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Biomedical subjects

A Thompson

Publications and source records attributed to A Thompson.

At least 217 records · Page 12Linked to original sources
PubMed1991

Diversity of immunoglobulin heavy chain gene segment rearrangement in B lymphoblastoid cell lines from X-linked agammaglobulinemia patients.

X-linked agammaglobulinemia (XLA) is characterized by an arrest in early B lymphocyte differentiation. Precursor B cells are present in the bone marrow (BM), whereas peripheral blood B cell numbers are severely decreased. A series of Epstein-Barr virus (EBV)-transformed B lymphoblastoid cell lines (BLCL) was established from peripheral blood of three XLA patients belonging to one pedigree. These BLCL manifested productive VHDJH rearrangements and a random utilization of the VH families. The CDR3 regions of the rearrangements varied in length from 12 to 47 nucleotides and included N regions in all cases. The results supported the conclusion that the few B lymphocytes in peripheral blood of XLA patients exhibit all mechanisms that generate immunoglobulin (Ig) heavy (H) chain diversity. However, no evidence for somatic mutation was found. Within the VH3 family 50% of the expressed VH gene segments belonged to a single subgroup and within the VH4 family a preferential utilization of one VH4 gene element was observed. The utilization of H chain joining (HH) elements was biased to JH4 and JH6 and a high percentage of the CDR3 regions was found to be generated by unconventional mechanisms, such as multiple D usage and the fusion of D elements to D segments with irregular recombination recognition signals. These unique features of the recombined and expressed VHDJH regions in XLA may explain the inability of XLA patients to respond to a variety of antigens. Alternatively, they could be secondary to a B lymphocyte maturation defect in XLA.

Agammaglobulinemia↗
PubMed1991

Mössbauer spectroscopic studies of iron in Pseudomonas aeruginosa.

The present Mössbauer spectroscopic studies of isolated bacterioferritin and whole cells of Pseudomonas aeruginosa have shown that the iron core of bacterioferritin is not altered on isolation. These studies have also shown that the bacterioferritin core is typically 85% oxidized within the cell and may contain a significant proportion of its iron as small clusters during the early stage of the stationary phase of cell growth.

Bacterial Proteins↗
PubMed1991

Reversible neurologic abnormalities associated with prolonged intravenous midazolam and fentanyl administration.

An encephalopathy developed in three infants in the intensive care unit after heavy sedation with midazolam and fentanyl for 4 to 11 days. The affected infants had poor social interaction, decreased visual attentiveness, dystonic postures, and choreoathetosis. Symptoms cleared completely in 5 days to 4 weeks. Retrospective review of records of all children treated in the intensive care unit with prolonged intravenous administration of midazolam revealed that 45 children could be assessed neurologically on withdrawal of sedation. Three children had definite and two had possible neurologic sequelae (5/45, 11.1%). All had received concomitant intravenous fentanyl therapy. Neurologic sequelae were significantly associated with young age, female gender, low serum albumin concentration, and concomitant administration of aminophylline. This encephalopathy may represent a benzodiazepine withdrawal syndrome, a prolonged agonist action on the benzodiazepine receptor, or the combined effects of multiple toxic, metabolic, and infectious insults to the central nervous system of infants in the intensive care unit. Prolonged use of intravenous midazolam sedation necessitates careful dosing, monitoring, and discontinuation, particularly in infants and young children.

Adolescent↗
PubMed1991

Genetic aspects of breast cancer.

Of all the factors contributing to breast cancer risk, a strong family history of the disease is the most powerful. Familial clustering is said to have been noted by the Ancient Romans but formal documentation began in the mid-nineteenth century (reviewed in Ref. 1). The French physician Paul Broca noted that in one family (probably his wife's) over four generations 10 out of 24 women had died from breast cancer while several more individuals, of both sexes, had suffered other malignancies. He concluded that this very large excess of cancers could not reasonably be attributed to chance. At the same time he recognized that occasional familial clusters of relatively common conditions would be expected even in the absence of any genetic predisposition and discounted several published reports of 'hereditary cancers', including some of the families collected by his English contemporary Sir James Paget.

Breast Neoplasms↗
PubMed1991

Regional mapping of the Batten disease locus (CLN3) to human chromosome 16p12.

The gene for Batten disease (CLN3) has been mapped to human chromosome 16 by demonstration of linkage to the haptoglobin locus, and its localization has been further refined using a panel of DNA markers. The aim of this work was to refine the genetic and physical mapping of this disease locus. Genetic linkage analysis was carried out in a larger group of families by using markers for five linked loci. Multipoint analysis indicated a most likely location for CLN3 in the interval between D16S67 and D16S148 (Z = 12.5). Physical mapping of linked markers was carried out using somatic cell hybrid analysis and in situ hybridization. A mouse/human hybrid cell panel containing various segments of chromosome 16 has been constructed. The relative order and physical location of breakpoints in the proximal portion of 16p were determined. Physical mapping in this panel of the markers for the loci flanking CLN3 positioned them to the bands 16p12.1----16p12.3. Fluorescent in situ hybridization of metaphase chromosomes by using these markers positioned them to the region 16p11.2-16p12.1. These results localize CLN3 to an interval of about 2 cM in the region 16p12.

Chromosome Mapping↗
PubMed1990

Severe combined immunodeficiency in man with an absence of immunoglobulin gene rearrangements but normal T cell receptor assembly.

An autosomal recessive type of severe combined immunodeficiency disease (SCID) was characterized by an absence of immunoglobulins (Ig) in the serum and of Ig+ lymphocytes in bone barrow (BM) and peripheral blood. In the BM CD10+/terminal deoxynucleotidyl transferase-positive lymphocytes were identified. Epstein-Barr virus-transformed B lymphoblastoid cell lines (BLCL) obtained from BM and peripheral blood did not synthesize Ig. The Ig heavy and light chain gene complexes in the BLCL had retained the germ-line configuration. Mature T cells were present but their numbers in peripheral blood were decreased. T lymphoblastoid cells derived from peripheral blood expressed normal T cell receptor (TcR) CD3 complexes and manifested various genomic TcR rearrangements. It was concluded that this type of SCID entailed a complete arrest of B lymphocyte differentiation in an early stage prior to Ig rearrangements and a quantitative defect of T lymphocytes which nevertheless allowed development of mature T cells. Repeated failures of BM transplantation and the striking absence of Ig assembly suggested that this SCID defect resides in the BM microenvironment.

Antigens, CD↗
PubMed1990

In-home pasteurization of raw goat's milk by microwave treatment.

Raw milk has been implicated as an important source of infection with the common bacterial agents associated with gastroenteritis. While established methods of home pasteurization can be cumbersome and tedious, we have demonstrated that a domestic microwave oven can be used effectively to reduce aerobic plate counts in raw goat's milk by up to 6 log cycles without impairing the organoleptic quality. Good keeping quality of the irradiated product was demonstrated by the 7-day holding standard plate count. Petrifilm SM and Petrifilm VRB were used successfully under field conditions. Further investigation must be undertaken to demonstrate that this method is equivalent to the legally accepted pasteurization procedures for the inactivation of such pathogenic bacteria as Salmonella spp., Listeria monocytogenes and the pasteurization standard Coxiella burnetti.

Animals↗
PubMed1990

Molecular cloning of a novel bone-forming compound: osteoinductive factor.

cDNA clones encoding osteoinductive factor (OIF) have been isolated from a bovine osteoblast library. Sequence analysis of these clones indicated that the 105-amino-acid OIF is synthesized as a larger 299-amino-acid precursor, the carboxyl terminus of which is cleaved to yield the mature protein. Northern blot analysis of bovine osteoblast mRNA revealed two OIF-specific transcripts of 1.9 and 2.4 kb. The polymerase chain reaction was used to obtain clones coding for human OIF from the osteosarcoma cell line, MG-63. The human OIF cDNA encodes a precursor of 298 amino acids that exhibits 94% identity to the bovine protein. Northern blot analysis of various cell lines and tissues indicated that expression of OIF transcripts is limited and may be restricted to cells of bone lineage.

Amino Acid Sequence↗
PubMed1989

A pulse radiolysis investigation of the oxidation of indolic melanin precursors: evidence for indolequinones and subsequent intermediates.

The rate constants associated with the series of successive transient absorptions initiated by one-electron oxidation of 5,6-dihydroxyindole (DHI), 5,6-dihydroxyindole-2-carboxylic acid (DHICA), precursors of melanin, and N-methyl-5,6-dihydroxyindole (NMDHI), a model compound, have been studied by pulse radiolysis. The initial transient species resulting from N3. oxidation reaction at pH 7.3-7.4 are assigned as the corresponding semiquinones. In each case, these radicals decayed, probably by disproportionation, into products most readily monitored in the 400-430 nm region. For DHI, the decay in this region could be fitted by two parent concentration independent first-order processes. These may correspond to transformations between 5,6-indolequinone, and its quinone-imine and quinone-methide tautomers. With NMDHI, on the other hand, a single longer-lived product with a peak around 430 nm predominated after decay of the corresponding radical, due almost certainly to N-methyl-5,6-indolequinone. The data appear to exclude significant melanin polymerisation by condensation of semiquinones, reaction of semiquinones with dihydroxyindoles, self-addition of indolequinones or tautomers, or reaction of indolequinones or tautomers with the parent dihydroxyindoles. It is suggested that polymerisation of melanin may rather occur by stepwise addition of indolequinone methide/imine to reduced oligomeric species.

Indoles↗
PubMed1989

Doppler echocardiographic measurement of low velocity motion of the left ventricular posterior wall.

A new noninvasive method using pulsed Doppler echocardiography was developed to assess left ventricular (LV) posterior wall motion dynamics. Seventeen normal subjects and 23 patients undergoing cardiac catheterization were prospectively studied. The sample volume was placed within the LV posterior wall endocardium just apical to the mitral valve sulcus using a posteriorly angulated low parasternal view. The wall filter was set at 100 Hz to record the low velocities of the LV posterior wall motion. The Doppler signal was morphologically similar to the rate of change of the LV posterior wall endocardium excursion obtained by a digitized M-mode echocardiogram, and showed 3 major waves: a systolic wave (S), an early diastolic wave (E) and a late diastolic wave (A). The peak velocities of LV posterior wall endocardium excursion were also determined by M-mode echocardiographic technique. We found a significant linear correlation between peak E-wave velocity and M-mode peak diastolic endocardial velocity (r = 0.90, p less than 0.001) and between peak S-wave velocity and M-mode peak systolic endocardial velocity (r = 0.81, p less than 0.001). M-mode peak systolic endocardial velocity showed an important overlap between control subjects and patients with normal and patients with abnormal LV posterior wall motion on the angiogram. In contrast, peak S-wave velocity was a better discriminator, and a peak S-wave velocity less than 7.5 cm/s was associated with abnormal LV posterior wall motion with an 83% sensitivity, 100% specificity and 95% accuracy. In patients with coronary artery disease but normal systolic LV posterior wall motion and normal global systolic LV function, peak S-wave velocity was not different when compared to control subjects. Peak E-wave velocity and E/A were significantly lower than in control subjects (p less than 0.01) and peak A-wave velocity was greater (p less than 0.01). In conclusion, these data suggest that pulsed Doppler echocardiography can be used for the direct analysis of LV posterior wall instantaneous low velocities and appears to be more informative than M-mode technique for systolic measurements. Thus, detection of abnormal LV posterior wall diastolic motion by pulsed Doppler echocardiography may, upon additional confirmation, be used as a new noninvasive method to gain insight into global LV diastolic performance.

Adult↗