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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

Establishment of a leukemia cell line with i(12p) from a patient with a mediastinal germ cell tumor and acute lymphoblastic leukemia.

We report the establishment of a leukemia cell line (UoC-B10) from a patient who developed leukemia several months after the diagnosis of a mediastinal yolk sac tumor. The patient's yolk sac tumor responded to combination chemotherapy, and a mature teratoma with focal areas of hematopoiesis was subsequently resected. However, 5 months after the initial diagnosis, the patient developed an acute lymphoblastic leukemia with a precursor B-cell phenotype. Cytogenetic analysis showed an i(12p) abnormality in the patient's leukemia cells and in the UoC-B10 cell line. The i(12p) was also identified retrospectively in the mediastinal tumor cells by fluorescent in situ hybridization analysis. The UoC-B10 cell line, which has been growing continuously for > 24 months in culture, was Epstein-Barr virus negative and was generally concordant with the patient's leukemia cells by analysis of immunophenotype, karyotype, and genotype. The UoC-B10 cell line possesses receptors for granulocyte-colony-stimulating factor, a cytokine which the patient received as part of his treatment protocol. This cell line may be useful in studying the relationship between i(12p) and hematological differentiation of human mediastinal germ cell tumors.

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

Deep inferior epigastric perforator flap for breast reconstruction.

The ideal material for reconstruction of a breast is fat and skin. Most current methods of autogenous reconstruction use myocutaneous flaps. We investigated the feasibility of transfer of skin and fat from the lower abdomen without muscle sacrifice. The flap is based on one, two, or three perforators of the deep inferior epigastric vessels. The study will demonstrate both experimentally and clinically this original technique for breast reconstruction. Fifteen breasts have been successfully reconstructed with this technique. This technique has all of the advantages of the free transverse rectus abdominis myocutaneous flap with decreased possibility of ventral hernia or muscle weakness.

Adult↗
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

The latissimus dorsi/scapular bone flap (the "latissimus/bone flap").

During the past 4 years, our trauma and reconstructive service has treated a number of patients with lower extremity trauma involving the loss of both soft tissue and significant segments of tibia. While there are many methods for reconstruction of such defects, we became interested in providing a one-stage reconstruction of both the soft tissues and the missing bone segments. Since our standard flap for lower extremity reconstruction is a latissimus dorsi flap, we became interested in transferring a portion of the lateral border of the scapula along with the latissimus muscle. We dissected 34 cadaver scapulas in order to verify the reliability of the blood supply to the lateral border of the scapula based on the thoracodorsal artery. We then performed 12 "latissimus/bone flaps" from 1988 to 1992. Prior to flap transfer, control of the wound was obtained with surgical debridement and aggressive wound management. The flap usually was performed 5 to 7 days after initial contact with the patient. The muscle was skin grafted. All patients reported are ambulating, with x-ray evidence of bony incorporation of the transferred bone segment into the tibia. We feel that inclusion of the lateral scapula bone with the latissimus dorsi is a useful adjunct in the management of lower extremity trauma.

Adolescent↗
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↗
PubMed1993

Impact of repackaging hazardous (infectious) hospital waste on the indoor air quality of a hospital.

With landfill bans on the disposal of hazardous (infectious) hospital wastes, many hospitals in the United States are faced with selecting alternative means of disposal. One alternative method of disposal is to repackage the waste and ship it off site for incineration. This paper reports on a study in which airborne bacteria were sampled in an area where waste was repackaged. Results of the sampling showed bacteria concentrations ranging from not detectable (central supply room) to 105 colonies/m3 air (approximately 40 feet from the incinerator room door). This would seem to indicate that the source of the bacteria was at or near the incinerator room door where the repackaging operation took place. Although some human pathogens were identified, most of the bacteria identified do not represent a serious health threat. However, Staphylococcus aureus was found in air samples collected from locations in the hospital served by the same ventilation system in the area of the repackaging operation. The waste handling practices used in hospitals need to be reevaluated, and the definition of 'sick building syndrome' needs to be expanded beyond chemicals to include microorganisms. More research is needed to characterize bacteria in air and to determine the impact of airborne bacteria on human health.

Air Microbiology↗
PubMed1993

Effect of pregnancy on the vasodepressor response to atrial natriuretic factor.

OBJECTIVE: We attempted to determine whether pregnancy alters the vasodepressor response to both physiologic and pharmacologic infusions of atrial natriuretic factor 99-126. STUDY DESIGN: Ten virgin and 10 pregnant (17 +/- 1 days of gestation) conscious, unrestrained Sprague-Dawley rats with chronic indwelling vascular catheters were studied. Mean arterial pressure and heart rate were measured in response to steady-state infusions of either saline solution or increasing concentrations of atrial natriuretic factor (range 5 to 2560 ng.kg-1.min-1). RESULTS: Basal mean arterial pressure was significantly lower in pregnant rats than in virgin rats (89 +/- 3 vs 97 +/- 2 mm Hg, p < 0.02). Atrial natriuretic factor induced significant dose-dependent decreases in mean arterial pressure and heart rate in virgin and pregnant rats (p < 0.001). The hypotensive effects of atrial natriuretic factor were blunted in the pregnant rats only in response to the highest concentrations of atrial natriuretic factor administered (-27 +/- 3 mm Hg in pregnant rats vs -43 +/- 3 mm Hg in virgin rats, p < 0.005). CONCLUSIONS: The vasodepressor response to physiologic infusions of atrial natriuretic factor was not affected by pregnancy status. However, pharmacologic infusions of atrial natriuretic factor resulted in a blunted vasodepressor response in the pregnant animals. This may be due to alterations in vascular atrial natriuretic factor receptors, changes in the clearance rate of atrial natriuretic factor, or the modulating effects of other vasoactive hormones.

Animals↗
PubMed1993

A comparison of the laser flare cell meter and fluorophotometry in assessment of the blood-aqueous barrier.

PURPOSE: To evaluate and compare the use of the Kowa laser flare cell meter and intravenous anterior chamber fluorophotometry in assessment of the blood-aqueous barrier after cataract surgery. METHOD: Laser flare and cell measurements and fluorophotometry were performed at 1 and 3 months after surgery in 48 eyes of 44 patients admitted for routine cataract surgery. The fellow pseudophakic eyes of these patients were used as controls. RESULTS: The two techniques measure different parameters, but both methods are able to document the integrity or breakdown of the blood-aqueous barrier. However, the laser flare cell meter is more sensitive in quantifying subtle changes in barrier function to large molecules (proteins). Various methods of assessing anterior chamber fluorophotometry data were also compared. Measurement of a diffusion coefficient (requiring the measurement of plasma fluorescence) was not found to be more sensitive than other methods and did not alter the clinical significance of data obtained from the measurement of anterior chamber fluorescence alone. CONCLUSIONS: Both the laser flare cell meter and fluorophotometry provide a method for the assessment of the postoperative blood-aqueous barrier. However, the laser flare cell meter is rapid, noninvasive, and relatively easier to use. Therefore, for clinical use, it has great practical advantages over fluorophotometry.

Adult↗
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↗