the clerodane type diterpene kolavenol. This is the first report on this compound. It showed a trypanocidal activity with an IC50 value of 2.5 microg/ml (8.6 microM) against Trypanosoma brucei rhodesiense, the causing agent of the acute form of human African trypanosomiasis.

Animals↗
PubMed1997

Identification, quantification, and relative concentrations of carotenoids and their metabolites in human milk and serum.

Thirty-four carotenoids, including 13 geometrical isomers and eight metabolites, in breast milk and serum of three lactating mothers have been separated, identified, quantified, and compared by high-performance liquid chromatography (HPLC)-photodiode array (PDA) detection-mass spectrometry (MS). Among the metabolites were two oxidation products of lycopene and four of lutein/ zeaxanthin. In addition, two metabolites of lutein, formed as a result of dehydration of this dihydroxycarotenoid under acidic conditions similar to those of the stomach, have also been identified in plasma and breast milk. The oxidative metabolites of lycopene with a novel five-membered-ring end group have been identified as epimeric 2,6-cyclolycopene-1,5-diols by comparison of their HPLC-UV/visible-MS profiles with those of fully characterized (1H- and 13C-NMR spectroscopy) synthetic compounds. The HPLC procedures employed also detected vitamin A, two forms of vitamin E (gamma- and alpha-tocopherol), and two non-carotenoid food components, i.e., piperine and caffeine, in serum and breast milk.

Adult↗
PubMed1997

Reduced glucose metabolism in the frontal cortex and basal ganglia of multiple sclerosis patients with fatigue: a 18F-fluorodeoxyglucose positron emission tomography study.

To investigate the pathophysiology of fatigue in MS, we assessed cerebral glucose metabolism (CMR-Glu) in 47 MS patients using PET and 18F-fluorodeoxyglucose. Applying the Fatigue Severity Scale (FSS), we first compared MS patients with severe fatigue (MS-FAT, n = 19, FSS > 4.9) and MS patients without fatigue (MS-NOF, n = 16, FSS < 3.7) on a pixel-by-pixel basis using Statistical Parametric Mapping (SPM95). Second, we compared FSS values of all 47 patients covering the whole range of this scale with CMRGlu using an analysis of covariance (SPM95). In addition, we determined global CMRGlu by region-of-interest analysis. Sixteen healthy subjects served as control subjects (CON). Global CMRGlu was significantly lower in both MS groups compared with CON (CON 43.3 +/- 6.9 mumol/100 mL/min, MS-FAT 34.7 +/- 4.4, MS-NOF 35.4 +/- 4.5) but was not related to fatigue severity. Comparing the two MS groups, SPM95 analysis revealed predominant CMRGlu reductions bilaterally in a prefrontal area involving the lateral and medial prefrontal cortex and adjacent white matter, in the premotor cortex, putamen, and in the right supplementary motor area of MS-FAT. In addition, there were CMRGlu reductions in the white matter extending from the rostral putamen toward the lateral head of the caudate nucleus. FSS values were inversely related to CMRGlu in the right prefrontal cortex. CMRGlu in the cerebellar vermis and anterior cingulate was relatively higher in MS-FAT than in MS-NOF patients. CMRGlu of both regions showed positive correlations with FSS values. Our data suggest that fatigue in MS is associated with frontal cortex and basal ganglia dysfunction that could result from demyelination of the frontal white matter.

Adult↗
PubMed1996

Neuropathy associated with "benign" anti-myelin-associated glycoprotein IgM gammopathy: clinical, immunological, neurophysiological pathological findings and response to treatment in 33 cases.

We studied 33 patients presenting with a peripheral neuropathy associated with non-malignant anti-myelin-associated glycoprotein (MAG) IgM monoclonal gammopathy (MG) in an attempt to delineate their clinical, immunological, electrophysiological and pathological characteristics; we also reviewed our experience concerning long-term follow-up and therapy. Peripheral neuropathy associated with non-malignant anti-MAG IgM MG was observed mostly in males (sex ratio 7.2), and mean age at onset was 67 years (range 46-81). A predominantly sensory pattern was noted in more than 80% of cases, although some patients were affected by a predominantly motor peripheral neuropathy. Although disease progression was slow in most cases, 45% of patients suffered severe disability, and in 2 cases, the patient's death appeared to stem directly from the neuropathy. The electrophysiological findings were indicative of a demyelinating process in 90% of cases, and electron microscopic examination of nerve biopsy specimens demonstrated widening of the myelin lamellae in more than 95% of cases. Most of our patients showed a disappointing response to steroids and chemotherapy or plasma exchanges. Intravenous immune globulin, evaluated in 17 patients, had a transient, mostly subjective effect in 35% and led to a clear-cut improvement in 24% of cases. We did not observe any correlation between the severity of the clinical picture and the anti-sulphoglucuronyl paragloboside antibody titre; in individual cases, clinical improvement occurred without lowering of IgM levels. Although the severity and the rate of progression may greatly vary from patient to patient, the combination of clinical, electrophysiological and pathological features delineates a characteristic pattern in peripheral neuropathy associated with non-malignant anti-MAG IgM MG.

Aged↗
PubMed1996

SGPG in ALS.

Explore the source record for details and available documents.

Amyotrophic Lateral Sclerosis↗
PubMed1995

[Recurrent Miller Fisher syndrome. Significance of anti-GQ1B antibodies].

In the present report, an unusual case of recurrent Miller Fisher syndrome is described. The patient presented within ten years three similar episodes of ophthalmoplegia, ataxia and areflexia associated with oropharyngeal weakness and signs of mild distal sensory neuropathy. An elevated titer of anti-GQ1b ganglioside antibodies correlated well with the clinical symptoms and signs. The pathogenic role of these antibodies in Miller Fisher syndrome is discussed.

Autoantibodies↗
PubMed1994

Pulmonary hyperplasia in the Fraser cryptophthalmos syndrome.

We report on 2 sibs with the Fraser cryptophthalmos syndrome who had pulmonary hyperplasia and laryngeal stenosis. A third unrelated patient with Fraser syndrome had laryngeal stenosis, renal agenesis, and normal lung development, rather than the expected pulmonary hypoplasia. Three additional cases of pulmonary hyperplasia in the Fraser syndrome were ascertained from a review. In all of these cases the likely mechanism for pulmonary hyperplasia is retention of fetal lung fluid by laryngeal or tracheal obstruction.

Abnormalities, Multiple↗
PubMed1993

[Fatal peripheral neuropathy with predominant motor involvement associated with anti-MAG IgM monoclonal gammapathy].

A 75 year old woman died of predominantly motor peripheral neuropathy with amyotrophy and fasciculations progressing to tetraplegia and death within 19 months. There was a mild distal sensory loss. At electrophysiology, the pattern was initially demyelinating and later became axonal. Nerve biopsy disclosed severe myelinated and unmyelinated fiber loss with wallerian degeneration. The remaining fibers had demyelination widening of the external myelin lamellae and intense hypermyelination. Serum contained an anti-MAG monoclonal IgM reacting with SGPG. Two siblings without monoclonal gammopathy had died of definite amyotrophic lateral sclerosis. This family association is discussed.

Aged↗
PubMed1992

Childhood peripheral neuropathy with autoantibodies to myelin glycoprotein P0.

The serum of a 4-year-old child with severe hypertrophic peripheral neuropathy contained high-titer polyclonal antibodies, mainly of IgG class, reacting with the 30-kd P0 glycoprotein of peripheral nerve. This was demonstrated by indirect immunofluorescence, immunoblot analysis of myelin proteins, and enzyme-linked immunosorbent assay with purified P0 glycoprotein. The antibodies did not react with myelin-associated glycoprotein, sulfated glycuronic acid-containing paragloboside (SGPG and SGLPG), or other peripheral nerve glycolipids or gangliosides. To our knowledge this is the first report of strong antibody activity specifically directed against P0. This antibody may play a causative role in the pathogenesis of the peripheral neuropathy in this patient.

Autoantibodies↗