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V Franklin

Publications and source records attributed to V Franklin.

18 recordsLinked to original sources
PubMed2003

A model for the preliminary biological screening of potential keratoprosthetic biomaterials.

A series of in vitro screening assays for the preliminary selection of biomaterials for use in the fabrication of artificial corneas (keratoprostheses) (KPros) have been investigated. These screening assays assessed the initial binding of inflammatory and cell adhesive proteins, activation of inflammatory proteins, adhesion of keratocytes, epithelial cells and macrophages and the production of inflammatory cytokines by keratocytes contacting biomaterials. Central optic biomaterials were selected on the basis of low-inflammatory and cell adhesion potential. Peripheral skirt materials were selected on the basis of low-inflammatory potential but good cell adhesion to anchor the implant within the host cornea. Green fluorescent protein (GFP) gene transfer was used in a novel context to investigate cell invasion in the absence of external staining techniques. Confocal laser scanning microscopy and scanning electron microscopy were used to investigate GFP positive keratocyte invasion of porous materials. The results of in vitro assays were compared to a corneal organ culture system in which the biomaterials were assessed within a stromal environment. A range of polyurethane-based interpenetrating polymers with a range of water contents were screened. All materials showed low-inflammatory potential. A reduction in biomaterial water content induced an increase in complement C3 and fibronectin binding and in cell adhesion to materials, whilst differences in co-monomer formulation had little impact. The screening methods used in the current study provide a suitable preliminary assessment regime for the in vitro evaluation of potential KPro materials.

Biocompatible Materials↗
PubMed2003

Insulin pumps.

Explore the source record for details and available documents.

Adolescent↗
PubMed2001

The N-terminal globular domain and the first class A amphipathic helix of apolipoprotein A-I are important for lecithin:cholesterol acyltransferase activation and the maturation of high density lipoprotein in vivo.

To investigate the role of the N terminus of apolipoprotein A-I (apoA-I) in the maturation of high density lipoproteins (HDL), two N-terminal mutants with deletions of residues 1-43 and 1-65 (referred to as Delta 1-43 and Delta 1-65 apoA-I) were studied. In vitro, these deletions had little effect on cellular cholesterol efflux from macrophages but LCAT activation was reduced by 50 and 70% for the Delta 1-43 and Delta 1-65 apoA-I mutants, respectively, relative to wild-type (Wt) apoA-I. To further define the role of the N terminus of apoA-I in HDL maturation, we constructed recombinant adenoviruses containing Wt apoA-I and two similar mutants with deletions of residues 7-43 and 7-65 (referred to as Delta 7-43 and Delta 7-65 apoA-I, respectively). Residues 1-6 were not removed in these mutants to allow proper cleavage of the pro-sequence in vivo. Following injection of these adenoviruses into apoA-I-deficient mice, plasma concentrations of both Delta 7-43 and Delta 7-65 apoA-I were reduced 4-fold relative to Wt apoA-I. The N-terminal deletion mutants, in particular Delta 7-65 apoA-I, were associated with greater proportions of pre beta-HDL and accumulated fewer HDL cholesteryl esters relative to Wt apoA-I. Wt and Delta 7-43 apoA-I formed predominantly alpha-migrating and spherical HDL, whereas Delta 7-65 apoA-I formed only pre beta-HDL of discoidal morphology. This demonstrates that deletion of the first class A amphipathic alpha-helix has a profound additive effect in vivo over the deletion of the globular domain alone (amino acids 1-43) indicating its important role in the production of mature alpha-migrating HDL. In summary, the combined in vitro and in vivo studies demonstrate a role for the N terminus of apoA-I in lecithin:cholesterol acyltransferase activation and the requirement of the first class A amphipathic alpha-helix for the maturation of HDL in vivo.

Adenoviridae↗
PubMed2001

Narrow-band ultraviolet B and broad-band ultraviolet A phototherapy in adult atopic eczema: a randomised controlled trial.

BACKGROUND: Narrow-band ultraviolet B (UVB) is an effective treatment for psoriasis, and open studies suggest that this phototherapy might improve atopic eczema. We did a randomised controlled trial to compare narrow-band UVB, UVA, and visible light phototherapy as second-line, adjunctive treatments in adult patients with moderate to severe atopic eczema. METHODS: Phototherapy was administered twice a week for 12 weeks. 26 patients were randomly assigned narrow-band UVB, 24 were assigned UVA, and 23 visible fluorescent light. The primary endpoints were change in total disease activity (sum of scores at six body sites) and change in extent of disease after 24 treatments compared with baseline. Data were analysed by the method of summary measures. FINDINGS: 13 patients withdrew or were excluded from analysis. Mean reductions in total disease activity over 24 treatments in patients who received narrow-band UVB and UVA, respectively, were 9.4 points (95% CI 3.6 to 15.2) and 4.4 points (-1.0 to 9.8) more than in patients who received visible light. Mean reductions in extent of disease after 24 treatments with narrow-band UVB and UVA were 6.7% (1.5 to 11.9) and -1.0% (-5.3 to 3.3) compared with visible light. A small proportion of patients developed erythema after phototherapy or had a flare in their eczema sufficient to withdraw from treatment. INTERPRETATION: Narrow-band UVB is an effective adjunctive treatment for moderate to severe atopic eczema, and the treatment is well tolerated by most patients.

Adolescent↗
PubMed2001

Proteolytic degradation and impaired secretion of an apolipoprotein A-I mutant associated with dominantly inherited hypoalphalipoproteinemia.

We have devised a combined in vivo, ex vivo, and in vitro approach to elucidate the mechanism(s) responsible for the hypoalphalipoproteinemia in heterozygous carriers of a naturally occurring apolipoprotein A-I (apoA-I) variant (Leu(159) to Arg) known as apoA-I Finland (apoA-I(FIN)). Adenovirus-mediated expression of apoA-I(FIN) decreased apoA-I and high density lipoprotein cholesterol concentrations in both wild-type C57BL/6J mice and in apoA-I-deficient mice expressing native human apoA-I (hapoA-I). Interestingly, apoA-I(FIN) was degraded in the plasma, and the extent of proteolysis correlated with the most significant reductions in murine apoA-I concentrations. ApoA-I(FIN) had impaired activation of lecithin:cholesterol acyltransferase in vitro compared with hapoA-I, but in a mixed lipoprotein preparation consisting of both hapoA-I and apoA-I(FIN) there was only a moderate reduction in the activation of this enzyme. Importantly, secretion of apoA-I was also decreased from primary apoA-I-deficient hepatocytes when hapoA-I was co-expressed with apoA-I(FIN) following infection with recombinant adenoviruses, a condition that mimics secretion in heterozygotes. Thus, this is the first demonstration of an apoA-I point mutation that decreases LCAT activation, impairs hepatocyte secretion of apoA-I, and makes apoA-I susceptible to proteolysis leading to dominantly inherited hypoalphalipoproteinemia.

Amino Acid Substitution↗
PubMed2000

Distinct central amphipathic alpha-helices in apolipoprotein A-I contribute to the in vivo maturation of high density lipoprotein by either activating lecithin-cholesterol acyltransferase or binding lipids.

Recombinant adenoviruses with cDNAs for human apolipoprotein A-I (wild type (wt) apoA-I) and three mutants, referred to as Delta4-5A-I, Delta5-6A-I, and Delta6-7A-I, that have deletions removing regions coding for amino acids 100-143, 122-165, and 144-186, respectively, were created to study structure/function relationships of apoA-I in vivo. All mutants were expressed at lower concentrations than wt apoA-I in plasma of fasting apoA-I-deficient mice. The Delta5-6A-I mutant was found primarily in the lipid-poor high density lipoprotein (HDL) pool and at lower concentrations than Delta4-5A-I and Delta6-7A-I that formed more buoyant HDL(2/3) particles. At an elevated adenovirus dose and earlier blood sampling from fed mice, both Delta5-6A-I and Delta6-7A-I increased HDL-free cholesterol and phospholipid but not cholesteryl ester. In contrast, wt apoA-I and Delta4-5A-I produced significant increases in HDL cholesteryl ester. Further analysis showed that Delta6-7A-I and native apoA-I could bind similar amounts of phospholipid and cholesterol that were reduced slightly for Delta5-6A-I and greatly for Delta4-5A-I. We conclude from these findings that amino acids (aa) 100-143, specifically helix 4 (aa 100-121), contributes to the maturation of HDL through a role in lipid binding and that the downstream sequence (aa 144-186) centered around helix 6 (aa 144-165) is responsible for the activation of lecithin-cholesterol acyltransferase.

Animals↗
PubMed2000

An in vivo comparison of the kinetics of protein and lipid deposition on group II and group IV frequent-replacement contact lenses.

PURPOSE: To investigate the degree and rate of deposition of protein and lipid on FDA group II and group IV contact lens materials over a period of up to 28 days of wear. METHODS: Twenty-two subjects wore a group IV lens (Acuvue) and a group II lens (Soflens 66) in a randomized, cross-over study. The lenses were randomly worn for periods between 1 and 28 days and then collected for laboratory-based deposition analysis. RESULTS: The group II lenses revealed an increased degree of lipoidal spoilage (p < 0.0001) and the group IV lenses exhibited increased protein spoilage (p < 0.0001). Surface protein for both materials reached a maximum after 1 day and did not increase over the 4-week wearing period (p = NS). Total protein for group IV lenses reached a maximum between 1 and 7 days and then reached a plateau, with no further increase occurring (p = NS), whereas total protein accumulation on the group II lens continued to increase across all time periods (p < 0.05). Lipid deposition on the group IV lens was maximal after 1 day and increased no further (p = NS), whereas lipid deposition on the group II material monotonously increased and progressively built-up over the 4 weeks of wear (p < 0.0001). CONCLUSIONS: The kinetics of contact lens deposition is mediated by the chemical structure of the contact lens material under consideration. Protein deposition occurs rapidly with group IV materials before reaching a maximum, whereas N-vinyl pyrrolidone-containing group II materials progressively accumulate protein and lipid deposits, with no plateau occurring.

Adult↗
PubMed1999

Deletion of the C-terminal domain of apolipoprotein A-I impairs cell surface binding and lipid efflux in macrophage.

The contribution of the amphipathic alpha-helices of apoA-I toward lipid efflux from human skin fibroblasts and macrophage was examined. Four apoA-I mutants were designed, each by deletion of a pair of predicted adjacent helices. Three mutants lacked two consecutive central alpha-helices [Delta(100-143), Delta(122-165), and Delta(144-186)], whereas the final mutant lacked the C-terminal domain [Delta(187-243)]. When compared to recombinant wild-type apoA-I and mutants with central domain deletions, Delta(187-243) exhibited a marked reduction in its ability to promote either cholesterol or phospholipid efflux from THP-1 macrophages. This mutant also demonstrated a decreased ability to bind lipids and to form lipoprotein complexes. In contrast, the four mutants and apoA-I equally supported cholesterol efflux from fibroblasts, albeit with a reduced capacity when compared to macrophages. Delta(187-243) bound poorly to the macrophage cell surface when compared to apoA-I, and competitive binding studies with the central domain and C-terminal deletions mutants showed that only Delta(187-243) did not compete effectively with [(125)I]apoA-I. Omission of PMA during cholesterol loading enhanced cholesterol efflux to both apoA-I (1.5-fold) and the C-terminal deletion mutant (2.5-fold). Inclusion of the Sandoz ACAT inhibitor (58-035) during loading and, in the absence of PMA, increased and equalized cholesterol efflux to apoA-I and Delta(187-243). Surprisingly, omission of PMA during cholesterol loading had minimal effects on the binding of apoA-I or Delta(187-243) to the THP-1 cell surface. Overall, these results show that cholesterol efflux from cells such as fibroblasts does not require any specific sequence between residues 100 and 243 of apoA-I. In contrast, optimal cholesterol efflux in macrophages requires binding of the C-terminal domain of apoA-I to a cell surface-binding site and the subsequent translocation of intracellular cholesterol to an efflux-competent pool.

Amides↗
PubMed1998

Importance of central alpha-helices of human apolipoprotein A-I in the maturation of high-density lipoproteins.

We have studied the role of amphipathic alpha-helices in the ability of apoA-I to promote cholesterol efflux from human skin fibroblasts and activate lecithin:cholesterol acyltransferase (LCAT). Three apoA-I mutants were designed, each by deletion of a pair of predicted adjacent central alpha-helices [Delta(100-143), Delta(122-165), Delta(144-186)], and expressed in Escherichia coli. This strategy was used to minimize disruption of the predicted secondary structure of the resulting protein. These three central deletion mutants have been previously shown to be expressed as stable folded proteins but to exhibit altered phospholipid-binding properties. When recombined with phospholipids to form homogeneous LpA-I containing equivalent amounts of POPC and tested for their ability to promote diffusional cholesterol efflux from normal [3H]cholesterol-labeled fibroblasts, each mutant and the wild-type recombinant protein (Rec.-apoA-I) promoted cholesterol efflux with very similar rates at all the concentrations tested. These experiments showed that all LpA-I could acquire cellular cholesterol with similar affinity and binding capacity. However, when the cell-incubated LpA-I were incubated with purified LCAT, two mutants, Delta(122-165) and Delta(144-186), appeared incapable of activating the enzyme. To directly determine their ability to activate LCAT, each mutant and the control were recombined with equivalent amounts of cholesterol and phospholipid and incubated with the purified enzyme. The results show that whereas deletion of residues 100-143 has little effect on LCAT activation, deletion of residues 122-165 or 144-186 results in an inability of the mutants to promote cholesterol esterification. In conclusion, our results show that no specific sequence in the central domain of apoA-I is required for efficient diffusional cholesterol efflux from normal fibroblasts; however, residues 144-186 appear critical for optimum LCAT activation and cholesteryl ester accumulation. Since deletion of residues 144-186 also perturbs phospholipid association and prevents the formation of large LpA-I particles [Frank, P. G., Bergeron, J., Emmanuel, F., Lavigne, J. P., Sparks, D. L., Denèfle, P., Rassart, E., and Marcel, Y. L. (1997) Biochemistry 36, 1798-1806], the data show that this pair of alpha-helices plays an important role in the maturation of HDL. Sequence analysis of these apoA-I helices further identifies specific residues that appear essential to this activity.

Amino Acid Sequence↗
PubMed1998

Influence of contact lens material surface characteristics and replacement frequency on protein and lipid deposition.

The aim of the study was to quantify the influence of both contact lens material and replacement frequency on protein and lipid deposition. The following hypotheses were tested: (1) both protein and lipid interaction with contact lenses are material-dependent, and (2) the key factors are the material ionicity for the protein deposition and the material chemical composition for the lipid deposition. Three high water content contact lens materials were tested: netrafilcon A (FDA group II, Gentle Touch), etafilcon A (FDA group IV, Acuvue), and vifilcon A (FDA group IV, Focus). Contact lens spoilation was analyzed using ultraviolet spectroscopy and fluorescence spectrophotometry. The results showed that (1) significantly more proteins were deposited on the ionic materials than on the nonionic materials, and that among the ionic materials, the higher the ionicity, the higher the level of protein deposition; (2) there were significantly more surface proteins on the ionic materials after 3 months than after 1 month of wear, but no difference over time was demonstrated for the nonionic materials; and (3) significantly more lipids were deposited onto the surface of vifilcon A than etafilcon A or netrafilcon A, and the presence of vinylpyrrolidone in the vifilcon A formulation was thought to be the cause of increased deposition. The protein and lipid interactions with contact lenses were found to be material- and time-dependent. Protein attraction was found to be related to the material ionicity. The presence of vinylpyrrolidone was a key factor in the attraction of lipids.

Contact Lenses, Hydrophilic↗
PubMed1997

Lipid and protein deposition of N-vinyl pyrrolidone-containing group II and group IV frequent replacement contact lenses.

PURPOSE: The purpose of this study was to investigate the degree of protein and lipid deposition that occurs on N-vinyl-2-pyrrolidone (NVP) containing group II (non-ionic, high water content) and NVP containing group IV (ionic, high water content) frequent replacement hydrogel contact lens materials. METHODS: Twenty subjects were fitted with Group II (Vasurfilcon A) and Group IV (Vifilcon A) contact lenses, which were replaced monthly. The lenses were worn as a contralateral pair for 3 consecutive monthly periods. At the end of each monthly period, the lenses were collected for analysis of protein and lipid deposits. Protein deposition (following extraction) was examined by transmission UV and lipoidal deposition was examined using fluorescence spectrophotofluorimetry. RESULTS: There was a significant difference in the lipid and protein deposition profiles between the two materials. The Group II lens deposited approximately 2x more lipid (38 versus 73 fluorescence units; P < 0.0001) and the Group IV lens deposited approximately 17x more protein (488 micrograms versus 28 micrograms; P < 0.0001). Whilst the mean results across months were not significantly different for either protein or lipid (P = NS), the results revealed significant inter- and intra-subject variation. CONCLUSIONS: Protein deposition was predominantly controlled by the ionic charge of the lens materials, whereas the lipid deposition was predominantly determined by the NVP content. This study demonstrates that inter-subject variation and material characteristics significantly influence the deposition profile of hydrogel contact lens materials.

Adolescent↗
PubMed1996

Spoilation and clinical performance of monthly vs. three monthly Group II disposable contact lenses.

Twelve subjects were fitted with a high water content, nonionic contact lens (Pilkington Barnes-Hind "Precision UV"), which was either replaced every month for 3 months or worn for 3 consecutive months before replacement occurred. Visual quality, high and low contrast acuity, and comfort were unaltered with either replacement schedule, but overall satisfaction was significantly greater with the shorter replacement schedule (p = 0.04). Front surface wettability revealed a large amount of intersubject variability and was reduced at the 3-month visit with the longer replacement period lenses (p = 0.003). Visible deposits also increased with longer replacement times (p < 0.05). Laboratory-based analytical results showed that both gross lipid and gross extractable protein significantly increased in the 3-month lenses compared with the 1-month lenses, with 44% less lipid accumulation and 60% less protein deposition occurring with the shorter replacement time. The results support the replacement of high water content lenses on a monthly basis.

Adult↗
PubMed1991

Early deposition trends on group I (Polymacon and Tetrafilcon A) and group III (Bufilcon A) materials.

One of the problems with hydrophilic contact lenses is that they are susceptible to spoilage. This study investigated the degree of spoilage associate with lenses of various surface changes during the early stages of wear and the effect of surfactant cleaning of lenses at this stage. Ten patients wore a control HEMA lens on one eye and either an ionic (Bufilcon A) or non-ionic (Tetrafilcon A) lens on the other for one week and used a peroxide system for disinfection. The lenses were then replaced with identical lenses, which were also worn for 1 week, with surfactant cleaning added to the care regimen. The lenses then were examined by fluorescence spectroscopy in order that the extent of lipid and protein deposition could be assessed. The results indicate that protein accumulation is highly material dependent, whereas lipid deposition is primarily patient dependent. Also the term "ionic" does not necessarily indicate equally enhanced deposition in all lenses so termed. Surfactant cleaning appears to be of little benefit in reducing deposits during the early stages of wear, its benefit in the long-term being of much greater significance.

Adult↗
PubMed1977

Fertility, ovulation and maturation of eggs in mares injected with HCG.

Pony mares were observed from January to August for incidence of oestrus, duration of oestrus, length of the oestrous cycle and for ovulation and fertility after injection of HCG. From January to 15 May most mares showed oestrus but the duration of oestrus was quite variable and few mares ovulated in response to HCG. From 15 May to 17 August oestrous cycles were more regular and ovulation was induced within 40-50 h by an intramuscular injection of 1500-5000 i.u. HCG. Pregnancy was established by one mating at a fixed time after HCG in 20 of 69 mares. Degenerate eggs were recovered from the oviducts of anoestrous recently ovulated, mated, unmated and pregnant mares. The first polar body was formed before ovulation in 2 eggs and had not formed in 2 recently ovulated eggs flushed from the oviduct. The second polar body formed after sperm penetration 10-12 h after ovulation. After formation of pronuclei, the first cleavage division occurred at 20 h and the second at 32 h after ovulation. Oestrus was inhibited by progesterone administered by vaginal devices but occurred within 1-3 days in 12 of the 20 mares after withdrawal of the devices.

Animals↗