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Biomedical subjects

M A Sullivan

Publications and source records attributed to M A Sullivan.

At least 19 recordsLinked to original sources
PubMed1992

83-kilodalton heat shock proteins of trypanosomes are potent peptide-stimulated ATPases.

A Crithidia fasciculata 83-kDa protein purified during a separate study of C. fasciculata trypanothione synthetase was shown to have ATPase activity and to belong to the hsp90 family of stress proteins. Because no ATPase activity has previously been reported for the hsp90 class, ATP utilization by C. fasciculata hsp83 was characterized: this hsp83 has an ATPase kcat of 150 min-1 and a Km of 60 microM, whereas the homologous mammalian hsp90 binds ATP but has no ATPase activity. Crithidia fasciculata hsp83 undergoes autophosphorylation on serine and threonine at a rate constant of 3.3 x 10(-3) min-1. Similar analysis was performed on recombinant Trypanosoma cruzi hsp83, and comparable ATPase parameters were obtained (kcat = 100 min-1, Km = 80 microM, kautophosphorylation = 6.3 x 10(-3) min-1). The phosphoenzyme is neither on the ATPase hydrolytic pathway nor does it affect ATPase catalytic efficiency. Both C. fasciculata and T. cruzi hsp83 show up to fivefold stimulation of ATPase activity by peptides of 6-24 amino acids.

Adenosine Triphosphatases↗
PubMed1991

Roentgenographic evaluation of the augmented breast.

We performed a retrospective study to determine the sensitivity of mammography in detecting breast cancer arising in women with augmented breasts. Of eight women with breast implants in whom breast cancer developed, six had mammograms before biopsy. Only two of the six cancers were identified mammographically (sensitivity = 33%), and one of these two was seen only in retrospect. In both cases, the mammographic findings suggested a benign rather than a malignant process. All eight women had a palpable mass and early disease, and all are clinically disease-free at present. The sensitivity of mammography in detecting palpable cancers in a control group of women without implants was 92% (118 of 128). For tumors of 2 cm or less, the sensitivity was 88% (58 of 66). These results suggest that the sensitivity of mammography in detecting breast cancer is decreased when implants are present. Further investigations are needed to determine the effects of prostheses on mammographic evaluations.

Adult↗
PubMed1991

Fear of AIDS related to development of obsessive-compulsive disorder in a child.

Fear of acquired immune deficiency syndrome (AIDS) has been associated with a variety of psychiatric disorders in adults and in some adolescents. A case is reported of a child with an unrealistic fear of AIDS who developed an obsessive-compulsive disorder. This case illustrates the importance of providing adequate AIDS information to children.

Acquired Immunodeficiency Syndrome↗
PubMed1990

Cloning and expression in Escherichia coli of a hypoxanthine-guanine phosphoribosyltransferase-encoding cDNA from Plasmodium falciparum.

The enzyme hypoxanthine-guanine phosphoribosyltransferase (HGPRT) of Plasmodium falciparum plays a key role in the salvage of preformed purine nucleotides from parasite-infected erythrocytes. Since P. falciparum cannot synthesize purines de novo, development of inhibitors specific for the parasite HGPRT should be an effective method of chemotherapy. To provide sufficient amounts of HGPRT for biochemical and crystallographic analysis, we have isolated the P. falciparum HPRT cDNA sequence and expressed it in an Escherichia coli strain deficient for both de novo purine synthesis and guanine utilization (strain GP120). GP120 cells containing the P. falciparum HPRT plasmid vector (pRD500), when grown in the presence of isopropyl-beta-D-thiogalactopyranoside (IPTG) which induces the tac promoter of the expression vector, produce a novel protein of 26 kDa, which is in agreement with the predicted Mr deduced from the HPRT cDNA open reading frame. In addition, we have demonstrated significant HGPRT activity in cell-free extracts of GP120[pRD500] cultures grown in minimal medium containing xanthine, as the sole source of purines, and IPTG.

Amino Acid Sequence↗
PubMed1989

Dental abnormalities and bone lesions associated with familial adenomatous polyposis: report of cases.

Dental abnormalities and bone lesions of the maxilla and mandible are found in more than 70% of patients with familial adenomatous polyposis (FAP). Dental abnormalities include impacted teeth (other than third molars), supernumerary teeth, congenitally missing teeth, and fused roots of molars. Bone lesions consist of osteomas--isolated or in clusters--in the maxilla and mandible. In this study of 24 patients, 75% had demonstrable dental abnormalities, and 79% had osteomas of the maxilla and mandible. Because dental abnormalities and bone lesions are present early in life, these features may be helpful in diagnosing this syndrome.

Adenomatous Polyposis Coli↗
PubMed1989

Usefulness of duplex ultrasound in evaluating vertebral arteries.

A criticism of duplex scanning of the carotid vessels is that the study is limited to evaluation of the carotid bifurcations, whereas with other vascular imaging studies the vertebral vessels can also be seen. We have prospectively collected data on our ability to evaluate the vertebral vessels on all patients who are sent for carotid evaluations. We have scanned 677 patients and have identified flow in one or both vertebral arteries in nearly 90% of these patients. Therefore, we urge that evaluation of vertebral vessels be made a routine part of the standard carotid duplex ultrasound examination.

Carotid Artery Diseases↗
PubMed1988

The identification of ulcerative plaque with high resolution duplex carotid scanning.

A retrospective study evaluated 50 patients who had pathologically proven intraplaque hemorrhage. The patients were pathologically divided into two groups by the presence or absence of intimal ulcerations. These two groups were then sonographically compared with regard to surface characteristics of the plaque, plaque size, size of the sonolucent area within the plaque, and location of the sonolucent area relative to the intimal surface. No defined sonographic characteristics could be used to separate these two groups of patients with heterogeneous plaques into those who had or did not have ulcerations. Most importantly, merely sonographically evaluating the surface of the plaque to determine if it was smooth or irregular could not be used as a successful means to identify which patients were at risk for ulceration.

Arteriosclerosis↗
PubMed1987

Transcription of eucaryotic tRNA1met and 5SRNA genes by RNA polymerase III is blocked by base mismatches in the intragenic control regions.

We have constructed duplex DNAs containing single G-T or A-C mismatches in the X. laevis tRNA1met gene. Mismatches within regions of this gene which are bound by transcription factor TFIIIC prevent transcription by RNA polymerase III. Homoduplexes with G-C----A-T mutations at some of the same sites, however, are transcribed efficiently in oocytes. Mismatches outside of the tRNA1met gene have no effect upon transcription. A survey of several point mutants in the Syrian hamster 5SRNA gene indicates that mismatches outside the internal control region somewhat reduce transcription, but a mismatch within the internal control region blocks transcription. Thus, the presence of mismatched bases in the region of DNA which interacts with RNA polymerase III transcription factors blocks transcription, perhaps by interfering with DNA renaturation following transit of the RNA polymerase.

Animals↗
PubMed1986

The role of spatial-frequency channels in the perception of local and global structure.

Adaptation and reaction-time techniques were used to examine the role of different spatial-frequency channels in the perception of local and global structure. Subjects were shown figures consisting of a large C composed of smaller Cs and asked to identify the orientation of either the global C or its local elements. Prior to performing the task subjects were adapted to different spatial frequencies and the effect on subsequent performance was assessed. Two main results were found. First, the adapting frequency that most affected the global task was often lower than that most affecting the local task, suggesting that high and low frequencies independently code the structure of an image. Second, reaction time to global figures was often faster than to local figures at all levels of detectability, again suggesting a role of low-frequency channels in global processing.

Adaptation, Ocular↗
PubMed1985

Effects of various dietary animal and vegetable proteins on serum and biliary lipids and on gallstone formation in the hamster.

The objective of this study was to determine the effects of various dietary animal (casein, bovine albumin and egg albumin) and vegetable (soy, cottonseed and peanut) proteins on serum and biliary constituents and gallstone formation in the hamster. Eighty-four hamsters (60 +/- 5 g) were assigned to either a control group (Purina rat chow) or to one of the 6 experimental groups. Experimental diets contained 20.0% protein. With the exception of hamsters fed egg albumin, gallstone incidence was greater among hamsters fed animal proteins. Hamsters fed egg albumin exhibited a lower concentration of total serum cholesterol and HDL-cholesterol than most of the other experimental groups. There were no significant differences between experimental groups for either HDL3-cholesterol concentration or VLDL-LDL-cholesterol concentration. Bile acid concentrations within the vegetable Protein-fed groups were significantly higher than within the animal protein-fed groups. Casein- and bovine albumin-fed hamsters showed a significantly higher percentage of biliary cholesterol in the bile fluid. As the percentage of biliary cholesterol increased, the percentage of bile acids was found to decrease.

Animals↗
PubMed1985

Abscess drainage with the aid of pelvic real-time sonography.

A case is described in which digital pelvic real-time ultrasound evaluation was used in order to determine the proper placement of a catheter for abscess drainage. This is the first description of utilizing this new technique as an adjunct to a surgical procedure.

Abscess↗
PubMed1985

Antisuppressor mutation in Escherichia coli defective in biosynthesis of 5-methylaminomethyl-2-thiouridine.

Mutations in three Escherichia coli K-12 genes were isolated that reduce the efficiency of the lysine-inserting nonsense suppressor supL. These antisuppressor mutations asuD, asuE, and asuF map at 61.9, 25.3, and 76.3 min, respectively, on the E. coli chromosome. Biochemical and genetic analysis of the mutant strains revealed the reason for the antisuppressor phenotype for two of these genes. The activity of lysyl-tRNA synthetase was reduced in strains with asuD mutations. The modification of 5-methylaminomethyl-2-thiouridine, the wobble base of tRNALys, was impaired in asuE mutant strains, presumably at the 2-thiolation step.

Chromosome Mapping↗
PubMed1985

Isolation and characterization of antisuppressor mutations in Escherichia coli.

Nonsense mutations in lacI have been shown to be useful as indicators of the efficiency of nonsense suppression. From strains containing supE and a lacI nonsense mutation, selection for LacI- mutants has resulted in the isolation of four antisuppressor mutations. Tn10 insertions linked to these mutations were isolated and used to group the four mutations into three loci. The asuA1 and asuA2 mutations are linked to trp, reduce suppression by supE approximately twofold, and affect a variety of suppressors. The asuB3 mutation was mapped by P1 cotransduction to rpsL but does not confer resistance to streptomycin. The asuC4 mutation reduced suppression by supE by 95% and was shown biochemically to result in the loss of two pseudouridine modifications from the 3' side of the anticodon stem and loop of tRNA2Gln. This mutation is linked to purF, suggesting that it is a new allele of hisT.

Base Sequence↗
PubMed1979

Ultrasonic evaluation of the stomach, small bowel, and colon.

A characteristic sonographic pattern that suggests a bowel lesion is pathologically significant in over 90% of patients with this pattern. The authors call this pattern the "pseudokidney sign" because it superficially resembles the ultrasonic appearance of the kidney. Although found occasionally in normal persons, this characteristic pattern should always lead the sonographer to consider a bowel lesion. Additional radiographic examinations, such as an upper-gastrointestinal series, small-bowel studies, and barium-enema examinations, are advised for definitive diagnosis.

Adult↗