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Biomedical subjects

J D Butler

Publications and source records attributed to J D Butler.

At least 19 recordsLinked to original sources
PubMed2001

Lysosomal ceroid depletion by drugs: therapeutic implications for a hereditary neurodegenerative disease of childhood.

Neuronal ceroid lipofuscinoses (NCLs) are the most common hereditary neurodegenerative diseases of childhood. The infantile form, INCL, is caused by lysosomal palmitoyl-protein thioesterase (PPT) deficiency, which impairs the cleavage of thioester linkages in palmitoylated proteins, preventing their hydrolysis by lysosomal proteinases. Consequent accumulation of these lipid-modified proteins (constituents of ceroid) in lysosomes leads to INCL. Because thioester linkages are susceptible to nucleophilic attack, drugs with this property may have therapeutic potential for INCL. We report here that two such drugs, phosphocysteamine and N-acetylcysteine, disrupt thioester linkages in a model thioester compound, [14C]palmitoyl approximately CoA. Most importantly, in lymphoblasts derived from INCL patients, phosphocysteamine, a known lysosomotrophic drug, mediates the depletion of lysosomal ceroids, prevents their re-accumulation and inhibits apoptosis. Our results define a novel pharmacological approach to lysosomal ceroid depletion and raise the possibility that nucleophilic drugs such as phosphocysteamine hold therapeutic potential for INCL.

Acetylcysteine↗
PubMed1998

Dysaesthetic neck pain with syncope.

Neurogenic dysaesthetic pain in the neck following surgery for tumours in the neck is rare. Rarer still is the combination of pain following surgery with syncope. We looked at four patients who had tumours within the neck excised and then went on to develop neurogenic dysaesthetic neck pain associated with syncope. Distinction is made between neurogenic dysaesthetic pain following neck surgery and glossopharyngeal neuralgia which has been previously reported in association with neck surgery and also glossopharyngeal neuralgia with syncope. Spinal cord stimulation was used successfully to treat the dysaesthetic pain and syncope in three of the patients while the fourth patient died from the effects of his tumour. Medical practitioners may wish to consider spinal cord stimulation in relation to treating neurogenic dysaesthetic neck pain with syncope.

Adult↗
PubMed1998

Granular cell tumor of the extrahepatic biliary tract.

Granular cell tumors (GCTs) are usually benign lesions that most commonly arise in the skin, subcutaneous tissue, tongue, and oral cavity. GCT of the biliary tract is rare, but most commonly occurs in young African-American females. We report the 58th case of GCT involving the extrahepatic biliary system, and review the world literature on this tumor in this location.

Adult↗
PubMed1996

Client centred hypnotherapy in the management of tinnitus--is it better than counselling?

The aim of this study was to assess whether client centred hypnotherapy (CCH) which required three sessions with a trained therapist was superior to a single counselling session in reducing the impact of tinnitus. Patients were randomly allocated to receive either counselling (n = 42) or CCH (n = 44). The outcome measures were: tinnitus loudness match, subjective tinnitus symptom severity score, trend of linear analogue scale, request for further therapy and whether the patient had an impression of improvement in their tinnitus after treatment. CCH was no better than counselling in reducing the impact of tinnitus using the three quantative measures of tinnitus, and requests for further follow up. The only significant difference between the two therapies was that 20 (45.5 per cent) of the CCH group reported a general sense of improvement compared to six (14.3 per cent) in the counselling group, this is significant p < 0.01. The study did not demonstrate whether this was a genuine hypnotic effect or simply a response to the additional attention from the therapist.

Adult↗
PubMed1994

Cystic fibrosis and phosphatidylcholine biosynthesis.

The cystic fibrosis (CF) gene defect may be associated with a defect in membrane recycling. We have investigated the metabolism of the main constituent of plasma membrane, phosphatidylcholine (PC). In this study of platelets and fibroblasts, we show an increased uptake of choline into PC of CF cells as compared with normal cells. No accumulation of PC was seen. Other patients with respiratory disease (not CF) showed normal rates of incorporation of choline into platelet PC. Platelets from heterozygote individuals showed intermediate turnover rates of choline incorporation into PC. The increase in choline incorporation into PC in CF platelets was not due to modified or increased sensitivity to either cAMP or prostaglandin E2. The total amount and the proportions of the major phospholipids in platelets of control and CF individuals were identical. These findings indicate an increased turnover rate of this phospholipid in CF cells rather than an increased net synthesis.

Base Sequence↗
PubMed1993

Niemann-Pick C disease: cystine and lipids accumulate in the murine model of this lysosomal cholesterol lipidosis.

Cystine levels in tissues of the murine BALB/C mouse model of type C Niemann-Pick disease were shown to be greatly elevated. Subcellular fractionation of liver homogenates by differential centrifugation suggested preferential accumulation in a fraction corresponding to lysosomes. Developmentally, a sharp increase in the accumulation of cystine in the mutant mouse liver occurs subsequent to a similar change in the accumulation of cholesterol, sphingomyelin and glucocerebroside. The lysosomal accumulation of cystine in this mutant mouse provides the experimental opportunity to study some aspects of the deficiency of lysosomal cystine transport noted in cystinosis.

Animals↗
PubMed1993

Ascorbic acid accumulation and transport in human fibroblasts.

As the initial step in the use of fibroblasts as a model system for 'in situ kinetics', ascorbic acid (vitamin C) accumulation in normal human fibroblasts was investigated for the first time. Ascorbic acid was transported into fibroblasts and accumulated against a concentration gradient up to 20-fold, as measured by h.p.l.c. with coulometric electrochemical detection. Ascorbic acid accumulation was mediated by two concentration-dependent transport activities. The first was a high-affinity activity with an apparent Km of 6 microM and an apparent Vmax. of 203 microM/h, and the second was a low-affinity activity with an apparent Km of 5 mM and an apparent Vmax. of 1.8 mM/h. Both activities were inhibited by metabolic inhibitors and inhibitors of ascorbic acid transport in human neutrophils. The low-affinity transporter could not be accounted for by diffusion. Although the high-affinity transport activity was comparable with that described for human neutrophils, the low-affinity transporter was different. These data provide the first evidence that two-component ascorbic acid transport may be a generalized mechanism for accumulation of this vitamin in humans.

2,4-Dinitrophenol↗
PubMed1993

Amino acid composition and N-terminal sequence of purified cystine binding protein of Escherichia coli.

Cystine Binding Protein (CBP), a commercially available crude protein extract obtained by osmotic shock of Escherichia coli (E. coli), was studied to characterize further its cystine binding properties and to elucidate its cystine transport activity. We report here the amino acid composition, the N-terminal amino acid sequence analysis and some binding characteristics of the purified cystine binding component of CBP. A search of the Swiss-Prot version 20 data base revealed that this sequence is unique.

Amino Acid Sequence↗
PubMed1992

Progesterone blocks cholesterol translocation from lysosomes.

Fluorescent microscopic examination of fibroblasts cultured with low density lipoprotein (LDL) and progesterone (10 micrograms/ml) for 24 h revealed extensive filipin-cholesterol staining of perinuclear lysosomes. Levels of unesterified cholesterol were 2-fold greater than in fibroblasts cultured with LDL alone. Progesterone strongly blocked cholesteryl ester synthesis. When cellular uptake of LDL was monitored in the presence of 58035, a specific inhibitor of acyl-CoA:cholesterol acyltransferase, excess unesterified cholesterol was not stored in lysosomes. Discontinuation of LDL uptake in conjunction with progesterone washout markedly reversed the filipin-cholesterol staining of lysosomes. Reversal of the lysosomal cholesterol lipidosis was associated with a rapid burst of cholesteryl ester synthesis and a normalization of the cellular levels of free and esterified cholesterol. In contrast to normal cells, progesterone removal from Niemann-Pick C fibroblasts did not reverse the lysosomal cholesterol accumulation of these mutant cultures. The metabolic precursor of progesterone, pregnenolone, also induced extensive accumulation of cholesterol in lysosomes. Other steroids induced less vacuolar cholesterol accumulation in the following decreasing order: corticosterone and testosterone, promegestone, RU 486. The relative inhibition of cellular cholesterol esterification by the steroids paralleled their respective abilities to sequester cholesterol in lysosomes rather than their inhibition of acyl-CoA:cholesterol acyltransferase activity in cell-free extracts. The progesterone-related inhibition and restoration of lysosomal cholesterol trafficking is a useful experimental means of studying intracellular cholesterol transport. A particularly important feature of its utility is the facile reversibility of the steroid-induced block. The lysosomal cholesterol lipidosis established with a hydrophobic amine, U18666A, was not as readily reversed.

Androstenes↗
PubMed1991

Ascorbic acid accumulation in human skin fibroblasts.

The transport and accumulation of ascorbic acid in normal human skin fibroblasts in culture was investigated by using high-performance liquid chromatographic separation and coulometric electrochemical detection. Results measured as picomole ascorbic acid per microgram cell protein were expressed in molar amounts after determining the volume of skin fibroblasts. Confluent fibroblasts contained undetectable amounts of ascorbic acid. On incubation with micromole per liter amounts of ascorbic acid in the medium, cells showed increasing uptake of ascorbic acid with time, accumulating a 15-fold excess in 3.5 h. Kinetic experiments suggested two transport mechanisms, a high-affinity and a low-affinity transport activity. Both transport activities were temperature sensitive and accumulated ascorbic acid against a concentration gradient.

Ascorbic Acid↗
PubMed1991

Ascorbic acid and in situ kinetics: a new approach to vitamin requirements.

Ascorbic acid requirements are based on preventing the deficiency disease scurvy and on urinary excretion of vitamin C. We proposed the first quantitative approach to determining optimal requirements for ascorbic acid and other vitamins, called in situ kinetics. In situ kinetics biochemically is based on the application of Michaelis-Menten reaction kinetics to ascorbic acid-dependent reactions in situ. Clinically in situ kinetics is based on determining vitamin availability to tissues so that cell-specific reactions can occur. The biochemical concepts of in situ kinetics are verified for the first time through studying ascorbic acid regulation of norepinephrine biosynthesis. The principles of in situ kinetics can now be applied to humans and human cells and for determining optimal requirements for ascorbic acid and for other vitamins.

Ascorbic Acid↗
PubMed1990

Depletion of cystine in cystinotic fibroblasts by homocysteine. Synergism of cysteamine with various reducing agents in depletion of cystine from cystinotic fibroblasts.

The present study shows that homocysteine depleted cystine from cystinotic fibroblasts in vitro. No toxic effects were noted as judged by morphology and growth patterns. Efflux of radioactivity from cystinotic cells prelabeled with [35S]cystine was greater in homocysteine-treated cystinotic cells than in untreated controls. This radioactivity was found, by high voltage electrophoresis separation of effluxed products, to consist mainly of [35S]cystine, along with smaller amounts of [35S]homocysteine-cysteine mixed disulfide. When homocysteine and cysteamine were presented together to cystinotic cells at dose levels individually ineffective in removing cystine from these cells, a marked synergistic effect was observed and cystine content fell to 10% of that seen in untreated cystinotic fibroblasts. Similarly, synergistic effects of cystine depletion from cystinotic cells were demonstrated when cells were treated with a combination of cysteamine and dithiothreitol or glutathione. Incubation of cystinotic cells with homocysteine, dithiothreitol, or cysteamine in combination with vitamin C did not yield synergistic effects. The above findings suggest a novel way to probe metabolic processes in these mutant cells. Exploration of these synergistic effects may lead to more efficacious therapeutic protocols for cystinosis.

Ascorbic Acid↗
PubMed1988

Type C Niemann-Pick disease. Lysosomal accumulation and defective intracellular mobilization of low density lipoprotein cholesterol.

The intracellular accumulation of unesterified cholesterol was examined during 24 h of low density lipoprotein (LDL) uptake in normal and Niemann-Pick C fibroblasts by fluorescence microscopy with filipin staining and immunocytochemistry. Perinuclear fluorescence derived from filipin-sterol complexes was observed in both normal and mutant cells by 2 h. This perinuclear cholesterol staining reached its peak in normal cells at 6 h. Subsequent development of fluorescence during the remaining 18 h of LDL incubation was primarily limited to the plasma membrane region of normal cells. In contrast, mutant cells developed a much more intense perinuclear fluorescence throughout the entire 24 h of LDL uptake with little enhancement of cholesterol fluorescence staining in the plasma membranes. Direct mass measurements confirmed that internalized LDL cholesterol more readily replenishes the plasma membrane cholesterol of normal than of mutant fibroblasts. Perinuclear filipin-cholesterol fluorescence of both normal and mutant cells was colocalized with lysosomes by indirect immunocytochemical staining of lysosomal membrane protein. Abnormal sequestration of LDL cholesterol in mutant cells within a metabolically latent pool is supported by the finding that in vitro esterification of cellular cholesterol could be stimulated in mutant but not in normal cell homogenates by extensive disruption of the intracellular membranous structures of cells previously cultured with LDL. Deficient translocation of exogenously derived cholesterol from lysosomes to other intracellular membrane sites may be responsible for the delayed homeostatic responses associated with LDL uptake by mutant Niemann-Pick Type C fibroblasts.

Cell Membrane↗
PubMed1988

Type-C Niemann-Pick disease: low density lipoprotein uptake is associated with premature cholesterol accumulation in the Golgi complex and excessive cholesterol storage in lysosomes.

Incubation of fibroblasts derived from patients with type-C Niemann-Pick disease with low density lipoprotein results in excessive intracellular accumulation of unesterified cholesterol. Cytochemical techniques revealed that this abnormal cholesterol accumulation is associated not only with a massive storage of cholesterol in lysosomes but also with a premature cholesterol enrichment of the Golgi complex. Cholesterol appeared also in the Golgi complex of some normal fibroblasts after 24 hr of low density lipoprotein loading. These findings indicate that components of the Golgi complex play a role in the intracellular translocation of exogenously derived cholesterol and that disruptions of the cholesterol transport pathway at the Golgi may, in part, be responsible for the deficiency in cholesterol utilization in type-C Niemann-Pick fibroblasts.

Cells, Cultured↗