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Biomedical subjects

R C Allen

Publications and source records attributed to R C Allen.

At least 91 records · Page 5Linked to original sources
PubMed1992

Methylation of HpaII and HhaI sites near the polymorphic CAG repeat in the human androgen-receptor gene correlates with X chromosome inactivation.

The human androgen-receptor gene (HUMARA; GenBank) contains a highly polymorphic trinucleotide repeat in the first exon. We have found that the methylation of HpaII and HhaI sites less than 100 bp away from this polymorphic short tandem repeat (STR) correlates with X inactivation. The close proximity of the restriction-enzyme sites to the STR allows the development of a PCR assay that distinguishes between the maternal and paternal alleles and identifies their methylation status. The accuracy of this assay was tested on (a) DNA from hamster/human hybrid cell lines containing either an active or inactive human X chromosome; (b) DNA from normal males and females; and (c) DNA from females showing nonrandom patterns of X inactivation. Data obtained using this assay correlated substantially with those obtained using the PGK, HPRT, and M27 beta probes, which detect X inactivation patterns by Southern blot analysis. In order to demonstrate one application of this assay, we examined X inactivation patterns in the B lymphocytes of potential and obligate carriers of X-linked agammaglobulinemia.

Animals↗
PubMed1991

A 3-month comparison of 1% and 2% carteolol and 0.5% timolol in open-angle glaucoma.

Carteolol, a nonselective beta-adrenergic antagonist with intrinsic sympathomimetic activity, was compared in 1% and 2% topical solutions with 0.5% timolol in 105 patients with primary open-angle glaucoma. In this double-masked, randomized 3-month trial, all three preparations significantly lowered intraocular pressure throughout the study, with no significant differences being observed. There were also no significant differences among the three preparations with regard to ocular or systemic adverse reactions, including heart rate and blood pressure.

Administration, Topical↗
PubMed1991

Antinuclear antibodies using HEp-2 cells in normal children and in children with common infections.

Antinuclear antibody (ANA) immunofluorescence tests, using HEp-2 cells, were performed on 100 children without a history of connective tissue disease. Eighteen (18%) were positive at titres greater than or equal to 1:40, nine (9%) being greater than 1:160. Interlaboratory variability was demonstrated with some specimens. No association with possible intercurrent infection was found to account for positive results. Of 44 children with proven infections five (11%) were positive. Antinuclear antibody may be found in some normal children when using the sensitive HEp-2 cell substrate, and in the absence of clinical features should not necessarily suggest the presence of a connective tissue disease.

Adolescent↗
PubMed1991

Insulin-like growth factor and growth hormone secretion in juvenile chronic arthritis.

Insulin-like growth factor (IGF-1) concentrations were determined in a series of 23 children with juvenile chronic arthritis in conjunction with anthropometric assessment. When standardised z scores were used significant decreases in height and weight were shown in comparison with the normal age/sex matched means. Severe growth disturbance was seen, particularly in those with prolonged disease duration, which was independent of corticosteroid treatment, indicating disease activity itself is a major factor in the growth retardation. Eight children had low IGF-1 z scores--that is, less than -2.00 from age/sex matched mean. Low IGF-1 z scores were associated with low weight z scores but not with low height z scores. Overnight growth hormone secretory profiles were determined in 10 patients, including seven with low IGF-1, and showed generally normal secretion in all but one patient, who subsequently attained normal concentrations coincident with catch up growth. Increased pulse frequency of overnight secretion was commonly seen. Low IGF-1 concentrations probably result from varying factors, particularly nutritional, but do not reflect marked endocrinological abnormalities in most patients.

Adolescent↗
PubMed1991

Analysis of the VNTR locus D1S80 by the PCR followed by high-resolution PAGE.

Allelic data for the D1S80 locus was obtained by using the PCR and subsequent analysis with a high-resolution, horizontal PAGE technique and silver staining. Compared with RFLP analysis of VNTR loci by Southern blotting, the approach described in this paper offers certain advantages: (1) discrete allele resolution, (2) minimal measurement error, (3) correct genotyping of single-band VNTR patterns, (4) a nonisotopic assay, (5) a permanent record of the electrophoretic separation, and (6) reduced assay time. In a sample of 99 unrelated Caucasians, the D1S80 locus demonstrated a heterozygosity of 80.8% with 37 phenotypes and 16 alleles. The distribution of genotypes is in agreement with expected values according to the Hardy-Weinberg equilibrium. Furthermore, the observed number of alleles and the level of heterozygosity, obtained through the protocol described here, were congruent with each other in accordance with the expectation of a mutation-drift equilibrium model for a single, homogeneous, random-mating population. Therefore, the analysis of D1S80 and similar VNTR loci by amplified fragment length polymorphism (AMP-FLP) may prove useful as models for population genetic issues for VNTR loci analyzed by RFLP typing via Southern blotting.

Blotting, Southern↗
PubMed1990

Nutritional assessment of children with juvenile chronic arthritis.

Nutritional assessment was performed in 38 children with juvenile chronic arthritis (polyarticular [15]; pauciarticular [13]; systemic [10]). This included anthropometric measurements (height, weight, mid-upper arm circumference and four skinfolds) and a 7 day weighed food record. The children were classified according to current type of arthritis which in some cases was not the same as the initial onset type. Mean height Z scores were significantly below the Z score population mean of 0 in the systemic (P = 0.02) and polyarticular (P = 0.009) groups. Mean weight Z scores were also below the mean in the polyarticular group (P = 0.001) but the systemic group did not reach significance. Mean energy intakes were significantly below the recommended dietary intake (RDI) in the systemic (P = 0.01) and polyarticular (P = 0.001) groups. Mean intakes of calcium and zinc were below the RDI of 100% in the polyarticular group (P = 0.0001). Thirteen (34%) of children were taking some form of self-prescribed vitamin and/or mineral supplement. Vitamin C was the most commonly used supplement, despite dietary intakes greatly exceeding the RDI. Nutritional assessment is essential in the management of patients with JCA, in particular those with systemic or polyarticular disease.

Adolescent↗
PubMed1989

Adenylate cyclase stimulation and intraocular pressure reduction by forskolin analogs.

Forskolin and 18 chemical analogs of forskolin were assayed for stimulation of adenylate cyclase activity in vitro and for their effects on intraocular pressure (IOP) in vivo. Adenylate cyclase activity was determined with a preparation of corpora striata from male Wistar rats and test drug concentrations of 0.3 to 300 microM. IOP effect was monitored after a single topical ocular application of a 1% suspension of the test drug to male New Zealand albino rabbits. Significant reductions in IOP occurred with compounds which had potent cyclase stimulatory properties. Most compounds with little cyclase stimulatory effect produced little or no decrease in IOP. A 1-substituted morpholino-acetoxy derivative, which may be a prodrug metabolized to active form by corneal esterases, showed little cyclase stimulation in vitro but produced significant reductions in IOP.

Adenylyl Cyclases↗
PubMed1988

Laser trabeculoplasty for glaucoma in aphakic and pseudophakic eyes after penetrating keratoplasty.

We used argon laser trabeculoplasty to treat medically uncontrolled glaucoma after penetrating keratoplasty in ten eyes that were aphakic or pseudophakic. These patients were examined over an average of 22.8 months (range, 12 to 37 months) after treatment. We found an average decrease in intraocular pressure of 9.1 mm Hg (range, +8 to -19), from an average of 30.6 mm Hg before treatment to an average of 21.5 mm Hg after treatment. Eight of ten eyes had a reduction of greater than 5 mm Hg, and six of ten eyes had intraocular pressure of less than 20 mm Hg. Visual function remained stable, and complications were rare. We now prefer argon laser trabeculoplasty to cyclocryotherapy for the initial treatment of patients with medically uncontrolled glaucoma who have predominantly open angles and a clear penetrating keratoplasty.

Aged↗
PubMed1988

Long-term evaluation of 0.25% levobunolol and timolol for therapy for elevated intraocular pressure.

In a one-year, double-masked, randomized study, the ocular hypotensive efficacy of twice-daily treatment with 0.25% levobunolol hydrochloride or timolol maleate was evaluated in 78 patients with glaucoma or ocular hypertension (phase 1). If intraocular pressure (IOP) was not well controlled during the study, the concentration of medication was increased to 0.5%, and the patient was followed up for an additional three months (phase 2). During phase 1, the mean IOP was reduced by 4.6 mm Hg in the timolol treatment group and by 5.1 mm Hg in the levobunolol treatment group. Seventy-one percent (29/41) of the patients in the timolol treatment group and 70% (26/37) of the patients in the levobunolol treatment group successfully completed phase 1. Of those patients who required the higher concentration of medication, 89% (8/11) in the timolol treatment group and 75% (3/4) in the levobunolol treatment group successfully completed phase 2. Higher concentration, however, did not produce greater IOP reduction. No statistically or clinically significant differences between the groups were noted in any of the efficacy or safety variables evaluated.

Adult↗
PubMed1988

A combination of levobunolol and dipivefrin for the treatment of glaucoma.

This double-masked prospective study compared the ocular hypotensive efficacy and the safety of 0.5% and 1% levobunolol hydrochloride with 0.5% timolol maleate when each was administered topically twice daily in combination with 0.1% dipivefrin hydrochloride. Forty-three patients whose intraocular pressure was previously controlled by concomitant treatment with timolol and dipivefrin were randomly assigned to receive 0.5% or 1% levobunolol and 0.1% dipivefrin, or to continue to receive 0.5% timolol and 0.1% dipivefrin for three months. In the groups receiving levobunolol and dipivefrin concurrently, continued intraocular pressure control was achieved equal to that attained with timolol and dipivefrin before study entry. We concluded that concomitant treatment with levobunolol and dipivefrin is equal in both efficacy and safety to concomitant treatment with timolol and dipivefrin.

Drug Combinations↗
PubMed1988

Immunoglobulin epitopes defined by synthetic peptides corresponding to joining region sequence: conservation of determinants and dependence upon the presence of an arginyl or lysyl residue for cross-reaction between light chains and T-cell receptor chains.

Joining or J region sequences of rearranging immunoglobulins and T-cell receptors show considerable sequence homology, particularly in their C-terminal portion corresponding to the fourth framework region of immunoglobulin variable regions. In order to test the question of whether serological cross-reactions between immunoglobulin variable regions and T-cell receptors were due to antigenic similarities in their J regions, we synthesized synthetic peptides corresponding to immunoglobulin J regions and to J regions predicted from gene sequence of the T-cell receptor beta chain. We found that antibodies produced against a synthetic 16-mer J beta sequence reacted with T-cell receptor chains and also with immunoglobulin light chains. The cross-reactivity was dependent upon the J signature sequence FG()GT(R or K)L where the presence of a positively charged lysyl or arginyl residue was essential for cross-reactivity. We were able to classify J region determinants into two distinct antigenic sets; one corresponding to JH and the other corresponding to J kappa, J lambda, J beta and J alpha. Although considerable homology occurs between JH and JL (or J beta) sequences, little cross-reactivity was observed between these two J subsets. Antibodies raised against polyclonal murine IgG immunoglobulins contained antibody subpopulations specifically reactive with either JH or J beta peptides. The serological data derived here using antipeptide antibodies are consistent with computer modeling studies that indicate that the conformations of T-cell receptor variable regions resemble those of classical immunoglobulins. Our data comparing cross-reactivities restricted to the J region indicate that the expression of the J region by intact T-cell receptor beta chains is probably more similar to that of light chains than it is to the corresponding region of heavy chains.

Animals↗
PubMed1987

Electrophoresis reliability: I. The contaminant issue.

The effects of the common contaminants--soil, oil, gasoline, salt, acid, base, bleach, and detergent--on various forensically used genetic marker systems were studied. The predicted effects of the various contaminants on the proteins and the electrophoretic separations agreed with the observed results. A contaminant that affected protein conformation also adversely affected the integrity of the electrophoretic system, thus signalling an anomaly. It also was pointed out that the ideal control study for the effects of contaminants on genetic markers in evidentiary material is often provided to forensic scientists--that is victim's blood on victim's clothing and other substrata. The data presented in this paper support the validity and reliability of electrophoretic analyses of evidentiary material with respect to the contaminant issue.

Blood Protein Electrophoresis↗
PubMed1986

A double-masked comparison of betaxolol vs timolol in the treatment of open-angle glaucoma.

We conducted a six-month prospective, double-masked randomized trial comparing betaxolol with timolol at 0.25% and 0.5% concentrations in the treatment of primary open-angle glaucoma in 38 patients. To qualify, patients had to demonstrate an average intraocular pressure in at least one eye of greater than or equal to 26 mm Hg without treatment. The median intraocular pressure was consistently lower in the timolol group than in the betaxolol group (after four weeks of therapy, it was 20.2 mm Hg for timolol vs 22.5 mm Hg for betaxolol; P less than .04). Adjunctive therapy was required in eight patients in the betaxolol group compared to one in the timolol group (P less than .05). Betaxolol appears to be a clinically effective and safe agent in the treatment of open-angle glaucoma. However, the magnitude of the decrease in intraocular pressure with it may not be as great as that with timolol and there may be a greater need for adjunctive therapy with it than with timolol.

Adult↗
PubMed1986

Gc (vitamin D-binding protein) binds the 33.5 K tryptic fragment of actin.

Limited proteolysis of G-actin was performed with trypsin and chymotrypsin to compare the binding sites for Gc and DNase. DNase I bound to the N-terminal area corresponding to the major cleavage site on G-actin (residues 62-68) and inhibited proteolysis, but did not bind the 33.5K C-terminal fragment (G-actin33.5) generated. In contrast, Gc did not exert any inhibitory effect upon proteolysis of the intact native G-actin42.0 molecule, although its presence protected G-actin33.5 from further proteolysis. This was shown by gel filtration to be due to the formation of complexes between Gc and G-actin33.5.

Actins↗