Search PubMed⌕ Search

Biomedical subjects

R C Allen

Publications and source records attributed to R C Allen.

At least 73 records · Page 4Linked to original sources
PubMed1994

Analysis of circulating phagocyte activity measured by whole blood luminescence: correlations with clinical status.

The present study was undertaken to determine if measurement and analysis of phagocyte function are useful for diagnosis and staging of infection. Circulating phagocyte activity was measured in healthy volunteers and sequentially in patients with acute infections of different types and severity, including those with diabetes mellitus or human immunodeficiency virus (HIV) infection. Using an automated luminescence system, these phagocyte functions were measured in whole blood: basal and phorbol 12-myristate 13-acetate (PMA)-stimulated oxidase activity, basal and PMA-stimulated simple dioxygenation (e.g., oxidase-driven haloperoxidase activity), and circulating and primed opsonin receptor-dependent dioxygenation. Multiple discriminant analysis of these data showed significant differences between healthy controls, diabetic patients, HIV-positive subjects, and patients with pneumonia or sepsis syndromes. Longitudinally, circulating phagocyte function correlated with clinical condition, severity of infection, and outcome. This methodology provides rapid, objective, and sensitive diagnostic and monitoring information for patients with infections.

Acquired Immunodeficiency Syndrome↗
PubMed1994

Prior exposure to endotoxin exacerbates lipopolysaccharide-induced hypoxemia and alveolitis in anesthetized swine.

We sought to determine whether a standardized "priming" event, namely a small dose of LPS, would alter physiological responses to a subsequent larger "challenge" dose of endotoxin. Accordingly, four groups of pigs (N = 5-6) were studied. One group received neither priming nor challenge doses of LPS. A second group were not primed but were infused with a challenge dose (250 micrograms/kg) of LPS. A third group were pretreated 18 h before being studied with a priming dose of LPS (20 micrograms/kg), but were not infused with a second dose of LPS. A fourth group received both priming and challenge doses of LPS. Priming with LPS exacerbated endotoxin-induced arterial hypoxemia, and decreased animal-to-animal variability in the degree of hypoxemia induced by a challenge dose of endotoxin. Priming blunted the early phase (30 min) and exacerbated the delayed phase (120-210 min) of LPS-induced pulmonary hypertension. Priming blunted LPS-induced release of prostacyclin and thromboxane A2. The use of a priming dose of LPS increases the severity and reproducibility of LPS-induced acute lung injury in swine.

6-Ketoprostaglandin F1 alpha↗
PubMed1994

Role of oxygen in phagocyte microbicidal action.

Immune information in the form of inflammatory mediators directs phagocyte locomotion and increases expression of opsonin receptors such that contact with an opsonized microbe results in receptor ligation and activation of microbicidal metabolism. Carbohydrate dehydrogenation and O2 consumption feed reactions that effectively lower the spin quantum number (S) of O2 from 1 to 1/2 and finally to 0. Oxidase-catalyzed univalent reduction of O2 (S = 1; triplet multiplicity) yields hydrodioxylic acid (HO2) and its conjugate base superoxide, O2- (S = 1/2; doublet multiplicity). Acid or enzymatic disproportionation of superoxide yields H2O2 (S = 0; singlet multiplicity). Haloperoxidase catalyzes H2O2-dependent oxidation of Cl- yielding HOCl (S = 0), and reaction of HOCl with H2O2 yields singlet molecular oxygen, 1O2 (S = 0; singlet multiplicity). The Wigner spin conservation rule restricts direct reaction of S = 1 O2 with S = 0 organic molecules. Lowering the S of O2 overcomes this spin restriction and allows microbicidal combustion. High exergonicity dioxygenation reactions yield electronically excited carbonyl products that relax by photon emission, i.e., phagocyte luminescence. Addition of high quantum yield substrates susceptible to spin allowed dioxygenation, i.e., chemiluminigenic substrates, greatly increases detection sensitivity and defines the nature of the oxygenating agent. Measurement of luminescence allows high sensitivity, real-time, and substrate-specific differential analysis of phagocyte dioxygenating activities. Under assay conditions where immune mediator and opsonin exposure are controlled, luminescence analysis of the initial phase of opsonin-stimulated oxygenation activity allows functional assessment of the opsonin receptor expression per circulating phagocyte and can be used to gauge the in vivo state of immune activation.

Animals↗
PubMed1994

Application of carrier testing to genetic counseling for X-linked agammaglobulinemia.

Bruton X-linked agammaglobulinemia (XLA) is a phenotypically recessive genetic disorder of B lymphocyte development. Female carriers of XLA, although asymptomatic, have a characteristic B cell lineage-specific skewing of the pattern of X inactivation. Skewing apparently results from defective growth and maturation of B cell precursors bearing a mutant active X chromosome. In this study, carrier status was tested in 58 women from 22 families referred with a history of agammaglobulinemia. Primary carrier analysis to examine patterns of X inactivation in CD19+ peripheral blood cells (B lymphocytes) was conducted using quantitative PCR at the androgen-receptor locus. Obligate carriers of XLA demonstrated > 95% skewing of X inactivation in peripheral blood CD19+ cells but not in CD19- cells. Carrier status for mothers of isolated affected males could be assessed in 10 of 11 families: 7 women showed skewing, and 3 did not. Five carriers were found in six families in which there were no living affected males. Among all those tested, one individual's carrier status was considered to be indeterminate and five women were noninformative for the carrier test. Results obtained by the carrier test were congruent with linkage analysis (where applicable) using the RFLPs DXS178 and DXS94 and two newly developed polymorphic microsatellite markers, DXS178CA and DXS101AAT. Refinements in techniques for primary carrier testing and genetic mapping of XLA now make possible an ordered approach to diagnosis, prenatal diagnosis, and genetic counseling.

Adult↗
PubMed1994

A prospective evaluation of surgically treated groin complications following percutaneous cardiac procedures.

During an 18-month study period, 100 noncardiac surgical complications of a percutaneous cardiac interventional procedure were treated at Emory University Hospital. These were predominantly pseudoaneurysms (61.2%), groin hematomas (11.2%) arteriovenous fistulae (10.2%), and external bleeding (6.1%). Less common complications included retroperitoneal hematomas (5.1%), arterial thromboses (3.1%), groin abscess (2.0%), and a mycotic pseudoaneurysm (1.0%). The complication rate following diagnostic catheterization was 0.6 per cent, after percutaneous transluminal angioplasty, 1.5 per cent, atherectomy 2.2 per cent, and after stent placement 16 per cent (P < 0.0001). The arterial puncture site was other than the common femoral artery in 34 per cent of cases. Risk factors for the development of complications were postprocedure anticoagulation (P < 0.0001), female gender (P < 0.005), increased age (P < 0.0001), and small stature (P < 0.0001). Duplex scanning had 98 per cent accuracy in diagnosis of suspected groin complications, and clinical diagnostic accuracy was 77 per cent. We describe our technique for repair of pseudoaneurysms and arteriovenous fistula and discuss the possible future role of ultrasound guided compression. Mean hospital stay after the procedure was 3.2 days. Morbidity of surgical repair was 21 per cent and mortality was 2.1 per cent. Groin complications following percutaneous cardiac procedures are related to the type of procedure performed, female gender, and periprocedure anticoagulation.

Abscess↗
PubMed1993

CD40 ligand gene defects responsible for X-linked hyper-IgM syndrome.

The ligand for CD40 (CD40L) is a membrane glycoprotein on activated T cells that induces B cell proliferation and immunoglobulin secretion. Abnormalities in the CD40L gene were associated with an X-linked immunodeficiency in humans [hyper-IgM (immunoglobulin M) syndrome]. This disease is characterized by elevated concentrations of serum IgM and decreased amounts of all other isotypes. CD40L complementary DNAs from three of four patients with this syndrome contained distinct point mutations. Recombinant expression of two of the mutant CD40L complementary DNAs resulted in proteins incapable of binding to CD40 and unable to induce proliferation or IgE secretion from normal B cells. Activated T cells from the four affected patients failed to express wild-type CD40L, although their B cells responded normally to wild-type CD40L. Thus, these CD40L defects lead to a T cell abnormality that results in the failure of patient B cells to undergo immunoglobulin class switching.

Animals↗
PubMed1993

Deficient expression of a B cell cytoplasmic tyrosine kinase in human X-linked agammaglobulinemia.

We describe a novel cytoplasmic tyrosine kinase, termed BPK (B cell progenitor kinase), which is expressed in all stages of the B lineage and in myeloid cells. BPK has classic SH1, SH2, and SH3 domains, but lacks myristylation signals and a regulatory phosphorylation site corresponding to tyrosine 527 of c-src. BPK has a long, basic amino-terminal region upstream of the SH3 domain. BPK was evaluated as a candidate for human X-linked agammaglobulinemia (XLA), an inherited immunodeficiency characterized by a severe deficit of B and plasma cells and profound hypogammaglobulinemia. BPK mapped to within 100 kb of a probe defining the polymorphism most closely linked to XLA at DXS178. Reduction in or the absence of BPK mRNA, protein expression, and kinase activity was observed in XLA pre-B and B cell lines. BPK is likely the XLA gene and functions in pathways critical to B cell expansion.

Agammaglobulinemia↗
PubMed1993

Nonrandom X chromosome inactivation in natural killer cells from obligate carriers of X-linked severe combined immunodeficiency.

X-linked severe combined immunodeficiency (XSCID) is characterized by hypogammaglobulinemia, markedly reduced numbers of T cells, absent mitogen responses, decreased numbers of NK cells, and normal or elevated numbers of B cells. The abnormalities in the NK cell and B cell lineages could be attributed to dependence of these cell lineages on T cells or T cell-derived factors, or to expression of the XSCID gene defect in these cell lineages. In past experiments, we have examined X chromosome inactivation patterns in T cells and cultured B cells from female obligate carriers of XSCID and have found that both cell lineages demonstrate nonrandom X chromosome inactivation. This indicates that the gene defect is intrinsic to both of these cell lineages. In the present experiments, a polymerase chain reaction technique was used to evaluate X chromosome inactivation patterns in highly purified populations of freshly isolated NK cells, B cells, CD4+ cells, and CD8+ cells from three obligate carriers of XSCID. All four lymphoid cell populations from these three women exhibited exclusive use of a single X as the active X. In contrast, both X chromosomes were used as the active X in neutrophils and monocytes. These findings indicate that the XSCID gene is expressed in the NK cell lineage as well as in T cells and B cells. This observation makes it highly unlikely that the XSCID gene is involved in Ag receptor gene rearrangements.

B-Lymphocytes↗
PubMed1993

Linkage analysis and physical mapping near the gene for X-linked agammaglobulinemia at Xq22.

The gene for X-linked agammaglobulinemia (XLA) has been mapped to Xq22. No recombinations have been reported between the gene and the probe p212 at DXS178; however, this probe is informative in only 30-40% of women and the reported flanking markers, DXS3 and DXS94, are 10-15 cM apart. To identify additional probes that might be useful in genetic counseling, we examined 11 polymorphisms that have been mapped to the Xq21.3-q22 region in 13 families with XLA. In addition, pulsed-field gel electrophoresis and yeast artificial chromosomes (YACs) were used to further characterize the segment of DNA within which the gene for XLA must lie. The results demonstrated that DXS366 and DXS442, which share a 430-kb pulsed-field fragment, could replace DXS3 as proximal flanking markers. Probes at DXS178 and DXS265 identified the same 145-kb pulsed-field fragment, and both loci were contained within a 200-kb YAC identified with the probe p212. A highly polymorphic CA repeat (DXS178CA) was isolated from one end of this YAC and used in linkage analysis. Probes at DXS101 and DXS328 shared several pulsed-field fragments, the smallest of which was 250 kb. No recombinations were seen between XLA and the DXS178-DXS265-DXS178CA complex, DXS101, DXS328, DXS87, or the gene for proteolipid protein (PLP). Key crossovers, when combined with the linkage data from families with Alport syndrome, suggested the following order of loci: cen-DXS3-DXS366-DXS442-(PLP, DXS101, DXS328, DXS178-DXS265-DXS178CA complex, XLA)-(DXS87, DXS94)-DXS327-(DXS350, DXS362)-tel.(ABSTRACT TRUNCATED AT 250 WORDS)

Agammaglobulinemia↗
PubMed1993

Acute lower extremity ischemia after cardiac surgery.

A retrospective review during a 5-year period (1987 to 1992) was conducted of all patients manifesting leg ischemia after major cardiac surgery. There were 7,620 procedures performed, and 65 (0.85%) patients (mean age: 65 years) were identified with acute ischemia. Diagnosis was made by physical examination, during which a cool pulseless extremity without pedal Doppler signals was noted in 63 of 65 patients (97%). An intra-aortic balloon pump (IABP) was inserted in 56 patients (86%). Treatment regimens included medical management (17), IABP removal (4), IABP removal and thromboembolectomy (24), thromboembolectomy and endarterectomy with patch angioplasty (10), femoral-femoral bypass (17), other bypasses (6), fasciotomy (10), and amputation (16). Morbidity was 92% and mortality was 46%. Mortality was 11% in those patients developing ischemia without an IABP. Acute leg ischemia after cardiac surgery is predictive of high morbidity and mortality. This reflects the compromised cardiac status and multi-system disease. Treatment alternatives are based on the overall clinical status, degree of arterial insufficiency, and distribution of pre-existing peripheral vascular disease. However, ultimate limb salvage had no influence on overall patient survival in our study.

Acute Disease↗
PubMed1993

Hepatic arterioportal fistula.

Hepatic arterioportal fistula (HAPF) is uncommon, arising largely from either a ruptured hepatic artery aneurysm or from penetrating trauma. It is being encountered increasingly, secondary to rising numbers of percutaneous transhepatic procedures. We will describe five cases of HAPF seen at Emory University Hospital over the last 5 years and conclude with a review of the current status of treatment of this condition. HAPF occurred secondary to ruptured hepatic artery aneurysm in two patients, operative injury in two patients, and after trauma in one patient. The predominant clinical manifestation in these patients were complications of portal hypertension, most commonly gastrointestinal bleeding. Angiography remains the definitive diagnostic procedure and it was used to accurately diagnose HAPF in all cases. However, duplex ultrasonography is rapidly becoming a useful screening tool and was the initial imaging modality in the most recent case. Several factors determine the therapeutic approach including the location of the HAPF and associated comorbidity. Due to the development of portal hypertension even asymptomatic fistulas should be treated. In general, surgery is the procedure of choice for extrahepatic fistula, while embolization is optimal for intrahepatic fistulas. Embolization is also useful for patients in whom associated comorbidity prohibits surgical treatment. The goal of surgery is to interrupt the fistula, to maintain hepatic arterial flow, and to close the defect in the portal vein.

Adolescent↗
PubMed1993

Paraanastomotic aneurysms of the abdominal aorta.

PURPOSE: Aneurysm formation after abdominal aortic bypass reconstruction is an infrequent but underestimated complication. Aneurysms may occur after aortic prosthetic reconstruction for both occlusive and aneurysmal disease, may occur early or late, and may be classified as a pseudoaneurysm or true aneurysm. METHODS: Thirty-one cases in 29 patients treated at a tertiary referral center from 1980 to 1992 were retrospectively reviewed. Iliac and femoral aneurysms were excluded. The indication for initial abdominal aortic grafting had been aneurysmal disease in 19 patient and occlusive disease in 10 patients. RESULTS: There were 25 pseudoaneurysms and six true aneurysms, the latter followed grafting for aneurysmal disease. The current aneurysm (mean size 7.1 cm) was at the proximal aortic anastomosis in 27 cases and at the distal aortic anastomosis in two cases. Symptoms at presentation included abdominal pain (14), mass (12), claudication (9), back pain (6), and gastrointestinal bleeding (3). Surgical management included interposition tube grafting (16), aortoiliofemoral bypass (9), and graft removal with extraanatomic bypass (3). The overall operative morbidity rate was 73%, and mortality rate was 21%. CONCLUSIONS: Paraanastomotic aortic aneurysms are being increasingly recognized and are associated with high morbidity and mortality rates. Patients should be periodically studied after aortic grafting with abdominal ultrasonography for early detection of this potentially serious complication. Elective surgical repair is advocated in the effort to minimize morbidity rates.

Aged↗
PubMed1993

Use of resonance ionization spectroscopy to detect DNA bands on ultrathin spin-coated gels.

Development of alternative electrophoresis procedures are necessary for large volume sequencing and mapping studies. The use of stable isotopes as DNA labels and ultrathin gels promises to greatly increase the rate of sequencing. Spin coating is presented as an alternative method for producing ultrathin polyacrylamide gels. The technique has the potential of producing gels of micron to submicron thicknesses by varying the viscosity of the acrylamide solution and the spinning speed. Thirty micron thick 6% (weight %) gels were produced in this manner. Tin-labeled DNA oligomers were electrophoresed and detected using sputter-initiated resonance ionization spectroscopy (SIRIS). The usefulness of SIRIS and laser atomization RIS (LARIS) to sample the surface and deeper layers of 240 microns thick gels was investigated. With LARIS, whole cross-sections of the gel can be atomized, possibly allowing complete sampling of labels.

DNA↗
PubMed1993

Resolution of DNA in the presence of mobility modifying polar and nonpolar compounds by discontinuous electrophoresis on rehydratable polyacrylamide gels.

Ultrathin-layer rehydratable gels were surface loaded and run in the horizontal position to study effects of mobility modification of DNA. Mobility modification of DNA fragments was achieved by the addition of nonpolar monosaccharides and their corresponding sugar alcohols as well as with glycerol and ethylene glycol in the leading ion buffer. These compounds show little effect when included in the trailing ion buffer. Disaccharides show no mobility modification. Trailing ions such as serine and members of the Good buffer series reduced also the RF of double- or single-stranded DNA. While beta-alanine had no effect, serine and members of the Good buffer series, particularly MOPSO, showed a marked ability to decrease the RF; presumably due to changing the unstacking limits. Rapid separation of sequencing gels with high resolution was achieved with discontinuous buffer systems. The potential methodology for high-resolution scanning of gels as DNA zones unstack from the moving boundary is suggested.

Buffers↗
PubMed1992

Electrophoresis and detection of tin-labeled DNAs on open-faced gels.

Alternative protocols are necessary for the use of polyacrylamide gel electrophoresis in genome scale sequencing and mapping studies. The use of radioisotopes and manual gel reading will have to be replaced with a flexible labeling system that can be detected at levels similar or to better than radioisotopes but allows automated, high-speed detection. Labeling with stable isotopes is such an alternative. These nondecaying isotopes have the potential to be detected in sub-attomole quantities, despite being surrounded by the gel matrix, due to the high selectivity and sensitivity of resonance-ionization spectroscopy coupled with a mass spectrometer. In this study the detection limits of sputter-initiated resonance ionization spectroscopy (SIRIS) are investigated using thin, open-faced polyacrylamide gels supported by plastic. This system allows reproducibility and flexibility in the choice of gel size and buffer system since the gel can be cast, washed free of polymerization by-products, dried, and stored until use. Various concentrations of an Sn-labeled oligomer were run on these gels and loads of 5 femtomoles/mm could be detected on a 240 microns thick gel. Gels as thin as 60 microns lower the detectable concentration loads to 1 femtomole/mm. The limiting factor is tin contamination in the gel which, if reduced, will further increase detection. Polymerase chain reaction (PCR) products can also be labeled and detected using Sn isotopes, which could prove useful in mapping studies. Also presented are techniques which will facilitate resolution of these PCR products on open-faced gels by employing discontinuous buffers systems and DNA mobility modifiers.

Chromosome Mapping↗
PubMed1992

Biomechanical performance of ophthalmic surgical needles.

The mechanical performance of ophthalmic surgical needles is studied. Standard biomechanical tests, devised to evaluate the performance of ophthalmic surgical needles, are presented. Four comparable groups of ophthalmic surgical needles were selected from two different manufacturers for these biomechanical studies. The results of this testing demonstrate that needle point geometry and needle composition are important determinants of needle performance. When comparable size needles were evaluated, the biomechanical performance of the recently introduced CS160-6 ophthalmic needle (Ethicon, Inc) was superior to the AU-5, CU-5, and SU-5 needles (Alcon, Inc). Whereas the development of these biomechanical tests has allowed the evaluation of these ophthalmic needles, these same tests can be used to assess the performance of other new ophthalmic surgical needles.

Alloys↗