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Biomedical subjects

J Zaleski

Publications and source records attributed to J Zaleski.

At least 19 recordsLinked to original sources
PubMed2001

1-methyl-4-nitraminopyridinium nitrate and 4-nitraminopyridinium methanesulfonate.

In the title compounds, C6H8N3O2+*NO3- and C5H6N3O2+*-CH3SO3-, respectively, the cations are almost planar; the twist of the nitramino group about the C-N and N-N bonds does not exceed 10 degrees. The deviations from coplanarity are accounted for by intermolecular N-H...O interactions. The coplanarity of the NHNO2 group and the phenyl ring leads to the deformation of the nitramino group. The C-N-N angle and one C-C-N angle at the junction of the phenyl ring and the nitramino group are increased from 120 degrees by ca 6 degrees, whereas the other junction C-C-N angle is decreased by ca 5 degrees. Within the nitro group, the O-N-O angle is increased by ca 5 degrees and one O-N-N angle is decreased by ca 5 degrees, whereas the other O-N-N angle remains almost unchanged. The cations are connected to the anions by relatively strong N-H...O hydrogen bonds [shortest H.O separations 1.77 (2)-1.81 (3) A] and much weaker C-H...O hydrogen bonds [H...O separations 2.30 (2)-2.63 (3) A].

Journal Article↗
PubMed2001

Structure of N,4-dinitroaniline and its complex with sulfolane at 85 K; on the proton donor-acceptor affinity of the primary nitramine (HNNO2) group.

The NNO2 group of the title compound is significantly less twisted with respect to the aromatic ring in comparison to a typical secondary nitramine. The amide nitrogen is trigonally hybridized. The nitramino group is almost planar. The C-C-N-N torsion angles vary between ca 13 and 42 degrees, whereas the twist along the N-N bond is much smaller and amounts to between ca 1 and 15 degrees. Those twist angles are governed by a crystal packing and are much larger in the case of crystals of pure N,4-dinitroaniline in comparison to that of its complex with sulfolane. The deviations of the internal angles of the aromatic ring from 120 degrees do not exceed 3 degrees. The presence of the nitro group increases the C-C-C valence angle of ca 2.0-2.6 degrees, whereas an analogous effect associated with the nitramino group is much smaller (ca 0.3-1.3 degrees), pointing to its weak electron-withdrawing properties. The nitramino group displays no tendency to conjugate with an electron-demanding substituent across the ring. It participates in hydrogen bonding only as a hydrogen-bonding donor. It does not act as a proton acceptor, despite the fact that nitramine rearrangement is catalysed by acids.

Journal Article↗
PubMed2001

Support of clinician image-related workflow by a user-edited, web-based patient list manager.

Clinician efficiency can be enhanced by worklists that compile useful data for rapid access at the time of need. The authors report development of a web-based, user-edited "Patient List Manager" for the Clinical Image Management System (CIMS). The CIMS List Manager interfaces with the CIMS Archive to provide the user with available studies. It has tools that let the user build personal lists from the available studies. Listed studies are moved from the archive to the cache for rapid access at the time of need. Users can build/edit the list through a browser (without viewing pictures) or from within the image viewer. In this way, the List Manager distributes list building into knowledgeable hands. This is particularly valuable at the current time when health system patient registries are not mature enough to reliably support building build anticipatory patient lists.

Humans↗
PubMed2001

The Digital Imaging and Communications in Medicine (DICOM) archive is a dynamic component of a clinician image-related workflow solution.

The authors investigated clinician transactions against the Digital Imaging and Communications in Medicine (DICOM) archive within a clinical image management system (CIMS) in support of patient care. A Neurosurgical Oncology practice was audited for image utilization. There were 400 requests for 233 image studies during 297 sessions. Fifty percent were for current studies, and 50% were for historical studies. Current studies alone were requested in 37% of the sessions, current plus historical in 31%, and historical alone in 32% of the sessions. Seventy percent of studies were within 8 weeks old and were rapidly available from the CIMS disk cache without an archive image transaction. Conversely, 30% were older than 8 weeks, requiring a clinician transaction against the archive for image retrieval. Approximately 25% of studies were older than 3 months and 10% older than 6 months. Clinician image needs are complex and any CIMS solution must include a DICOM archive that can support clinician-based transactions.

Database Management Systems↗
PubMed2001

1-Nitroindoline.

In the title compound, C(8)H(8)N(2)O(2), the nitramino group is planar and only slightly twisted with respect to the indoline rings. The bridgehead N--C bond is slightly shorter than in typical secondary aromatic nitramines. The N--N bond has some double-bond character. The molecules are connected by weak C--H...O hydrogen bonds, forming chains parallel to the z direction.

Journal Article↗
PubMed2001

Two trans-4-aminoazoxybenzenes.

Two isomeric trans-4-aminoazoxybenzenes, trans-1-(4-aminophenyl)-2-phenyldiazene 2-oxide (alpha, C(12)H(11)N(3)O) and trans-2-(4-aminophenyl)-1-phenyldiazene 2-oxide (beta, C(12)H(11)N(3)O), have been characterized by X-ray diffraction. The alpha isomer is almost planar, having torsion angles along the C(aryl)-N bonds of only 4.9 (2) and 8.0 (2) degrees. The relatively short C(aryl)-N bond to the non-oxidized site of the azoxy group [1.401 (2) A], together with the significant quinoid deformation of the respective phenyl ring, is evidence of conjugation between the aromatic sextet and the pi-electron system of the azoxy group. The geometry of the beta isomer is different. The non-substituted phenyl ring is twisted with respect to the NNO plane by ca 50 degrees, whereas the substituted ring is almost coplanar with the NNO plane. The non-oxidized N atom in the beta isomer has increased sp(3) character, which leads to a decrease in the N-N-C bond angle to 116.8 (2) degrees, in contrast with 120.9 (1) degrees for the alpha isomer. The deformation of the C-C-C angles (1-2 degrees ) in the phenyl rings at the substitution positions is evidence of the different character of the oxidized and non-oxidized N atoms of the azoxy group. In the crystal structures, molecules of both isomers are arranged in chains connected by weak N-H.O (alpha and beta) and N-H.N (beta) hydrogen bonds.

Journal Article↗
PubMed2001

Aminoguanidinium(2+) aminoguanidinium(1+) hexachloroantimonate(III) at 295 and 92 K.

The crystal and molecular structure of the title compound, (CH(7)N(4))(CH(8)N(4))[SbCl(6)], has been determined at 295 and 92 K. It is composed of isolated [SbCl(6)](3-) octahedra and aminoguanidinium mono- and dications. One of four of the crystallographically inequivalent aminoguanidinium cations is disordered at both temperatures. Two crystallographically inequivalent [SbCl(6)](3-) octahedra were found to possess three significantly longer Sb-Cl bonds than three other octahedra. The shorter bonds are in the range 2.456 (2)-2.577 (2) A, whereas the longer ones are between 2.705 (2) and 2.931 (2) A. Each short Sb-Cl bond is located trans to a long bond. It is argued that this deformation is caused by N-H.Cl hydrogen bonds.

Journal Article↗
PubMed2000

2,3-Dihydro-3-methyl-2-nitrimino-1,3-thiazole.

The title compound ¿alternatively, 3-methyl-2-[oxido(oxo)hydrazono]-2,3-dihydro-1,3-thiazole¿, C(4)H(5)N(3)O(2)S, was obtained by methylation of N-(2-thiazolyl)nitramine. The molecule lies on a mirror plane and the thiazole ring is planar, regular in shape and aromatic. The S atom participates in the aromatic sextet via an electron pair on the 3p(z) orbital. In the crystal, the molecules are arranged in parallel layers, bound to each other by weak C-H.O and C-H.N hydrogen bonds and by S.O dipolar interactions, with an interlayer separation of 3.23 A.

Journal Article↗
PubMed1997

Toxicity of allyl alcohol in primary cultures of freshly isolated and cryopreserved hepatocytes maintained on hydrated collagen gels.

The toxicity of allyl alcohol was compared in freshly isolated and cryopreserved hepatocytes that were either placed in suspension or maintained on hydrated collagen gels in a sandwich configuration. The purpose of this study was to evaluate whether the two types of cells displayed the same sensitivity to allyl alcohol when maintained in vitro over relatively prolonged periods of time. The important differentiated functions of urea synthesis, secretion of albumin, and metabolism of ethoxycoumarin, a model drug substrate, were used as end points of toxicity. Cryopreserved hepatocytes incubated in physiological buffer shortly after removal from liquid nitrogen were more sensitive to allyl alcohol than freshly isolated hepatocytes. In contrast, cryopreserved and freshly isolated hepatocytes maintained on hydrated collagen gels responded identically to allyl alcohol. Thus, the increased sensitivity of cryopreserved hepatocytes in suspension to allyl alcohol is a transient phenomenon that disappears after the cells have been allowed to recover on hydrated collagen gels. Dissipation of the mitochondrial membrane potential by allyl alcohol, as indexed by rhodamine 123 fluorescence, was also the same in freshly isolated and cryopreserved hepatocytes maintained on hydrated collagen matrices. This loss of mitochondrial membrane potential caused by allyl alcohol preceded inhibition of albumin and urea biosynthesis. Collectively, the results indicate that cryopreserved cells maintained on hydrated collagen gels provide a useful system to define the actions of certain hepatotoxic agents over relatively prolonged periods of time in vitro.

1-Propanol↗
PubMed1997

A systematic review of the psychiatric/mental health nursing research literature 1982-1992.

The purpose of this study was to assess the quality of quantitative psychiatric/mental health nursing research articles published in English between 1982 and 1992, worldwide. Criteria for selection of articles included nurse authorship or co-authorship, use of a quantitative design and pertinence to an aspect of the nursing process with psychiatric/mental health patients. One hundred and ninety-four articles met these criteria. The quality of each article was assessed by two nurse experts using Duffy's Research Appraisal Checklist (RAC). Forty-six point nine per cent of the articles were rated as superior, 50% as average and 3.1% as below average. Other findings identified journals that published research articles, countries in which research was completed, applicability of funding and qualifications of the authors. The major implications of this study are that nurses can be directed to superior articles; more publication of research by nurse authors is warranted, research is being completed with little financial support, highly rated research publications tend to get funding and editorial policies affect the quality of publication.

Authorship↗
PubMed1997

Variables and designs in psychiatric/mental health nursing research articles published from 1982 to 1992.

Research designs and variables of interest were classified in 194 mental health psychiatric articles published between 1982 and 1992. Common variables only could be identified in 100 articles and independent and dependent variables were identified in the remaining 94 articles. The majority of research designs were descriptive. The variables pertained to diverse interests from nurse and patient perspectives, specifically including patients' behavioural responses to illness, care and caregivers. These variables were then compared by the writers to the current research foci as identified in the recent literature. As listed, these are: biological psychiatry; working with the chronically and persistently mentally ill; shifting of care to the community; working with consumers; and outcome research. There is some link between research published between 1982 and 1992 and current trends in design and a few variables of interest. However, current researchers in mental health psychiatric nursing need to change foci and their relationships with other disciplines to ensure relevancy in their research programmes.

Humans↗
PubMed1996

Actions of selected hepatotoxicants on freshly isolated and cryopreserved rat hepatocytes.

The present study compares the actions of the hepatotoxic agents allyl alcohol, acetaminophen, and carbon tetrachloride on energy metabolism in freshly isolated and cryopreserved rat hepatocytes. After 30 min incubation of freshly isolated hepatocytes at 37 degrees C to allow metabolic equilibration, hepatocytes were supplemented with cryoprotectants and cooled in a stepwise manner to liquid nitrogen temperature. Hepatocytes stored in liquid nitrogen for 2 weeks to 6 months were thawed and centrifuged through Percoll to remove damaged cells. Despite similarities in energy status as indexed by ATP content and the rate of urea synthesis in freshly isolated and cryopreserved hepatocytes, cryopreserved hepatocytes were more sensitive to hepatotoxicants. All three hepatotoxicants caused ATP and rates of urea synthesis to decline to a greater extent in cryopreserved than in freshly isolated hepatocytes. Rates of oxygen uptake were higher in cryopreserved cells than in freshly isolated hepatocytes and declined in cryopreserved cells but not in freshly isolated cells during the initial period of incubation. Rates of mitochondrial respiration stimulated with site-specific substrates were comparable in freshly isolated and cryopreserved cells permeabilized with digitonin. Allyl alcohol and acetaminophen inhibited site-specific respiration to the same extent in both groups of cells. Collectively, these results suggest that increased sensitivity to hepatotoxic agents and elevated oxygen consumption in cryopreserved hepatocytes recovered after storage in liquid nitrogen are related to higher demand for energy in these cells rather than to permanent injury caused by cryopreservation and irreversible uncoupling of oxidative phosphorylation.

1-Propanol↗
PubMed1994

Predominance of glucuronidation over sulfation in metabolism of 1-hydroxybenzo[a]pyrene by isolated rat hepatocytes.

This study shows that 1-hydroxybenzo[a]pyrene glucuronide and 1-hydroxybenzo[a]pyrene sulfate are formed in isolated rat hepatocytes. Formation of these conjugates by hepatocytes incubated with 1-acetoxy-[G-3H]benzo[a]pyrene (100 microM) as a source of intracellular 1-hydroxy-[G-3H]benzo[a]pyrene was documented by comparison of the spectra of metabolites separated by HPLC with the spectra of 1-hydroxybenzo[a]pyrene glucuronide and 1-hydroxybenzo[a]pyrene sulfate standards. The rates of 1-hydroxybenzo[a]pyrene glucuronidation and sulfation were 7.72 +/- 1.03 and 0.68 +/- 0.02 nmol x mg dry wt.-1 x 30 min-1, respectively. The rate of 1-hydroxybenzo[a]pyrene glucuronide production by intact cells corresponded well with the total activity of UDP-glucuronosyltransferase(s) determined in permeabilized hepatocytes. Cryopreserved hepatocytes fully retained a high capacity to glucuronidate the benzo[a]pyrene phenol.

Animals↗
PubMed1993

Preservation of the rate and profile of xenobiotic metabolism in rat hepatocytes stored in liquid nitrogen.

A simple procedure for cryopreservation of rat hepatocytes that allows recovery of viable cells retaining activities of phase I and phase II drug metabolism equivalent to freshly isolated cells is described. The cooling process was initiated 30 min after incubation of freshly isolated hepatocytes at 37 degrees in Krebs-Ringer bicarbonate buffer containing 15 mM glucose to allow for metabolic equilibration. At the end of this period, hepatocyte suspensions were supplemented with 1.7% albumin, 13.3% dimethyl sulfoxide, and the synthetic buffers, 3-[N-morpholino]propanesulfonic acid (MOPS) and N-[2-hydroxyethyl]piperazine-N'-[2-ethanesulfonic acid] (HEPES). Hepatocytes were cooled in a stepwise manner to -196 degrees by holding the cells for 1 hr at -20 degrees and then for 1 hr at -70 degrees before transfer into liquid nitrogen. After thawing and removal of damaged cells by centrifugation in Percoll, the total recovery of viable hepatocytes subjected to freezing was about 42%. The contents of ATP, ADP, and AMP were not altered significantly in cells stored in liquid nitrogen. The metabolic competence of cryopreserved hepatocytes was further confirmed by their ability to synthesize urea from NH4Cl and ornithine at the same high rate that was observed in freshly isolated cells (693 +/- 68 and 740 +/- 68 nmol.mg dry wt-1 x hr-1, respectively). Similarly, cryopreservation did not affect drug-metabolizing systems as indicated by the metabolism of benzo[a]pyrene and 7-ethoxycoumarin, two model substrates. In both freshly isolated and cryopreserved hepatocytes, 7-ethoxycoumarin was O-deethylated to 7-hydroxycoumarin at essentially the same rates (8.66 +/- 0.75 and 8.25 +/- 0.53 nmol.mg dry wt-1.hr-1, respectively) and 7-hydroxycoumarin accumulated in hepatocyte suspensions almost exclusively in the conjugated form. The storage of hepatocytes in liquid nitrogen also did not affect the complex metabolism of benzo[a]pyrene to total oxygenated metabolites and, more importantly, to metabolites conjugated with glutathione, glucuronic acid, and sulfuric acid. Thus, cryopreserved hepatocytes represent a valid and convenient model to study drug biotransformation in intact cells.

Adenine Nucleotides↗
PubMed1992

Conjugation of benzo(a)pyrene 7,8-dihydrodiol-9,10-epoxide in infant Swiss-Webster mice.

Benzo(a)pyrene 7,8-dihydrodiol-9,10-epoxide (BPDE), accepted as the ultimate carcinogen of benzo(a)pyrene, has a very short half-life in aqueous solutions yet induces lung tumors when injected into infant mice. To evaluate the possibility that metabolites of BPDE, principally in the form of stable conjugates, contribute to binding to DNA in peripheral tissues, infant mice were injected i.p. with 39 nmol (+/- ) anti-BPDE. One h after injection, 5% of the dose was recovered in serum and appeared mostly as conjugated metabolites (54% as glucuronides and 16% as glutathione conjugates). Amounts of direct acting electrophiles in serum estimated by trapping with DNA comprised less than 0.02% of the injected dose. No more than 10% of the radioactivity in extracts of liver, lung, and kidney was recovered as BPDE. Glutathione conjugates predominated in the liver and lung, whereas glucuronides were the major metabolites in kidney. Radioactivity bound to DNA in liver, lung, and kidney was 21.5, 42.7, and 7.8 pmol/mg, respectively. Despite the rapid conversion of BPDE to stable conjugates, 32P-postlabeling profiles of DNA adducts in lung closely resembled that noted after addition of BPDE directly to lung homogenate. Thus, the reactive intermediate as well as stable conjugates of BPDE may be transported to target tissues where they initiate tumors.

7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide↗