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Biomedical subjects

B Hall

Publications and source records attributed to B Hall.

At least 19 recordsLinked to original sources
PubMed1999

Omafilcon A (Proclear) soft contact lenses in a dry eye population.

PURPOSE: We conducted a 3-month, randomized, comparative cross-over study to evaluate the clinical performance of lenses manufactured from omafilcon A on subjects with signs and symptoms of dry eye. The subjects' own daily wear soft lenses were used as controls. METHODS: Seventy-six subjects with objective evidence of dry eye, as defined in the NEI/Industry Workshop Report 1995, were fit with either the omafilcon A lenses (Proclear) or new control lenses. Subjects wore the lenses for 6 weeks and then crossed over to bilateral wear of the other lenses for an additional 6 weeks. During each part of the study, we examined subjects at 1 week, 1 month, and 6 weeks. Signs and symptoms of dry eye were evaluated, and on-eye dehydration of the lens was assessed. RESULTS: When the subjects were wearing the omafilcon A lenses, there was a statistically significant improvement in a number of subjective parameters including comfort, dryness, frequency of eye irritation, and frequency of burning. We found significantly less on-eye dehydration of the lens and fluorescein corneal staining with the omafilcon A lenses. CONCLUSIONS: This study indicated that the daily wear of omafilcon A lenses provided better comfort, fewer symptoms, less on-eye dehydration, and less fluorescein corneal staining than other soft daily wear contact lenses in subjects with mild to moderate dry eye.

Adolescent↗
PubMed1998

Epilepsy needs revisited: a revised epilepsy needs document for the UK.

We revisit epilepsy needs in the United Kingdom, and update our previous publication to take into account new epidemiological data, changes in investigation and treatment and trends in the organization of health and other caring agencies. This document attempts to define and quantify the scope, content and standards of services required, from primary care settings to specialized centres. Reference is also made to the role of other agencies.

Adult↗
PubMed1998

Sternal defects associated with congenital pericardial and cardiac defects.

We describe three cases of sternal defects of varying severity associated with other congenital anomalies. In the most severe case, both anterior and posterior defects were seen, with near-absence of the sternum and pericardium continuous with a large omphalocele. This resulted in external location of organs usually confined within the thoracic and abdominal cavities. A ventricular septal defect was present, and the arterial duct was absent. The course of the ascending aorta was anomalous. The baby had anencephaly and rachischisis. In the intermediate case, a proximal sternal cleft was associated with shortening of the sternum, and absence of the manubrium. Anterior pericardial and diaphragmatic defects were seen, while a scalp defect and an encephalocele were present on the posterior aspect of the head. This baby had tricuspid atresia. The remaining case had only an anterior defect with a shortened sternum. A supra-umbilical omphalocele contained a left ventricular diverticulum without interposing pericardium or diaphragm. Ventricular and atrial septal defects were present. The first two cases can be considered as representing failure of development of both an anterior and a posterior midline field. The third case, much milder than the other two, represents failure of development of an anterior field.

Abnormalities, Multiple↗
PubMed1998

Snapshot of a large dynamic replicon in a halophilic archaeon: megaplasmid or minichromosome?

Extremely halophilic archaea, which flourish in hypersaline environments, are known to contain a variety of large dynamic replicons. Previously, the analysis of one such replicon, pNRC100, in Halobacterium sp. strain NRC-1, showed that it undergoes high-frequency insertion sequence (IS) element-mediated insertions and deletions, as well as inversions via recombination between 39-kb-long inverted repeats (IRs). Now, the complete sequencing of pNRC100, a 191,346-bp circle, has shown the presence of 27 IS elements representing eight families. A total of 176 ORFs or likely genes of 850-bp average size were found, 39 of which were repeated within the large IRs. More than one-half of the ORFs are likely to represent novel genes that have no known homologs in the databases. Among ORFs with previously characterized homologs, three different copies of putative plasmid replication and four copies of partitioning genes were found, suggesting that pNRC100 evolved from IS element-mediated fusions of several smaller plasmids. Consistent with this idea, putative genes typically found on plasmids, including those encoding a restriction-modification system and arsenic resistance, as well as buoyant gas-filled vesicles and a two-component regulatory system, were found on pNRC100. However, additional putative genes not expected on an extrachromosomal element, such as those encoding an electron transport chain cytochrome d oxidase, DNA nucleotide synthesis enzymes thioredoxin and thioredoxin reductase, and eukaryotic-like TATA-binding protein transcription factors and a chromosomal replication initiator protein were also found. A multi-step IS element-mediated process is proposed to account for the acquisition of these chromosomal genes. The finding of essential genes on pNRC100 and its property of resistance to curing suggest that this replicon may be evolving into a new chromosome.

Chromosome Mapping↗
PubMed1998

Cloning of the Nocardia corallina polyhydroxyalkanoate synthase gene and production of poly-(3-hydroxybutyrate-co-3-hydroxyhexanoate) and poly-(3-hydroxyvalerate-co-3-hydroxyheptanoate).

The polyhydroxyalkanoate (PHA) synthase gene (phaCNc) from Nocardia corallina was identified in a lambda library on a 6-kb BamHI fragment. A 2.8-kb XhoII subfragment was found to contain the intact PHA synthase. This 2.8-kb fragment was subjected to DNA sequencing and was found to contain the coding region for the PHA synthase and a small downstream open reading frame of unknown function. On the basis of DNA sequence, phaCNc is closest in homology to the PHA synthases (phaCPaI and phaCPaII) of Pseudomonas aeruginosa (approximately 41% identity and 55% similarity). The 2.8-kb XhoII fragment containing phaCNc was subcloned into broad host range mobilizable plasmids and transferred into Escherichia coli, Klebsiella aerogenes (both containing a plasmid bearing phaA and phaB from Ralstonia eutropha), and PHA-negative strains of R. eutropha and Pseudomonas putida. The recombinant strains were grown on various carbon sources and the resulting polymers were analyzed. In these strains, the PHA synthase from N. corallina was able to mediate the production of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) containing high levels of 3-hydroxyhexanoate when grown on hexanoate and larger even-chain fatty acids and poly(3-hydroxyvalerate-co-3-hydroxyheptanoate) containing high levels of 3-hydroxyheptanoate when grown on heptanoate or larger odd-chain fatty acids.

Acyltransferases↗
PubMed1997

Birth defects and childhood cancer in offspring of survivors of childhood cancer.

OBJECTIVE: To determine the effect of chemotherapy for cancer during childhood and adolescence on subsequent pregnancy outcome and the occurrence of cancer in the offspring. DESIGN: We reviewed the history of 405 former patients with pediatric cancer. A self-administered questionnaire was completed by members of a cohort of consecutively treated patients who were aged 18 years or older at the most recent follow-up visit and who were at least 5 years beyond the initial diagnosis of their cancer. SETTING: Department of Pediatrics of a National Cancer Institute-designated comprehensive cancer center. RESULTS: One hundred forty-eight patients reported 280 pregnancies. Ninety-one of the patients who reported 1 or more liveborn or stillborn infants following the completion of treatment had received 1 or more chemotherapeutic agents as part of their treatment of cancer. The frequency of congenital anomalies was 3.3% among the liveborn offspring of the treated women and 3.3% among the liveborn offspring of the spouses or female companions of the treated men. No cases of childhood cancer have been diagnosed among the offspring. CONCLUSIONS: The present data suggest that prior treatment with mutagenic chemotherapeutic agents, in the dosage ranges examined, does not increase the frequency of congenital anomalies in the offspring of former pediatric and adolescent patients with cancer. Although no cases of childhood cancer have been observed thus far among the offspring, additional follow-up is necessary to adequately assess their risk of childhood cancer.

Abnormalities, Drug-Induced↗
PubMed1997

Occurrence of puma lentivirus infection in cougars from Washington.

Puma lentivirus (PLV) antibodies were detected in 13 (25%) of 52 serum samples obtained from cougars (Felis concolor) collected by hunters. The serum samples were collected from November 1993 through January 1994 from four specific regions throughout the state of Washington (USA), and included the Olympic Mountains, the Cascade Mountains, the Blue Mountains, and the Selkirk Mountains. More (38%) seropositive cougar samples originated from the Cascade Mountains than from any other site. The overall seroprevalence for PLV infection in Washington cougars was higher than previously reported for cougars sampled in Oregon and Idaho (USA), but lower than in cougars sampled in Arizona, Colorado, and California (USA).

Animals↗
PubMed1997

Six month clinical evaluation of a biomimetic hydrogel contact lens.

PURPOSE: We performed a six-month, comparative, contralateral/bilateral study to assess the clinical performance of the Proclear contact lens, which is manufactured from a novel, biomimetic, 59% water content, hydrogel material (Omafilcon A). Omafilcon A is a hydrogel polymer and is based on a new biomimetic approach to the design of biomaterials for biomedical applications. The polymer incorporates a synthetic analogue of the phosphorylcholine (PC) headgroup, an important component found in all human cells. METHODS: Forty-two subjects were fit with the Proclear lens for 6 months of daily wear; 20 subjects wore a Proclear lens in one eye and a Permaflex lens in the fellow as a control, while 22 subjects wore Proclear lenses in both eyes. A one-step hydrogen peroxide system was used for disinfection and no protein remover was used. RESULTS: No subject was required to withdraw due to unacceptable physiological findings with the Proclear lens. At the 3-month visit, corneal staining was present in 33% of the Proclear eyes compared to 72% of the Permaflex-wearing eyes. At one month, the Proclear lens was graded significantly more comfortable than the Permaflex lens (P < 0.01), and all 11 of the subjects who expressed a preference did so in favor of the Proclear lens. Overall, the fitting characteristics and visual performance of the Proclear lens did not appear to vary during the study. Spectrofluorimetric analysis of worn lenses confirm that Proclear showed minimal protein and lipid spoliation, which was found to be independent of wear time and subject variations. In contrast, despite the use of a surfactant cleaner, Permaflex lenses showed measurable and significant levels of lipid spoilation. Despite significant differences in average mean thicknesses and the level of bulk water in the lenses, in vivo dehydration of the Proclear lens was significantly lower than that of the Permaflex lens. CONCLUSIONS: The results of this study have confirmed the viability of biomimetic PC-hydrogels in contact lens applications. In vivo and in vitro analyses tended to confirm that Omafilcon A has a number of superior material attributes, as compared to conventional hydrogels when used in contact lens applications.

Adolescent↗
PubMed1997

Clinical comparison of Omafilcon A with four control materials.

PURPOSE: The purpose of this study was to assess the clinical performance of hydrogel contact lenses manufactured from a novel, biomimetic, 59% water content, hydrogel material (Omafilcon A) as compared with a representative range of control materials (Polymacon, Etafilcon A, Atlafilcon A, and Welcon CE). METHOD: Thirty subjects were enrolled in a 2-month, double-masked, randomized, comparative, daily wear study. Subjects wore two sets of lenses; each pair was worn for 1 month. In each part of the study, subjects wore a Proclear (Biocompatibles Ltd.) test lens (Omafilcon A) in one eye and a control lens in the other eye. In vivo lens dehydration was measured after 1 week of lens wear. Lenses were collected at the end of the study and subjected to in vitro spectrofluorimetric analysis to measure protein and lipid deposits. RESULTS: Omafilcon A showed significantly less lipid spoilation than all the controls and significantly less protein than the Etafilcon A and Atlafilcon A lenses. High levels of protein were found on the Group 4 lenses (Etafilcon A) and high levels of lipid were found on the Group 2 lenses (Weicon CE). The Omafilcon A lenses exhibited significantly less on-eye dehydration than the Etafilcon A lenses (P < 0.0001) and the Weicon CE lenses (P < 0.005). The majority of subjects expressed a preference for the Proclear lens, generally for reasons of comfort. Some minor differences in aspects of lens fit were noted between the test and control lenses, however, none of these were felt to be great enough to affect comfort. CONCLUSIONS: We hypothesize that the reduced spoliation seen with the Omafilcon A lens relates to the biomimetic nature of the material which incorporates phosphorylcholine.

Adsorption↗
PubMed1996

Chromosomal integration dependent induction of junB by growth factors requires multiple flanking evolutionarily conserved sequences.

The junB locus contains nine flanking evolutionarily conserved sequences (FECS) that share 72% to 91% sequence identity between human and mouse. These FECS encompass the same regions of flanking DNA necessary for maximal mitogenic induction of junB. Most of the cis elements reported to date that affect junB regulation also reside within FECS. These observations suggest that the persistence of FECS through evolution reflects a necessary role in junB transcriptional regulation. In this report, we identify specific regulatory cis elements within junB FECS II and III and provide a quantitative analysis of the contribution made by these sequences to junB induction. These cis elements include a Serum Response Element (SRE), two Ets sites previously unrecognized as contributing to junB expression, and two novel Ets-linked motifs (ELMs). In general, mutating any single element significantly impairs junB induction. Moreover, the same mutations alter the structure of junB 5' flanking DNA within chromatin. Collectively, these results suggest that multiple proteins bound within FECS confederate to form a functional promoter complex, the activity of which is dependent upon a specific chromatin architecture.

Animals↗
PubMed1996

Measurement of surgically induced corneal deformations using three-dimensional confocal microscopy.

The goal of this study was to develop and apply a new set of experimental techniques for measuring the local deformations induced by partial-thickness corneal incisions in situ. Eight adult cat eyes were enucleated and cannulated, with corneal viability maintained as close to in vivo conditions as possible and intraocular pressure (IOP) carefully controlled. Experimental measurements were made pre/post radial keratotomy (RK) surgery in situ at IOPs of 15, 30, and 45 mm Hg. Incision depth and cross-sectional profiles were measured at the midpoint of selected incisions using three-dimensional (3-D) tandem scanning confocal microscopy (TSCM); central corneal curvature was estimated using a commercial corneal topographical analysis system, and corneal thickness was assessed by both 3-D TSCM and ultrasonic pachymetry. Corneas were then processed for light microscopy and incision depth was measured histologically. Finite element models were developed for comparison with the experimental measurements. There was no significant change in central corneal thickness (-5.3 +/- 3.9%, n = 8) over the course of the experiments, demonstrating that normal endothelial cell function and normal stromal hydration was maintained. The in situ TSCM incision depth measurements were significantly correlated with the histological measurements (slope = 0.95, R = 0.854, p < 0.01, n = 13 incisions). Measured incision gape at the top (anterior) of the stroma was 64.9 +/- 13.4, 87.3 +/- 12.6, and 108.7 +/- 14 microns at IOPs of 15, 30, and 45 mm Hg, respectively. The 3-D incision profiles were nonlinear in shape; comparison with the finite element models suggests that the shape of the wound profile may provide unique information regarding the shear stiffness of the cornea. Overall, the data suggest that TSCM measurements of the cross-sectional profile of the incisions immediately after RK under controlled in situ conditions provide important data regarding the mechanical behavior of the cornea after refractive surgery. These data should provide the foundation for future studies into the relationships between local tissue mechanics and corneal wound healing.

Animals↗
PubMed1996

Antisense acid invertase (TIV1) gene alters soluble sugar composition and size in transgenic tomato fruit.

Invertase (beta-fructosidase, EC 3.2.1.26) hydrolyzes sucrose to hexose sugars and thus plays a fundamental role in the energy requirements for plant growth and maintenance. Transgenic plants with altered extracellular acid invertase have highly disturbed growth habits. We investigated the role of intracellular soluble acid invertase in plant and fruit development. Transgenic tomato (Lycopersicon esculentum Mill.) plants expressing a constitutive antisense invertase transgene grew identically to wild-type plants. Several lines of transgenic fruit expressing a constitutive antisense invertase gene had increased sucrose and decreased hexose sugar concentrations. Each transgenic line with fruit that had increased sucrose concentrations also had greatly reduced levels of acid invertase in ripe fruit. Sucrose-accumulating fruit were approximately 30% smaller than control fruit, and this differential growth correlated with high rates of sugar accumulation during the last stage of development. These data suggest that soluble acid invertase controls sugar composition in tomato fruit and that this change in composition contributes to alterations in fruit size. In addition, sucrose-accumulating fruit have elevated rates of ethylene evolution relative to control fruit, perhaps as a result of the smaller fruit size of the sucrose-accumulating transgenic lines.

Aging↗
PubMed1996

Breaking the silence on elder abuse.

Elder abuse has been described as the silent crime-silent, but not insignificant. The magnitude of the problem for Canadians was revealed in a national survey of 2,000 randomly selected seniors residing in private dwellings: four per cent of respondents reported some form of abuse. The perpetrators were usually people in positions of trust, such as family members or caregivers.

Aged↗
PubMed1995

Localization of the mouse lissencephaly-1 gene to mouse chromosome 11B3, in close proximity to D11Mit65.

Lissencephaly is a human brain malformation manifested by a smooth cerebral surface and severe mental retardation. Some of the patients have been shown to have deletions in chromosome 17p13.3, and recently, LIS-1 has been proposed to be the disease-associated gene. We have now mapped the mouse homolog of LIS-1 to mouse chromosome 11B3 by using fluorescence in situ hybridization to metaphase chromosomes. The analysis of yeast artificial chromosome clones placed Lis-1 in close proximity to the microsatellite marker D11Mit65.

1-Alkyl-2-acetylglycerophosphocholine Esterase↗
PubMed1995

Net uptake of plasma homocysteine by the rat kidney in vivo.

Hyperhomocysteinemia is a common finding in dialysis-dependent end-stage renal disease (ESRD) patients, but its etiology and refractoriness to standard homocysteine-lowering B-vitamin therapy are poorly understood. In the absence of actual in vivo data, it has been hypothesized that loss of normal renal parenchymal uptake and metabolism of homocysteine is an important determinant of hyperhomocysteinemia in ESRD, given that urinary homocysteine excretion by healthy kidneys is trivial. We assessed net renal uptake and metabolism of homocysteine using an established rat model for measuring arteriovenous amino acid differences across the rat kidney, along with simultaneous determination of renal plasma flow, urine flow, and urinary homocysteine concentration. Substantial homocysteine uptake and metabolism by normal rat kidneys was demonstrated, and we also confirmed that urinary homocysteine excretion is minimal. These data suggest that loss of the sizable homocysteine metabolizing capacity of the intact kidneys may be an important determinant of the refractory, potentially atherothrombotic hyperhomocysteinemia frequently observed in ESRD.

Animals↗
PubMed1995

Repeat callers and the Samaritan telephone crisis line--a Canadian experience.

Telephone crisis lines are increasingly providing a much needed service in the community to the lonely, the depressed, and the suicidal. The Samaritan volunteer crisis line discussed here is open to any person at any time, day or night. The instant availability of such an anonymous service attracts callers who use the line inappropriately; these people are often referred to as repeat callers. The Samaritans discovered that repeat callers were creating serious problems for both staff and volunteers. The difficult task was to develop a policy to restrict the repeat callers, but at the same time ensuring that the mandate of the crisis line was offered to them. This article examines the characteristics of repeat callers, and makes suggestions about the management of the chronic caller.

Behavior Therapy↗