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Biomedical subjects

J J Miller

Publications and source records attributed to J J Miller.

At least 19 recordsLinked to original sources
PubMed1992

Purification, subunit structure and inhibitor profile of cathepsin A.

Cathepsin A (EC 3.4.16.1), a lysosomal carboxypeptidase, has been purified 1374-fold from pig kidney. Purification steps included concanavalin A-Sepharose and phenyl-Sepharose chromatography and chromatofocusing. The specific activity (16.9 U/mg) of the purified enzyme was significantly higher than previously reported values. The enzyme preparation appeared homogeneous when analyzed by non-denaturing polyacrylamide gel electrophoresis and was free of detectable protease contamination. The molecular mass (M(r) = 97,000), isoelectric point (5.0), and sensitivity to inhibitors were consistent with reported properties of cathepsin A. However, the previously reported three-peptide chain structure was not observed. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis in the presence or absence of 2-mercaptoethanol demonstrated that the enzyme is composed of two M(r) 47,000 subunits, each of which dissociate in the presence of 2-mercaptoethanol into two polypeptide chains of 19,000 and 31,000.

Amino Acid Sequence↗
PubMed1992

Double-blind crossover comparison of human and porcine insulins in patients reporting lack of hypoglycaemia awareness.

There has been much debate about reports that some insulin-treated diabetic patients lose awareness of hypoglycaemic symptoms on changing from porcine to human insulin. In a double-blind, crossover study, we sought differences between porcine and human insulin in the frequency and characteristics of hypoglycaemic episodes among patients who reported a reduction of awareness of hypoglycaemia after changing treatment. We studied 50 patients referred by their physicians because of complaints of lack of awareness of hypoglycaemia on human insulin. They had had diabetes for a mean of 20 (SD 12) years and 70% had good or acceptable glycaemic control. Each patient was treated in a double-blind manner for four 1-month periods, two with human and two with porcine insulin, in random order. Only 2 patients correctly identified the sequence of insulin treatments used; 8 or 9 would have been expected to do so by chance alone. The mean percentage of hypoglycaemic episodes associated with reduced or absent awareness was 64% (SD 30%) for human insulin and 69% (31%) for porcine insulin. We could find no statistically significant differences between the insulin species with respect to glycaemic control or the frequency, timing, severity, or awareness of hypoglycaemia. Reduced hypoglycaemia awareness is common with both human and porcine insulins.

Adolescent↗
PubMed1992

The fasciitis-morphea complex in children.

OBJECTIVE: To describe the clinical presentation and treatment of the combined syndrome of fasciitis and morphea in children. SETTING: The rheumatic disease clinic of a university children's hospital. PATIENTS: Six children who were referred for signs or symptoms of fasciitis were observed. SELECTION PROCEDURES: All children who were referred for fasciitis were included in the study. INTERVENTIONS: Therapy included prednisone initially and subsequent long-term treatment with penicillamine and alternate-day doses of prednisone. MEASUREMENTS AND RESULTS: Symptoms of morphea appeared 1 year before to 4 years after the first signs of fasciitis were observed. The fasciitis was characterized by usually symmetrical, centrifugal swelling, pain, and contracture formation. The morphea and fasciitis did not appear in the same areas of the body. CONCLUSIONS: The fasciitis and morphea are clearly linked manifestations. The fasciitis, but not the morphea, appears to respond to treatment with steroids. Treatment with penicillamine may ameliorate the sclerosis of the morphea but does not stop new lesions from appearing.

Adolescent↗
PubMed1992

Adaptation to juvenile rheumatic disease: a controlled evaluation of functional disability with a one-year follow-up.

Compared the adaptation of 165 patients with juvenile rheumatic disease (JRD) to that of their healthy siblings. Patients were divided into those with mild functional disability and those with moderate/severe disability. Adaptation in several domains was assessed by parents and children on two occasions 1 year apart. The adjustment difficulties of the JRD children were limited primarily to social functioning but appeared also in the psychological and family problems domains. Compared to "mild" patients, "moderate/severe" patients had more adjustment difficulties; in some areas, mild patients functioned as well as their healthy siblings. Some Time 1 differences were replicated at Time 2. The results help to delineate (a) the specific domains in which children with chronic disease have adjustment difficulties and (b) the factors that put children at risk for developing adjustment problems.

Activities of Daily Living↗
PubMed1992

Antibodies to lipid A in pauciarticular juvenile arthritis: clinical studies.

IgG antibodies to monophosphoryl lipid A (MPL) are more concentrated in synovial fluids than in the blood of children with pauciarticular juvenile arthritis. Correlations between IgG anti-MPL levels and numbers of inflamed joints were highly significant in 2 of 10 patients followed for 8 years and suggestive in 2 patients followed for shorter periods. A fifth patient had a correlation between IgM anti-MPL and joint count.

Adolescent↗
PubMed1991

Angiotensin carboxypeptidase activity in urine from normal subjects and patients with kidney damage.

Angiotensin carboxypeptidase (ACP) activity has been detected in urine samples from normal subjects and patients with hypertension and diabetes by determining the enzyme's ability to convert angiotensin I to des-Leu angiotensin I. Gel filtration chromatography of a concentrated urine sample indicated that about equal amounts of the enzyme exist as 100 kDa and 500 kDa molecular weight forms, respectively. This ACP activity co-eluted with activity that cleaved histidine from des-Leu angiotensin I to form angiotensin II and activity that cleaved tyrosine from benzyloxycarbonyl-glutamyl-tyrosine (ZGT). These results suggest that the urinary ACP activity is due to cathepsin A as we have reported previously for the porcine kidney enzyme. Analysis of sequential urine samples from a single individual over a 6-day period revealed as much as a 6-fold fluctuation in creatinine-normalized ACP activity. Of five male healthy adult subjects, the creatinine-normalized urinary ACP activity ranged from 1.7 to 3.7 mU/mL with a mean of 2.8 mU/mL. However, five male patients with renovascular hypertension had elevated levels of ACP activity with a mean of 11.6 mU/mL. Of five male patients with diabetic nephropathy, all had elevated ACP activity levels with a mean of 21.0 mU/mL. It is concluded that ACP activity in the urine is due to cathepsin A probably derived from kidney tissue, and that the release is increased in patients with kidney damage. We suggest that urinary ACP activity should be evaluated further for a possible relationship to renal hypertension and as a potentially early marker for diabetic nephropathy.

Carboxypeptidases↗
PubMed1991

Complement C5a receptor assay for high throughput screening.

The complement C5a receptor on U937 cells, a human histiocytic lymphoma cell line, stimulated with dibutyryl-cAMP have been stabilized for at least 3 months at a dilute, ready to use concentration. [125I]-Bolton Hunter labeled C5a, (recombinant, human) has been prepared by reverse phase HPLC to 2200 Ci/mmol. Using a filtration binding assay the Kd from receptor saturation analysis is 10-40 pM and there are 50,000-100,000 receptor sites per cell. These reagents have permitted the development of a reliable, reproducible and convenient drug screening assay, in kit format, for compounds acting at the C5a receptor.

Complement C5a↗
PubMed1991

Antibodies to core lipid fractions of endotoxin in children with rheumatic disease.

The titer of IgG and IgM antibodies to two fragments of endotoxin derived from Salmonella minnesota R 595, lipid A width a 2-keto-3-deoxyoctanate oliosaccharide (KDO lipid A), and monophosphoryl lipid A (mono-P lipid), were measured in normal children, children with cystic fibrosis, and children with SLE and all forms of chronic juvenile arthritis. Elevated titers of IgM anti mono-P lipid A were found in all of the rheumatic diseases, but not in cystic fibrosis. The elevated IgM titers were not correlated with concentration of activation fragments of C3 or C4, but IgG anti mono-P lipid A titers, even though not usually elevated, did correlate with C3a and C3d concentrations. The elevated IgM titers to mono-P lipid A may represent a genetically determined hyper-reactivity to normal gastrointestinal antigens, an increased antigenic stimulus from the intestinal tract, or polyspecificity of an antibody of undetermined primary reactivity.

Antibodies, Bacterial↗
PubMed1991

Approaches to minimizing interference by cross-reacting molecules in immunoassays.

Here we review techniques useful in eliminating or reducing interferences caused by molecules that cross-react in immunoassays. The biochemical rationale for using these techniques is discussed. Examples are taken from recent studies aimed at reducing interferences caused by endogenous molecules such as digoxin-like immunoreactive factors or steroid hormones. In this context the role of protein-binding of cross-reacting molecules is also considered. Immunoassay ligand selectivity can be inherently limited by the heterogeneity of the antigenic response or by the structural similarity of epitopes on multiple ligands. Certain empirical approaches have proved useful in maximizing the analytical specificity of immunoassays. These approaches include isolating the relevant ligands before immunoassay, adjusting the kinetic or equilibrium conditions used during the assays, and developing more specific antisera. The physicochemical properties of the cross-reacting molecule best dictate which technique(s) to use. The approaches discussed here are general and apply to minimizing interference caused by a wide variety of both endogenous and exogenous cross-reacting molecules.

Antibody Specificity↗
PubMed1990

Characteristics of a thrombin inhibitor secreted by activated platelets.

A 77-kDa complex of thrombin and a protein secreted by activated platelets had little if any thrombin amidolytic activity, indicating that the secreted protein is an inhibitor. The molecular weight of the inhibitor before reaction with thrombin was approximately 50,000. The apparent second-order rate constant for complex formation was estimated to be 1.3 x 10(6) M-1 s-1 (mean of four measurements); it was not affected by heparin or heparinase. These properties distinguish this inhibitor from other protease inhibitors secreted by platelets. The inhibitor reacted with trypsin and possibly with urokinase but not with factor Xa.

Antithrombins↗
PubMed1990

C3 activation products correlate with antibodies to lipid A in pauciarticular juvenile arthritis.

IgM antibodies to monophosphoryl-lipid A were found to be elevated in sera from children with all forms of juvenile arthritis (JA) and systemic lupus erythematosus. Of more interest, in patients with pauciarticular JA, IgG antibody titers to monophosphoryl-lipid A were found to be correlated with the C3a concentration and the C3d:C3 ratio. Although the full specificity of these antibodies is unknown, they are the first that have been found to be correlated with complement activation products in any form of JA.

Arthritis, Juvenile↗
PubMed1990

Immunologic abnormalities of juvenile arthritis.

Many immunologic abnormalities have been found in children with all forms of chronic arthritis, but few are clinically useful or well understood. However, in children with arthritis it is important to distinguish among those with rheumatoid factor, antinuclear antibodies, or hypogammaglobulinemia. Rheumatoid factor is specific for adult-type rheumatoid arthritis; the presence of antinuclear antibodies increases the likelihood that the child may develop uveitis; and hypogammaglobulinemia may be associated with complicating infections. Other unusual antibodies, autoantibodies, antigen-antibody complexes, and complement activation products are found in children with arthritis, but none of these define a diagnostic or consistent group of diseases. Similarly, changes in the numbers of immunologically active cells and regulating mechanisms occur but not in specific patterns. As yet, none of the known immunologic abnormalities explain the pathogenesis of these diseases and only a few appear disease specific.

Agammaglobulinemia↗