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Biomedical subjects

W Peters

Publications and source records attributed to W Peters.

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

ARDS in patients with thermal injury.

OBJECTIVE: To determine the time to onset of the adult respiratory distress syndrome (ARDS) in patients with thermal injury requiring mechanical ventilation. Secondarily, to consider the burn-related risk factors, demographics, incidence, and mortality for ARDS in this population. DESIGN: Retrospective chart review; ARDS defined according to the American-European Consensus Conference and the Lung Injury Severity Score definitions. SETTING: Regional, tertiary referral, adult burn unit in a university teaching hospital. PATIENTS AND PARTICIPANTS: Patients with thermal injury requiring mechanical ventilation, admitted between 1 January 1991 and 28 February 1995. INTERVENTIONS: None. MEASUREMENTS AND RESULTS: Of 469 consecutive admissions, 126 (26.9%) received intubation and mechanical ventilation. ARDS was defined according to the American-European Consensus and Lung Injury Severity Score (score > 2.5) definitions. The mean time to onset of ARDS from admission to the burn unit was 6.9 +/- 5.2 and 8.2 +/- 10.7 days when defined by the American-European Consensus and Lung Injury Severity Score definitions respectively (p = 0.41). Of the intubated patients, 53.6 and 45.2% developed ARDS according to the American-European Consensus and Lung Injury Severity Score definitions, respectively (p = 0.19). Using multivariate logistic analysis, only age proved to be an independent risk factor for the development of ARDS (p = 0.03), although there was a trend toward an increased incidence of inhalation injury in patients with ARDS. Mortality was not significantly greater (41.8 vs 32.2%) in those with ARDS compared to those without (p = 0.27). CONCLUSIONS: According to the American-European Consensus Conference and the Lung Injury Severity Score definitions, ARDS is common in the adult burn population and has a delayed onset compared to most critical care populations. We found age to be a major predisposing factor for ARDS.

APACHE↗
PubMed1999

Microneme antigens of Eimeria bovis recognized by two monoclonal antibodies.

Two IgG1 monoclonal antibodies (mAbs 8-23F9 and 9-21G9) were developed after immunization of mice with homogenates of Eimeria bovis first-generation merozoites. Both mAbs reacted with antigens in the apical two-thirds of the parasites and immune electron microscopy determined the micronemes as targets. When tested by immunoblotting, mAb 8-23F9 failed to react with antigens separated under reducing conditions; under nonreducing conditions it recognized two components of >200 kDa. mAb 9-21G9 bound to antigens of 135 and 180 kDa after electrophoresis under reducing conditions and to a series of components when separated without reduction. The epitope of mAb 8-23F9 was destroyed by treatment of the antigen with endoglycosidase H and removal of phosphocholine (PC) by phospholipase C. Since mAb 8-23F9 does not recognize cytidine-linked PC, the data suggest that PC in combination with N-linked sugars and/or N-glycans is part of its epitope. In the case of mAb 9-21G9, endoglycosidase H did not alter the epitope. When E. bovis merozoite antigen was treated with phospholipase C the number of mAb 9-21G9-reactive constituents increased, suggesting that PC may otherwise mask the epitope. mAb 8-23F9 also bound to the apical area and the surface of E. bovis sporozoites and recognized a >200-kDa sporozoite component. When sporozoites invaded Vero cells in vitro, epitope-bearing components were released onto the host cell surface and became part of the early parasitophorous vacuole wall. At day 5 the binding of the mAb was again confined to the intracellular parasite. mAb 9-21G9 did not react with sporozoites but recognized the apical area of intra-cellular trophozoites on day 5 after invasion of host cells in vitro. When testing was done against a variety of other Apicomplexa in various assays, the only cross-reaction observed occurred with mAb 8-23F9, which bound to a conformationally determined 180-kDa component of Toxoplasma gondii cystozoites.

Animals↗
PubMed1999

A monoclonal antibody reacts species-specifically with amylopectin granules of Eimeria bovis merozoites.

An IgG1 monoclonal antibody (mAb 35B9) developed against first-generation merozoites of Eimeria bovis was shown by immunoelectron microscopy to react selectively with antigens localized in amylopectin granules. Amylopectin does not contribute to the epitope, as enzymatic degradation of carbohydrates in the parasite did not alter the binding pattern of mAb 35B9. When tested by immunoblotting, despite its organelle specificity the mAb recognized a variety of E. bovis merozoite I components with predominant molecules of 135 and 200 kDa. The epitope was not affected by treatment with endoglycosidase H; thus, N-linked sugar residues should not be involved in it. Alkaline cleavage (beta-elimination), however, destroyed the epitope; thus, the involvement of O-linked carbohydrates cannot be excluded. Treatment of E. bovis merozoite extract with phospholipase C changed the binding pattern of mAb 35B9 in a way that suggests the presence of phosphorylcholine molecules on several antigens recognized by the mAb, albeit not belonging to the epitope but rather masking it. The epitope was not found in free sporozoites of E. bovis or young intracellular parasites up to day 4 after invasion of cells in vitro, whereas 5-day-old trophozoites were found to contain it. It seems to be species-specific, as it could not be shown in sporozoites or merozoites of E. tenella or in stages of several other Coccidia.

Amylopectin↗
PubMed1999

High-dose therapy with autologous hematopoietic cell support as salvage treatment for patients with breast cancer who have relapsed after previous high-dose chemotherapy.

Twenty-six patients with breast cancer who had relapsed after previously receiving high-dose chemotherapy and autologous hematopoietic cell support received a second course of high-dose cytoreductive therapy and autologous hematopoietic cell support as salvage therapy. Several different high-dose therapy regimens were employed for the second transplant, including a radiolabeled immunoconjugate. Two patients died of treatment-related complications. The remaining 24 patients relapsed a median of 126 (range 22-635) days after salvage transplant. All have since died. The median survival after salvage transplant was 362 (range 31-931) days. We conclude that second courses of high-dose therapy as salvage treatment are generally well-tolerated but their efficacy is modest. Alternative treatment strategies are needed for these patients.

Adult↗
PubMed1999

Cyclophosphamide and paclitaxel as initial or salvage regimen for the mobilization of peripheral blood progenitor cells.

Peripheral blood progenitor cells are now commonly used for hematologic reconstitution after myelosuppressive chemotherapy for hematologic and solid malignancies. The purpose of this study was to evaluate the activity of paclitaxel 170 mg/m2 and cyclophosphamide 2 g/m2 (CP) with filgrastim (human G-CSF) for mobilization of PBPCs as the first or second maneuver after failure with filgrastim alone. Sixty-four patients with stage II-IV breast cancer received (CP) followed by filgrastim (10 microg/kg/day). In 35 (55%) this was the first maneuver while it was for salvage in 29 (45%) patients. The median number of aphereses was two (range, 1-7). In 83% of the patients apheresis was initiated on days 10-11 following chemotherapy. The median numbers of CD34+ cells/kg, CD34+ cells/apheresis/kg and total nucleated cells/kg collected were 8.7 x 10(6) (2.11-73.5), 3.97 x 10(6) (0.3-36.75) and 164.15 x 10(8) (9-660), respectively. All the patients yielded at least 2 x 10(6) CD34+ cells/kg. CP mobilization salvaged the 29 patients who failed mobilization with filgrastim alone. When used as first-line mobilization the yield of CD34+ cells x 10(6)/kg was higher than in the salvage group (16.93 vs 3.94, P < 0.001). Patients receiving CP as salvage reached the target of 5 x 10(6) CD34+ cells/kg in only 45% (13/29) of cases vs 94.3% as first maneuver. CP followed by filgrastim is a safe and effective regimen for the mobilization of PBPCs in patients with breast cancer and shows significant activity in patients who failed to mobilize with filgrastim, suggesting a higher mobilization potential.

Adult↗
PubMed1999

The mouse Ptprr gene encodes two protein tyrosine phosphatases, PTP-SL and PTPBR7, that display distinct patterns of expression during neural development.

The protein tyrosine phosphatases PTP-SL and PTPBR7 differ only in the length of their N-terminal domain. We show here that PTP-SL and PTPBR7 are isoforms derived from a single gene (Ptprr) through developmentally regulated use of alternative promoters. Isoform-specific reverse transcriptase-polymer chain reaction (RT-PCR) and RNA in situ hybridization experiments reveal that PTPBR7 is expressed during early embryogenesis in spinal ganglia cells as well as in developing Purkinje cells. Post-natally, PTPBR7 is expressed in various regions of the adult mouse brain, but expression in Purkinje cells has ceased and is replaced by the PTP-SL-specific transcript. In transient transfection experiments it is confirmed that PTPBR7 is a type I transmembrane protein tyrosine phosphatase (PTPase). PTP-SL, however, appears to be a cytosolic membrane-associated PTPase that is located at perinuclear vesicular structures that partly belong to the endosomal compartment. Thus, during maturation of Purkinje cells, a gene-promoter switch results in the replacement of a receptor-type PTPase by a cytosolic vesicle-associated isoform.

Aging↗
PubMed1999

The chemotherapy of rodent malaria. LVII. Drug combinations to impede the selection of drug resistance, Part 1: Which model is appropriate?

The principle has finally been accepted that, whenever possible, antimalarial drugs should be deployed in appropriate combinations in endemic areas, in order to minimize the inevitability that monotherapy will, probably sooner than later, select populations of drug-resistant parasites. Which laboratory models can predict the combinations of old or novel compounds that are likely to be of practical value in minimizing this risk? Very few relevant data on the use of Plasmodium falciparum in vitro have been published. Most research has been carried out with one or other strain of chloroquine-sensitive P. berghei or with chloroquine-resistant P. yoelii ssp. NS in mice. The two most widely used procedures to select for resistance are the 'serial technique' (ST), in which drug selection pressure in vivo is gradually increased, and the '2% relapse technique' (2%RT), in which a single, large drug dose is applied at the time of each passage. Both procedures have been used to demonstrate the ability of pairs of drugs (e.g. sulfadoxine with pyrimethamine, cycloguanil with dapsone, pyrimethamine or sulphonamides with chloroquine, mepacrine or mefloquine) or triple combinations (e.g. sulfadoxine-pyrimethamine with chloroquine, mefloquine or pyronaridine) to delay the development of resistance. The relative merits of the ST and 2%RT are discussed and the data obtained by these procedures are compared with the results of deploying drug combinations in man, especially against multidrug-resistant P. falciparum. It is concluded that, even though the rodent malaria models are imperfect, no better alternatives are available at present with which to predict the value of antimalarial combinations for the protection of the individual components. The 2%RT is considered to be the procedure of first choice.

Animals↗
PubMed1999

The chemotherapy of rodent malaria. LVI. Studies on the development of resistance to natural and synthetic endoperoxides.

Chloroquine-sensitive Plasmodium berghei N and chloroquine-resistant P. yoelii ssp. NS were exposed to selection pressure, in the '2% relapse technique', from artemisinin, artesunate, a bicyclic, synthetic endoperoxide Ro 41-3823 (an analogue of arteflene) or Fenozan B07, a synthetic 1,2,4-trioxane endoperoxide. Whereas resistance against artemisinin did develop to a moderate level in both parasites, only a low level of resistance or none developed to the other compounds, and resistant parasites readily lost resistance once drug-selection pressure was withdrawn. The relevance of these observations and the experience of other investigators are discussed in relation to the possible risk that resistance may be developed in nature once endoperoxides are deployed widely against multidrug-resistant P. falciparum.

Animals↗
PubMed1999

Silicon assays in women with and without silicone gel breast implants--a review.

During the past 5 years, as the failure properties of silicone gel breast implants have emerged, there has been considerable interest in measuring the levels of silicone and silicon in blood, serum, breast milk, and body tissues. Assays have been done in control patients without implant exposure, and in patients with silicone gel implants in an attempt to predict implant failure. Nuclear magnetic resonance measurements of silicone compounds have not been helpful because of their low sensitivity of detection. However, all compounds containing the element silicon, which includes silicone, have been measured accurately. Modern techniques, such as electrothermal atomic absorption spectrometry, direct-current plasma emission spectrometry, and inductively coupled plasma emission spectroscopy have allowed precise measurement of silicon in body fluids and tissues. Using these techniques, recent studies have demonstrated consistent levels of silicon in the blood and plasma of control women without exposure to implants. In one study, plasma silicon was shown to be 140 +/- 10 ng per milliliter. In four other studies, serum silicon levels in control patients were the following: mean, 130 +/- 70 ng per milliliter; mean, 170 +/- 100 ng per milliliter; median, 100 ng per milliliter (range, 30-209 ng per milliliter); and 10 to 250 ng per milliliter. Three independent studies have shown that women with silicone gel implants have higher blood and serum silicon levels than control subjects, but their values were still within the range of control subjects. One study has shown that the mean silicon level in breast milk was not significantly different between 15 implant patients and 34 control patients. The measurement of silicon in control breast tissue has shown consistent results in three different studies, with most tests varying from <0.2 to 2.2 microg per gram dry weight. Three studies have shown that capsules from women with silicone gel breast implants had markedly elevated silicon levels compared with control breast tissue. Median silicon levels varied from 9,980 to 14,390 microg per gram dry weight. There was no significant difference in capsule silicon level between intact and ruptured implants or associated with implant duration in situ or year of implantation. Four studies have shown that capsules from saline implants had elevated levels of silicon compared with control tissue, but their silicon levels were much lower than those of gel implants. The median levels of silicon in the capsules of these studies were as follows: 7.7, 71.5, 198, and 1,100 microg per gram dry weight. Based on current knowledge, because of the large variability among patients, the use of silicon measurements in blood, serum, breast milk, or implant capsule tissue has no clinical role for the effective monitoring of implant leakage in women with silicone gel breast implants.

Breast Implants↗
PubMed1999

Atrial sensing and AV synchrony in single lead VDD pacemakers: a prospective comparison to DDD devices with bipolar atrial leads.

INTRODUCTION: Single lead VDD pacing has offered an alternative to DDD systems in patients with isolated AV block. Up to now, however, the relative performance of these pacemaker systems was not systematically compared. METHODS AND RESULTS: Three hundred sixty patients who received either a VDD pacemaker (n = 180) or a DDD device (n = 180) with a bipolar atrial lead were investigated prospectively for a mean period of 30 +/- 13 months. Pacemaker function was analyzed by telemetry, Holter monitoring, and exercise ECG. Time of implantation and fluoroscopy was significantly lower with VDD devices (44.3 +/- 5.1 min vs 74.4 +/- 13.5 min and 4.6 +/- 2.5 min vs 10.3 +/- 5.6 min in DDD pacemakers, respectively). Intermittent atrial undersensing occurred in 23.3% of patients with a VDD pacemaker and in 9.4% with DDD devices (NS). The incidence of atrial tachyarrhythmias did not differ between the VDD (6.7%) and the DDD group (6.1%). Sinus node dysfunction developed in 1.9% of patients, but the vast majority (85.7%) of patients were asymptomatic. There was a tendency for a higher rate of operative revisions in the DDD group (6.1% vs 3.3% in VDD pacemakers, P = 0.15). Cumulative maintenance of AV-synchronized pacing mode was 94.9% in patients with VDD pacemakers and 92.1% with DDD devices (NS). CONCLUSION: With the benefit of a simpler implant procedure, long-term outcome of single lead VDD pacing is equivalent to DDD pacing in patients with AV block and preoperative normal sinus node function.

Aged↗
PubMed1999

Cartilaginous metaplasia in the capsule of a Dacron-backed silicone gel breast prosthesis.

Capsular metaplastic changes described as "synovial metaplasia" have been reported in association with silicone gel breast prostheses. Initially this finding was thought to be more common with textured implants. Recent studies have shown no relation between implant shell type (textured vs. smooth). The incidence of this metaplasia has been shown to decrease with the age of the implant, suggesting that it is a transitional finding in capsular maturation. The metaplastic cells in the synovial metaplasia may have secretory characteristics, but the exact etiology and function of the metaplasia are not yet fully understood. Experimentally, a similar connective tissue reaction has been induced by repeated injections of air to produce the so-called "air pouch." The current study describes cartilaginous metaplasia in the capsule surrounding a silicone-filled, Cronin-type, Dacron-backed breast prosthesis. At 26 years after bilateral breast augmentation, this patient presented with breast pain and firmness. During surgical removal the implants were intact but the capsules were densely hyalinized, irregularly calcified, and on one side there was cartilaginous metaplasia within the connective tissue of the capsule. This had occurred independently of calcification. This was believed to be an unusual tissue response. Review of the English literature failed to identify a comparable case.

Breast↗
PubMed1998

New Sesquiterpene Lactones from Illicium floridanum

In continuation of our phytochemical investigation of Illicium floridanum Ellis (American star anise, star bush), three new sesquiterpene lactones possessing the anisatin-type carbon skeleton (8,9-seco-prezizaane skeleton), 14-acetoxy-3-oxofloridanolide (1), 13-acetoxy-14-(n-butyryloxy)floridanolide (2), and 3beta-acetoxy-14-n-butyryloxy-10-deoxyfloridanolide (3), were isolated from fruits of this plant. Their structures were elucidated by 1D and 2D NMR measurements. The molecular structure of 1 was obtained by single crystal X-ray diffraction. The 11,3-delta-lactone structure of the compound previously described as debenzoyldunnianin in our previous communication, on grounds of NMR spectral evidence and X-ray crystallographic analysis is revised to a delta-lactone closed between C-11 and C-7 (compound 4). The neurotoxic sesquiterpene lactone anisatin (5) and its isomer 2alpha-hydroxyneoanisatin (3-deoxy-2alpha-hydroxyanisatin, 6) were also isolated and identified by spectroscopic means. The presence of the neurotoxin 5 in relatively high amounts in the fruits and leaves confirms and explains early reports on the toxicity of this plant.

Journal Article↗