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Biomedical subjects

S Seifert

Publications and source records attributed to S Seifert.

At least 37 records · Page 2Linked to original sources
PubMed2000

Calculating the costs of gun injuries. A new methodology.

A new method for assessing the costs of gun injuries to a health system examines data on paid amounts, comprehensive medical expenses, and expenses over time. The authors extracted claims using injury diagnosis codes from billing forms and medical charts. The study demonstrates that a claims database can be used to accurately measure health care costs associated with gun injuries. The study is the first to include gun-related injuries treated in ambulatory care settings and to track actual payments over time.

Adolescent↗
PubMed1999

Solution structure of copper ion-induced molecular aggregates of tyrosine melanin.

Melanin, the ubiquitous biological pigment, provides photoprotection by efficient filtration of light and also by its antioxidant behavior. In solutions of synthetic melanin, both optical and antioxidant behavior are affected by the aggregation states of melanin. We have utilized small-angle x-ray and neutron scattering to determine the molecular dimensions of synthetic tyrosine melanin in its unaggregated state in D(2)O and H(2)O to study the structure of melanin aggregates formed in the presence of copper ions at various copper-to-melanin molar ratios. In the absence of copper ions, or at low copper ion concentrations, tyrosine melanin is present in solution as a sheet-like particle with a mean thickness of 12.5 A and a lateral extent of approximately 54 A. At a copper-to-melanin molar ratio of 0.6, melanin aggregates to form long, rod-like structures with a radius of 32 A. At a higher copper ion concentration, with a copper-to-melanin ratio of 1.0, these rod-like structures further aggregate, forming sheet-like structures with a mean thickness of 51 A. A change in the charge of the ionizable groups induced by the addition of copper ions is proposed to account for part of the aggregation. The data also support a model for the copper-induced aggregation of melanin driven by pi stacking assisted by peripheral Cu(2+) complexation. The relationship between our results and a previous hypothesis for reduced cellular damage from bound-to-melanin redox metal ions is also discussed.

Biophysical Phenomena↗
PubMed1999

Olanzapine overdose mimicking opioid intoxication.

We report significant central nervous system depression and the previously unreported phenomenon of pupillary constriction after acute overdose of olanzapine (Zyprexa) in 4 patients. Phase 2 trials describe a typically benign course in overdose, and published abstracts note a wide spectrum of clinical effects with supratherapeutic ingestion of olanzapine. Our patients demonstrated profound central nervous system depression, and 2 required advanced airway support. All 4 patients recovered with supportive care. Olanzapine should be added to opioid and alpha(2)-adrenergic agonist intoxication in the differential diagnosis of the patient with depressed mental status and miosis.

Adult↗
PubMed1999

Synthesis and autoradiographic evaluation of a novel high-affinity Tc-99m ligand for the 5-HT2A receptor.

The synthesis and in vitro autoradiography of a novel Tc-99m ligand with subnanomolar affinity to the 5-HT2A receptor is reported. The complex combines the 4-(4-fluoro)-benzoyl piperidine portion derived from the 5-HT2A receptor antagonist ketanserin with a neutral oxotechnetium(V) chelate in form of a mixed ligand "3 + 1" unit containing the SNS/S donor set. The analogous rhenium compound has been synthesized as a surrogate for the Tc-99m complex for use in receptor binding assays and for complete structural characterization. In competition experiments the Tc-99 complex as well as its Re analogue display subnanomolar affinity toward the 5-HT2A receptor (Ki 0.44 nM for Tc, 0.25 nM for Re). The subnanomolar 5-HT2A receptor binding of the Re complex was confirmed by functional in vitro antagonism of contractile effects evoked by 5-HT in rat arterial tissue. Re 1 inhibited 5-HT-induced, 5-HT2A receptor-mediated contractions of isolated rat tail artery in a competitive fashion and possessed nanomolar affinity (pA2 = 9.08, pA2 representing the negative decadic logarithm of the Re 1/5-HT2A-receptor dissociation constant [mol/L]). Like ketanserin, Re 1 displayed moderate affinity for adrenergic alpha1D (pA2 = 8.23) and histamine H1 receptors (pA2 = 8.00), and was >600-fold up to 10,700-fold less active at several neurotransmitter receptor subtypes. In vitro autoradiographic studies clearly indicate the accumulation of the Tc-99m compound in 5-HT2A-receptor-rich areas of the brain. This enrichment can be blocked by 5-HT2A receptor antagonists such as mianserin and ketanserin and is therefore specific.

Animals↗
PubMed1999

Detection of simulated interstitial lung disease and catheters with selenium, storage phosphor, and film-based radiography.

PURPOSE: To evaluate the diagnostic performance of storage phosphor and digital selenium radiography (DSR) with asymmetric and symmetric screen-film systems at different speeds in the detection of simulated interstitial lung disease and catheters. MATERIALS AND METHODS: Patterns of simulated interstitial lung disease and catheters were superimposed over an anthropomorphic chest phantom. Hard-copy images were generated at DSR (200-, 400-, and 600-speed), storage phosphor radiography (200- and 400-speed), and asymmetric (400-speed) and symmetric (200- and 400-speed) screen-film imaging. Surface doses were measured, and receiver operating characteristic analyses were performed. RESULTS: No statistically significant differences were found between the detector systems with the same speeds for each interstitial pattern. Significantly poorer results were found at 600-speed DSR than at 200-speed DSR. Detection of catheters and nodules over high-attenuation areas was significantly worse with the symmetric screen-film system than with the other detectors. The surface dose with the DSR system, without a grid, was about 50% less than that of the other detector systems, with grids, at the same speed. CONCLUSION: No significant difference was found in the diagnostic performance at DSR, storage phosphor radiography, and film-based radiography for simulated interstitial lung disease at corresponding speeds; there was a reduction in the surface dose of about 50% with the 400-speed DSR system.

Catheterization↗
PubMed1998

Stability versus reactivity of "3+1" mixed-ligand technetium-99m complexes in vitro and in vivo.

"3+1" technetium-99m mixed-ligand complexes as relevant to the development of a third generation of 99mTc radiopharmaceuticals were investigated in vivo and in vitro in the blood of rats. Surprisingly, in whole blood the complexes, which proved to be stable in saline, PBS of pH 7.4 and in plasma, were converted into two radioactive, more hydrophilic metabolites. Small structural differences in the complex molecule have a profound influence on the rate of metabolism of the complexes. To obtain an understanding of this unexpected reactivity, transchelation reactions with glutathione (GSH) were hypothesized and this hypothesis substantiated by challenge experiments carried out with a series of 99mTc and analogous rhenium complexes and GSH. In vitro studies in human plasma, whole blood and erythrocytes also revealed conversion of the complexes, though, at a much slower rate. Structural parameters influencing the stability of the complexes and consequences for the radiopharmaceutical design are discussed.

Animals↗
PubMed1997

Structural modification of receptor-binding technetium-99m complexes in order to improve brain uptake.

Low brain uptake is a generally accepted problem in developing technetium-99m brain receptor imaging agents. For a class of potential 5-HT2A receptor-binding agents we tried to improve the original low brain uptake of 0.4% injected dose (ID) in rats 5 min p.i. by modifying the lipophilic properties of the molecules. Because of the presence of a protonable nitrogen, which according to the pKa value leads to ionization of the molecule at blood pH, the pKa value was considered to be the parameter most suitable for adjustment of lipophilicity. Insertion of ether-oxygen in the molecule of five candidates lowers the apparent pKa value from 10.0 to 8.3 and dramatically increases the brain uptake to 1.3% ID at 5 min. The direct relationship between brain uptake and apparent pKa cannot be simply explained by the increase in the pKa-governed proportion of the neutral species.

Animals↗
PubMed1997

Virtual cutting in medical data.

In this paper we present a method for virtual 3D cutting operations in 3D tomographic data. When cutting interactively the user specifies a series of 3D cutting points and corresponding cut depths on the surface of the object. Each pair of succeeding cutting points then defines a freeform shape of the incision. A 3D meshing algorithm constructs a Finite Element mesh formed by tetrahedrons, representing the surgical intervention.

Computer Simulation↗
PubMed1994

Breaking home care tradition with home repairs and other services.

In reaching out to provide comprehensive care to the elderly in its community, the VNA of Texas saw a need for nontraditional services such as home repair. Customer satisfaction with the services led the agency to expand to other arenas, but just how cost effective has it been?

Activities of Daily Living↗
PubMed1993

Reconstitution of intestinal Na(+)-phosphate cotransporter.

The rabbit intestinal brush-border membrane Na(+)-phosphate cotransporter was purified from sodium dodecyl sulfate (SDS)-brush-border membrane vesicles (BBMV) protein (SDS-treated Ca(2+)-precipitated BBMV) by a three-column chromatography protocol. The purification included a preparative scale chromatofocusing chromatography column over the pH range from 7.4 to 4 after solubilization in 3-[(3-cholamidopropyl)-diamethylammonia]-1-propanesulfonate (CHAPS), a chromatofocusing column over the pH range from 5.6 to 4 after solubilization in n-octyl glucoside, and gel filtration chromatography on a Sephacryl S-200 column. Verification of Na(+)-phosphate cotransporter purification involved substrate affinities, substrate stoichiometry, and inhibitor sensitivity after proteoliposome reconstitution and SDS-polyacrylamide gel electrophoresis (PAGE). After gel filtration Na(+)-dependent phosphate uptake was 3,300-fold enriched compared with the cell homogenate. A single 130-kDa polypeptide was visualized by SDS-PAGE under reducing conditions using silver stain. The coenrichment of this 130-kDa polypeptide and proteoliposome reconstituted Na(+)-dependent phosphate uptake suggest that the intestinal brush-border membrane Na(+)-phosphate cotransporter has been purified and proteoliposome reconstituted.

Animals↗
PubMed1993

Medical Illness Simulating Trauma (MIST) syndrome: case reports and discussion of syndrome.

Medical Illness Simulating Trauma (MIST) Syndrome is a clinical syndrome characterized by pain, discomfort, or the observation of a mass that is presented to the physician as the result of trauma. The underlying cause of the patient's symptom(s), however, is a medical condition unrelated to the trauma. The reported trauma may not actually have occurred and if it did, is only coincidentally related to the onset of symptoms, which bring attention to a previously unrecognized or ignored pain, discomfort, or mass. The incidence of MIST Syndrome is unknown. MIST Syndrome is distinguished from other conditions and syndromes presenting with histories that are inconsistent with subsequent findings by the lack of intent to deceive the physician or misrepresent the physiologic nature of the underlying medical condition. This syndrome can be a source of error or delay in diagnosis and treatment.

Adolescent↗
PubMed1991

[Psoriasis in a female chimpanzee].

Psoriasis, a widespread genodermatosis in Homo sapiens, also appears in primates. We report on a female chimpanzee in Leipzig Zoo. After years of captivity the animal developed erythematosquamous, highly hyperkeratotic, lesions, some confluent, on the knees, elbows, back of the hands and feet and on the forearms and the seat, which showed histologically characteristic features of psoriasis. It may be that both previous infections and psychic stress resulting from social isolation had caused eruption of the disease. In the literature single cases of psoriasiform dermatoses have also been described in other species of monkeys and even in a springer spaniel. Nonetheless, the search for an animal model of psoriasis vulgaris is still going on.

Animals↗
PubMed1989

[Cefoxitin in the preventive treatment of infectious complications in high-risk gastro-jejuno-colic and biliary surgery].

Cefoxitin is a bactericidal beta lactam antibiotic of the cephamycins group, with wide antimicrobial efficacy and active against both aerobes and anaerobes. In this study, 58 patients were divided in four groups according to the site of the disease (stomach, gallbladder and biliary tract, jejunum ileum and colon-rectum). The efficacy of cefoxitin in the prophylaxis of surgical infections was assessed for each group and for all patients. When compared with the combination of antibiotics used previously, cefoxitin led to a reduction of the mean duration of fever (7.2 and 5 days respectively with ampicillin/cloxacillin and lincomycin/gentamycin, 3.2 days with cefoxitin). Cefoxitin also led to a reduction in the incidence of surgical infections (50% with ampicillin/cloxacillin, 9.19% with lincomycin/gentamycin, 8.6% with cefoxitin) and in the incidence of localized surgical infections (29.6%, 20.3%, 8.6% respectively). In this study, cefoxitin has been found to be very useful and well tolerated in the prophylaxis of surgical infections.

Adult↗
PubMed1989

[Biomechanico-clinical interpretation of firearm wounds. General problems (III). A propedeutic ABC on terminal ballistics].

The surgeon should have a comprehensive knowledge of firearms as thermochemico-ballistic machines in order to come to grips in an adequate manner with the wounds they inflict on the human body. The traces left on the body to all intents and purposes embrace a cultural "cul de sac" which risks being defrauded of most of its content by a lack of those propedeutics elements which painstaking reflection is capable of affording us. Only the interpretation of each individual ballistic phase, both as a complete phenomenon in itself and as a component in a single articulated complex, can offer such elements: credit is due at least for a wholehearted commitment in this direction, while never losing sight at any time of the clinical perspective of such wounds.

Forensic Medicine↗