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Biomedical subjects

E Bell

Publications and source records attributed to E Bell.

At least 37 records · Page 2Linked to original sources
PubMed1998

Use of an automated anesthesia information system to determine reference limits for vital signs during cesarean section.

INTRODUCTION: We evaluated whether automated anesthesia information systems can be used to calculate reference limits (population-based "normal values") for vital signs. We considered four populations of women undergoing cesarean section: healthy under spinal anesthesia, healthy under general anesthesia, pre-eclamptic/eclamptic under spinal anesthesia, and pre-eclamptic/eclamptic under general anesthesia. METHODS: Reference limits were calculated for each of the study populations by determination of percentiles for: minimum heart rate, maximum heart rate, minimum arterial oxyhemoglobin saturation (SaO2), minimum mean arterial pressure (MAP), maximum MAP, decrease in MAP, and increase in MAP. RESULTS: There was one adverse anesthetic outcome among the 1,300 women in the study; the woman sustained a post-dural puncture headache. The 5th percentiles of SaO2 were at least 95% saturation under spinal versus 90% under general. Under spinal anesthesia, 95th percentiles for decreases in MAP from baseline were 63 mmHg for healthy and 75 mmHg for pre-eclamptic/eclamptic women. Under general anesthesia, the 95th percentiles for maximum MAP were 161 and 177 mmHg, respectively. Two women of the 1,300 patients experienced simultaneously a minimum SaO2 < 92% and minimum MAP < 50 mmHg. DISCUSSION: Automated anesthesia information systems can be used to determine reference limits for vital signs during anesthesia. Reference limits may play a role in malpractice cases when an expert claims that care by an anesthesiologist was sub-standard as shown by vital signs that were not maintained within the normal range during the critical portions of an anesthetic. Automated anesthesia information systems may enhance expert witnesses' clinical judgment.

Adult↗
PubMed1998

Advantage of the presence of living dermal fibroblasts within in vitro reconstructed skin for grafting in humans.

Methods for serial cultivation of human keratinocytes can provide large quantities of epidermal cells, which have the potential of restoring the vital barrier function of the epidermis in extensive skin defects such as burns. To investigate the value of combining an epidermis with a dermal component, fibroblasts originated from the superficial dermis were used to seed a collagen lattice as described by E. Bell (dermal equivalent). Beginning in 1981, we grafted 18 patients (burns and giant nevi) using 35 grafts 10 x 10 cm in size. In the course of this work, the original technique was modified and improved as experience was gained. We began by using small skin biopsy samples as a source of keratinocytes cultured on a dermal equivalent before grafting in a one-step procedure, but this gave poor cosmetic results, because of a nonhomogeneous epidermalization. We then chose to cover the graft bed using a two-step procedure. The first step consisted of grafting a dermal equivalent to provide a dermal fibroblast-seeded substrate for subsequent in vivo epidermalization by cultured epidermal sheets. Whatever the epidermalization technique used, a living dermal equivalent applied to the graft bed was found to reduce pain, to provide good hemostasis, and to improve the mechanical and cosmetic properties of the graft. A normal undulating dermal-epidermal junction reappeared by 3 to 4 months after grafting and elastic fibers were detectable 6 to 9 months after grafting. As a result of the biosynthesis of these products, the suppleness (e.g., elasticity) of the grafts was closer to that of normal skin than the cicatricial skin usually obtained with epidermal sheets grafted without the presence of living dermal cells. This rapid improvement of the mechanical properties of the graft could be attributed to the presence of fibroblasts cultured from the dermis and seeded into the collagen matrix.

Adult↗
PubMed1997

Characterization of the interaction between the Staphylococcus aureus clumping factor (ClfA) and fibrinogen.

The ability of Staphylococcus aureus to adhere to adsorbed fibrinogen and fibrin is believed to be an important step in the initiation of biomaterial and wound-associated infections. In this study, we show that the binding site in fibrinogen for the recently identified S. aureus fibrinogen-binding protein clumping factor (ClfA) is within the C-terminus of the fibrinogen gamma chain. S. aureus Newman cells expressing ClfA adhered to microtitre wells coated with recombinant fibrinogen purified from BHK cells, but did not adhere to wells coated with a purified recombinant fibrinogen variant where the 4 C-terminal residues of the gamma chain were replaced by 20 unrelated residues. In addition, a synthetic peptide corresponding to the 17 C-terminal amino acids of the fibrinogen gamma chain effectively inhibited adherence of ClfA-expressing cells to fibrinogen. In western ligand blots, a recombinant truncated ClfA protein called Clf33 (residues 221-550) recognized intact recombinant fibrinogen gamma chains, but failed to recognize recombinant fibrinogen gamma chains where the 4 C-terminal amino acids were altered by deletion or substitution. Previous studies have shown that the C-terminal domain of fibrinogen gamma chains contains a binding site for the integrin alphaIIb beta3 (glycoprotein gpIIb/IIIa) receptor on platelets [Kloczewiak, M., Timmons, S., Bednarek, M. A., Sakon, M. & Hawiger, J. (1989) Biochemistry 28, 2915-1919; Farrell, D. H., Thiagarajan, P., Chung, D. W. & Davie, E. W. (1992) Proc. Natl. Acad. Sci. USA 89, 10729-10732; Hettasch, J. M., Bolyard, M. G. & Lord, S. T. (1992) Thromb. Haemostasis 68, 701-706]. We now show that Clf33 inhibits ADP-induced, fibrinogen-dependent platelet aggregation in a concentration-dependent manner and inhibits adhesion of platelets to immobilized fibrinogen under fluid shear stress, indicating that the binding sites for the platelet integrin and the staphylococcal adhesin overlap. The interaction between Clf33 and fibrinogen was further characterized using the BIAcore biosensor. When soluble Clf33 was allowed to bind to immobilized fibrinogen, a Kd of 0.51 +/- 0.19 microM was experimentally determined using equilibrium binding data. It was also shown that the synthetic C-terminal gamma-chain peptide effectively inhibited this interaction.

Adenosine Diphosphate↗
PubMed1997

Jasmonate is essential for insect defense in Arabidopsis.

The signaling pathways that allow plants to mount defenses against chewing insects are known to be complex. To investigate the role of jasmonate in wound signaling in Arabidopsis and to test whether parallel or redundant pathways exist for insect defense, we have studied a mutant (fad3-2 fad7-2 fad8) that is deficient in the jasmonate precursor linolenic acid. Mutant plants contained negligible levels of jasmonate and showed extremely high mortality ( approximately 80%) from attack by larvae of a common saprophagous fungal gnat, Bradysia impatiens (Diptera: Sciaridae), even though neighboring wild-type plants were largely unaffected. Application of exogenous methyl jasmonate substantially protected the mutant plants and reduced mortality to approximately 12%. These experiments precisely define the role of jasmonate as being essential for the induction of biologically effective defense in this plant-insect interaction. The transcripts of three wound-responsive genes were shown not to be induced by wounding of mutant plants but the same transcripts could be induced by application of methyl jasmonate. By contrast, measurements of transcript levels for a gene encoding glutathione S-transferase demonstrated that wound induction of this gene is independent of jasmonate synthesis. These results indicate that the mutant will be a good genetic model for testing the practical effectiveness of candidate defense genes.

Journal Article↗
PubMed1996

Mechanical design of mussel byssus: material yield enhances attachment strength

The competitive dominance of mussels in the wave-swept rocky intertidal zone is in part due to their ability to maintain a secure attachment. Mussels are tethered to the substratum by a byssus composed of numerous extracellular, collagenous threads secreted by the foot. Each byssal thread has three serially arranged parts: a corrugated proximal region, a smooth distal region and an adhesive plaque. This study examines the material and structural properties of the byssal threads of three mussel species: Mytilus californianus, M. trossulus, and M. galloprovincialis. Tensile tests in general reveal similar material properties among species: the proximal region has a lower initial modulus, a lower ultimate stress and a higher ultimate strain than the distal region. The distal region also yields at a stress well below its ultimate value. In whole thread tests, the proximal region and adhesive plaque are common sites of structural failure and are closely matched in strength, while the distal region appears to be excessively strong. We propose that the high strength of the distal region is the byproduct of a material designed to yield and extend before structural failure occurs. Experimental and theoretical evidence is presented suggesting that thread yield and extensibility provide two important mechanisms for increasing the overall attachment strength of the mussel: (1) the reorientation of threads towards the direction of applied load, and (2) the 'recruitment' of more threads into tension and the consequent distribution of applied load over a larger cross-sectional area, thereby reducing the stress on each thread. This distal region yield behavior is most striking for M. californianus and may be a key to its success in extreme wave-swept environments.

Journal Article↗
PubMed1995

A chloroplast lipoxygenase is required for wound-induced jasmonic acid accumulation in Arabidopsis.

Plant lipoxygenases are thought to be involved in the biosynthesis of lipid-derived signaling molecules. The potential involvement of a specific Arabidopsis thaliana lipoxygenase isozyme, LOX2, in the biosynthesis of the plant growth regulators jasmonic acid (JA) and abscisic acid was investigated. Our characterization of LOX2 indicates that the protein is targeted to chloroplasts. The physiological role of this chloroplast lipoxygenase was analyzed in transgenic plants where cosuppression reduced LOX2 accumulation. The reduction in LOX2 levels caused no obvious changes in plant growth or in the accumulation of abscisic acid. However, the wound-induced accumulation of JA observed in control plants was absent in leaves of transgenic plants that lacked LOX2. Thus, LOX2 is required for the wound-induced synthesis of the plant growth regulator JA in leaves. We also examined the expression of a wound- and JA-inducible Arabidopsis gene, vsp, in transgenic and control plants. Leaves of transgenic plants lacking LOX2 accumulated less vsp mRNA than did control leaves in response to wounding. This result suggests that wound-induced JA (or some other LOX2-requiring component of the wound response pathway) is involved in the wound-induced regulation of this gene.

Abscisic Acid↗
PubMed1995

Arabidopsis thaliana Atvsp is homologous to soybean VspA and VspB, genes encoding vegetative storage protein acid phosphatases, and is regulated similarly by methyl jasmonate, wounding, sugars, light and phosphate.

The soybean vegetative storage proteins, VSP alpha and VSP beta, are acid phosphatases that accumulate to very high levels in hypocotyls, young leaves and flowers and pods. The genes encoding the soybean VSP are activated by jasmonate, wounding, sugars and light and down regulated by phosphate and auxin. In this study, expression of an Arabidopsis thaliana gene (Atvsp) encoding a protein homologous to soybean Vsp alpha and Vsp beta, was examined and compared to expression of the soybean Vsp genes. Atvsp mRNA was present at high levels in flowers and buds and at low levels in roots, stems, leaves and siliques. Expression of Atvsp in leaves could be induced by wounding or by treatment of illuminated plants with methyl jasmonate and sucrose. Roots of plants with wounded leaves also accumulated Atvsp mRNA indicating that this gene can be regulated by a transmissible wound signal. Phosphate partially inhibited expression of Atvsp. Arabidopsis proteins of 29 and 30 kDa crossreacted with antibodies against soybean VSP. These proteins were very abundant in flowers and the proteins accumulated in leaves and roots of plants treated with methyl jasmonate. The level of these proteins in flowers was similar to the levels of soybean VSP in young soybean leaves. Overall, these data indicate that Arabidopsis Atvsp and soybean VspA/B genes are regulated similarly and that in both plants, the gene products can accumulate to high levels. This suggests that genes homologous to VspA/B may be of greater general significance than previously recognized.

Acetates↗
PubMed1995

A community-wide outbreak of hepatitis A: risk factors for infection among homosexual and bisexual men.

PURPOSE: To assess risk factors for hepatitis A infection among homosexual and bisexual men during a community-wide outbreak of hepatitis A in New York City. PATIENTS AND METHODS: Twenty-five homosexual and bisexual men, 20 to 49 years of age with hepatitis A identified from health department surveillance data (cases) were compared with 42 homosexual and bisexual men of similar age distribution who were seronegative for hepatitis A virus and identified from private physician offices (controls). Odds ratio (OR) were determined for acute hepatitis A infection according to demographics, numbers of sexual partners, frequency of specific sexual behaviors, and self-reported human immunodeficiency virus status. RESULTS: Cases had more anonymous sex partners (0 to 1 partner versus > 1 partner) than controls during the 6 weeks before illness onset (OR = 4.4, 95% confidence interval [CI] 1.4 to 14.4). Cases were more likely than controls to have engaged in group sex (OR = 3.8, 95% CI 1.1 to 12.6). Among specific sexual behaviors examined, oral-anal intercourse (oral role) and digital-rectal intercourse (digital role) with anonymous sex partners were more commonly reported by cases than controls (OR = 9.7, 95% CI 1.2 to 78.7 and OR = 2.6, 95% CI 1.0 to 7.4, respectively). Multivariate analysis showed that > 1 anonymous sex partner, group sex, oral-anal intercourse, and digital-rectal intercourse were associated with illness in models controlling for duration of sexual activity. Because these variables were highly correlated, independent risk could not be evaluated in a single model. CONCLUSIONS: Hepatitis A infection among homosexual and bisexual men is associated with oral-anal and digital-rectal intercourse, as well as with increasing numbers of anonymous sex partners and group sex. These findings reinforce the importance of developing educational activities for homosexual and bisexual men that focus on risk reduction for hepatitis A as well as other sexually transmitted disease spread via the fecal-oral route.

Adult↗
PubMed1995

A model for rational introduction of new and expensive medicines.

The reported impact of human monoclonal IgM antibody (HA1A) on the mortality rate from Gram-negative bacteraemia aroused considerable interest in its use in Glasgow Royal Infirmary. However, the commercial preparation of HA1A was extremely expensive. With this in mind, the Infirmary's Drugs and Therapeutics Committee introduced a system whereby the commercial preparation of HA1A could be introduced in a controlled fashion, thereby establishing a model which would encourage targeting the prescription of new, highly expensive treatments to appropriate patients. This model provides the clinician with a set of objective criteria to be met before prescribing such a preparation, thus preventing unnecessary increases in the hospital drug budget and justifying using expensive resources.

Antibodies, Monoclonal↗
PubMed1995

Actinomycosis presenting as carcinoma.

Actinomycosis is rare compared to carcinoma, but the two conditions can present with very similar clinical pictures. Two cases of actinomycosis are reported, one thoracic and one pelvic-abdominal which presented as carcinoma and proceeded to surgery without a histological diagnosis having been established.

Actinomycosis↗
PubMed1994

Typhoid fever in New York City, 1980 through 1990.

BACKGROUND: Although typhoid fever incidence decreased in the 1960s and 1970s in New York City and elsewhere, it did not disappear. In this article, trends associated with various modes of transmission of Salmonella typhi in New York City patients are described. METHODS: Typhoid fever surveillance reports from 1980 to 1990 were reviewed for clinical, demographic, and epidemiologic characteristics. Cases of typhoid fever were classified as travel related or domestically acquired. RESULTS: In all, 479 typhoid cases were identified, of which 67% were travel related. The age groups most frequently affected were children and adolescents. Cases more than doubled in the decade, and the ratio of travel-related cases to domestically acquired cases increased steadily from 63% to 80%. Travelers to Southeast Asia were at three times higher risk than those visiting South America and eight times higher than those visiting the Caribbean. The case-fatality proportion was 1.5%. CONCLUSION: The trends of S typhi infection in New York City followed the trends observed in the United States since 1978, which demonstrates the importance of international travel. Although food and water precautions may be effective for short-term travelers, selective use of oral antityphoid vaccines for New York City travelers to high-risk endemic countries should be encouraged.

Adolescent↗
PubMed1994

Lessons from Cuba: mass campaign administration of trivalent oral poliovirus vaccine and seroprevalence of poliovirus neutralizing antibodies.

The immunogenicity of trivalent oral poliovirus vaccine (TOPV), which is less effective in tropical than in temperate areas, may potentially be improved in several ways, including increasing the number of doses. Little information is available on TOPV when more than 6 doses are given. The situation in Cuba provides a unique opportunity to relate the seroprevalence of neutralizing antibodies to the dose of TOPV because Cuba has not reported culture-confirmed poliomyelitis since 1973 and TOPV is only administered in twice yearly 1-week mass immunization campaigns. Sera from 2000 children nationwide were studied for neutralizing antibody among children who received 0, 2, 4, 6 and 8 doses of TOPV. These doses were administered in the period 1989-91, when TOPV (from the USSR) was being used with 500,000, 200,000, and 300,000 median tissue-culture-infecting doses (TCID50) for types 1, 2 and 3, respectively--the 5:2:3 formulation. Seroprevalence of neutralizing antibody after two TOPV doses was 91.5% for type 1, 90.8% for type 2, and 45.9% for type 3. Seroprevalence of type-3 neutralizing antibody after 6 doses remained low (73.4%), but increased to 83.5% after 8 doses (P < 0.05). Although 16.5% of the children remained unprotected for type-3 infection even after 8 doses, mass campaign immunization strategies were sufficient to eradicate the transmission of wild poliovirus in Cuba. Because the seroprevalence of type-1 neutralizing antibody was high (91.5%) after two campaign doses, additional studies using different formulations are needed to determine whether simultaneous improvement in the type-3 response to two campaign doses can be achieved.

Antibodies, Viral↗
PubMed1993

An audit of emergency echocardiography in a district general hospital.

Eighty patients (43 M, 37 F), aged 23-89 years who were referred for emergency echocardiography over a 12-month period were prospectively studied in order to determine the reasons for emergency echocardiography and the influence of its results on patient management. The most frequent emergency request was to clarify whether the basis for cardiomegaly in a haemodynamically unstable patient was pericardial effusion or left ventricular dilatation. Other reasons for requests were for assessment for source of systemic emboli, acute complications of myocardial infarction, endocarditis, valve dysfunction and cardiac trauma. As a consequence of the emergency echocardiography, management was immediately influenced in 19 patients. This study has provided information on the specific settings in which emergency echocardiography can be justified.

Adult↗