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Biomedical subjects

E J Lewis

Publications and source records attributed to E J Lewis.

At least 19 recordsLinked to original sources
PubMed1992

A bifunctional genetic regulatory element of the rat dopamine beta-hydroxylase gene influences cell type specificity and second messenger-mediated transcription.

Dopamine beta-hydroxylase, the enzyme which converts dopamine to norepinephrine, is expressed in a cell type-restricted pattern in neuroendocrine tissue. A segment of the rat gene containing 395 bases of 5'-flanking sequence regulates expression of a reporter gene in a cell type-selective pattern in mammalian cell cultures. Using deletion mutants of the 5'-flanking sequence, we have identified a 30-base genetic regulatory element, designated DB1, which enhances transcription from a heterologous promoter 5-20-fold in neuroendocrine cell lines. DB1-specific DNA-protein complexes are found in nuclear extracts from all cell lines examined, but the migration pattern differs between cell lines. The 5'-flanking region of the dopamine beta-hydroxylase gene is also responsive to cyclic AMP and phorbol ester treatment of SHSY-5Y neuroblastoma cells. The simultaneous presence of both effectors results in synergistic increases in DBH1 mRNA and reporter gene activity. The second messenger regulatory element was localized to the region containing the DB1 element, and reporter plasmids containing multiple copies of the DB1 element are responsive to treatment with inducers. The results of this study identify a cis-acting regulatory element which influences both cell type selectivity and second messenger responsiveness of the rat dopamine beta-hydroxylase gene.

Animals↗
PubMed1992

A controlled trial of plasmapheresis therapy in severe lupus nephritis. The Lupus Nephritis Collaborative Study Group.

BACKGROUND: The prognosis of patients with systemic lupus erythematosus who have glomerulonephritis is poor, despite treatment with immunosuppressive therapy. Plasmapheresis therapy has been used, but there have been few controlled clinical observations of its efficacy. METHODS: We carried out a randomized, controlled trial comparing a standard-therapy regimen of prednisone and cyclophosphamide (standard therapy) with a regimen of standard therapy plus plasmapheresis in 86 patients with severe lupus nephritis in 14 medical centers. The patients underwent plasmapheresis three times weekly for four weeks. Drug therapy was standardized, with strict adherence to nine detailed medical-management protocols. RESULTS: Forty-six patients received standard therapy, and 40 patients received standard therapy plus plasmapheresis. The mean follow-up was 136 weeks. Six patients (13 percent) in the standard-therapy group and eight patients (20 percent) in the plasmapheresis group died. Renal failure developed in 8 patients (17 percent) in the standard-therapy group, as compared with 10 (25 percent) in the plasmapheresis group. Thirty patients (35 percent) reached stopping points--14 (30 percent) in the standard-therapy group and 16 (40 percent) in the plasmapheresis group. A similar number of patients in each group had a decrease in both the serum creatinine concentration and urinary protein excretion to approximately normal values. Patients treated with plasmapheresis had a significantly more rapid reduction of serum concentrations of antibodies against double-stranded DNA and cryoglobulins. CONCLUSIONS: Treatment with plasmapheresis plus a standard regimen of prednisone and cyclophosphamide therapy does not improve the clinical outcome in patients with systemic lupus erythematosus and severe nephritis, as compared with the standard regimen alone.

Adult↗
PubMed1992

Interaction of polycations with cell-surface negative charges of epithelial cells.

The interaction between various polycations and cultured glomerular epithelial cells was studied by cell electrophoresis. It was shown that the glomerular epithelial cell presents a negatively charged surface which imparts a zeta potential of -29.0 +/- 1.5 mV at the peripheral layer of the plasma membrane. The pH at which the GEC charge became 50% reduced (pKa) was determined to be 3.0. A variety of polycations of various sizes and fixed and flexible geometries were tested for their capacity to neutralize the cell charge. All the polycations except cytochrome c and lysozyme were capable of completely neutralizing the cell. Cytochrome c could maximally neutralize only 50% of charge and lysozyme only 72% of charge. However, reduced and 'relaxed' molecules of cytochrome c and lysozyme efficiently neutralized the cell surface, as did larger sized 'flexible' polylysines. On the basis of these findings, we conclude that all polycations are not equal in their capacity to neutralize the cell surface. Flexible molecules in contrast to molecules with rigid structures were more effective in neutralizing the cell. This may likely be due to the exposure and availability of more cationic groups in a flexible molecule which results in stabilization of interaction with cells.

Animals↗
PubMed1992

Regulated expression of the tyrosine hydroxylase gene by membrane depolarization. Identification of the responsive element and possible second messengers.

Prolonged depolarization has been used as a model of adaptive changes in the expression of various proteins, such as ion channels and neurotransmitter biosynthetic enzymes, in response to increased trans-synaptic activity in the nervous system. In depolarized PC12 cells, tyrosine hydroxylase (TH) mRNA levels increased severalfold (Kilbourne, E. J., and Sabban, E. L. (1990) Mol. Brain Res. 8, 121-127). In this study, membrane depolarization caused an increase in the expression of the reporter gene chloramphenicol acetyltransferase (CAT), under transcriptional control of the 5' region of the rat TH gene. These results indicate that membrane depolarization leads to increased transcription of the TH gene. Protein kinase C inhibitors had no effect on the induction of TH mRNA by depolarization, as well as the increase in formation of CAT under control of the upstream region of the TH gene. The depolarization responsive element in the TH gene was mapped to the region containing the cAMP responsive element. This region of the TH gene also increased CAT activity in response to the calcium ionophore, ionomycin. Interestingly, combined treatment with cAMP analogs and membrane depolarization had a greater effect than either alone on TH mRNA levels, as well as on CAT activity in PC12 cells transfected with the plasmid containing the cAMP responsive element.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1992

Progression and remission of renal disease in the Lupus Nephritis Collaborative Study. Results of treatment with prednisone and short-term oral cyclophosphamide.

OBJECTIVE: To describe the clinical course of severe lupus nephritis and to identify the risk factors for progression to renal failure among patients treated with prednisone and short-term courses of low-dose oral cyclophosphamide. DESIGN: Ancillary analyses of data from the Lupus Nephritis Collaborative Study (LNCS). SETTING: University hospital medical centers (14). PATIENTS: The 86 patients who participated in the LNCS (mean follow-up, 136 weeks [2.6 years]) and a subgroup of 63 patients with follow-up of more than 48 weeks (mean follow-up, 160 weeks [3.1 years]). MEASUREMENTS: Initial clinical and pathologic features, response to therapy within 48 weeks, and subsequent clinical events, including development of renal failure. MAIN RESULTS: Renal failure developed in 18 patients (21%). An observed elevation in serum creatinine concentration was the only initial feature predictive of subsequent renal failure. Mean (+/- SD) initial serum creatinine levels were higher in patients who subsequently developed renal failure (244 +/- 134 mumol/L [2.76 +/- 1.52 mg/dL] compared with 163 +/- 103 mumol/L [1.85 +/- 1.17 mg/dL]; P = 0.007). The risk for renal failure was higher among patients with initial serum creatinine levels greater than 106 mumol/L (1.2 mg/dL) (29% compared with 6.5%; P = 0.014). Response to therapy (defined as resolution of initial serum creatinine elevations within 48 weeks) refined the prognosis based on initial serum creatinine determinations. The risk for subsequent renal failure was higher among patients who failed to respond to therapy within 48 weeks (30% compared with 0%; P = 0.015). By comparison, 9% of patients with normal initial serum creatinine levels progressed to renal failure after 48 weeks. CONCLUSIONS: Initial serum creatinine levels and responses to initial therapy with prednisone and short-term cyclophosphamide, as used in the LNCS, can guide further therapy. Patients with normal initial serum creatinine levels or resolution of initial serum creatinine elevations within 48 weeks have a low risk for renal failure and may not require long-term treatment with cyclophosphamide.

Administration, Oral↗
PubMed1992

Soluble and membrane-bound forms of dopamine beta-hydroxylase are encoded by the same mRNA.

A full length cDNA clone for bovine dopamine beta-hydroxylase was expressed in rat pheochromocytoma PC12 cells by stable transformation of this cell line with a plasmid expression vector. The recombinant protein exhibited dopamine beta-hydroxylase enzyme activity and was found in both the soluble and membrane fractions of the secretory vesicle. Immunoprecipitation of cell extracts from recombinant cell lines with dopamine beta-hydroxylase antisera followed by fractionation on sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed two subunits, which migrated to relative molecular masses of 76 and 78 kDa. The recombinant protein co-fractionated with neurotransmitter when subcellular structures were separated by sucrose gradient density centrifugation, suggesting that the protein was routed to the secretory vesicles. Dopamine beta-hydroxylase immunoreactivity in those sucrose gradient fractions presumed to contain secretory vesicles was resistant to treatment with trypsin unless the nonionic detergent Triton X-100 was also present to disrupt membrane structure. The 76- and 78-kDa isoform were each found in both the membrane and soluble fractions of the secretory vesicle. Treatment of cultured cells with nerve growth factor or 8-(4-chlorophenylthio)-cyclic AMP alters the relative distribution of the subunits such that the 76-kDa form predominates. The subcellular distribution of a dopamine beta-hydroxylase cDNA clone lacking the first 16 nucleotide residues was also determined. The predicted amino acid sequence of the protein encoded by this cDNA would be deleted of the first 13 residues of the signal sequence, which were reported to be present in the membrane-bound form, but not the soluble form, of native dopamine beta-hydroxylase (Taljanidisz, J., Stewart, L., Smith, A. J., and Klinman, J. P. (1989) Biochemistry 28, 10054-10061). Immunoprecipitable dopamine beta-hydroxylase derived from expression of the deleted cDNA was found in both the membrane-bound and soluble fractions of the secretory vesicle. These experiments demonstrate that the membrane-bound and soluble forms of dopamine beta-hydroxylase are derived from one primary translation product, which is also sufficient to produce enzyme activity. In addition, the amino-terminal amino acids encoding residues 1-13, which compose the hydrophilic region of the signal sequence, are not necessary for the biogenesis of membrane-bound dopamine beta-hydroxylase.

Adrenal Glands↗
PubMed1992

Renal scanning 99mTc diethylene-triamine pentaacetic acid glomerular filtration rate (GFR) determination compared with iothalamate clearance GFR in diabetics. The Collaborative Study Group for The study of Angiotensin-Converting Enzyme Inhibition in Diabetic Nephropathy.

Traditionally, creatinine clearance is used as an estimation of the glomerular filtration rate (GFR) because of its relative ease and low cost. Errors in collection limit its usefulness. Estimation of GFR using 99mTc diethylene-triamine pentaacetic acid (Tc-DTPA) by direct scintigraphic determination of fractional radionuclide accumulation within each kidney does not require blood or urine sampling, takes 10 to 15 minutes to perform, and has been reported to give a GFR that correlates with 24-hour urinary creatinine clearance (CC) in hospitalized patients (r = 0.95). To assess its usefulness in the outpatient diabetic with nephropathy, 24 patients with type I diabetes underwent 56 iothalamate clearances during water diuresis and 56 simultaneous Tc-DTPA GFR estimations. GFR was also estimated from 24-hour urinary CC, 100/creatinine, and by the formula of Cockcroft and Gault. Tc-DTPA GFR estimation by direct renal scanning correlated relatively poorly with iothalamate GFR (r = 0.74) in this patient population when all levels of iothalamate GFR were compared (n = 56), but improved (r = 0.80) when iothalamate GFR values greater than or equal to 120 mL/min were excluded from analysis (n = 45). Given all levels of iothalamate GFR, the best correlation was obtained with the estimation using the equation of Cockcroft and Gault (r = 0.86).

Adult↗
PubMed1992

Role of pathology indices in the management of severe lupus glomerulonephritis. Lupus Nephritis Collaborative Study Group.

The principal value of the renal biopsy in patients with SLE is as a therapeutic guide. Although semiquantitative indices of nephron loss (chronicity = CI) and acute potentially reversible inflammation (activity = AI) are reported by some to have separate values from traditional classifications of glomerular pathology as predictors of outcome and therapeutic guides, this point remains controversial. We have tested the predictive value of the AI and CI in a large group of patients with severe lupus glomerulonephritis (SLE GN) and a mean follow-up of 281 weeks +/- 116 (mean +/- SD). A total of 86 patients entered into the study of plasmapheresis in severe SLE GN by the Lupus Nephritis Collaborative Study Group, and long-term follow-up was available in 83. The predictive value of the AI and the CI was described over the entire range of cut-off points by the method of receiver operator characteristics (ROC). ROC analysis demonstrated that there was no level of either AI or CI that predicted the outcome of death or renal failure with sufficient sensitivity and specificity to be useful in the individual patient. The CI signifies renal damage and nephron loss, whereas the AI describes potentially reversible pathology. Neither the CI nor the AI taken by itself predicts individual outcomes of renal failure or death in patients with aggressively treated SLE GN. Since the indices fail to identify the patient whose disease will progress to renal failure, they are both insufficient as therapeutic guides and add little to the management of the patient with severe SLE GN.

Adult↗
PubMed1992

A controlled clinical trial of angiotensin-converting enzyme inhibition in type I diabetic nephropathy: study design and patient characteristics. The Collaborative Study Group.

A placebo-controlled, double-blind clinical trial has been initiated to determine whether angiotensin-converting enzyme inhibitor (ACEI) therapy with captopril (25 mg three times daily) slows the progressive loss of renal function in patients with type 1 diabetes mellitus. Entry criteria include; (1) ages 18 to 50 yr; (2) onset of insulin-dependent diabetes before the age of 30 yr, insulin dependent for at least 7 yr; (3) 24-h urine protein excretion > 500 mg, plus: (a) diabetic retinopathy or (b) if no retinopathy, a renal biopsy diagnosis of diabetic nephropathy; (4) serum creatinine (SCr) < 2.5 mg/dL; (5) informed consent. Patients follow strict medical management protocols. Systemic blood pressure is controlled to predefined goals (< 140-90 mm Hg). The primary outcome of the Study is a doubling of the patients' entry SCr to at least 2 mg/dL confirmed by a > 50% decrease in GFR by radioactive iothalamate clearance technique. Baseline characteristics of the cohort at entry into the Study are (mean +/- SD): male/female, 52%/48%; age, 35 +/- 8 yr; duration of diabetes, 21 +/- 7 yr; duration of proteinuria, 2.8 +/- 3.3 yr; duration of retinopathy, 4.5 +/- 4.1 yr; 50% of cohort presented with hypertension, duration, 4 +/- 4.7 yr; blood pressure, 139/86 +/- 19/12; SCr, 1.35 +/- 0.44 mg/dL; GFR 78 +/- 32 mL/min; BUN, 24 +/- 11 mg/dL; proteinuria, 3.1 +/- 3.3 g/day; cholesterol, 236 +/- 50 mg/dL; total glycosylated hemoglobin, 11.1 +/- 2.1%.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1992

Tolerance to enteral tube feeding diets in hypoalbuminemic critically ill, geriatric patients.

Tolerance of elemental (for example, Peptamen [PEP]) or free amino acid (for example, Vivonex TEN [VIV]) tube feeding diets is controversial, especially in the critically ill patient who is hypoalbuminemic. A prospective, randomized trial was conducted to compare differences between feeding PEP (n = 8) or VIV (n = 8) in critically ill, elderly (average age of 66 years) patients. Diets were administered through nasogastric or postpyloric feeding tubes. Eleven patients had diseases of the gastrointestinal tract; all underwent surgical treatment. Patients were fed each diet at full strength, beginning with 20 to 30 milliliters per hour and advancing by 10 to 20 milliliters every day until goal rate was reached, usually on day 4. Assessment was made for ability to comply with rate of tube feeding ordered, compliance with caloric goal and tolerance (as evidenced by abdominal discomfort and diarrhea). Diarrhea was qualitatively defined as more than three stools per day and then quantitatively as the mean number of stools daily. There were no significant differences between the two groups in terms of compliance with prescribed tube feeding order or caloric goal or the presence of diarrhea and abdominal discomfort. There was a significant difference between the two groups in terms of the actual number of stools per day (PEP equals 1.38 versus VIV equals 2.25, p less than 0.02). Serum albumin concentrations upon initiation of the diets were 2.3 grams per deciliter in both groups. We conclude that tolerance to the two diets were similar because it was possible to feed enterally either PEP or VIV in critically ill, hypoalbuminemic patients (serum albumin concentrations of less than 2.5 grams per deciliter) successfully, irrespective of diet. Although there were more stools in the VIV group, this did not reduce compliance with the goals.

Aged↗
PubMed1991

Immunotactoid glomerulopathy.

During the past 10 years, immunotactoid glomerulopathy has become recognized with increasing frequency. The lesion is characterized histologically by highly organized ultrastructural deposits that appear to be composed of immunoglobulin and complement and are negative for amyloid by Congo red stain. Clinically and/or serologically, patients have no evidence of cryoglobulinemia, amyloidosis, systemic lupus erythematosus, or a paraproteinemia, disorders associated with glomerular deposits, which also have a highly organized tactoidal or fibrillar characteristic. Immunotactoid glomerulopathy does not appear to be a multisystemic disease process and thus may represent a primary glomerulopathy. Patients with immunotactoid glomerulopathy present with proteinuria (nephrotic range in more than 60%) and over half of the patients have hypertension, hematuria, and renal insufficiency. Progression to end stage renal disease has occurred in more than 40% of patients reported to date. The experience in treating this disorder using prednisone and/or immunosuppression is limited and has not been impressive. Four patients have successfully undergone renal transplantation, but proteinuria recurred in two and was associated with the recurrence of immunotactoid glomerulopathy in the renal allograft. Although we have gained insight into the clinical course and histopathology of this disorder over the past few years, we still know little about its pathogenesis, an area for further research.

Adult↗
PubMed1991

Serum C3 levels are diagnostically more sensitive and specific for systemic lupus erythematosus activity than are serum C4 levels. The Lupus Nephritis Collaborative Study Group.

To determine whether serum C3 or C4 is more likely to be normal during systemic lupus erythematosus (SLE) remission and abnormal during SLE relapse we studied twelve SLE patients who presented with severe nephritis. The patients were followed long term (12 to 77 months) through multiple relapses (N = 41) and remissions (N = 13) defined by protocol. A total of 471 serum samples were obtained at defined intervals during these relapses and remissions and were analyzed for C3 and C4 levels by two different methods: nephelometry (N) and radial immunodiffusion (R). During SLE remission (defined by protocol and without reference to serum complement levels), C3 measured by N-assay (C3N) and by R-assay (C3R) tended to be normal (specificity of 93% and 71%, respectively). By contrast, C4 measured by N-assay (C4N) and by R-assay (C4R) showed no such tendency (specificity of 50% for both C4N and C4R). During SLE relapse (defined by protocol and without reference to serum complement levels), C3N and C3R were more likely to be abnormal (sensitivity 95% and 85%, respectively) compared with C4N and C4R (sensitivity 56% and 54%, respectively, P less than 0.001 compared with corresponding values for the C3 assay). Analysis by receiver-operator characteristic (ROC) curves demonstrated that the reduced diagnostic sensitivity of C4 versus C3 is not explained by use of an inappropriate lower limits of normal (LLN) for C4.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Novel, potent and selective inhibitors of protein kinase C show oral anti-inflammatory activity.

Clarification of the precise role of protein kinase C (PKC) in cellular functional responses has been hampered by a lack of potent, selective inhibitors. The structural lead provided by staurosporine, a potent but non-selective protein kinase (PK) inhibitor, was used to derive a series of bis(indolyl)maleimides of which the most potent, Ro 31-8425 (I50: PKC = 8 nM) showed 350-fold selectivity for PKC over cAMP-dependent protein kinase. Ro 31-8425 antagonised cellular processes triggered by phorbol esters (potent, specific PKC activators) and inhibited the allogeneic mixed lymphocyte reaction, suggesting a role for PKC in T-cell activation. Methylation of the primary amine in Ro 31-8425 produced an analogue. Ro 31-8830 which, when administered orally, produced a dose-dependent inhibition of a phorbol ester-induced paw oedema in mice (minimum effective dose = 15 mg/kg). Ro 31-8830 also selectively inhibited the secondary inflammation in a developing adjuvant arthritis model in the rat. The results presented here suggest that these selective inhibitors of PKC may have therapeutic value in the treatment of T-cell-mediated autoimmune diseases.

Administration, Oral↗
PubMed1991

A chemical score to evaluate the protein quality of commercial parenteral and enteral formulas: emphasis on formulas for patients with liver failure.

Essential amino acids, found in abundance in high-quality dietary protein, are required daily by hospitalized patients and healthy persons to maintain the dynamic process of protein metabolism. One method for assessing dietary protein quality is by determining a diet's chemical score, ie, the ratio of a gram of the limiting amino acid in a test diet to the same amount of the corresponding amino acid in a reference diet (eg, whole-egg protein) multiplied by 100. This investigation used the chemical score to evaluate the protein quality of 9 parenteral and 17 enteral diets commonly used to feed hospitalized patients. Standard parenteral and enteral products (ie, formulas that had not been designed for patients with a specific disease state) had chemical scores that ranged from 46% to 70%. Limiting amino acids were either methionine (plus cysteine) or phenylalanine (plus tyrosine). Products designed for patients with renal failure had the highest scores, which ranged from 85% to 145%. Products that were enriched with branched-chain amino acids for trauma patients had scores that ranged from 38% to 73%. The only product available for patients with pulmonary compromise had a score of 50%. The lowest scores, which ranged from 5% to 13%, were found in products for patients with hepatic failure. All products, except those with chemical scores below 13%, may be fed in relatively small amounts of protein (7 to 33 g) to satisfy the minimum daily requirements of essential amino acids, although such levels would not meet minimal daily nitrogen requirements. We recommend that dietitians use the chemical score to assess the protein quality of parenteral and enteral diets.

Amino Acids, Essential↗