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Biomedical subjects

R J Allen

Publications and source records attributed to R J Allen.

At least 19 recordsLinked to original sources
PubMed1995

Mutational analysis of familial and sporadic hyperekplexia.

Hyperekplexia is a rare, autosomal dominant neurological disorder characterized by hypertonia, especially in infancy, and by an exaggerated startle response. This disorder is caused by mutations in the alpha 1 subunit of the inhibitory glycine receptor (GLRA1). We previously reported two GLRA1 point mutations detected in 4 unrelated hyperekplexia families; both mutations were at nucleotide 1192 and resulted in the replacement of Arg271 by a glutamine (R271Q) in one case and a leucine (R271L) in the other. Here, 5 additional hyperekplexia families are shown to have the most common G-to-A transition mutation at nucleotide 1192. Haplotype analysis using polymorphisms within and close to the GLRA1 locus suggests that this mutation has arisen at least twice (and possibly four times). In 2 additional families, a third mutation is also presented that changes a tyrosine at amino acid 279 to a cysteine (Y279C). Five patients with atypical clinical features and equivocal or absent family history of hyperekplexia and 1 patient with a classical presentation but not family history are presented in whom a mutation in the GLRA1 gene was not detected. Thus, only clinically typical hyperekplexia appears to be consistently associated with GLRA1 mutations, and these affect a specific extracellular domain of the protein.

Base Sequence↗
PubMed1995

Superior gluteal artery perforator free flap for breast reconstruction.

The purpose of this paper is to present a new method of breast reconstruction utilizing skin and fat from the buttock without muscle sacrifice. Cadaver dissections were done to study the musculocutaneous perforators of the superior gluteal artery and vein. Eleven breasts were reconstructed successfully with skin/fat flaps based on the superior gluteal artery with its proximal perforators. Long flap vascular pedicles allow the internal mammary or thoracodorsal vessels to be used as recipient vessels. This new technique has several advantages over the previously described gluteus maximus myocutaneous flaps, including long vascular pedicle and no muscle sacrifice.

Adult↗
PubMed1994

Biochemical and molecular studies of 132 patients with galactosemia.

We evaluated 132 galactosemia patients for the Q188R (glutamine-188 to arginine) mutation in the human galactose-1-phosphate uridyltransferase (GALT) gene and for GALT activity in their hemolysates by a sensitive radioisotopic method. In those without any detectable GALT activity (GG), the Q188R mutation constituted 67% of the alleles. In patients with detectable GALT activity (GV), only 16% of the alleles were accounted for by Q188R. In all patients who were homozygous for the Q188R mutation, no erythrocyte GALT activity could be demonstrated. There was an extensive variation in the amount of detectable GALT activity ranging from 0.1% to 5% of the normal values among the GV patients. There was a difference in the frequency of Q188R mutation in the GALT alleles among patients belonging to different racial and ethnic groups. In Caucasian and Hispanic patients, the frequency was not far different (64% and 58%, respectively). On the other hand, only 12% of the GALT alleles with Q188R were found in African-American patients.

Adolescent↗
PubMed1994

Strategies for establishing a critical care obstetric service.

Critical care obstetrics is gaining increased recognition as a subspecialty of perinatal medicine. As the specialty continues to expand, many institutions may consider establishing a critical care obstetric service. However, implementing such a service is not feasible for every institution because of space limitations, budgetary constraints, lack of necessary resources, and/or a limited number of critically ill obstetric patients. This article explores strategies for examining the feasibility of establishing a critical care obstetric service, suggests methods of implementation, and offers an alternative when establishing a critical care obstetric service is not feasible.

Feasibility Studies↗
PubMed1994

MRI characterization of cerebral dysgenesis in maternal PKU.

MPKU pregnancies, with or without dietary treatment to reduce maternal plasma phenylalanine (phe), show variable, increased non-physiologic levels, as the putative cause of fetal teratogenicity. Cerebral dysgenesis with clinical neonatal microcephaly and congenital heart disease indicates altered organ morphogenesis. Although there is not an established precise relationship between maternal phe levels and outcome, dietary restriction before or early in gestation is universally advised. Both human experience and animal research have suggested differential organ responses to high and low phe levels. Structural microencephaly may be due to reduced brain volume or abnormal regional brain development. Infants in MPKU are also at risk to develop PKU. Microencephaly was evident by MRI in 8 of 21 infants born to 12 MPKU mothers; 2 infants of one mother developed PKU. All levels of gestational plasma phe were associated with otherwise structurally normal infant microencephalic brains appropriate for age in myelination. CHD occurred in one microencephalic infant of a classic MPKU treated in the first trimester. Maternal, cord and neonatal plasma phenylalanine at delivery did not correlate with teratogenic effects. Only untreated 'classic' MPKU fetal effects appear predictable.

Abnormalities, Multiple↗
PubMed1991

Referrals for vascular hypertension in a group of 45-64-year-old patients.

Two hundred and ten consecutive 45-66-year-old patients underwent a routine eye examination and a decision was made whether to refer each patient on the basis of fundus appearance and other non-sphygmomanometric criteria. Blood pressure was then measured and the referral decision was reviewed. Of the 33 (15.7%) patients finally referred, only 5 (2.4%) would have been referred on the non-sphygmomanometric findings. It is suggested that optometrists include a protocol of blood pressure measurement as part of the eye examination routine.

Blood Pressure Determination↗
PubMed1990

Medicinal leeches: once again at the forefront of medicine.

Medical grade leeches have recently been used in the management of acute problems relative to venous congestion in patients with traumatic injuries and surgical problems. Specific cases, especially in the realm of reconstructive microsurgery, have demonstrated the effectiveness and application of leech therapy. Specific contraindications include arterial insufficiency from either anatomic or mechanical obstruction. We present five illustrative cases of successful therapeutic intervention.

Acute Disease↗
PubMed1989

Emission of airborne bacteria from a hospital incinerator.

Only five studies have been found in the literature which provide any indication of the effectiveness of incineration for rendering infectious hospital waste innocuous. Although there is an indication from these studies for release of bacteria in stack gas, none of the studies identified the bacteria or determined the source of bacteria. The purpose of the present study was to investigate the potential for a hospital incinerator to release human pathogenic bacteria into the ambient environment. In this study, waste spiked with Bacillus subtillis was burned in a hospital incinerator. Although bacteria were found in the incinerator stack gas, (concentrations ranged from not detectable to 1157 colonies/m3 of air) no Bacillus subtilis was recovered from the stack gas. The results suggest that the source of the stack gas bacteria was not from unburned waste or from outdoor air. Analysis of samples of air from the incinerator room (not simultaneous with the stack gas samples) indicates that the source of the stack gas bacteria was most likely the combustion air.

Air Microbiology↗
PubMed1985

Valproic acid toxicity.

Explore the source record for details and available documents.

Chemical and Drug Induced Liver Injury↗
PubMed1984

Determination of pantothenic acid in multivitamin pharmaceutical preparations by reverse-phase high-performance liquid chromatography.

A high-performance liquid chromatographic procedure was developed for the analysis of calcium pantothenate in nutritional supplements. The method involves a simple extraction using phosphate buffer and sonication. Chromatographic separation is obtained using an aminopropyl-loaded silica gel column in the reverse-phase mode. A UV detector set at 210 nm was used to monitor the effluent. Quantitative recoveries were obtained, and precision of the method is discussed. The method is applicable to multivitamin tablets, calcium pantothenate raw material, and yeast grown in the presence of high levels of calcium pantothenate. The results of the method are compared with results obtained from the USP microbiological method of analysis. It was concluded that the procedure is rapid, accurate, easily automated, and practical for routine quality control use.

Chromatography, High Pressure Liquid↗
PubMed1983

Biotinidase deficiency: the enzymatic defect in late-onset multiple carboxylase deficiency.

Late-onset multiple carboxylase deficiency is characterized clinically by skin rash, alopecia, seizures and ataxia and occasionally by candidiasis and developmental delay. Biochemically, these individuals exhibit findings consistent with a combined deficiency of the biotin-dependent carboxylases. We have found that the activity of the enzyme biotinidase is also deficient in the sera of five affected children (0 to 3% of mean control activity, 5.80 +/- 0.89 nmol X min-1 X ml-1 serum), and believe that it represents the primary biochemical defect in this disease. Biotinidase catalyzes the removal of biotin from the epsilon-amino group of lysine, through which biotin is covalently bound to the four known human carboxylases, thereby regenerating biotin for reutilization. The deficient activity in our patients was not due to an inhibitor, particularly biotin. It is also not a consequence of feedback control in affected individuals under treatment with pharmacologic doses of biotin. The biotinidase activities of the parents of those children who were available for study were intermediate between deficient and normal values (46% to 65% of mean normal activity). Children lacking biotinidase activity are unable to recycle biotin, and are thus entirely dependent upon exogenous biotin to prevent deficiency. Our findings indicate that the primary biochemical defect in late-onset multiple carboxylase deficiency is in biotinidase activity which is inherited as an autosomal recessive trait.

Amidohydrolases↗
PubMed1983

Kearns-Sayre syndrome with reduced plasma and cerebrospinal fluid folate.

A young woman with Kearns-Sayre syndrome and progressive central nervous system deterioration over 15 years had decreased plasma and cerebrospinal fluid folate levels while receiving phenytoin for a seizure disorder. A muscle biopsy showed a "ragged red fiber" myopathy with reduced muscle carnitine and mitochondrial enzymes. Computed tomographic brain scans showed cerebral white matter hypodensities and bilateral calcification of the basal ganglia. The mechanism for the folate deficiency and altered ratio of plasma to cerebrospinal fluid folate is unknown, but the deficiency may be responsive to replacement therapy.

Adolescent↗