Follow-up of a suspected excess of brain tumours among Namibian children.
Explore the source record for details and available documents.
Brain Neoplasms↗
Biomedical subjects
S Hecht
Publications and source records attributed to S Hecht.
Long-term inter-episode stability of syndromes underlying mania.
OBJECTIVE: To explore the stability of diverse manic presentations across manic recurrences. METHOD: A total of 253 bipolar patients who experienced two or more hospitalizations, because of consecutive manic (or mixed) episodes, during a 20-year period were included. All patients had second hospitalizations with an mean interval of 773 days, while 126 and 91 patients had third and fourth hospitalizations with mean intervals of 1559 and 2237 days from the index hospitalization, respectively. Seven symptom scores, previously factor-validated, were calculated. RESULTS: Depressive mood, irritable aggression, psychomotor/thought inhibition, mania, emotional lability/agitation and psychosis were moderately correlated across the index and subsequent hospitalizations. CONCLUSION: A majority of diverse manic presentations were stable across manic recurrences. The stability was not restricted to two consecutive recurrences but appeared widespread over the long-term course of bipolar disorder. The finding may serve for the development of more effective long-term treatment strategies and a clinically more reasonable subtyping of mania.
Adolescent↗
Studies on the nonmevalonate pathway to terpenes: the role of the GcpE (IspG) protein.
Recombinant Escherichia coli cells engineered for the expression of the xylB gene in conjunction with genes of the nonmevalonate pathway were supplied with (13)C-labeled 1-deoxy-D-xylulose. Cell extracts were analyzed directly by NMR spectroscopy. (13)C-labeled 2C-methyl-D-erythritol 2,4-cyclodiphosphate was detected at high levels in cells expressing xylB, ispC, ispD, ispE, and ispF. The additional expression of the gcpE gene afforded 1-hydroxy-2-methyl-2-(E)-butenyl 4-diphosphate as an intermediate of the nonmevalonate pathway. Hypothetical mechanisms involving conserved cysteine residues are proposed for the enzymatic conversion of 2C-methyl-D-erythritol 2,4-cyclodiphosphate into 1-hydroxy-2-methyl-2-(E)-butenyl 4-diphosphate catalyzed by the GcpE protein.
Amino Acid Sequence↗
Biosynthesis of terpenoids: efficient multistep biotransformation procedures affording isotope-labeled 2C-methyl-D-erythritol 4-phosphate using recombinant 2C-methyl-D-erythritol 4-phosphate synthase.
This paper describes the recombinant expression of the ispC gene of Escherichia coli specifying 2C-methyl-D-erythritol 4-phosphate synthase in a modified form that can be purified efficiently by metal-chelating chromatography. The enzyme was used for the preparation of isotope-labeled 2C-methyl-D-erythritol 4-phosphate employing isotope-labeled glucose and pyruvate as starting materials. The simple one-pot methods described afford numerous isotopomers of 2C-methyl-D-erythritol 4-phosphate carrying (3)H, (13)C, or (14)C from commercially available precursors. The overall yield based on the respective isotope-labeled starting material is approximately 50%.
Aldose-Ketose Isomerases↗
Enzyme-assisted preparation of isotope-labeled 1-deoxy-d-xylulose 5-phosphate.
Recombinant 1-deoxy-D-xylulose 5-phosphate synthase of Bacillus subtilis was used for the preparation of isotope-labeled 1-deoxy-D-xylulose 5-phosphate using isotope-labeled glucose and/or isotope-labeled pyruvate as starting materials. The simple one-pot methods described afford almost every conceivable isotopomer of 1-deoxy-D-xylulose 5-phosphate carrying (13)C or (14)C from commercially available precursors with an overall yield around 50%.
Bacillus subtilis↗
Use of buserelin to induce ovulation in the cyclic mare.
Inducing ovulation in a cyclic mare is often necessary. For this purpose, hCG has been used commonly, but the response can be reduced after successive administrations. The aims of this study were to test the effectiveness of buserelin in hastening ovulation in estrus mares, and its influence on fertility; and to investigate the effect of treatment on LH secretion. Five crossover trials were designed to compare the effect of two treatments: buserelin (40 microg in 4 doses i.v. at 12 h intervals) vs placebo (Experiments 1 and 2); buserelin 40 microg (in 4 doses i.v.) vs 20 microg (Experiment 3); buserelin (4 doses of 20 microg i.v.) vs hCG (1 dose of 2,500 IU i.v.) (Experiment 4); or buserelin (3 doses of 13.3 microg at 6 h interval) vs hCG (Experiment 5). In Experiment 2, blood samples were taken hourly until ovulation, for LH measurements. In Experiment 1, buserelin treatment significantly hastened ovulation. Reduction of the dose by half (Experiment 3) did not alter the effectiveness. In Experiments 4 and 5, buserelin was as effective as hCG in inducing ovulation between 24 and 48 h after initiation of treatment. Buserelin treatment induced a rise in LH concentration during the 48 h period of the experiment, and LH concentrations before ovulation were significantly higher in buserelin treated cycles than in placebo cycles. These experiments demonstrated the usefulness of two new protocols of administration of buserelin, as an alternative to hCG for induction of ovulation. One hypothesis explaining the mechanism of action is that the persistant rise in LH concentration could modify the ratio of biological/immunological LH, as it occurs physiologically, thereby hastening ovulation.
Animals↗
Encapsulation of functional moieties within branched star polymers: effect of chain length and solvent on site isolation.
Porphyrin and pyrene photoactive cores have been encapsulated within an isolating polymeric shell using an efficient and general strategy based on the use of dendritic initiators for the ring-opening polymerization of epsilon-caprolactone to yield functional core star polymers. The isolation of the core functionalities has been studied using fluorescence quenching and fluorescence resonance energy transfer (FRET) techniques as well as solvatochromic probes. With increasing chain length as well as solvent polarity, enhanced site isolation of the core has been observed. These findings have been correlated to actual molecular dimensions independently measured by pulsed field gradient spin-echo (PGSE) NMR. The developed synthetic methodology offers a rapid route to efficient encapsulation of functional moieties and therefore has potential for the design of new materials.
Journal Article↗
Studies on the nonmevalonate pathway of terpene biosynthesis. The role of 2C-methyl-D-erythritol 2,4-cyclodiphosphate in plants.
2C-methyl-D-erythritol 2,4-cyclodiphosphate was recently shown to be formed from 2C-methyl-D-erythritol 4-phosphate by the consecutive action of IspD, IspE, and IspF proteins in the nonmevalonate pathway of terpenoid biosynthesis. To complement previous work with radiolabelled precursors, we have now demonstrated that [U-13C5]2C-methyl-D-erythritol 4-phosphate affords [U-13C5]2C-methyl-D-erythritol 2,4-cyclodiphosphate in isolated chromoplasts of Capsicum annuum and Narcissus pseudonarcissus. Moreover, chromoplasts are shown to efficiently convert 2C-methyl-D-erythritol 4-phosphate as well as 2C-methyl-D-erythritol 2,4-cyclodiphosphate into the carotene precursor phytoene. The bulk of the kinetic data collected in competition experiments with radiolabeled substrates is consistent with the notion that the cyclodiphosphate is an obligatory intermediate in the nonmevalonate pathway to terpenes. Studies with [2,2'-13C2]2C-methyl-D-erythritol 2,4-cyclodiphosphate afforded phytoene characterized by pairs of jointly transferred 13C atoms in the positions 17/1, 18/5, 19/9, and 20/13 and, at a lower abundance, in positions 16/1, 4/5, 8/9, and 12/13. A detailed scheme is presented for correlating the observed partial scrambling of label with the known lack of fidelity of the isopentenyl diphosphate/dimethylethyl diphosphate isomerase.
Capsicum↗
Phosphorylation of 1-deoxy-D-xylulose by D-xylulokinase of Escherichia coli.
1-deoxy-D-xylulose 5-phosphate serves as a precursor for the biosynthesis of the vitamins thiamine and pyridoxal and for the formation of isopentenyl pyrophosphate and dimethylallyl pyrophosphate via the nonmevalonate pathway of terpenoid biosynthesis. Earlier studies had shown that Escherichia coli incorporates unphosphorylated 1-deoxy-D-xylulose into the terpenoid side chain of ubiquinones with high efficacy. We show that D-xylulokinase of E. coli (EC 2.7.1.17) catalyzes the phosphorylation of 1-deoxy-D-xylulose at the hydroxy group of C-5 at a rate of 1.6 micromol.mg min-1. This reaction constitutes a potential salvage pathway for the generation of 1-deoxy-D-xylulose 5-phosphate from exogenous or endogenous 1-deoxy-D-xylulose as starting material for the biosynthesis of terpenoids, thiamine and pyridoxal.
Amino Acid Sequence↗
Biosynthesis of terpenoids. 2C-Methyl-D-erythritol 2,4-cyclodiphosphate synthase (IspF) from Plasmodium falciparum.
The putative catalytic domain of an open reading frame from Plasmodium falciparum with similarity to the ispF gene of Escherichia coli specifying 2C-methyl-D-erythritol 2,4-cyclodiphosphate synthase was expressed in a recombinant E. coli strain. The recombinant protein was purified to homogeneity and was found to catalyze the formation of 2C-methyl-D-erythritol 2,4-cyclodiphosphate from 4-diphosphocytidyl-2C-methyl-D-erythritol 2-phosphate at a rate of 4.3 micromol x mg(-1) x min(-1). At lower rates, the recombinant protein catalyzes the formation of 2-phospho-2C-methyl-D-erythritol 3,4-cyclophosphate from 4-diphosphocytidyl-2C-methyl-D-erythritol 2-phosphate and the formation of 2C-methyl-D-erythritol 3,4-cyclophosphate from 4-diphosphocytidyl-2C-methyl-D-erythritol. Divalent metal ions such as magnesium or manganese are required for catalytic activity. The enzyme has a pH optimum at pH 7.0. Recombinant expression of the full-length open reading frame afforded insoluble protein that could not be folded in vitro. The enzyme is a potential target for antimalarial drugs directed at the nonmevalonate pathway of isoprenoid biosynthesis.
Amino Acid Sequence↗
Biosynthesis of terpenoids: 4-diphosphocytidyl-2C-methyl-D-erythritol synthase of Arabidopsis thaliana.
A hypothetical gene with similarity to the ispD gene of Escherichia coli was cloned from Arabidopsis thaliana cDNA. The ORF of 909 bp specifies a protein of 302 amino acid residues. The cognate chromosomal gene consists of 2,071 bp and comprises 11 introns with a size range of 78-202 bp. A fragment comprising amino acid residues 76-302 was expressed in a recombinant E. coli strain. The protein was purified to homogeneity and was shown to catalyze the formation of 4-diphosphocytidyl-2C-methyl-d-erythritol from 2C-methyl-d-erythritol 4-phosphate with a specific activity of 67 micromol small middle dotmin(-1) mg(-1). The Michaelis constants for 4-diphosphocytidyl-2C-methyl-d-erythritol and CTP were 500 microM and 114 microM, respectively.
Amino Acid Sequence↗
Biosynthesis of terpenoids: YgbB protein converts 4-diphosphocytidyl-2C-methyl-D-erythritol 2-phosphate to 2C-methyl-D-erythritol 2,4-cyclodiphosphate.
In many microorganisms, the putative orthologs of the Escherichia coli ygbB gene are tightly linked or fused to putative orthologs of ygbP, which has been shown earlier to be involved in terpenoid biosynthesis. The ygbB gene of E. coli was expressed in a recombinant E. coli strain and was shown to direct the synthesis of a soluble, 17-kDa polypeptide. The recombinant protein was found to convert 4-diphosphocytidyl-2C-methyl-D-erythritol 2-phosphate into 2C-methyl-D-erythritol 2,4-cyclodiphosphate and CMP. The structure of the reaction product was established by NMR spectroscopy using (13)C-labeled substrate samples. The enzyme-catalyzed reaction requires Mn(2+) or Mg(2+) but no other cofactors. Radioactivity from [2-(14)C]2C-methyl-D-erythritol 2,4-cyclodiphosphate was diverted efficiently to carotenoids by isolated chromoplasts from Capsicum annuum and, thus, was established as an intermediate in the deoxyxylulose phosphate pathway of isoprenoid biosynthesis. YgbB protein also was found to convert 4-diphosphocytidyl-2C-methyl-D-erythritol into 2C-methyl-D-erythritol 3,4-cyclophosphate. This compound does not serve as substrate for the formation of carotenoids by isolated chromoplasts and is assumed to be an in vitro product without metabolic relevance.
Bacterial Proteins↗
Biosynthesis of terpenoids: YchB protein of Escherichia coli phosphorylates the 2-hydroxy group of 4-diphosphocytidyl-2C-methyl-D-erythritol.
A comparative analysis of all published complete genomes indicated that the putative orthologs of the unannotated ychB gene of Escherichia coli follow the distribution of the dxs, dxr, and ygbP genes, which have been shown to specify enzymes of the deoxyxylulose phosphate pathway of terpenoid biosynthesis, thus suggesting that the hypothetical YchB protein also is involved in that pathway. To test this hypothesis, the E. coli ychB gene was expressed in a homologous host. The recombinant protein was purified to homogeneity and was shown to phosphorylate 4-diphosphocytidyl-2C-methyl-D-erythritol in an ATP-dependent reaction. The reaction product was identified as 4-diphosphocytidyl-2C-methyl-D-erythritol 2-phosphate by NMR experiments with various (13)C-labeled substrate samples. A (14)C-labeled specimen of this compound was converted efficiently into carotenoids by isolated chromoplasts of Capsicum annuum. The sequence of E. coli YchB protein is similar to that of the protein predicted by the tomato cDNA pTOM41 (30% identity), which had been implicated in the conversion of chloroplasts to chromoplasts.
Amino Acid Sequence↗
[Neuropsychological deficits in the initial acute episode of schizophrenia. A comparison with chronic schizophrenic patients].
By administering an extensive battery of neuropsychological tests, cognitive performance of 66 patients with first episode schizophrenia, 49 patients with chronic schizophrenia and 40 healthy controls has been assessed in the areas of memory functions, speech and cognitive flexibility/abstraction. The three groups were comparable with regard to age, gender and education. Both patient groups showed a significant generalized neuropsychological impairment relative to controls. Patients with first episode were most impaired in visual motor processing and attention (VSM). Besides impairment in VSM, performance in abstraction/flexibility was significantly worse in chronic schizophrenics compared to first episode schizophrenics. Our findings suggest that neuropsychological functions are already impaired at the onset of the illness. Whether cognitive impairment in performance that is attributed to frontal dysfunctions is deteriorating during the course of the illness or is predicting an unfavourable course can only be answered by prospective follow-up studies.
Acute Disease↗
Noninvasive estimation of pulmonary artery diastolic pressure in patients with tricuspid regurgitation by Doppler echocardiography.
OBJECTIVES: The purpose of this study was to determine whether Doppler echocardiographic assessment of right ventricular pressure at the time of pulmonary valve opening could predict pulmonary artery diastolic pressure. BACKGROUND: Doppler echocardiography has been used to estimate right ventricular systolic pressure noninvasively. Because right ventricular and pulmonary artery diastolic pressure are equal at the time of pulmonary valve opening, Doppler echocardiographic estimation of right ventricular pressure at this point might provide an estimate of pulmonary artery diastolic pressure. METHODS: We studied 31 patients who underwent right heart catheterization and had tricuspid regurgitation. Pulmonary flow velocity was recorded by pulsed wave Doppler echocardiography, and tricuspid regurgitant velocity was recorded by continuous wave Doppler echocardiography. The time of pulmonary valve opening was determined as the onset of systolic flow in the pulmonary artery. Tricuspid velocity at the time of pulmonary valve opening was measured by superimposing the interval between the onset of the QRS complex on the ECG and the onset of pulmonary flow on the tricuspid regurgitant envelope. The tricuspid gradient at this instant was calculated from the measured tricuspid velocity using the Bernoulli equation. This gradient was compared to the pulmonary artery diastolic pressure obtained by right heart catheterization. MEASUREMENTS AND RESULTS: The pressure gradient between the right atrium and right ventricle obtained at the time of pulmonary valve opening ranged from 9 to 31 mm Hg (mean, 19+/-5) and correlated closely with invasively measured pulmonary artery diastolic pressure (range, 9 to 36 mm Hg; mean, 21+/-7 mm Hg; r = 0.92; SEE, 1.9 mm Hg). CONCLUSION: Doppler echocardiographic measurement of right ventricular pressure at the time of pulmonary valve opening is a reliable noninvasive method for estimating pulmonary diastolic pressure.
Aged↗
[Case report. Colic symptoms in a cow].
Explore the source record for details and available documents.
Animals↗
The stability of estrogen and progesterone receptor expression on breast carcinoma cells stored as PreservCyt suspensions and as ThinPrep slides.
BACKGROUND: Analysis of estrogen receptor (ER) and progesterone receptor (PR) status is an important ancillary test in the evaluation of positive breast fine-needle aspirates. This study compares the detection of ER and PR in breast carcinoma cells suspended in PreservCyt with that achieved with stored ThinPrep slides (TP). METHODS: ER and PR positive mammary tumor cells (cell line ZR-75-1 spiked in PreservCyt by the American Type Culture Collection) were used to evaluate the stability of immunodetection of ER and PR under two conditions: 1) TP slides prepared immediately from PreservCyt and stored air-dried (stored TP) for up to 56 days, and 2) TP prepared from cells suspended in PreservCyt (newly prepared TP) on Days 1, 2, 5, 14, 21, 42, and 56. At each of the time periods, stored TP and newly prepared TP were analyzed for ER and PR using the same immunocytochemical staining protocol. The percentage of positive cells was calculated by counting 1000 cells/TP. RESULTS: Positivity for ER and PR was demonstrated in both stored TP and newly prepared TP on Days 1, 2, 5, 14, 21, 42, and 56. Over the 56-day period, the number of ER positive cells ranged from 41% to 57% in stored TP and from 38% to 58% in newly prepared TP. The number of PR positive cells ranged from 31% to 41% in stored TP and from 26% to 37% in newly prepared TP. Mild, nonspecific cytoplasmic and nuclear staining occurred in all newly prepared TP (PR > ER). CONCLUSIONS: ER and PR antigenicity was preserved in both stored TP and newly prepared TP of mammary tumor cells over a 56-day storage period. This demonstrates that ER and PR status can be evaluated in cytologic material from breast carcinoma using the ThinPrep technique.
Biopsy, Needle↗
Neuropsychological impairment and psychopathology in first-episode schizophrenic patients related to the early course of illness.
The objective of the present study was to explore whether the early course of illness including first onset of psychotic symptoms influences neuropsychological functioning and psychopathology in first-episode schizophrenics. Patients with a short prodromal period (n = 20) and patients with a long prodromal period (n = 20) and controls matched with regard to age, gender and education (n = 40) were administered a battery of standardized neuropsychological tests and psychopathological rating scales. The results indicate an overall difference in neuropsychological performance with the schizophrenic patients scoring lower than controls. Schizophrenic patients scored significantly lower in all subtests except in visual memory and abstraction/flexibility than controls. No significant difference between neuropsychological performance between patient samples was found. Psychopathology was more pronounced in the long prodromal period group rating higher on negative and affective symptoms compared with the short prodromal period group. The data suggests that neuropsychological deficits in first-episode schizophrenia are independent of the early course of schizophrenia, and although negative symptoms are associated with the length of the prodromal period, they do not imply greater neuropsychological impairment.
Adult↗