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B Martin

Publications and source records attributed to B Martin.

At least 145 records · Page 8Linked to original sources
PubMed1998

Stacks on tracks: the plant Golgi apparatus traffics on an actin/ER network.

We have visualized the relationship between the endoplasmic reticulum (ER) and Golgi in leaf cells of Nicotiana clevelandii by expression of two Golgi proteins fused to green fluorescent protein (GFP). A fusion of the transmembrane domain (signal anchor sequence) of a rat sialyl transferase to GFP was targeted to the Golgi stacks. A second construct that expressed the Arabidopsis H/KDEL receptor homologue aERD2, fused to GFP, was targeted to both the Golgi apparatus and ER, allowing the relationship between these two organelles to be studied in living cells for the first time. The Golgi stacks were shown to move rapidly and extensively along the polygonal cortical ER network of leaf epidermal cells, without departing from the ER tubules. Co-localization of F-actin in the GFP-expressing cells revealed an underlying actin cytoskeleton that matched precisely the architecture of the ER network, while treatment of cells with the inhibitors cytochalasin D and N-ethylmaleimide revealed the dependency of Golgi movement on actin cables. These observations suggest that the leaf Golgi complex functions as a motile system of actin-directed stacks whose function is to pick up products from a relatively stationary ER system. Also, we demonstrate for the first time in vivo brefeldin A-induced retrograde transport of Golgi membrane protein to the ER.

Actins↗
PubMed1998

Accuracy and precision of access recirculation measurements by the hemodynamic recirculation monitor.

The hemodynamic monitor (HDM) is a device that uses magnetic principles to accurately measure access recirculation during hemodialysis. The measurement is based on differential conductivity between arterial and venous blood flow rates in the dialysis blood tubing sets. One milliliter of hypertonic saline is injected into the venous line of the blood tubing set as a conductivity "tracer." As the tracer enters the patient, the presence of access recirculation causes a percentage of the hypertonic saline to recirculate into the arterial line and is detected and quantified by the HDM; the percentage of access recirculation is calculated in under 1 minute. Clinical studies were performed in two centers on 106 patients with various forms of blood access (eg, arteriovenous fistulae, Gore-tex grafts [WL Gore and Associates, Flagstaff, AZ], Permcaths [Quinton Instrument Co, Bothell, WA], subclavian catheters). Access recirculation was detected under routine dialysis conditions in only 13 patients. In the remaining cases, attempts at inducing access recirculation were made by reversing the arterial and venous lines and/or increasing the blood pump to its maximum sustainable rate for a given patient. A 15-minute protocol was then instituted. Three blood samples (arterial, venous, and "peripheral" [stop-flow technique]) were first obtained to determine urea measurements and for subsequent calculation of access recirculation; immediately afterward, an HDM recirculation measurement was recorded to allow correlation of urea and HDM access recirculation results (accuracy). Two further HDM access recirculation measurements were made to analyze the precision or repeatability of the HDM test. This protocol was attempted up to three times in each patient on different dialysis days. Two hundred fifty-nine studies were made, and a strong linear correlation was obtained between urea and HDM results (r = 0.94, slope 0.95) over a range of access recirculation (5% to 60%) demonstrating accuracy. Repeated HDM access recirculation results showed a characteristic SD of 1.8% over the whole range of values, demonstrating a precision superior to the 6% expected using the urea method. When zero access recirculation was indicated by the HDM, "ground truth" tests were performed by injecting 1 mL of hypertonic saline (HS) into one injection port of the blood tubing set then 0.1 mL of HS into the other to simulate 10% access recirculation; the mean results were 9.96%+/-1.59% (+/-SD; n = 93), confirming the accuracy of the method.

Arteriovenous Shunt, Surgical↗
PubMed1998

Heidelberg retinal flowmetry: factors affecting blood flow measurement.

AIMS: To evaluate factors affecting Heidelberg retinal flowmeter (HRF) measurements of retinal and optic nerve head blood flow in human subjects. METHODS: The angle of incidence between laser beam and fundus, and camera distance from the eye, were evaluated for their effect upon measures of blood volume, velocity, and flow in a single 100 x 100 x 400 microns volume of temporal peripapillary retinal tissue in normal volunteers. Both intra and intersession reproducibility of these measures were studied. Intersession data were obtained by taking one image per week for 4 weeks. Finally, the intersession haemodynamic data were examined in the entire image (640 x 2560 x 400 microns), using histograms of pixel by pixel blood flow. RESULTS: Measures of blood volume, velocity, and flow from a single anatomical site were unaffected by laser beam to fundus angle of incidence (n = 12). As camera distance from the eye was increased (from 2 to 5 to 7 cm), flow measurements showed increasing individual changes, despite unaltered measured vessel lengths and constant overall mean flow (n = 14). The coefficient of variation for two intersession images of optic nerve head blood flow averaged 7% (n = 20); in contrast, the 4 week intersession coefficient of variation averaged 30% (n = 15). Intersession reproducibility was increased by using flow histograms from the entire image: the coefficients of variation averaged 16% for total flow and 17% for flow in the pixel of median flow. CONCLUSION: HRF measures of flow are independent of the laser beam to fundus angle of the incidence and dependent upon camera distance from the eye. Intersession reproducibility is best using pixel by pixel analysis of the entire image.

Blood Flow Velocity↗
PubMed1998

Selective phosphodiesterase inhibitors modulate the activity of alveolar macrophages from sensitized guinea-pigs.

The aim of this study was to investigate the effects of selective phosphodiesterase (PDE)3 and PDE4 inhibitors on arachidonate release by alveolar macrophages from sensitized and challenged guinea-pigs. Guinea-pigs were sensitized and challenged with ovalbumin administered by aerosol. Bronchoalveolar lavage was performed 48 h later and the PDE and cyclic adenosine monophosphate (cAMP) contents of or the arachidonate release from alveolar macrophages, stimulated in vitro with N-formyl-Met-Leu-Phe (fMLP), were evaluated. PDE3 and PDE4 activities were detected in preparations of macrophage lysate from sensitized challenged and sensitized control animals. Oral pretreatment, prior to antigen challenge in sensitized guinea-pigs, with rolipram or Ro 20-1724 (PDE4 inhibitors) but not milrinone (PDE3 inhibitor) significantly reduced the arachidonate release from alveolar macrophages. In vitro incubation of alveolar macrophages from challenged guinea-pigs with Ro 20-1724 or the cAMP analogue dibutyryl cAMP (db-cAMP) but not milrinone or the cyclic guanosine monophosphate (cGMP) analogue 8-bromo-cGMP (8-br-cGMP) significantly reduced arachidonate release. Incubation of the cells with a combination of milrinone plus rolipram or Ro 20-1724 elicited a marked and significant reduction in arachidonate release by alveolar macrophages stimulated with fMLP. In conclusion, these data show that phosphodiesterase-4 isoenzyme may regulate the release of inflammatory mediators such as arachidonate from macrophages through an increase in intracellular cyclic adenosine monophosphate. This suggests that phosphodiesterase-4 inhibitors have potential in the treatment of inflammatory disorders of the lung.

4-(3-Butoxy-4-methoxybenzyl)-2-imidazolidinone↗
PubMed1998

MR imaging of diffuse cavernous hemangioma of the rectosigmoid colon.

OBJECTIVE: We retrospectively reviewed five pathologically proven cases of diffuse cavernous hemangioma of the rectosigmoid colon to define the MR imaging features of this entity. CONCLUSION: Diffuse cavernous hemangioma of the rectosigmoid colon is revealed as rectosigmoid wall thickening with high signal intensity on T2-weighted MR images. Such wall thickening is associated with abnormal perirectal fat. The extent of bowel involvement and extrarectal locations are well shown on T2-weighted MR images.

Adolescent↗
PubMed1998

Differences between plasma and adipose tissue biomarkers of carotenoids and tocopherols.

Biomarkers of dietary exposure or nutritional status are sought actively to overcome limitations of traditional dietary methodology. We compared plasma and adipose tissue biomarkers for carotenoids and tocopherols. The data consisted of samples from 91 men and 122 women, ages 45-70 years, from the control group of the European Community Multicentre Study on Antioxidants, Myocardial Infarction, and Cancer of the Breast (EURAMIC) Study. Pearson correlations between plasma and adipose tissue measurements for beta-carotene, lycopene, and alpha-tocopherol adjusted for smoking status displayed low, although significant, correlations of 0.39, 0.24, and 0.39, respectively. The correlation was further stratified by sex. After being corrected for measurement error using deattenuation factors obtained from a reproducibility study, the stratified correlation coefficients were as high as 0.80 for beta-carotene in men, 0.62 for lycopene in women, and 0.52 for alpha-tocopherol in women. In addition, plasma and adipose tissue measurements from the myocardial infarction (MI) subset of the EURAMIC study population were used to evaluate the odds of MI, adjusting for confounders. We found that the concentration of lycopene in plasma was not positively associated significantly with MI (odds ratio, 1.78; P = 0.26). Adipose tissue lycopene, in contrast to reports elsewhere on the total population, showed an inverse association with MI (odds ratio, 0.62; P = 0.15). These results suggest that plasma and adipose carotenoids represent different markers for nutritional status and cannot be used interchangeably in epidemiological and dietary validation studies.

Adipose Tissue↗
PubMed1997

Isolation and purification of two major serum amyloid A isotypes SAA1 and SAA2 from the acute phase plasma of mice.

A new procedure was developed for isolation of two major serum amyloid A (SAA) isotypes SAA1 and SAA2 from acute-phase plasma of mice. The procedure included preparation of high-density lipoproteins (HDLs) and their separation by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE). The SAA proteins (Mr 12,000) were electroeluted and afterwards purified from SDS by gel permeation chromatography on a Fractogel TSK-40F column in aqueous 50% acetonitrile-0.1% TFA. Finally, the SAA proteins free from SDS were fractionated by high-performance liquid chromatography on a Vydac 214TP54 column (250 x 4.6 mm I.D., particle size 5 microm), yielding two major fractions with k=5.2 and k=5.5. The N- and C-terminal sequence analyses and mass spectrometry demonstrated the purity of these two major fractions and their identity with apo SAA1 (k=5.2) and apo SAA2 (k=5.5). The developed procedure is applicable to small amounts of pooled murine plasma (6-7 ml) and could be readily modified from small to large scale preparations.

Acute-Phase Reaction↗
PubMed1997

A magnetic colloid system for isolation of rare cells from blood for fish analysis.

To improve cell recovery of trophoblast and nucleated red blood cells from maternal blood for diagnosis of chromosomal abnormalities, we have investigated the use of a magnetic sorting system that utilizes a ferrofluid. The main advantage of this system is that the beads used are small enough to allow visualization of chromosome-specific sequences by fluorescence in situ hybridization (FISH). The ferrofluid was validated using MAb340, a trophoblast-specific antibody, and anti-CD71, used to sort for nucleated red blood cells. Antigen-positive cells could be efficiently sorted from a 1000-fold excess of antigen-negative cells and easily stained by FISH. We are currently evaluating its use on maternal blood samples.

Blood Cells↗
PubMed1997

Evaluation of neuropathy in patients on suramin treatment.

Suramin, a promising chemotherapeutic agent, causes a dose-limiting sensorimotor polyneuropathy. We undertook a phase 1 study of suramin that included serial neurologic and electrophysiologic examinations as part of the safety evaluation. We found that 6 of 41 (15%) patients developed suramin-induced demyelinating neuropathy which resembled Guillain-Barre syndrome clinically. There was 1 asymptomatic patient with electrophysiologic abnormalities suggestive of a demyelinating neuropathy. In addition, 1 patient with mild axonal neuropathy at baseline had deterioration of his symptoms during suramin treatment. Four asymptomatic patients developed electrophysiologic findings suggestive of a mild axonal neuropathy. We conclude that: (1) serial electrophysiologic monitoring is helpful for early detection of suramin-induced neuropathy; and (2) fixed dosing schedule of suramin without adaptive control does not lead to an increased incidence of demyelinating neuropathy when compared to adaptively controlled dosing schedules.

Adult↗
PubMed1997

Hemodynamic and visual function effects of oral nifedipine in patients with normal-tension glaucoma.

PURPOSE: To investigate ocular hemodynamic and visual function changes in patients with normal-tension glaucoma after treatment with a calcium channel blocker (nifedipine). METHODS: In 21 patients with normal-tension glaucoma, color Doppler imaging of the ophthalmic, central retinal, and short posterior ciliary arteries was carried out after a 4-week washout of prior drug treatment and again after 6 months of treatment with nifedipine (30 mg per day). Visual field sensitivity, spatial contrast sensitivity, and intraocular pressure were also recorded. RESULTS: Three subjects experienced intolerable side effects from the drug and were removed from the study. In two other patients, visual function was substantially reduced after 4 months of treatment; nifedipine was discontinued. In the remaining 16 subjects, mean intraocular pressure, retrobulbar hemodynamics, visual field mean sensitivity, and contrast sensitivity at 3, 12, and 18 cycles per degree (cpd), respectively, were unchanged after nifedipine treatment. Contrast sensitivity at 6 cpd, however, improved after drug treatment (P = .004). Individuals with the greatest improvements in contrast sensitivity at 6 cpd showed the largest increases in ophthalmic arterial peak systolic velocity (r = .57; P = .02) and end-diastolic velocity (r = .65; P = .001). CONCLUSION: Nifedipine fails to provide uniform visual function or retrobulbar hemodynamic responses in patients with normal-tension glaucoma. Those patients who do show improved visual function also show improved indices of retrobulbar perfusion.

Administration, Oral↗
PubMed1997

Results at 43 months' follow-up of a double-blind, randomized, prospective clinical trial using intravesical interferon alpha-2b in the prophylaxis of stage pT1 transitional cell carcinoma of the bladder.

OBJECTIVES: To assess the intravesical efficacy of 60 million units of interferon (IFN) alpha-2b in preventing recurrences of Stage pT1 transitional cell carcinoma of the bladder, as well as to assess its local and systemic toxicity. METHODS: A total of 90 patients were included in a double-blind, randomized, prospective clinical trial and divided into two groups of 45 patients. After complete transurethral resection, 60 million units IFN alpha-2b was instilled in one group; in the other, double-distilled water was used. The therapeutic regimen consisted of weekly instillation for 12 weeks, followed by once-monthly instillation until patients had completed 1 year of treatment. RESULTS: Only 78 patients were evaluable. After 12 months of follow-up, the relapse rate was 28.2% (11 of 39) for the IFN group and 35.8% (14 of 39) for the control group (P = NS). After 43 months (range 9 to 67), relapse rates were 53.8% (21 of 39) and 51.2% (20 of 39), respectively (P = NS). Progression, mortality, and local or systemic toxicity were similar in both groups. Flu-like syndrome was not reported. CONCLUSIONS: At the dose used in this study, IFN alpha-2b proved ineffective in the prophylaxis of Stage pT1 transitional cell carcinoma of the bladder compared with a control group. Toxicity was virtually absent.

Administration, Intravesical↗
PubMed1997

Hemodialysis access blood flow rates can be measured by a differential conductivity technique and are predictive of access clotting.

Blood flow in peripheral arteriovenous fistulae and grafts as used for hemodialysis access can be derived from measurements of the amount of access recirculation induced by reversing the dialysis blood lines and a knowledge of the dialyzer blood flow rate. The Hemodynamic Monitor (HDM; GAMBRO Healthcare, Lakewood, CO) is a device that uses magnetic principles to accurately and precisely measure access recirculation during hemodialysis. The measurement is based on differential conductivity between arterial and venous blood flows in the dialysis blood tubing sets following the injection of hypertonic saline into the venous line as a conductivity tracer. Clinical studies were performed on 41 patients from two centers who had arteriovenous fistulae (25 patients) or Goretex grafts (16 patients; W.L. Gore & Associates, Flagstaff, AZ); each patient was studied on two successive dialysis days under variable conditions of dialyzer blood flow, and multiple measurements were made according to a standard protocol. The protocol involved temporarily reversing the arterial and venous lines, then performing an HDM recirculation test and recording the result along with the dialyzer blood flow rate as per the machine blood pump setting. The access blood flow rates measured 1,125+/-581 mL/min (mean+/-SD) on day 1 and 1,140+/-680 mL/ min on day 2 (P > 0.05 [NS]), with an absolute range of 221 to 3,118 mL/min. These flow rates are similar to those measured by other techniques. There was an excellent correlation between access blood flow rates measured in individual patients on days 1 and 2, even in a subset of 13 patients who had the dialyzer blood flow rates altered by > or =100 mL/min, suggesting the independence of access from dialyzer blood flow rates. Analysis of repeated measurements of access blood flow under identical conditions showed a characteristic standard deviation from the mean across the patient population of 7.89%, indicating that the HDM results are repeatable in clinical application. The influence of the measured access blood flow on the outcome of that access was determined after an 8-month follow-up period. Of the 41 accesses, nine were lost to clotting; seven of 14 that had initial blood flow rates less than 750 mL/min clotted, while only two of 27 with flow rates greater than 750 mL/min subsequently clotted (P = 0.005). The data show that the HDM can provide clinically important information on access blood flow.

Arteriovenous Shunt, Surgical↗
PubMed1997

Effects of Ginkgo biloba extract (EGb 761) on learning and possible actions on aging.

A study of the effect of Ginkgo biloba extract (EGb 761) has shown enhancing effects on training in adult and aged Swiss mice. An analysis of inbred mice has confirmed this sensitivity to EGb 761, but depending on the strains, with different effects at different ages. The most interesting results are related to improvements in performances observed with aged mice of the DBA/2J strain. The results obtained with inbred strains in the study of the mossy fibers of the hippocampus make it possible to suggest a link between the improvements in training and the histological structure of the hippocampus. This possibility, which can be confirmed by further studies, is presented here.

Aging↗
PubMed1997

Biotransformation of the naturally occurring isothiocyanate sulforaphane in the rat: identification of phase I metabolites and glutathione conjugates.

Sulforaphane (SFN) is a naturally occurring isothiocyanate present in cruciferous vegetables, such as broccoli, that has been identified as a potent inducer of glutathione S-transferase activities in laboratory animals. The present studies were carried out to elucidate the metabolic fate of SFN in the rat. Particular emphasis was placed on glutathione (GSH)-dependent pathways because conjugation with GSH is a major route by which many isothiocyanates are eliminated in mammals. Male Sprague-Dawley rats were administered a single dose of SFN (50 mg kg-1 ip), and bile and urine were collected over ascorbic acid. Analysis of biological fluids was carried out by ionspray LC-MS/MS using the neutral loss (129 Da) and precursor ion (m/z 164) scan modes to detect GSH and N-acetylcysteine (NAC) conjugates, respectively. In bile, five thiol conjugates (designated M1-M5) were detected. Metabolites M2 and M4 were identified as the GSH conjugates of SFN and erucin (ERN, the sulfide analog of SFN), respectively, by comparing their LC-MS/MS properties with those of standards obtained by synthesis. M1 was characterized as the GSH conjugate of a desaturated metabolite of SFN (tentatively assigned the structure of delta 1-SFN), suggesting that the parent compound also undergoes oxidative metabolism. Metabolites M3 and M5 were identified as the NAC conjugates of SFN and ERN, respectively, and together with the NAC conjugate of delta 1-SFN, these species also were detected in urine. Quantitative determination of the former two mercapturates in urine indicated that approximately 60% and approximately 12% of a single dose of SFN is eliminated in 24 h as the NAC conjugates of SFN and ERN, respectively. The corresponding figures in rats dosed with ERN were approximately 67% and approximately 29%. When the GSH conjugate of SFN was incubated with phosphate buffer (pH 7.4, 37 degrees C), < 1% of the conjugate dissociated to liberate free SFN. On the other hand, the conjugate underwent a facile thiol exchange reaction (> 70% conversion) when incubated in the presence of excess cysteine, thereby acting as an effective carbamoylating agent. It is concluded that SFN undergoes metabolism by S-oxide reduction and dehydrogenation and that GSH conjugation is the major pathway by which the parent compound and its phase I metabolites are eliminated in the rat.

Animals↗
PubMed1997

Smooth muscle myosin light chain kinase is transiently expressed in skeletal muscle during embryogenesis and muscle regeneration both in vivo and in vitro.

By using a polyclonal antibody raised against smooth muscle Myosin Light Chain Kinase of adult chicken we show that the 135 kDa smooth muscle Myosin Light Chain Kinase isoform is present in neonatal and regenerating rat skeletal muscle, as well as in adult atrial myocardium. No reaction was evident in adult skeletal muscle fibres. In neonatal and in early regenerating muscle smooth muscle Myosin Light Chain Kinase is associated with embryonic myosin as revealed by their co-presence in muscle fibres. Experiments in vitro show the same results in myotubes. In atrial myocardium there is a patchy positivity in certain group of myocytes. Immunoblotting experiments show in muscle cell cultures, in neonatal and in regenerating skeletal muscle a protein band with electrophoretic mobility corresponding to that of smooth muscle Myosin Light Chain Kinase. These results suggest that the expression of smooth muscle Myosin Light Chain Kinase is not fully tissue-specific and that regulation of the contractile machinery could be different during myogenesis and in adulthood, in relation to the peculiar dynamic characteristics of developing muscles.

Animals↗
PubMed1997

Physostigmine: going ... going ... gone? Two cases of central anticholinergic syndrome following anaesthesia and its treatment with physostigmine.

Two patients presented with very different signs of central anticholinergic syndrome following general anaesthesia for which they had received premedication with hyoscine. Both responded dramatically to 1 mg of intravenous (i.v.) physostigmine, which produced a rapid return to a normal level of consciousness. The aetiology of central anticholinergic syndrome is multi-factorial, but the diagnosis should be considered in all patients who demonstrate abnormal post-anaesthetic awakening. It is recommended that 1 mg of intravenous physostigmine is a safe and effective treatment for central anticholinergic syndrome, and that a supply of this important drug must be kept readily available in the recovery area of the operating theatre department.

Adult↗
PubMed1997

Control of recombination rate during transformation of Streptococcus pneumoniae: an overview.

Despite the fact that natural transformation was described long ago in Streptococcus pneumoniae, only a limited number of recombination genes have been identified. Two of them have recently been characterized at the molecular level, recA which encodes a protein essential for homologous recombination and mmsA which encodes the homologue of the Escherichia coli RecG protein. After a survey of the available information regarding the function of RecA, RecG, and other proteins such as the mismatch repair proteins HexA and HexB that can affect the outcome of recombinants, the different levels at which horizontal genetic exchange can be controlled are discussed. It is shown that the specific induction of the recA gene which occurs in competent cells is required for full recombination proficiency. Results regarding the ability of the Hex generalized mismatch repair system to prevent recombination between partially divergent sequences during transformation are also summarized. A structural analysis of homeologous recombinants which suggests that formation of mosaic recombinants can occur independently of mismatch repair in a single-step transformation is also reported. Finally, arguments in favor of an evolutionary origin of transformation as a means of genome evolution are discussed and the different types of recombination events observed which could potentially contribute to S. pneumoniae genome evolution are listed.

DNA Repair↗