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Biomedical subjects

N Porter

Publications and source records attributed to N Porter.

At least 19 recordsLinked to original sources
PubMed2006

Autologous hematopoietic stem cell transplants that utilize total body irradiation can safely be carried out entirely on an outpatient basis.

Outpatient hematopoietic stem cell transplants (HSCT) are usually performed in patients receiving minimally mucotoxic preparative regimens; total body irradiation (TBI)-based regimens typically are excluded. To improve resource utilization and patient satisfaction, we developed a totally outpatient HSCT program for TBI regimens and compared outcomes for our first 100 such transplants to 32 performed as in-patients during the same interval, for caregiver or financial reasons. Symptoms were managed predominately with oral agents; pain management consisted of transdermal fentanyl and oral morphine solution. Except for more unmarried in-patients, the two groups were matched. Time to engraftment, severity of mucositis and transplant duration were identical for the two groups. Twenty-seven of the outpatients were admitted (median-6 days), primarily for progressing infection. Thus 92% of all transplant days were outpatient. There were no septic episodes or hospital admissions for pain management. There were no deaths to day 30 in either group and 100-day survival was identical. There was a mean cost savings of Dollars 16,000 per outpatient transplant and outpatient patient/caregiver quality of life was similar to that reported for in-patients. Patients undergoing severely mucotoxic regimens can be safely transplanted in an outpatient setting with a significant cost saving, with no increase in morbidity or mortality.

Adult↗
PubMed2006

Patients' understanding of disease status and treatment plan at initial hematopoietic stem cell transplantation consultation.

Patients referred for hematopoietic stem cell transplantation (HSCT) often have knowledge deficits about their disease and overestimate their prognosis making it difficult initially to discuss potentially life-threatening transplant options. To determine patients' understanding of their disease and the adequacy of a 3-h consultation at our center, we developed a survey that measured perceived knowledge deficits of disease, prognosis, and emotional status before and after their initial consultation. Ninety nine consecutive eligible patients completed the survey. Although 76.7% claimed adequate information about their disease pre-HCST visit, 51.5 and 41.4% respectively lacked knowledge about their 1-year prognosis with and without any therapy. After the visit, 66.7% of the patients had obtained enough information to make an informed decision regarding HSCT versus 23.2% pre-visit, and a significant reduction in the need for further information was reported by 53.5% of patients (P<0.001). Patients were not overwhelmed or confused by the visit and there was a small but significant decrease in negative affect. Measures to increase patients understanding of their disease and its prognosis pre-HSCT consultation visit are warranted; however, a 3-h consultation visit provides the majority of patients with sufficient information to make an informed decision about the risk/benefit ratio of HSCT.

Data Collection↗
PubMed2005

Formation of hazardous by-products resulting from the irradiation of natural organic matter: comparison between UV and VUV irradiation.

The use of ultraviolet (UV) or vacuum ultraviolet (VUV) photo-oxidation followed by biological treatment for the removal of natural organic matter (NOM) in drinking water is a potential water treatment technique under investigation. This paper reports on the trihalomethane formation potential (THMFP), the haloacetic acid formation potential (HAAFP), and formation of nitrite and peroxide following both UV and VUV irradiation of NOM prior to biological treatment. The total THMFP was found to decrease with increasing UV and VUV irradiation dose, although there was a linear increase in bromoform formation. Determination of the THMFP of NOM fractions obtained after irradiation, showed that the hydrophobic fraction was dominated by chlorinated species which accounted for the majority of the total THMFP, while bromoform was observed only in the hydrophilic fraction of NOM. VUV irradiation reduced the HAAFP with increasing dose, in contrast, UV irradiation had a limited effect on the overall HAAFP. Following UV or VUV irradiation, the chlorinated species accounted for the majority of HAAFP; however, significant formation of brominated haloacetic acid (HAA) was observed. The nitrate concentration of the untreated water directly influenced the concentration of nitrite produced as a consequence of UV and VUV irradiation. Hydrogen peroxide formation was greater during VUV irradiation than during UV irradiation. Samples exposed to various doses of UV or VUV irradiation (up to 138 J cm(-2)) were deemed non-cytotoxic (African green monkey kidney cells) and non-mutagenic (Ames test).

Animals↗
PubMed2005

Fractionation of UV and VUV pretreated natural organic matter from drinking water.

Recent studies have examined the potential of ultraviolet (UV, 254 nm) and vacuum ultraviolet (VUV, 185 nm + 254 nm) irradiation as either a pretreatment for a biological process or as a sole treatment for the removal of natural organic matter as dissolved organic carbon from drinking water. To understand the potential of UV and VUV irradiation followed by subsequent biological treatment, treated water was fractionated into four components: very hydrophobic acid (VHA), slightly hydrophobic acid (SHA), hydrophilic charged (CHA), and hydrophilic neutral (NEU). The VHA fraction was found to be very susceptible to both UV and VUV irradiation, and the fragmentation products of the high molecular weight VHA and SHA molecules contributed to the CHA and NEU fractions to form a pool of biodegradable, non-UV-absorbing, low molecular weight moieties. The NEU fraction was the most difficult to remove, as most of the components in this fraction were refractory to both the biological and photo-oxidative processes. Therefore, enhanced removal of the NEU fraction is required to increase the effectiveness and potential of the treatment process.

Carbon↗
PubMed2001

Double-blind comparative trial of oral ondansetron versus oral granisetron versus IV ondansetron in the prevention of nausea and vomiting associated with highly emetogenic preparative regimens prior to stem cell transplantation.

The optimal management of transplantation preparative regimen-induced nausea and vomiting remains unknown. We conducted a Phase III double-blind study to determine the efficacy and costs of oral ondansetron versus oral granisetron versus IV ondansetron and PRN rescue antiemetics for the prevention/control of nausea and vomiting associated with high-dose chemotherapy or chemoradiotherapy prior to stem cell transplantation. One hundred two patients were randomized to receive either 8 mg PO ondansetron every 8 hours, 1 mg PO granisetron every 12 hours, or 32 mg IV ondansetron every 24 hours plus 10 mg IV dexamethasone daily during and 1 day after the various preparative regimens. Study arms were compared in terms of emetic episodes, subjective nausea, amount and cost of rescue antiemetics used, and total costs. Response was defined as complete response (CR), no emesis with no or mild nausea and no rescue antiemetics; major response (MR), 1 episode of emesis or moderate nausea with or without rescue antiemetics; and major efficacy (ME), CR + MR. Subjective nausea was assessed using a 100-mm visual analog scale (VAS) with 0 = no nausea. Ninety-six patients completed the study; the trial was analyzed according to intention-to-treat. Overall CR rates were: 48% for oral ondansetron, 47% for oral granisetron, and 49% for IV ondansetron. Overall ME rates were 82% for oral ondansetron, 84% for oral granisetron, and 81% for IV ondansetron. Mean VAS scores were 32 for oral ondansetron, 32 for oral granisetron, and 27 for IV ondansetron. None of the differences were statistically significant. A cost analysis revealed significant differences among all arms (P = .0001, all comparisons). All 3 regimens had similar efficacy in this BMT population; oral ondansetron was the most cost-effective.

Administration, Oral↗
PubMed2000

Functional analysis of putative restriction-modification system genes in the Helicobacter pylori J99 genome.

Helicobacter pylori is a gram-negative bacterium, which colonizes the gastric mucosa of humans and is implicated in a wide range of gastroduodenal diseases. The genomic sequences of two H.pylori strains, 26695 and J99, have been published recently. About two dozen potential restriction-modification (R-M) systems have been annotated in both genomes, which is far above the average number of R-M systems in other sequenced genomes. Here we describe a functional analysis of the 16 putative Type II R-M systems in the H. pylori J99 genome. To express potentially toxic endonuclease genes, a unique vector was constructed, which features repression and antisense transcription as dual control elements. To determine the methylation activities of putative DNA methyltransferases, we developed polyclonal antibodies able to detect DNA containing N6-methyladenine or N4-methylcytosine. We found that <30% of the potential Type II R-M systems in H.pylori J99 strain were fully functional, displaying both endonuclease and methyltransferase activities. Helicobacter pylori may maintain a variety of functional R-M systems, which are believed to be a primitive bacterial 'immune' system, by alternatively turning on/off a subset of numerous R-M systems.

Adenine↗
PubMed2000

A novel use for lead shields in theatre: the Hartshill window.

The problem of radiation exposure to surgeons during radiographic screening has been previously highlighted. We describe a simple, cheap and reusable device for reducing exposure time and improving image quality during the treatment of wrist and hand fractures.

Fractures, Bone↗
PubMed1997

Clinical supervision: the art of being supervised.

Clinical supervision has been described as being of paramount importance to the development of nursing (Bishop 1994). It is now accepted that clinical supervision is an integral part of nursing practice (Waterworth et al 1997). This article summarises the pre-requisites for successful supervision and emphasises the role of the practitioner in the scheme (UKCC 1996). The author suggests how supervisees can influence the type and quality of their supervision.

Confidentiality↗
PubMed1996

Haemoglobin Hallamshire (beta146 HIS --> TYR): a new high oxygen affinity haemoglobin responsible for familial erythrocytosis.

A new high oxygen affinity haemoglobin with the beta chain mutation beta146 HIS --> TYR is described. This variant was detected in a fit 34-year-old man with true erythrocytosis. The abnormal haemoglobin was identified as an extra band on cellulose acetate electrophoresis at pH 6.3 and was later confirmed by beta globin gene sequencing and oxygen dissociation studies. Whole blood containing Haemoglobin Hallamshire has a P50 of 18 mmHg. This newly described haemoglobin variant was also responsible for erythrocytosis in the mother and maternal half cousin of the index case. The identification of Haemoglobin Hallamshire provides confirmatory evidence of the important role of the C-terminal end of the chain in haemoglobin function.

Adult↗
PubMed1995

Xenovulene A, a novel GABA-benzodiazepine receptor binding compound produced by Acremonium strictum.

Xenovulene A, a novel inhibitor of benzodiazepine binding to the GABA-benzodiazepine receptor is produced by submerged fermentation of Acremonium strictum. It was isolated from the mycelium by solvent extraction and purified by chromatography on Sephadex LH-20 and octadecyl silica. The structure of xenovulene A was determined to be a novel oxygenated sesquiterpene containing a humulene moiety by interpretation of various spectroscopic data, especially from 2D NMR experiments. Xenovulene A inhibited binding of the benzodiazepine, flunitrazepam, with an IC50 of 40 nM in an in vitro assay using bovine synaptosome membrane preparations.

Acremonium↗
PubMed1991

Observation of the light-triggered binding of pyrone to chymotrypsin by Laue x-ray crystallography.

Crystals of gamma-chymotrypsin inhibited with the photodissociable group trans-p-diethylamino-o-hydroxy-alpha-methylcinnamate were irradiated with a 1-msec flash from a high-energy xenon flashlamp in the presence of the mechanism-based inhibitor 3-benzyl-6-chloro-2-pyrone. The ensuing reaction was monitored by collection of sequential, single-exposure Laue x-ray diffraction patterns. The experiment was also performed in solution to verify the regeneration of catalytic activity and the subsequent inhibition of the enzyme by pyrone after photolysis. The resulting crystallographic structures show the presence of covalently bound cinnamate prior to photolysis, the generation of "free" enzyme after irradiation of the crystal, and the slow formation of a pyrone-inhibited complex several hours after photolysis. The structure of the free enzyme shows a significant proportion of the active sites in the crystal to contain a naturally occurring, noncovalently bound tetrapeptide inhibitor [Dixon, M.M. & Matthews, B.W. (1989) Biochemistry 28, 7033-7038], even after cinnamate acylation and photolysis. Data collected simultaneously with irradiation show the crystal to be slightly disordered during photolysis, leading to streaked x-ray photos. The resulting maps are suggestive of a bicyclic coumarin species produced by photolysis and deacylation; however, the electron density is difficult to model unambiguously by one unique chemical state. Nevertheless, Laue crystallography is shown to be capable of visualizing time-dependent chemical changes in the active site of an enzyme.

Binding Sites↗
PubMed1991

Lichen-forming fungi: potential sources of novel metabolites.

The challenge for today's pharmaceutical industry lies in the discovery and development of new, pharmacologically active molecules. Metabolites produced by microorganisms, and fungi in particular, are a resource for which the therapeutic potential has been recognized, but one that remains largely unexplored and unexploited. Approximately 20% of all known fungal species are obligate symbionts in lichens; this major group of fungi has been long neglected by mycologists, and overlooked by industry.

Ascomycota↗
PubMed1991

Positive selection of antibiotic-producing soil isolates.

Stepwise discriminant analysis was used to identify the most powerful selective substrates which could be used to formulate media capable of enriching for antibiotic-producing soil isolates. This was achieved by characterizing a collection of 74 soil bacteria, including eubacteria and actinomycetes, according to their ability to produce antibacterial antibiotics and their growth responses to 43 physiological and nutritional tests. The characters which were selective for actinomycetes relative to eubacteria included growth on proline (1%, w/v) and humic acid (0.1%) as sole sources of both carbon and nitrogen, growth on nitrate as a nitrogen source, and growth at pH 7.7-8.0. Growth on proline (1%) and humic acid (0.1%) as sole carbon/nitrogen sources, growth on asparagine as a nitrogen source, and growth in the presence of vitamins were among the characteristics which allowed antibiotic-producing actinomycetes to be differentiated from non-antibiotic-producing strains. Several simple isolation media which incorporated the selective substrates identified by discriminant analysis succeeded in increasing the proportion of actinomycetes isolated from soil samples. Furthermore, the percentage of isolates capable of antibiotic production was considerably increased.

Actinomycetales↗
PubMed1990

Photolysis and deacylation of inhibited chymotrypsin.

Inhibited chymotrypsin was reactivated through the photolysis of the covalently bound light-reversible cinnamates described in our previous paper [Stoddard, B.L., Bruhnke, J., Porter, N.A., Ringe, D., & Petsko, G. (1990) Biochemistry 29, 4871-4879]. The light-induced deacylation was accomplished both in solution and in protein crystals, with the release of inhibitor from the crystal monitored and confirmed by X-ray diffraction. The product of photolysis has been characterized as a 3-methylcoumarin, leading to a mechanism for light-driven deacylation of an internal lactonization that is dependent on the presence of an internal hydroxyl nucleophile. The acyl enzyme formed from cinnamate A is not suitable for photochemical studies, as the complex has a short half-life in solution and does not have a chromophore that is well separated from protein absorbance. Cinnamate B, with a p-diethylamino substituent, shows an enzyme deacylation rate enhancement of 10(9) for the cis photoisomer relative to the trans starting material. The half-life and deacylation rate of this compound in the E-I complex after photon absorption have been directly measured by subsecond UV absorption studies. X-ray diffraction studies of photoactivation using a flow cell show that the cinnamate B acyl enzyme complex is fully capable of light-induced isomerization and regeneration of native enzyme in the crystalline state. The E-I complex formed upon binding of cinnamate A, however, shows little if any effect from irradiation due to competitive absorbance by the highly concentrated protein at the shorter UV wavelengths. Photolysis of cinnamate B appears to occur on a time scale fast enough for applications in crystallographic studies of enzymatic intermediate-state structures.

Chymotrypsin↗