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M D Herman

Publications and source records attributed to M D Herman.

11 recordsLinked to original sources
PubMed2006

Implementation of semi-automated cloning and prokaryotic expression screening: the impact of SPINE.

The implementation of high-throughput (HTP) cloning and expression screening in Escherichia coli by 14 laboratories in the Structural Proteomics In Europe (SPINE) consortium is described. Cloning efficiencies of greater than 80% have been achieved for the three non-ligation-based cloning techniques used, namely Gateway, ligation-indendent cloning of PCR products (LIC-PCR) and In-Fusion, with LIC-PCR emerging as the most cost-effective. On average, two constructs have been made for each of the approximately 1700 protein targets selected by SPINE for protein production. Overall, HTP expression screening in E. coli has yielded 32% soluble constructs, with at least one for 70% of the targets. In addition to the implementation of HTP cloning and expression screening, the development of two novel technologies is described, namely library-based screening for soluble constructs and parallel small-scale high-density fermentation.

Amino Acid Sequence↗
PubMed2003

Effect of dietary coenzyme Q and fatty acids on the antioxidant status of rat tissues.

Wistar rats were fed with different diets with or without supplement coenzyme Q(10) (CoQ(10)) and with oil of different sources (sunflower or virgin olive oil) for six or twelve months. Ubiquinone contents (CoQ(9) and CoQ(10)) were quantified in homogenates of livers and brains from rats fed with the four diets. In the brain, younger rats showed a 3-fold higher amount of ubiquinone than older ones for all diets. In the liver, however, CoQ(10) supplementation increased the amount of CoQ(9) and CoQ(10) in both total homogenates and plasma membranes. Rats fed with sunflower oil as fat source showed higher amounts of ubiquinone content than those fed with olive oil, in total liver homogenates, but the total ubiquinone content in plasma membranes was similar with both fat sources. Older rats showed a higher amount of ubiquinone after diets supplemented with CoQ(10). Two ubiquinone-dependent antioxidant enzyme activities were measured. NADH-ferricyanide reductase activity in hepatocyte plasma membranes was unaltered by ubiquinone accumulation, but this activity increased slightly with age. Both cytosolic and membrane-bound dicumarol-sensitive NAD(P)H:(quinone acceptor) oxidoreductase (DT-diaphorase, EC 1.6.99.2) activities were decreased by diets supplemented with CoQ(10). Animals fed with olive oil presented lower DT-diaphorase activity than those fed with sunflower oil, suggesting that the CoQ(10) antioxidant protection is strengthened by olive oil as fat source.

Animals↗
PubMed1998

Melatonin receptor subtype expression in human cerebellum.

We report the distinct cellular distribution in the human cerebellar cortex of the mammalian mt1 (Mel1a) and MT2 (Mel1b) (1) melatonin receptor subtypes. Specific binding of the non-selective radioligand 2-[125I]iodomelatonin to the outer molecular layer was significantly higher than to the granule cell layer. Melatonin receptor subtype expression was assessed by in situ hybridization using selective and specific digoxigenin-labeled antisense oligonucleotide probes. This is the first demonstration of MT2 melatonin receptor mRNA expression in human cerebellar Bergmann glia and astrocytes. On the other hand, the mt1 melatonin receptor mRNA was expressed in both basket-stellate cells and granule cells. We conclude that mt1 and MT2 melatonin receptors are heterogeneously expressed in human cerebellar cortex.

Astrocytes↗
PubMed1993

The effect of polyamines on voltage-activated calcium channels in mouse neuroblastoma cells.

1. Putrescine has been implicated in modulating cytoplasmic calcium concentration and is correlated with selective neuronal vulnerability in cerebral ischaemia. In order to determine whether putrescine modulates voltage-activated calcium channels, whole-cell and single channel patch clamp experiments were performed with N1E-115 mouse neuroblastoma cells. 2. L-type calcium channel currents showed a 34 +/- 21% increase (n = 6 cells) during external application of 1 mM putrescine. There was no change in the kinetics of the current and no shift in the current-voltage relationship along the voltage axis. 3. T-type calcium channel currents were not affected by 1 mM putrescine. 4. The effect of putrescine on single L-type calcium channels was studied using the cell-attached configuration of the patch clamp technique. Putrescine (5 mM) applied to the bathing solution, but not present in the pipette, caused an increase in open time of the single channel current without changing the conductance of the channel. In 345 depolarizing steps compiled from three cells, the number of channel openings longer than 3 ms increased from six to seventy-six, and the number of channel openings longer than 9 ms increased from zero to twenty-seven. This single channel study supports the hypothesis that putrescine acts on the L-type channel from the inside of the cell. 5. External application of 1 mM spermine and 1 mM spermidine had no effect on T- and L-type calcium channels. Thus, the effect of putrescine is probably not mediated by the higher polyamines. 6. In order to test whether the effect of putrescine is mediated by a second messenger, specific protein kinase C and cyclic AMP-dependent protein kinase inhibitors, staurosporine and KT5720, respectively, were applied prior to putrescine. When cells were preconditioned with 200 nM staurosporine, the increase of the L-type calcium current by 1 mM putrescine was inhibited. By contrast, 200 nM KT5720 did not inhibit the putrescine effect. Therefore, the increase of L-type channel currents by putrescine may be mediated by protein kinase C but not the cyclic AMP-dependent protein kinase. 7. The putrescine-induced enhancement of the L-type calcium channel activity may play an important role in calcium-induced neurotoxicity.

Alkaloids↗
PubMed1993

Systemic T-cell lymphoma presenting with isolated neurological dysfunction and intraparenchymal brain lesions. Case report.

Secondary non-Hodgkin's lymphoma of the central nervous system is typically a late manifestation of systemic T-cell lymphoma, with a 2-month median survival time after the development of neurological disease. Of the reported patients with this late complication, only 1% manifest spread of the disease to the brain parenchyma. The authors report a patient with an unusual initial neurological presentation of systemic T-cell lymphoproliferative disorder and associated space-occupying lesions of the brain parenchyma. The diagnosis was supported by extensive molecular, immunological, and histopathological analysis. Neurological symptoms appeared early in the course of systemic disease and were characterized by spontaneous exacerbations and remissions. The patient has survived for more than 5 years since the onset of his neurological symptoms. Histopathological characterization including immunoperoxidase staining for T-cell markers, DNA content, and cell-cycle analysis of brain tissue obtained at stereotactic biopsy were compared to those of atypical lymphoid cells of peripheral blood, bone marrow, and liver. The neurological manifestations and possible etiologies of T-cell lymphoma are discussed.

Adult↗
PubMed1991

Developmental phases of sleep and motor behaviour in a cat mother-infant system: a time-lapse video approach.

The evolution of sleep patterns in developing kittens was studied using time-lapse video technology and direct observation. The duration, frequency, and onset of the behavioural states and interactions of the cats were analyzed and then organized into phases that represent major changes in developmental structure during the first 6 weeks of kitten life. We have demonstrated that the kittens began exhibiting adult bi-cyclic sleep patterns on approximately Day 30 of development. During the 10-day period that preceded this consolidation of sleep pattern, REM sleep decreased by half, with a reciprocal increase in NREM sleep. These changes were coincident with an increase in kitten patterned motor behaviour and an increase in stimulation of the kittens by the mother during her bi-cyclic active periods.

Animals↗
PubMed1990

Ethanol effects on two types of voltage-activated calcium channels.

Ethanol has been shown to suppress calcium uptake into depolarized synaptosomes, to reduce the durations of calcium spikes in cultured cells and to reduce calcium conductances in invertebrate neurons. Voltage-activated calcium channels therefore appear to be an important target of ethanol action. However, the interactions of ethanol with specific types of calcium channels have yet to be defined. This study examined the effects of ethanol on two different populations of calcium channels in N1E-115 neuroblastoma and in NG108-15 neuroblastoma x glioma hybrid cells. Transient (type I) and long-lasting (type II) calcium channel currents were recorded with the whole-cell voltage clamp technique. At concentrations above 30 mM, ethanol reversibly suppressed both types of calcium channel currents, without changing the voltage dependence of activation. Concentration-response curves were essentially the same for type I and type II channels. Ethanol at concentrations of 100 and 300 mM blocked currents by approximately 15 and 40%, respectively. The voltage dependence of type I channel inactivation was not altered by ethanol concentrations as high as 300 mM, nor was there evidence of a use-dependent blocking action. The effects of ethanol on calcium channels were similar in NG108-15 cells; both channel types were blocked by ethanol at about the same concentrations as were effective in N1E-115 cells. Because ethanol interacts with opiate receptors in some systems, and leucine-enkephalin is known to block type II currents in NG108-15 cells, we examined whether the ethanol block of type II currents could be altered by naloxone.(ABSTRACT TRUNCATED AT 250 WORDS)

Action Potentials↗
PubMed1989

Interactions of the pyrethroid fenvalerate with nerve membrane sodium channels: temperature dependence and mechanism of depolarization.

Depolarization of nerve membranes is an important component of the mode of action of pyrethroids, and its negative temperature dependence parallels that of insecticidal activity. We studied the mechanism and temperature dependence of depolarization of crayfish giant axons by pyrethroids, using intracellular microelectrode and voltage clamp techniques. Membrane depolarization caused by tetramethrin and fenvalerate was greater at 10 degrees C than at 21 degrees C, and was reversible upon changing the temperature. Short-duration depolarizing pulses in voltage-clamped fenvalerate-treated axons induced prolonged sodium currents that are typical of other pyrethroids, but the decay of the tail current following repolarization was extremely slow, lasting several minutes at the large negative holding potential of -120 mV. At the normal resting potential, the tail current did not decay completely, and even without stimulation, a steady-state sodium current developed, which could account for the depolarization. The steady-state current induced by fenvalerate at the resting potential was much larger at 8 degrees C than at 21 degrees C, accounting for the negative temperature dependence of the depolarization. The negative temperature dependence of the steady-state current seems to be due ultimately to the great stabilizing effect of low temperature on the open-modified channel. When the steady-state current was induced at the resting potential, hyperpolarization to more negative potentials caused it to decay with exactly the same time course as tail currents induced by short-duration depolarizing pulses, indicating that both types of currents are carried by identically-modified channels. The modified channels were shown to be inactivated very slowly at potentials more positive than - 100 mV, accounting for the limited depolarization observed in micro-electrode experiments. Even when applied directly to the internal face of the membrane, the effect of fenvalerate on the sodium channel developed slowly, taking more than 90 min to reach its final level. Fenvalerate did not significantly affect potassium currents.

Animals↗
PubMedDate not supplied

Two siblings with the Chiari I malformation.

Two siblings with symptoms characteristic of the Chiari I malformation are described. The malformations were confirmed by magnetic resonance imaging scans and at surgery. Upon review of the world literature, no instance of the Chiari I malformation in a single family has been reported.

Arnold-Chiari Malformation↗