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S Smith

Publications and source records attributed to S Smith.

At least 847 records · Page 47Linked to original sources
PubMed1986

Evaluation of thioesterase II as a serum marker for rat mammary cancer.

Thioesterase II, the key enzyme which regulates the production of medium-chain fatty acids by the mammary fatty acid synthetase, is expressed specifically in epithelial cells of the rat mammary gland, regardless of their state of differentiation, and we consider the enzyme to be a reliable marker for this cell type. The objective of this study was to determine whether this enzyme is expressed universally in tumors originating from rat mammary epithelial cells and whether it might be shed into the serum of host animals. Immunoreactive thioesterase II was detected in all of the epithelial derived mammary tumors tested, being highest in tumors that exhibited obvious epithelial morphology. Two of the tumors, R3230AC and DMBA 1, were transplanted into Fischer 344 rats and the levels of thioesterase II in the tumor and serum were monitored by enzyme immunoassay. Thioesterase II content of the transplanted tumors fell to, and remained at, a low level during the first week following transplantation. During this period the transplanted tumor established a new network of blood vessels; no thioesterase II was detectable in the serum. Subsequently, thioesterase II levels in the tumors returned to the values observed before transplantation and thioesterase II was detectable in the serum. Of 51 rats transplanted with the R3230AC tumor, 37 showed elevated serum thioesterase II levels; of 40 transplanted with the DMBA 1 tumor, 35 showed elevated serum thioesterase II. Furthermore, there was a statistically significant correlation between serum thioesterase II and tumor burden in both tumor model systems. The identity of the serum antigen reacting with anti-thioesterase II antibodies was confirmed, by Western immunoblotting, to be full-length thioesterase II polypeptide. Parallel studies with fatty acid synthetase, an enzyme with an ubiquitous tissue distribution, indicated as expected that serum levels of this enzyme were unlikely to provide a reliable index of mammary tumor status. These results indicate that thioesterase II may be a useful serum marker for mammary cancer.

Animals↗
PubMed1986

Group treatment of general practice anxiety problems.

This study examined the effects on anxiety levels and primary care team workload of group psychological treatment for anxiety compared with individual treatment. Patients making high demands on primary care services were selected for group treatment, following which demands for services were considerably reduced. Two types of group treatment were used: the anxiety support group required less staff time to run than the anxiety management group but neither treatment had a clinically significant impact on anxiety symptoms. Individual psychological treatment was more effective in reducing levels of anxiety but required slightly more staff time per patient. These findings show that there is no close correspondence between reduction of anxiety and reduction of service costs and underline the importance of evaluating treatment effects with reference to the specific objectives of treatment.

Adult↗
PubMed1986

Acute chest syndrome in children with sickle cell disease. A retrospective analysis of 100 hospitalized cases.

We reviewed the clinical features of 100 cases of the sickle cell chest syndrome in 57 pediatric patients hospitalized with radiographic findings of pulmonary or pleural disease. Pulmonary infiltration was more common in the lower lobes (86%) than in the upper (25%) or middle lobes (22%). Pleural effusions were present in 38% of cases. Chest syndrome was recognized on presentation in 79% of cases, but was recognized only later in 21% of patients admitted for other indications. Patients recognized initially were more often febrile on admission (68%) than were subsequently recognized patients (33%) (p less than 0.01), but fever eventually occurred in 99 of 100 cases. Pain was an antecedent or coincident problem in 67% of cases. Median hospital stay was 7 days in those 58 cases in which narcotics were given, but only 4 days in those 42 cases in which narcotics were not administered (p less than 0.001). Polyvalent pneumococcal vaccine had been administered to 44 of our 57 patients at some time before their hospitalizations, and 18 patients had been on oral penicillin prophylaxis. Blood was cultured in 93 cases and in only two instances grew Streptococcus pneumoniae. Serologic evidence of Hemophilus influenzae type b infection was found in two additional patients. We conclude that the sickle cell chest syndrome is an acute febrile pulmonary disease frequently associated with pain and/or narcotic analgesic therapy but infrequently associated with proven bacterial infection.

Adolescent↗
PubMed1985

Political animals.

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Community Health Nursing↗
PubMed1985

Mammalian fatty acid synthetase is a structurally and functionally symmetrical dimer.

We have explored a comprehensive experimental approach to determine whether the two condensing-enzyme active centers of the mammalian fatty acid synthetase are simultaneously functional. Our strategy involved utilization of trypsinized fatty acid synthetase, which is a nicked homodimer composed of two pairs of 125 + 95-kDa polypeptides. These core polypeptides lack the chain-terminating thioesterase domains but retain all other functional domains of the native enzyme and can assemble long-chain acyl moieties at a rate equal to that of the native enzyme. The 4'-phosphopantetheine content of these enzyme preparations, estimated from the amount of beta-alanine present, from the amount of taurine formed by performic acid oxidation and from the amount of carboxymethylcysteamine formed by alkylation with iodo[2-14C]acetate, was typically 0.86 mol/mol 95-kDa polypeptide. The stoichiometry of long-chain acyl-enzyme synthesis, measured with radiolabeled precursors, indicated that 0.84 mol acyl-chains were assembled/mol 95-kDa polypeptide. When the small amount of apoenzyme present is taken into account, this stoichiometry translates to 1.94 acyl chains per holoenzyme dimer. The 125-kDa polypeptide of one subunit could be cross-linked to the 95-kDa polypeptide of the other subunit by 1,3-dibromo-2-propanone yielding a single molecular species of 220 kDa. Cross-linking was accompanied by a loss of condensing-enzyme activity. This result is consistent with a structurally symmetrical model for the animal fatty acid synthetase [J.K. Stoops and S.J. Wakil (1981) J. Biol. Chem. 256, 5128-5133] in which the juxtaposed 4'-phosphopantetheine and cysteine thiols of opposing subunits that form the two potential catalytic centers for condensing activity are readily susceptible to cross-linking. Both half-maximal cross-linking and 50% inhibition of activity were observed with 1 mol 1,3-dibromo-2-propanone bound/mol enzyme. After assembly of long-chain acyl moieties on the 4'-phosphopantetheine residues, no vacant condensing-enzyme active sites were demonstrable either by cross-linking with 1,3-dibromo-2-propanone or by formation of carboxymethylcysteamine on treatment with iodoacetate. These results are consistent with a structurally and functionally symmetrical model for the mammalian fatty acid synthetase in which the two condensation sites are simultaneously active.

Acetone↗
PubMed1985

Modification of mammalian fatty acid synthetase activity by NADP.

Experiments are described which show that the mammalian fatty acid synthetase, in the presence of NADP, synthesizes stoichiometric amounts of enzyme-bound acetoacetyl moieties. The acetoacetyl moieties can neither undergo the normal transfer reaction to a CoA acceptor, nor participate in the normal reaction sequence once NADPH is made available. Our results indicate that, since it is the product of the condensation reaction which accumulates on the inhibited enzyme, the previously held view that NADP inhibits the condensation step in fatty acid synthesis is probably incorrect.

Acetyl Coenzyme A↗
PubMed1985

Stoichiometry of substrate binding to rat liver fatty acid synthetase.

Two rat liver fatty acid synthetase preparations, containing 1.6 and 2.0 mol of 4'-phosphopantetheine/mol of synthetase, showed specific activity of 2006 and 2140 nmol of NADPH oxidized/min per mg of protein respectively. The two synthetase preparations could be loaded with either 3.3-4.4 mol of [1-14] acetate or 2.9-3.7 mol of [2-14C]malonate, by incubation with either [1-14C] acetyl-CoA or [2-14C]malonyl-CoA. The 4'-phosphopantetheine site could be more than 90% saturated and the serine site about 80% saturated with malonate derived from malonyl-CoA. However, with acetyl-CoA as substrate, binding at both the 4'-phosphopantetheine and cysteine thiol sites did not reach saturation. We interpret these results to indicate that, whereas the equilibrium constant for transfer of substrates between the serine loading site and the 4'-phosphopantetheine site is close to unity, that for transfer of acetyl moieties between the 4'-phosphopantetheine and cysteine sites favours formation of the 4'-phosphopantetheine thioester. Thus, despite the apparent sub-stoichiometric binding of acetate, the results are consistent with a functionally symmetrical model for the fatty acid synthetase which permits simultaneous substrate binding at two separate active centres.

Acetates↗
PubMed1985

Ligand displacement immunoassay--demonstration of its use for the measurement of serum phenobarbital and phenytoin.

We describe a clinically useful ligand displacement immunoassay for the measurement of serum or plasma phenobarbital and phenytoin. A conjugate of drug-specific antiserum covalently bound to micro-crystalline cellulose and a beta-galactosidase-labelled drug derivative is prepared as a lyophilized reagent. Sample is added to the conjugate and, after 5-min incubation at room temperature, the bound and displaced enzyme-ligand are separated by brief centrifugation. The enzyme activity of the displaced enzyme-ligand is measured on a spectrophotometer or centrifugal analyser. Linear calibration curves are obtained with appropriate sample dilution, allowing generation of the standard curve with a saline zero reference and a single calibrator. The performance of the assay compared favourably with other immunoassays; comparison studies with clinical specimens gave a correlation with EMIT of 0.96 (n = 122) for phenobarbital and 0.95 (n = 96) for phenytoin.

Humans↗
PubMed1985

The use of a monosaccharide linkage group in a heterologous solid-phase enzyme immunoassay for phenytoin.

The preparation is described of monosaccharide-hapten derivatives containing a galactosyl linkage group which bears little structural resemblance to the straight-chain hydrocarbons commonly used for attaching haptens to proteins for use as immunogens. These derivatives are readily synthesised and are coupled to enzymes under mild conditions to produce bridge-heterologous enzyme immunoassays. The use of beta-galactosidase-monosaccharide-phenytoin derivatives in the development of sensitive phenytoin enzyme immunoassays is described and the assays are compared with hapten-heterologous, site-heterologous and homologous phenytoin enzyme immunoassays prepared using other phenytoin derivatives. This technique has application in the development of immunoassays for haptens which have only one functional group to which linkage groups can be attached for covalent coupling of the hapten to proteins.

Animals↗
PubMed1985

Induction of proline-rich glycoprotein synthesis in mouse salivary glands by isoproterenol and by tannins.

Glycoproteins which contain about 45 mol% proline were dramatically induced in mouse parotid and submandibular glands by isoproterenol treatment, but these unusual proteins were not detected in control animals. These acid-soluble substances were obtained by extracting tissues with 10% trichloroacetic acid, as reported previously for isolating proline-rich proteins from rat submandibular glands (Mehansho, H., and Carlson, D.M. (1983) J. Biol. Chem. 258, 6616-6620). Three major proline-rich glycoproteins were induced in parotid glands with apparent molecular weights of 66,000 (GP-66p), 45,000 (GP-45p), and 27,000 (GP-27p), whereas only one such protein was expressed by the submandibular glands (66,000 (GP-66sm]. Both GP-66p and GP-66sm contained about 19% carbohydrate with the following molar ratios, respectively; GalNAc, 1.0, 1.0; Gal, 1.6, 2.3; GlcNAc, 0.8, 1.1; sialic acid, 0.9, 1.9. The peptide chains of GP-66p and GP-66sm appear to be identical by amino acid compositions, glycopeptide analysis, and preliminary amino acid sequencing data. Northern blot analysis of RNAs from parotid glands of normal and isoproterenol-treated rats, probed with a 32P-labeled proline-rich protein cDNA, confirmed that control animals were devoid of mRNAs encoding these proteins and that isoproterenol treatment dramatically induced expression of these genes. Feeding sorghum high in tannins caused changes in the parotid glands similar to those observed upon isoproterenol treatment, as noted earlier with rats (Mehansho, H., Hagerman, A., Clements, S., Butler, L., Rogler, J., and Carlson, D.M. (1983) Proc. Natl. Acad. Sci. U.S.A. 80, 3948-3952). These glycoproteins have high affinities for tannins as demonstrated by competitive binding curves.

Amino Acids↗
PubMed1985

The relationship of insulin production to glucose metabolism in severe sepsis.

Basal glucose metabolism was evaluated in eight stable, infected patients by measuring hepatic glucose production rates in relation to stress endocrine profile and by comparing these data to five injured, noninfected patients. All patients exhibited normal total-body oxygen consumptions and cardiac indices. Fasting basal insulin values were similar in both groups (6 microU/cc) despite a significantly higher plasma glucose level in septic patients (106 +/- 14 mg/dL) compared to nonseptic patients (88 +/- 10 mg/dL). Septic patients exhibited splanchnic glucose production and calculated glucose clearance rates, 53% and 34% higher, than injured nonseptic patients, respectively. In addition, septic patients exhibited a decreased pancreatic insulin secretory response to an intravenous glucose tolerance test as evidenced by a significantly depressed peak insulin value (17 microU/cc) relative to injured patients (77 microU/cc). These findings indicate that insulin suppression is evident in sepsis even in the absence of shock and suggest that sepsis-related basal hyperglycemia does not appear to be associated with peripheral insulin resistance.

Aged↗
PubMed1985

Inhibition of the functional interaction between fatty acid synthetase and thioesterase II by modification of a single cysteine thiol on the thioesterase.

Medium-chain S-acyl fatty acid synthetase thioester hydrolase (thioesterase II), a discrete, monomeric, serine active-site enzyme, modifies the product specificity of the de novo lipogenic pathway by hydrolyzing the thioester bond linking the growing acyl chain to the 4'-phosphopantetheine of the fatty acid synthetase. The mechanism of interaction of thioesterase II and fatty acid synthetase has been studied by probing the thioesterase with sulfhydryl-modifying reagents. Modification of a single cysteine thiol with 5,5'-dithiobisnitrobenzoate destroyed the ability of thioesterase II to catalyze hydrolysis of S-acyl fatty acid synthetase thioesters but had no effect on the ability of the enzyme to hydrolyze the model substrate, decanoyl-S-pantetheine. The inhibition was readily reversed on removal of the thionitrobenzoate moiety from the thioesterase with dithiothreitol. The results of kinetic experiments indicated that loss of the capacity of the thioesterase to hydrolyze the natural substrate could be attributed to an inability of the 5,5'-dithiobisnitrobenzoate-modified enzyme to bind to the fatty acid synthetase. Modification of the same cysteine thiol with methyl methanethiolsulfonate did not affect the ability of thioesterase II to hydrolyze either the natural or model substrates. The results are interpreted to indicate that cysteine thiol, remote from the catalytic active-site serine residue, is present on a binding domain of the thioesterase which interfaces with the fatty acid synthetase. Modification of this thiol with the large thionitrobenzoate moiety, but not with the small CH3S- moiety, inhibits the functional interaction either by steric hindrance or by perturbation of the polypeptide configuration at the binding domain.

Animals↗
PubMed1985

Echinococcal disease of the kidney presenting as a renal filling defect.

We report a unique case of renal echinococcal disease. The patient presented with only a left renal pelvic filling defect without hepatic, pulmonary or other renal involvement. Management consisted of successful exploration and removal of the hydatid mass without sacrifice of renal tissue. The pathogenesis, diagnosis and treatment of echinococcal disease are reviewed.

Echinococcosis↗
PubMed1985

Ultrasound-guided biopsy.

Ultrasound-guided biopsy is a good and feasible technique in dogs. Although we have only used it for biopsy of liver and kidney, it can have further uses. In our use of ultrasound-guided biopsy of kidney and liver, we have found that we can achieve adequate biopsy samples using the Franklin modified Vim-Silverman and Tru Cut biopsy of kidney and liver. The fine-needle biopsies of the liver were adequate for examination of hepatocytes but inadequate to evaluate structure owing to small size of the sample. In contrast, the renal fine-needle samples were both poor in quality and quantity. This technique has the advantages of being noninvasive, quick, and easy, and it can be performed with the patient under local anesthesia. It has an advantage over blind percutaneous biopsy because the needle can be visualized in the organ and the organ scanned after biopsy for possible complications. Another advantage is that, unlike other radiographic biopsy procedures, ionizing radiation is not used for imaging.

Animals↗
PubMed1985

Long-term effect of uninephrectomy on serum creatinine concentration and arterial blood pressure.

Medical records of patients having unilateral nephrectomies done between 1953 and 1978 at a university hospital were reviewed after 5 to 30 years of follow-up to determine if this procedure causes insidious renal insufficiency. Forty patients (selected from 571) ranging in age from 20 to 72 years met the following criteria for inclusion in the study: subject over 20 years of age at nephrectomy; initial serum creatinine concentration less than 1.6 mg/dL; normal arterial blood pressure (less than 150/90 mm Hg); absence of risk factors for chronic renal disease, eg, systemic lupus erythematosis, diabetes mellitus, chronic glomerulonephritis; an initial and a follow-up serum creatinine level; at least 5 years of follow-up. After a mean follow-up of 11.8 years, paired analysis of changes in serum creatinine concentrations showed insignificant differences between pre- and post-nephrectomy levels (0.19 +/- 0.11 mg/dL +/- SEM). Only one patient had a post-nephrectomy serum creatinine level above 2.0 mg/dL. Six patients (four women, two men) developed hypertension (15%) after uninephrectomy, an incidence of hypertension not greater than that found in the population at large. We conclude that uninephrectomy at ages older than 20 years does not lead to renal insufficiency or hypertension in adult patients with normal prenephrectomy serum creatinine and blood pressure levels.

Adult↗