Search PubMed⌕ Search

Biomedical subjects

T M Kelly

Publications and source records attributed to T M Kelly.

At least 19 recordsLinked to original sources
PubMed1998

Use of the cell division protein FtsZ as a means of differentiating among Bartonella species.

Genes coding for homologs of the highly conserved cell division protein FtsZ were isolated from Bartonella henselae and Bartonella quintana, the causative agents of cat scratch disease and trench fever, respectively. DNA fragments coding for the ftsZ open reading frames (ORFs) were cloned into Escherichia coli following PCR amplification with primers based on the ftsZ sequence of the closely related species Bartonella bacilliformis. The amino acid sequences predicted from the cloned B. henselae and B. quintana ftsZ ORFs are 81 to 83% identical to the corresponding protein in B. bacilliformis. Like the FtsZ protein of B. bacilliformis, the B. henselae and B. quintana homologs are about twice as large as the FtsZ proteins reported in most other organisms. Localized sequence differences within the C-terminal coding regions of the Bartonella ftsZ genes were used as the basis for species-specific identification of these organisms at both the DNA and protein levels. Oligonucleotide primers which permit the amplification of an ftsZ fragment from each of the Bartonella species without amplifying DNA from the other two species were designed. Anti-FtsZ antisera raised in rabbits against synthetic peptides corresponding to the relatively divergent C-terminal regions were shown via Western blot analysis to react only with the FtsZ protein from the cognate Bartonella species. These observations raise the possibility that the differences in ftsZ sequences can be used as the basis for diagnostic tests to differentiate among these closely related pathogens.

Amino Acid Sequence↗
PubMed1997

Hypocalcemia and skeletal disease as presenting features of celiac disease.

OBJECTIVE: To describe 15 patients examined for hypocalcemia, skeletal disease, or both in whom the diagnosis of celiac disease was subsequently made. DESIGN: Observational case series. PATIENTS: Fifteen patients (7 women and 8 men) were examined for hypocalcemia (n = 11), skeletal disease (n = 3), or both (n = 1). The diagnosis of celiac disease was subsequently made. The mean age of the patients was 62 years, and 11 patients were 60 years of age or older. RESULTS: Four patients had no gastrointestinal symptoms, 7 patients had mild or intermittent gastrointestinal symptoms, and 4 patients had persistent diarrhea. Ten patients had experienced weight loss. The serum total alkaline phosphatase level was elevated in 10 of 15 patients, the parathyroid hormone level was elevated in all patients, and the urinary calcium level was low in all 6 of the patients tested. The level of 25-hydroxyvitamin D was frankly low in 4 patients, marginal in 8 patients, and normal in 3 patients. Bone mineral density was reduced in all 8 patients in whom it was measured. CONCLUSIONS: Celiac disease should be considered in patients with unexplained metabolic bone disease or hypocalcemia, especially because gastrointestinal symptoms may be absent or mild. Advanced age does not exclude the diagnosis of celiac disease.

Adult↗
PubMed1997

Conduction block in acute and chronic spinal cord injury: different dose-response characteristics for reversal by 4-aminopyridine.

The effect of the potassium channel blocker, 4-aminopyridine (4-AP), on conduction of action potentials in injured guinea pig spinal cord axons was measured using isolated tracts in oxygenated Krebs' solution at 37 degrees C. The dose-response characteristics of acutely and chronically injured axons were compared. The maximal improvement of conduction occurred in acutely injured axons at a concentration of 100 microM 4-AP, but in chronically injured spinal cord at 10 microM. The threshold for significant response to 4-AP was between 0.5 and 1 microM in chronically injured cords, and between 1 and 10 microM following acute compression injury. The difference in susceptibility to potassium channel blockade may be related to underlying differences in the mechanism of conduction block at the two stages of injury. Initially, junctions between axons and myelin are acutely disrupted, altering primarily the leakage resistance of the myelin sheath and periaxonal space. In chronically injured cords, there is widespread but incomplete process of repair in the lesion site, which leaves many axons partially myelinated. The difference in sensitivity to 4-AP suggests there is also some modification of the accessibility of axonal potassium channel or a change in their affinity for the drug.

4-Aminopyridine↗
PubMed1996

Expression and immunoaffinity purification of human inducible nitric-oxide synthase. Inhibition studies with 2-amino-5,6-dihydro-4H-1,3-thiazine.

Recombinant human inducible nitric-oxide synthase (rH-iNOS) was expressed in the baculovirus system and purified by a novel immunoaffinity column. rH-iNOS and its native counterpart from cytokine-stimulated primary hepatocytes exhibited similar molecular mass of 130 kDa on SDS-polyacrylamide gel electrophoresis, recognition by antipeptide antibodies, specific activities, and IC50 values for inhibitors. The active dimeric form exhibited a specific activity range of 114-260 nmol/min/mg at 37 degrees C and contained 1.15 +/- 0.04 mol of calmodulin/monomer. The enzyme exhibited a Soret lambdamax at 396 nm with a shoulder at 460 nm and contained 0. 28-0.64 mol of heme/monomer. Dithionite reduction under CO yielded an absorbance maximum at 446 nm, indicating a P450-type heme. Imidazole induced a type II difference spectrum, reversible by L-Arg. 2-Amino-5,6-dihydro-4H-1,3-thiazine (ADT) was competitive versus L-Arg (Ki = 22.6 +/- 1.9 nM), reversed the type II difference spectrum induced by imidazole (Kd = 17.7 nM), and altered the CO-ferrous absorbance of rH-iNOS. L-Arg did not perturb the CO-ferrous adduct directly, but it partially reversed the ADT-induced absorbance shift, indicating that both bind similarly to the protein but interact differently with the heme.

Chromatography, High Pressure Liquid↗
PubMed1996

Carcinoembryonic antigen induces cytokine expression in Kuppfer cells: implications for hepatic metastasis from colorectal cancer.

The mechanism by which carcinoembryonic antigen (CEA) causes enhancement of hepatic metastasis from colorectal cancer is not defined. We hypothesize that binding of CEA to an 80-kDa Kupffer cell receptor by the peptide sequence Pro-Glu-Leu-Pro-Lys (PELPK) induces cytokine production in the hepatic microenvironment, which then impacts on the formation of hepatic metastasis from colorectal cancer. We have, therefore, isolated Kupffer cells and treated them in vitro with CEA, its gene family member nonspecific cross-reacting antigen, PELPK-albumin conjugate, and lipopolysaccharide as a positive control. Spent media was examined for the content of cytokines interleukin (IL) 1alpha, IL-1beta, IL-6, and tumor necrosis factor alpha using the ELISA. Simultaneously, mRNA was extracted from the same cells and amplified using reverse transcription-PCR to evaluate the induction of specific cytokine transcripts. As expected, lipopolysaccharide stimulated cytokine production. CEA, nonspecific cross-reacting antigen, and PELPK-albumin induced secretion of all of the cytokines tested; the response was higher in general with PELPK-albumin. The levels of cytokine mRNA showed a similar profile. These responses were not seen when a similar but irrelevant peptide conjugate PELGK-albumin was used. These results demonstrate that binding of the peptide PELPK to the 80-kDa receptor results in the release of a series of cytokines that have the potential to activate hepatic sinusoidal endothelium. This may explain CEA-induced enhancement of experimental hepatic metastasis.

Animals↗
PubMed1996

Active-site structure analysis of recombinant human inducible nitric oxide synthase using imidazole.

Nitric oxide synthase catalyzes the pyridine nucleotide-dependent oxidation of L-arginine to nitric oxide and L-citrulline. It is a specialized cytochrome P450 monooxygenase that is sensitive to inhibition by imidazole. Steady-state kinetic studies on recombinant human inducible nitric oxide synthase (rH-iNOS) demonstrate that imidazole and 1-phenylimidazole are competitive and reversible inhibitors versus L-arginine. Structure-activity relationship and pH dependence studies on the inhibition suggest that the neutral form of imidazole may be the preferred species and that the only modifications allowed without the loss of inhibition are at the N-1 position of imidazole. Optical spectrophotometric studies of rH-iNOS with imidazole and 1-phenylimidazole yielded type II difference spectra exhibiting Kd values of 63 +/- 2 and 28 +/- 3 microM, respectively. These values were in good agreement with the steady-state Ki of 95 +/- 10 and 38 +/- 4 microM, respectively, and confirms the site of binding is at the sixth axial ligand of the heme. Imidazole (2.2 mM) also perturbed the Kd of L-arginine from 3.03 +/- 0.45 to 209 +/- 10 microM. The observed increase in the Kd for L-arginine is consistent with imidazole being a competitive inhibitor versus L-arginine. The IC50 values of imidazole and 1-phenylimidazole were lower in the absence of exogenous BH4, and both inhibitors also competitively inhibited the BH4-dependent activation of the enzyme. These data taken together suggest that the L-arginine, dioxygen, and the BH4 binding sites are in close proximity in rH-iNOS. Furthermore, these studies demonstrate the usefulness of imidazole compounds as active site probes for recombinant human iNOS.

Arginine↗
PubMed1996

Purification and analysis of an 80-kDa carcinoembryonic antigen-binding protein from Kupffer cells.

The receptor-mediated interaction of Kupffer cells with carcinoembryonic antigen (CEA) has led to the identification of an 80-kDa CEA-binding Kupffer cell protein. This study is aimed at the isolation and analyses of this protein from rat Kupffer cells. The binding protein was purified using a combination of gel filtration, preparative polyacrylamide gel electrophoresis (PPAGE), and affinity chromatography using a CEA-Sepharose column. Fractions obtained from the gel filtration produced two major and few minor peaks with CEA-binding activity. Maximum reactivity was detected in the first major peak. The first major peak protein was partially precipitated following fractionation with 30% loss of activity in the precipitate. Fractions with CEA-binding activity were pooled and separated on the basis of molecular weight (MW) in PPAGE. The fractions between MW 70 and 90 kDa were pooled and affinity purified using CEA-Sepharose affinity chromatography. The purity of the 80-kDa protein was demonstrated by a single protein band on SDS-polyacrylamide gel. The protein was further identified by an anti-80-kDa binding protein antibody in Western blot analysis. The pI of the 80-kDa protein is 4.95. Amino acid analysis demonstrated no histidine; higher percentages of glutamine (13.3%), leucine (11.2%), asparagine and alanine (10.4%), and lysine (9.2%) were observed. Protein microsequencing revealed two unique sequences, one with 16 amino acids and the other with 11 amino acids. The 16-amino-acid sequence has less than 50% homology with a large sample of unrelated proteins, whereas the sequence containing 11 amino acids has 60-70% homology with the alpha chain of collagen from a variety of species but no significant homology with other known proteins, suggesting the presence of collagen-like domains in the 80-kDa receptor.

Amino Acid Sequence↗
PubMed1996

Exercise testing and training of patients with malignant ventricular arrhythmias.

Malignant ventricular arrhythmias account for a significant number of deaths annually. Improved therapies have increased survival for this patient population. These patients, however, remain at high risk due to their history of sudden cardiac death and the preponderance of poor ventricular function in this population. This high risk status may have excluded them from participation in cardiac rehabilitation programs or from undergoing exercise testing in some medical centers. Although the risk of complications, especially arrhythmias, is quite real, the experience in some centers has indicated that it is manageable. This experience and some guidelines for exercise testing and training of patients with malignant ventricular arrhythmias are reviewed in this paper.

Arrhythmias, Cardiac↗
PubMed1996

Validity of DSM-III-R diagnosis by psychological autopsy: a comparison with clinician ante-mortem diagnosis.

Psychological autopsies are an important research tool in establishing risk factors associated with suicide. We report the results of a validity study comparing psychological autopsy-generated DSM-III-R diagnoses in suicides and non-suicides with chart diagnoses generated by clinicians who had treated the subjects prior to death. The Structured Clinical Interview for DSM-III-R Disorders (SCID-P) and the Structured Clinical Interview for DSM-III-R Personality Disorders (SCID-II) were used to make independent post-mortem diagnoses. Comparison of research diagnoses with clinician ante-mortem diagnoses generated kappa coefficients of 0.85 for Axis I diagnoses and 0.65 for Axis II conditions. These kappa coefficients compare favourably with direct patient interview reliability studies. This provides evidence for the validity of the psychological autopsy as a method of determining psychiatric diagnosis.

Accidents↗
PubMed1996

Insulin-resistant lipolysis in abdominally obese hypertensive individuals. Role of the renin-angiotensin system.

Resistance to the capacity of insulin to suppress lipolysis may be an important link in the association between abdominal obesity and hypertension. Furthermore, a more active renin-angiotensin system in adipose tissue may contribute to insulin-resistant lipolysis in abdominally obese hypertensive subjects. We determined nonesterified fatty acid concentrations and turnover as well as lipid oxidation under basal conditions and during steady-state euglycemia with two levels of insulinemia (72 and 287 pmol/L) in lean normotensive, abdominally obese normotensive, and abdominally obese hypertensive subjects. To assess the role of the renin-angiotensin system in determining non-esterified fatty acid turnover, we repeated studies in the abdominally obese hypertensive subjects after double-blind random assignment to placebo or enalapril for 1 month each. The main findings were the following: (1) Nonesterified fatty acid flux was significantly higher in abdominally obese hypertensive subjects at both levels of insulinemia than in either abdominally obese normotensive or lean normotensive subjects and correlated significantly with both mean blood pressure and total systemic resistance during the higher level of insulinemia. (2) Enalapril significantly improved insulin-resistant lipolysis in the abdominally obese hypertensive subjects. The improvement in insulin suppressibility of nonesterified fatty acid flux at the high hormonal concentrations correlated positively with the magnitude of reduction in blood pressure. (3) Basal lipid oxidation and suppression in response to insulin were similarly impaired in both obese groups. Resistance to the antilipolytic actions of insulin is thus a characteristic feature in abdominally obese hypertensive subjects and may be linked to the elevated blood pressure in these individuals. A more active renin-angiotensin system may partly explain the insulin-resistant lipolysis in this form of hypertension.

Adult↗
PubMed1995

Cardiac rehabilitation in the time of health-care reform.

Cardiac rehabilitation has evolved into a medically efficacious, cost-effective intervention for patients with ischemic heart disease. Most aspects of this therapy are well developed, and guidelines for programs exist. As the health-care delivery system undergoes scrutiny and evolution, it would be prudent for the practitioners of cardiac rehabilitation to evaluate the methods they use to deliver their services. Program administrators should reconsider traditional approaches that are largely based on reimbursement criteria. Goal-directed, patient-centered service delivery will allow individualization of care. A model for such an approach to cardiac rehabilitation is presented.

Cost-Benefit Analysis↗
PubMed1995

Glucose metabolism in abdominally obese hypertensive and normotensive subjects.

To determine whether the combination of obesity and hypertension results in additive defects in oxidative and nonoxidative glucose metabolism and the association of these changes with altered hemodynamic actions of insulin, we studied 11 abdominally obese hypertensive, 6 abdominally obese normotensive, and 7 lean normotensive nondiabetic subjects. Endogenous glucose production and glucose metabolized were calculated from a euglycemic clamp at 72 and 287 pmol insulin/m2 per minute. Glucose metabolized divided by insulin was lower at 72 pmol/m2 per minute in both obese groups than in lean normotensive subjects, at 148 +/- 14, 144 +/- 33, and 373 +/- 69 (mumol/m2 per minute)/(pmol/L), respectively (P < .01). Similar results were obtained during the higher insulin dose. Nonoxidative and oxidative glucose disposals by indirect calorimetry were lower in both abdominally obese groups (P < .05). Hepatic glucose production was completely suppressed in lean subjects at the lower insulin dose and in all three groups at the higher insulin dose. Hemodynamic responses during the clamp were not significantly different among the three groups. Abdominal obesity is associated with defects in insulin-regulated oxidative and nonoxidative glucose disposal as well as in insulin suppression of hepatic glucose production. Mild hypertension does not exacerbate these defects. Whereas the global impairment in glucose metabolism suggests the presence of an early defect or defects, including reduced tissue perfusion, systemic and regional hemodynamic responses to insulin were not altered. These findings do not support a direct role for insulin resistance in the pathogenesis of the hypertension associated with abdominal obesity.

Abdomen↗
PubMed1995

Idiotypic and anti-idiotypic antibodies interfere in a standard radioimmunoassay for beta-endorphin.

Human anti-beta-endorphin and anti-idiotypic antibodies competitively inhibited the binding of rabbit anti-beta-endorphin antibodies to beta-endorphin. Furthermore, human and rabbit antibodies demonstrated cross-reactive idiotypic binding interactions. Competition for binding to beta-endorphin and idiotypic binding between human and commercially produced rabbit antibodies interfered in a standard radioimmunoassay to detect beta-endorphin. Purified human anti-beta-endorphin antibodies falsely elevated the calculated concentrations of samples with standardized concentrations of beta-endorphin. Anti-beta-endorphin antibodies were also falsely measured as beta-endorphin in samples that did not contain beta-endorphin. In contrast, anti-idiotypic antibodies lowered the calculated concentrations. These data suggest the occurrence of complex competition between several competitors rather than inhibition by a single competitor (i.e., unlabeled peptide) in subjects that produce specific antibody. Competitive and idiotypic binding interactions between human and animal antibodies may affect radioimmunoassay for other substances in subjects that produce specific antibodies.

Animals↗
PubMed1994

An Escherichia coli gene (FabZ) encoding (3R)-hydroxymyristoyl acyl carrier protein dehydrase. Relation to fabA and suppression of mutations in lipid A biosynthesis.

Escherichia coli strain SM101 harbors a temperature-sensitive allele (lpxA2) of the gene encoding UDP-Glc-NAc acyltransferase (the first enzyme of the lipid A pathway). SM101 is temperature-sensitive for lipid A biosynthesis and growth. To determine whether or not E. coli mutants lacking lipid A can be isolated, we examined temperature-resistant revertants of SM101. All regained the ability to synthesize lipid A. However, some were not true revertants but had acquired mutations in a neighboring gene (orf17), while retaining the original lpxA2 lesion. Cell extracts of such revertants displayed 2-5 fold reductions in the specific activity of (3R)-hydroxymyristoyl-ACP dehydrase. Wild-type cells that overproduced the protein encoded by orf17 overproduced (3R)-hydroxymyristoyl-ACP dehydrase activity as much as 170-fold, suggesting that orf17 is the structural gene for the dehydrase. The proposed function of orf17 is further supported by its sequence similarity to fabA, the structural gene for (3R)-hydroxydecanoyl dehydrase of E. coli. We suggest that bypass of the lpxA2 phenotype by mutations in orf17 may be due to an increased (3R)-hydroxymyristoyl-ACP pool. The orf17 gene (which we now designate fabZ) is not regulated by fadR. However, orf17 may be related to sefA, a suppressor of certain lesions in the cell division/lipid A biosynthesis gene, envA.

Amino Acid Sequence↗
PubMed1994

Serum antibody for somatostatin-14 and prodynorphin 209-240 in patients with obsessive-compulsive disorder, schizophrenia, Alzheimer's disease, multiple sclerosis, and advanced HIV infection.

Patients with obsessive-compulsive disorder (OCD) demonstrated significant levels of antibody for somatostatin-28, its C-terminal fragment somatostatin-14, and prodynorphin. In contrast there were lower levels of reactivity for somatostatin-28(1-14) (the N-terminal fragment of somatostatin-28) and negligible reactivity for several other peptides including beta-endorphin and corticotropin. Healthy volunteers and disease controls [schizophrenia, Alzheimer's disease, multiple sclerosis, and subjects with advanced human immunodeficiency virus (HIV) infection] exhibited negligible reactivity. These data raise the consideration of an autoimmune mechanism for some OCD.

Adult↗
PubMed1994

Maxillofacial prosthetics: a preliminary analysis of Resource Based Relative Value Scale.

A study done by the American Academy of Maxillofacial Prosthetics to evaluate the Medicare Resource Based Relative Value Scale (RBRVS) as it relates to maxillofacial prosthetics. The method of RBRVS formulation is described. The degree of difficulty and treatment time were determined for nine Physicians' Current Procedural Terminology-edition 4 (CPT-4) codified maxillofacial procedures. A preliminary survey indicates that practice expense and malpractice expense ratios were 66% and 1%, respectively. Correlation of maxillofacial procedures to other medical procedures was not performed because an additional study with a greater sample size is needed.

Ear↗
PubMed1994

Biosynthesis of a structurally novel lipid A in Rhizobium leguminosarum: identification and characterization of six metabolic steps leading from UDP-GlcNAc to 3-deoxy-D-manno-2-octulosonic acid2-lipid IVA.

Lipopolysaccharides (LPSs) are prominent structural components of the outer membranes of gram-negative bacteria. In Rhizobium spp. LPS functions as a determinant of the nitrogen-fixing symbiosis with legumes. LPS is anchored to the outer surface of the outer membrane by the lipid A moiety, the principal lipid component of the outer bacterial surface. Several notable structural differences exist between the lipid A of Escherichia coli and that of Rhizobium leguminosarum, suggesting that diverse biosynthetic pathways may also exist. These differences include the lack of phosphate groups and the presence of a 4'-linked GalA residue in the latter. However, we now show that UDP-GlcNAc plays a key role in the biosynthesis of lipid A in R. leguminosarum, as it does in E. coli. 32P-labeled monosaccharide and disaccharide lipid A intermediates from E. coli were isolated and tested as substrates in cell extracts of R. leguminosarum biovars phaseoli and viciae. Six enzymes that catalyze the early steps of E. coli lipid A biosynthesis were also present in extracts of R. leguminosarum. Our results show that all the enzymes of the pathway leading to the formation of the intermediate 3-deoxy-D-manno-2-octulosonic acid (Kdo2)-lipid IVA are functional in both R. leguminosarum biovars. These enzymes include (i) UDP-GlcNAc 3-O-acyltransferase; (ii) UDP-3-O-(R-3-hydroxymyristoyl)-GlcNAc deacetylase; (iii) UDP-3-O-(R-3-hydroxymyristoyl)-GlcN N-acyltransferase; (iv) disaccharide synthase; (v) 4'-kinase; and (vi) Kdo transferase. Our data suggest that the early steps in lipid A biosynthesis are conserved and that the divergence leading to rhizobial lipid A may occur at a later stage in the pathway, presumably after the attachment of the Kdo residues.

Acetates↗