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D J Weber

Publications and source records attributed to D J Weber.

At least 55 records · Page 3Linked to original sources
PubMed1999

Sporicidal activity of a new low-temperature sterilization technology: the Sterrad 50 sterilizer.

This study was undertaken to evaluate the efficacy of a new low-temperature sterilization system that recently has been cleared by the Food and Drug Administration, the Sterrad 50. Flat stainless steel carriers were inoculated with approximately 10(6) Bacillus stearothermophilus spores. These carriers were placed aseptically in the middle of 40-cm-long stainless steel-lumened test units of varying diameters (1 mm, 2 mm, and 3 mm). After inoculation, the test units were processed in the Sterrad 50. After sterilization, the carriers were assayed for growth of the B. stearothermophilus spores. Our data demonstrated that the Sterrad 50 was highly effective in killing the B. stearothermophilus spores (no positive carriers with 30 tests of each lumen-diameter test unit). The Sterrad 50 is likely to be clinically useful for the sterilization of heat-sensitive medical equipment.

Equipment Contamination↗
PubMed1999

The use of dipolar couplings for determining the solution structure of rat apo-S100B(betabeta).

The relative orientations of adjacent structural elements without many well-defined NOE contacts between them are typically poorly defined in NMR structures. For apo-S100B(betabeta) and the structurally homologous protein calcyclin, the solution structures determined by conventional NMR exhibited considerable differences and made it impossible to draw unambiguous conclusions regarding the Ca2+-induced conformational change required for target protein binding. The structure of rat apo-S100B(betabeta) was recalculated using a large number of constraints derived from dipolar couplings that were measured in a dilute liquid crystalline phase. The dipolar couplings orient bond vectors relative to a single-axis system, and thereby remove much of the uncertainty in NOE-based structures. The structure of apo-S100B(betabeta) indicates a minimal change in the first, pseudo-EF-hand Ca2+ binding site, but a large reorientation of helix 3 in the second, classical EF-hand upon Ca2+ binding.

Animals↗
PubMed1999

Structural changes in the C-terminus of Ca2+-bound rat S100B (beta beta) upon binding to a peptide derived from the C-terminal regulatory domain of p53.

S100B(beta beta) is a dimeric Ca2+-binding protein that interacts with p53, inhibits its phosphorylation by protein kinase C (PKC) and promotes disassembly of the p53 tetramer. Likewise, a 22 residue peptide derived from the C-terminal regulatory domain of p53 has been shown to interact with S100B(beta beta) in a Ca2+-dependent manner and inhibits its phosphorylation by PKC. Hence, structural studies of Ca2+-loaded S100B(beta beta) bound to the p53 peptide were initiated to characterize this interaction. Analysis of nuclear Overhauser effect (NOE) correlations, amide proton exchange rates, 3J(NH-H alpha) coupling constants, and chemical shift index data show that, like apo- and Ca2+-bound S100B(beta beta), S100B remains a dimer in the p53 peptide complex, and each subunit has four helices (helix 1, Glu2-Arg20; helix 2, Lys29-Asn38; helix 3, Gln50-Asp61; helix 4, Phe70-Phe87), four loops (loop 1, Glu21-His25; loop 2, Glu39-Glu49; loop 3, Glu62-Gly66; loop 4, Phe88-Glu91), and two beta-strands (beta-strand 1, Lys26-Lys28; beta-strand 2, Glu67-Asp69), which forms a short antiparallel beta-sheet. However, in the presence of the p53 peptide helix 4 is longer by five residues than in apo- or Ca2+-bound S100B(beta beta). Furthermore, the amide proton exchange rates in helix 3 (K55, V56, E58, T59, L60, D61) are significantly slower than those of Ca2+-bound S100B(beta beta). Together, these observations plus intermolecular NOE correlations between the p53 peptide and S100B(beta beta) support the notion that the p53 peptide binds in a region of S100B(beta beta), which includes residues in helix 2, helix 3, loop 2, and the C-terminal loop, and that binding of the p53 peptide interacts with and induces the extension of helix 4.

Amino Acid Sequence↗
PubMed1999

Nosocomial infections in the ICU: the growing importance of antibiotic-resistant pathogens.

Patients hospitalized in ICUs are 5 to 10 times more likely to acquire nosocomial infections than other hospital patients. The frequency of infections at different anatomic sites and the risk of infection vary by the type of ICU, and the frequency of specific pathogens varies by infection site. Contributing to the seriousness of nosocomial infections, especially in ICUs, is the increasing incidence of infections caused by antibiotic-resistant pathogens. Prevention and control strategies have focused on methicillin-resistant Staphylococcus aureus, vancomycin-resistant Enterococcus, and extended-spectrum beta-lactamase-producing Gram-negative bacilli, among others. An effective infection control program includes a surveillance system, proper handwashing, appropriate patient isolation, prompt evaluation and intervention when an outbreak occurs, adherence to standard guidelines on disinfection and sterilization, and an occupational health program for health-care providers. Studies have shown that patients infected with resistant strains of bacteria are more likely than control patients to have received prior antimicrobials, and hospital areas that have the highest prevalence of resistance also have the highest rates of antibiotic use. For these reasons, programs to prevent or control the development of resistant organisms often focus on the overuse or inappropriate use of antibiotics, for example, by restriction of widely used broad-spectrum antibiotics (e.g., third-generation cephalosporins) and vancomycin. Other approaches are to rotate antibiotics used for empiric therapy and use combinations of drugs from different classes.

Anti-Bacterial Agents↗
PubMed1998

S100A1 utilizes different mechanisms for interacting with calcium-dependent and calcium-independent target proteins.

While previous studies have identified target proteins that interact with S100A1 in a calcium-dependent manner as well as target proteins that interact in a calcium-independent manner, the molecular mechanisms of S100A1-target protein interaction have not been elucidated. In this study, point and deletion mutants of S100A1 were used to investigate the contribution of carboxyl terminal amino acids to S100A1 interaction with calcium-dependent and calcium-independent target proteins. First, a recombinant rat S100A1 protein (recS100A1) expressed in bacteria exhibited physical and chemical properties indistinguishable from native S100A1. Next, proteins lacking the carboxyl-terminal nine residues of recS100A1 (Delta85-93), or containing alanine substitutions at Phe 88 (F88A), Phe 89 (F89A), or Trp 90 (W90A), both Phe 88 and Phe 89 (F88/89A), or all three aromatic residues (F88/89A-W90A) were recombinantly expressed. Like recS100A1, F88A, F89A, and W90A proteins interacted with phenyl-Sepharose in a calcium-dependent manner. However, the Delta85-93 protein did not interact with phenyl-Sepharose, indicating that a phenyl-Sepharose-binding region (PSBR) of recS100A1 had been disrupted. The F88/89A and F88/89A-W90A proteins exhibited reduced calcium-dependent interaction with phenyl-Sepharose when compared with recS100A1, demonstrating that the carboxyl-terminal aromatic residues Phe 88, Phe 89, and Trp 90 comprise the PSBR of S100A1. Fluorescence studies showed that the Delta85-93 protein exhibited reduced calcium-dependent interaction with the dodecyl CapZ peptide, TRTK, while W90A bound TRTK with a Kd of 5.55 microM. These results demonstrate that the calcium-dependent target protein-binding site and the PSBR are indistinguishable. In contrast to the calcium-dependent target TRTK, activation of the calcium-independent target protein aldolase A by the point and deletion mutant S100A1s was indistinguishable from native S100A1. These results demonstrate that carboxyl-terminal residues are not required for S100A1 modulation of calcium-independent target protein aldolase A. Alltogether, these results indicate that S100A1 utilizes distinct mechanisms for interaction with calcium-independent and calcium-dependent target proteins.

Amino Acid Sequence↗
PubMed1998

Measurement of altered aspartyl residues in the scrapie associated form of prion protein.

In transmissible spongiform encephalopathies (TSE), the endogenous protease-sensitive prion protein (PrP-sen) of the host is converted to a pathologic form (PrP-res) that has greatly enhanced proteinase K resistance, insolubility, and beta sheet content. To investigate the possibility that alterations at aspartyl or asparaginyl residues in the form of D-aspartate and/or L-isoaspartate could play a role in either the formation or stabilization of PrP-res in TSE-infected animals, we assayed for the presence of these abnormal residues in PrP-res. Protein D-aspartyl/L-isoaspartyl carboxyl methyltransferase (PIMT) was used to methylate and radiolabel altered aspartyl residues, which were detected in PrP-res, but at low levels (0.5 mole%). The scarcity of D-aspartyl and/or L-isoaspartyl groups in PrP-res suggests that this modification is unlikely to be primarily responsible for the differences between PrP-res and PrP-sen. However, it remains possible that such modifications in substoichiometric numbers of PrP molecules could help to initiate the PrP-res formation or stabilize PrP-res polymers in vivo.

Animals↗
PubMed1998

Solution structure of calcium-bound rat S100B(betabeta) as determined by nuclear magnetic resonance spectroscopy,.

The three-dimensional structure of Ca2+-bound rat S100B(betabeta) has been determined using data from a series of two-dimensional (2D), three-dimensional (3D), and four-dimensional (4D) nuclear magnetic resonance (NMR) experiments. Each S100beta subunit (91 residues) contains four helixes (helix 1, E2-R20; helix 2, K29-N38; helix 3, Q50-D61; and helix 4, F70-A83) and one antiparallel beta-sheet (strand 1, K26-K28; and strand 2, E67-D69) which brings the normal and pseudo EF-hands together. As found previously for rat apo-S100B(betabeta) [Drohat, A. C., et al. (1996) Biochemistry 35, 11577-11588], helixes 1, 1', 4, and 4' associate to form an X-type four-helix bundle at the symmetric dimer interface. Additionally, Ca2+ binding does not significantly change the interhelical angle of helixes 1 and 2 in the pseudo EF-hand (apo, Omega1-2 = 132 +/- 4 degrees; and Ca2+-bound, Omega1-2 = 137 +/- 5 degrees). However, the interhelical angle of helixes 3 and 4 in the normal EF-hand (Omega3-4 = 106 +/- 4 degrees) changed significantly upon the addition of Ca2+ (DeltaOmega3-4 = 112 +/- 5 degrees) and is similar to that of the Ca2+-bound EF-hands in calbindin D9K, calmodulin, and troponin (84 degrees </= Omega </= 128 degrees). Further, the four helixes within each S100beta subunit form a splayed-type four-helix bundle (four perpendicular helixes) as observed in Ca2+-bound calbindin D9K. The large Ca2+-dependent conformational change involving helix 3 exposes a cleft, defined by residues in the hinge region, the C-terminal loop, and helix 3, which is absent in the apo structure. This surface on Ca2+-bound S100B(betabeta) is likely important for target protein binding.

Animals↗
PubMed1998

Risk factors for horizontal transmission of hepatitis B virus in a rural district in Ghana.

Most hepatitis B virus (HBV) infections in sub-Saharan African infants and children are acquired through horizontal transmission, but the exact mechanisms of spread have not been documented. The authors conducted a study in rural Ghana which determined seroprevalence in a probability sample of 1,385 individuals of all ages, and evaluated risk factors for horizontal transmission of HBV in a subsample of 547 children aged 1-16 years who were not hepatitis B surface antigen (HBsAg) carriers. Most residents in this district live in compounds which typically contain 2-4 households each. Overall prevalence of HBV seropositives (any HBV marker) was 74.7% (95% confidence interval (CI) 72.5%-76.9%). Prevalence of HBsAg was 20.9% (95% CI 18.8%-23.1%). The data suggest a continuous nonuniform acquisition of HBV infection with advancing age predominantly through horizontal transmission in childhood, with the household, rather than the domestic compound, being the primary place for transmission. The behaviors most strongly associated with prevalence of HBV were sharing of bath towels (OR = 3.1, 95% CI 2.1-4.5), sharing of chewing gum or partially eaten candies (OR = 3.4, 95% CI 2.3-5.0), sharing of dental cleaning materials (OR = 2.5, 95% CI 1.3-4.6), and biting of fingernails in conjunction with scratching the backs of carriers (OR = 2.5, 95% CI 1.6-4.3).

Adolescent↗
PubMed1998

The Ca(2+)-dependent interaction of S100B(beta beta) with a peptide derived from p53.

S100B(beta beta) was found to interact with the tumor suppressor protein, p53, and inhibit its PKC-dependent phosphorylation and tetramer formation [Baudier, J., Delphin, C., Grunwald, D., Khochbin, S., and Lawrence, J. J. (1992) Proc. Natl. Acad. Sci. U.S.A. 89, 11627-11631]. Since PKC-dependent phosphorylation at the C-terminus of p53 is known to effect transcription and p53 tetramer formation [Sakaguchi, K., Sakamoto, H., Lewis, M. S., Anderson, C. W., Erickson, J. W., Appella, E., and Xie, D. (1997) Biochemistry 36, 10117-10124], we examined the interaction of S100B(beta beta) with a peptide derived from the C-terminal regulatory domain of p53 (residues 367-388). In this paper, we report that S100B(beta beta) binds to the p53 peptide (CaK3 < or = 23.5 +/- 6.6 microM) in a Ca(2+)-dependent manner, and that the presence of the p53 peptide was found to increase the binding affinity of Ca2+ to S100B(beta beta) by 3-fold using EPR and PRR methods, whereas the peptide had no effect on Zn2+ binding to S100B(beta beta). Fluorescence and NMR spectroscopy experiments show that the p53 peptide binds to a region of S100B(beta beta) that probably includes residues in the "hinge" (S41, L44, E45, E46, I47), C-terminal loop (A83, C84, H85, E86, F87, F88), and helix 3 (V52, V53, V56, T59). Together these data support the notion that S100B(beta beta) inhibits PKC-dependent phosphorylation by binding directly to the C-terminus of p53.

Amino Acid Sequence↗
PubMed1998

S100B(betabeta) inhibits the protein kinase C-dependent phosphorylation of a peptide derived from p53 in a Ca2+-dependent manner.

S100B(betabeta) is a dimeric Ca2+-binding protein that is known to inhibit the protein kinase C (PKC)-dependent phosphorylation of several proteins. To further characterize this inhibition, we synthesized peptides based on the PKC phosphorylation domains of p53 (residues 367-388), neuromodulin (residues 37-53), and the regulatory domain of PKC (residues 19-31), and tested them as substrates for PKC. All three peptides were shown to be good substrates for the catalytic domain of PKC. As for full-length p53 (Baudier J, Delphin C, Grunwald D, Khochbin S, Lawrence JJ. 1992. Proc Natl Acad Sci USA 89:11627-11631), S100B(betabeta) binds the p53 peptide and inhibits its PKC-dependent phosphorylation (IC50 = 10 +/- 7 microM) in a Ca2+-dependent manner. Similarly, phosphorylation of the neuromodulin peptide and the PKC regulatory domain peptide were inhibited by S100B(betabeta) in the presence of Ca2+ (IC50 = 17 +/- 5 microM; IC50 = 1 +/- 0.5 microM, respectively). At a minimum, the C-terminal EF-hand Ca2+-binding domain (residues 61-72) of each S100beta subunit must be saturated to inhibit phosphorylation of the p53 peptide as determined by comparing the Ca2+ dependence of inhibition ([Ca]IC50 = 29.3 +/- 17.6 microM) to the dissociation of Ca2+ from the C-terminal EF-hand Ca2+-binding domain of S100B(betabeta).

Amino Acid Sequence↗
PubMed1998

Comparative evaluation of the sporicidal activity of new low-temperature sterilization technologies: ethylene oxide, 2 plasma sterilization systems, and liquid peracetic acid.

OBJECTIVE: This study was undertaken to evaluate the efficacy of 4 new low-temperature sterilization technologies: ethylene oxide with hydrochlorofluorocarbons, a liquid peracetic acid immersion system (Steris System 1 Processor), and 2 plasma sterilization processes that use vaporized hydrogen peroxide (Sterrad 100 and the Sterrad 100S). The Sterrad 100S system potentially improves sterilizer efficacy by using 2 cycles of a diffusion stage and a plasma stage per sterilization cycle. METHODS: Flat stainless steel carriers were inoculated with approximately 10(6) Bacillus stearothermophilus spores. These carriers were aseptically placed in the middle of 40 cm long stainless steel lumens (hollow tubes). Two types of lumen were used:(1) a lumen test unit with a removable 5 cm center piece (1.2 cm diameter) of stainless steel sealed to the narrower steel tubing by hard rubber septums and (2) a straight lumen. Three different diameters of the lumen test unit (1, 2, and 3 mm) and a single diameter of the straight lumen (3 mm) were studied. At least 40 replicates were performed for each type of lumen and sterilization method. After inoculation, the test unit was evaluated in 1 of the low-temperature sterilization technologies. After sterilization, the carriers were cultured in trypticase soy broth for 14 days at 55 degrees C and assessed for growth of B stearothermophilus spores. RESULTS: Our results demonstrated that ethylene oxide with hydrochlorofluorocarbons, the Sterrad 100s, and the Sterrad 100S half cycle were highly effective in killing approximately 10(6) B stearothermophilus spores present in the center of narrow-lumen stainless steel tubes. As the lumen diameter decreased with the lumen test unit, the Sterrad 100 demonstrated reduced ability to kill B stearothermophilus spores present on the carrier. At the smallest diameter tested (1 mm), the Sterrad 100 system failed 74% of the time. The Steris System 1 was not effective in completely eliminating the 10(6) inoculum under test conditions. CONCLUSION: The Sterrad 100S was significantly superior to the Sterrad 100 system and equivalent to ethylene oxide with hydrochlorofluorocarbons. Introduction of this new Sterrad 100S system should improve the margin of safety and reduce processing costs by its use of a shorter cycle time. The Steris System 1 is limited by diffusion of the chemical sterilant into the interior of the lumen test unit.

Disinfectants↗
PubMed1998

Levels of microbial contamination on surgical instruments.

OBJECTIVE: To ascertain the microbial load and type of organisms on used surgical instruments following standard cleaning, which consisted of the use of a washer sterilizer followed by sonic cleaning. DESIGN: In this prospective experimental study, used surgical instruments were immersed in Peptamin Tween broth, the broth agitated, and then filtered through a 0.45 microm filter. Quantitative cultures were performed, and all microbes were identified by using standard techniques. SETTING: This study was conducted at a 660-bed university hospital. RESULTS: The microbial load remaining on used surgical instruments after cleaning was as follows: 36 (72%) instruments 0 to 10 colony-forming units (CFU), 7 (14%) instruments 11 to 100 CFU, and 7 (14%) instruments > 100 CFU. Organisms contaminating the instruments included coagulase-negative staphylococcus (56%) followed by Bacillus (22%) and diphtheroids (14%). No other microbes were isolated from more than 4% of the instruments. CONCLUSION: Most used nonlumen surgical instruments contain less than 100 CFU of relatively nonpathogenic microorganisms after cleaning. This suggests that new low-temperature sterilization technologies are likely to be highly effective in preventing cross-transmission of infection via nonlumen medical instruments.

Bacteria↗
PubMed1998

Cost of varicella in France: a study in day care centers.

To assess the cost of varicella in young children in France, a prospective study was done in day care centers. Children (1263), who were 3 months to 3 years old and attending day care, were followed over a varicella season. For every child who developed varicella (n = 200), detailed information was obtained by use of parental questionnaires. Questions concerned medical care, days missed from work for parents, and the need for extra baby-sitting. On average, each sick child had one consultation with a physician and received three medications. In half of the families (52%), at least 1 parent had to miss work an average of 4.5 days to care for a sick child. Total costs to society were estimated to be US$352 per family, with medical costs accounting for 22% of the cost. The average eventual cost to parents was $89 per family, including $80 of non-medical costs. This study emphasizes the important socioeconomic impact of varicella in the day care setting in France.

Chickenpox↗
PubMed1998

Clinical effectiveness of low-temperature sterilization technologies.

The elimination of chlorofluorocarbons by the Clean Air Act has led to the development of alternative technologies for low-temperature sterilization in the healthcare setting, including 100% ethylene oxide, ethylene oxide with other stabilizing gases, immersion in peracetic acid, and gas plasmas. The ideal sterilant does not exist, and infection control professionals should understand the advantages and disadvantages of these processes. However, when combined with adherence to standard cleaning protocols, the available data suggest that the currently available Food and Drug Administration-cleared low-temperature sterilization technologies can inactivate a clinically relevant inoculum of highly resistant organisms.

Central Supply, Hospital↗