Showing papers on "Ultraviolet light published in 1989"

Polymerase chain reaction amplification applied to the determination of β‐like globin gene cluster haplotypes

Abstract: We report here on the application of the polymerase chain reaction (PCR) technique for the determination of the beta-like gene cluster haplotypes. Seven fragments containing each one of the following polymorphic sites--Xmnl 5' to the G gamma gene, HindIII in the IVSII of G gamma and A gamma gene, HincII 3' and inside the gamma gene, Hinfl 5' of the beta gene, and HpaI 3' of the beta gene--are amplified using the PCR technique. Each amplified fragment is subsequently digested with the appropriate enzyme, analyzed by electrophoresis on agarose gel containing ethidium bromide, and visualized under ultraviolet light. This technique has the advantages of rapidity, safety, and cost-effectiveness.

Wavelength dependence of pyrimidine dimer formation in DNA of human skin irradiated in situ with ultraviolet light

Abstract: The UV components of sunlight are believed to be a major cause of human skin cancer, and DNA is thought to be the principal molecular target. Alterations of the intensity and wavelength distribution of solar UV radiation reaching the surface of the earth, for example by depletion of stratospheric ozone, will change the effectiveness of solar radiation in damaging DNA in human skin. Evaluation of the magnitude of such effects requires knowledge of the altered sunlight spectrum and of the action spectrum for damaging DNA in human skin. We have determined an action spectrum for the frequency of pyrimidine dimer formation induced in the DNA of human skin per unit dose of UV incident on the skin surface. The peak of this action spectrum is near 300 nm and decreases rapidly at both longer and shorter wavelengths. The decrease in our action spectrum for wavelengths less than 300 nm is attributed to the absorption of the upper layers of the skin, an in situ effect that is inherently included in our measurements. Convolution of the dimer action spectrum with the solar spectra corresponding to a solar angle of 40 degrees under current levels of stratospheric ozone (0.32-cm O3 layer) and those for 50% ozone depletion (0.16-cm O3 layer), indicate about a 2.5-fold increase in dimer formation. If the action spectrum for DNA damage that results in skin cancer resembles that for dimer induction in skin, our results, combined with epidemiological data, suggest that a 50% decrease in stratospheric ozone would increase the incidence of nonmelanoma skin cancers among white males in Seattle, Washington, by 7.5- to 8-fold, to a higher incidence than is presently seen in the corresponding population of Albuquerque, New Mexico.

Ultraviolet Light Exposure and Risk of Posterior Subcapsular Cataracts

Abstract: • Posterior subcapsular (PSC) cataracts are a visually disabling form of cataract and account for 40% of surgical cases. Although PSC opacities may occur following intraocular inflammation, trauma, or use of steroids, the cause is often unknown. A case-control study was undertaken to investigate the role of exposure to ultraviolet light in the B range (UV-B) and other potential risk factors for the development of PSC cataracts. Surgical PSC cataract cases from a large rural ophthalmic practice on the lower eastern shore of Maryland were matched with phakic controls without PSC cataract changes from the same geographic area by age, sex, and referral pattern. All patients with PSC opacities who underwent cataract surgery in a 12-month period were chosen. One hundred sixty-eight cases and 168 controls were interviewed regarding sunlight exposure, drug use, occupational history, history of diabetes, hypertension, and other diseases. Matched-pairs analyses indicated that a history of relatively high exposure to UV-B was associated with increased risk of PSC cataracts. The association of PSC cataracts with steroid use and diabetes was reconfirmed. Subjects with blue eyes and less than high school education were also at increased risk for PSC cataracts. Smoking and hypertension were not found to be PSC cataract risk factors. These data suggest that UV-B exposure may be an important risk factor for PSC cataracts.

System and method for computer automated manufacturing using fluent material

Abstract: A system and method for constructing a three-dimensional object (10) from a design created on a CAD machine (14) is disclosed which includes a support (B) which may be indexed along two coordinate axes (X, Y) and a movable dispensing head (A) which indexes along a Z-axis. A fluent material (54) is dispensed or extruded from head (A) and as it is dispensed, the fluent material is subjected to a treatment by treatment sources (D) which cause the fluent material to transform into a fixed solidified state in the form of a three-dimensional object. Fluent material (54) may be a polymeric material which is solidified by an energy beam of ultraviolet light (56) upon dispensing. A shield (E) is provided to shield the dispensing head (A) and strand of material (54) so that the material is treated at the proper time and location to cause it to solidify properly to form the three-dimensional object. In accordance with the method, indexing takes place in desired steps so a dimensionally accurate object is formed.

Acid haze air pollution and breast and colon cancer mortality in 20 Canadian cities.

Abstract: Sulfur dioxide absorbs ultraviolet light in the region of the spectrum which is most active in forming vitamin D on the skin. Sulfate particles reflect light at this wavelength. High concentrations of these pollutants (acid haze) may lead to vitamin D deficiencies in exposed populations. Epidemiologic and laboratory evidence suggests that vitamin D plays a role in reducing risk of colon and breast cancer. We examined the association between sulfur dioxide and ultraviolet-light-blocking aerosols in 20 Canadian cities, and age-adjusted breast and colon cancer mortality rates in the census divisions encompassing these cities. Statistically significant positive associations were found between these two measures of air pollution and age-adjusted mortality rates for colon cancer in women (multiple r = +.74, p = 0.003), and men (multiple r = +.61, p = 0.03), and breast cancer in women (multiple r = +.69, p = 0.007). Mortality rates for all other reported cancer sites were also examined, and no statistically significant positive associations were found consistently in both sexes. The ecological nature of this study is emphasized, and the possibility that an indirect association could explain these findings is discussed.

Purification and administration of dna repair enzymes

Abstract: Methods for purifying DNA repair enzymes are provided in which an aqueous solution of a DNA repair enzyme in an impure state is applied to a molecular sieve column having an exclusion limit which will retard the DNA repair enzyme but will not retard contaminants larger than the DNA repair enzyme. The DNA repair enzyme in an enhanced state of purity is eluted isocratically from the molecular sieve column in an elution buffer and applied directly to a DNA affinity column in the same buffer without intermediate dialysis, ultrafiltration, or other procedures. The DNA repair enzyme is eluted from the DNA affinity column using, for example, a salt gradient. The method is rapid, inexpensive, simple to perform, and has been found to produce a homogeneous final product. In accordance with other aspects of the invention, the purified DNA repair enzymes are encapsulated in liposomes and administered to living cells in situ. This form of administration has been found to be non-toxic to the cells and to result in increased incision of damaged DNA, enhanced DNA repair synthesis, and increased cell survival after exposure to ultraviolet light. In certain preferred embodiments, DNA repair enzymes are administered in pH sensitive liposomes.

Cell Cycle Responses of Two X-ray Sensitive Mutants Defective in DNA Repair

Abstract: SummaryBoth the xrs and V-3 lines of Chinese hamster ovary cells exhibit marked sensitivity to ionizing radiation. They are also sensitive to agents such as bleomycin and H2O2 but exhibit normal responses to ultraviolet light and mitomycin C. Both cell lines are defective in split-dose repair and repair of double-strand breaks in DNA. Analysis of response to radiation as a function of age in the cell cycle indicates that both cell lines exhibit a marked sensitivity in late G1 and early S phase with more limited sensitization throughout the remainder of the cell cycle.

A neuromodulator of synaptic transmission acts on the secretory apparatus as well as on ion channels

Abstract: THE mechanisms that underlie synaptic plasticity have been largely inferred from electrophysiological studies performed at sites remote from synaptic terminals. Thus the mechanisms involved in plasticity at the secretory sites have remained ill-defined. We have now used somatic synapses of cultured Helisoma neurones1–3 to directly assess presynaptic ion conductances and study the secre-tory apparatus. At these synapses we determined the actions of a modulatory neuropeptide, Phe-Met-Arg-Phe-NH2 (FMRFa), on the release of the neurotransmitter acetylcholine (ACh). Using voltage- and calcium-clamp techniques, we have demonstrated that FMRFa causes a presynaptic inhibition of ACh release by (1) reducing the magnitude of the voltage-dependent calcium current, and (2) regulating the secretory apparatus. The photolabile calcium cage, nitr-5 (refs 3–8), was dialysed into the presynaptic cell. In response to ultraviolet light, calcium was released from nitr-5 and ACh secretion was stimulated. Under conditions of constant inter-nal calcium, FMRFa reduced the rate of ACh release. Thus we conclude that FMRFa reduces the influx of calcium during the action potential and decreases the sensitivity of the secretory apparatus to elevated internal calcium, thereby contributing to a presynaptic inhibition of transmitter release.

The effects of ultraviolet-B radiation on loblolly pine. I. Growth, photosynthesis and pigment production in greenhouse-grown seedlings

Abstract: One-year old loblolly pine (Pinus taeda L.) seedlings were grown in an unshaded greenhouse for 7 months under 4 levels of ultraviolet-B (UV-B) radiation simulating stratospheric ozone reductions of 16, 25 and 40% and included a control with no UV-B radiation. Periodic measurements were made of growth and gas exchange characteristics and needle chlorophyll and UV-B-absorbing-compound concentrations. The effectiveness of UV-B radiation on seedling growth and physiology varied with the UV-B irradiance level. Seedlings receiving the lowest supplemental UV-B irradiance showed reductions in growth and photosynthetic capacity after only 1 month of irradiation. These reductions persisted and resulted in lower biomass production, while no increases in UV-B-absorbing compounds in needles were observed. Seedlings receiving UV-B radiation which simulated a 25% stratospheric ozone reduction showed an increase in UV-B-absorbing-compound concentrations after 6 months, which paralleled a recovery in photosynthesis and growth after an initial decrease in these characteristics. The seedlings grown at the highest UV-B irradiance (40% stratospheric ozone reduction) showed a more rapid increase in the concentration of UV-B-absorbing compounds and no effects of UV-B radiation on growth or photosynthetic capacity until after 4 months at this irradiance. Changes in photosynthetic capacity were probably the result of direct effects on light-dependent processes, since no effects were observed on either needle chlorophyll concentrations or stomatal conductance. Further studies are necessary to determine whether these responses persist and accumulate over subsequent years.

Self-aligned, high resolution resonant dielectric lithography

Abstract: Methods of fabricating electrical contacts on both sides of a thin membrane to form a millimeter wave, self-aligned, opposed gate-source transistor are disclosed. The transistor structure has a subhalf-micron gate, dual-drains placed symmetrically around both sides of the gate, and a source approximately half the length of the gate. The source is directly opposite, and centered under, the gate on the opposite surface of a semiconductor thin film. The gate electrode is fabricated on the first surface of the thin film using conventional single surface lithography, and is used as a conformed mask for the source lithography, thereby self-aligning the source to the gate. The source is formed by resonant dielectric lithography, wherein the gate side of the thin film is irradiated by collimated ultraviolet light to expose a negative resist on the source side with a resolution of less than a wavelength. Lateral diffraction effects affect the relative dimension of the source with respect to the gate. The electron-beam lithographic process utilizes electron scattering in the thin film for the same purpose. This new untraviolet lithography process avoids the need to handle the thin film until after source metallization has been completed.

A stable blue-light-derived signal modulates ultraviolet-light-induced activation of the chalcone-synthase gene in cultured parsley cells.

Abstract: Run-off transcription assays were used to demonstrate that both the ultraviolet (UV)-B and blue-light receptors control transcription rates for chalcone-synthase mRNA in the course of light-induced flavonoid synthesis in parsley (Petroselinum crispum Miller (A.W. Hill)) cell-suspension cultures. Blue and red light alone, presumably acting via a blue-light receptor and active phytochrome (far-red absorbing form) respectively, can induce accumulation of chalcone-synthase mRNA. The extent of the response is however considerably smaller than that obtained when these wavebands are applied in combination with UV light. A preirradiation with blue light strongly increases the response to a subsequent UV pulse and this modulating effect of blue light is stable for at least 20 h. The modulating effect is abolished by a UV induction but can be reestablished by a second irradiation with blue light.

Plastic lens composition and method for the production thereof

Abstract: A method for making a plastic lens and a plastic lens made thereby. The method comprises disposing a liquid monomer or a monomer mixture and a photosensitive initiator into a mold cavity and directing ultraviolet light to act on the lens forming material in the cavity to produce a lens therefrom.

Expression of Basic Fibroblast Growth Factor in the Rat Ovary: Detection of mRNA Using Reverse Transcription-Polymerase Chain Reaction Amplification

Abstract: Development of the ovarian follicle and corpus luteum involves proliferation and differentiation of several cell types: granulosa cells, thecal cells, and various stromal cells, particularly the endothelial cells that compose the rich thecal and luteal vascular networks. Basic fibroblast growth factor (bFGF) is a potent mitogen for cells of mesodermal and neuroectodermal origin, including endothelial cells. With the use of reverse transcription-polymerase chain reaction (PCR), we have examined the expression of bFGF in the rat ovary. RNA was extracted from fetal bovine aortic endothelial cells, hypothalami of adult rats, and either whole ovaries or isolated granulosa cells from PMSG-primed immature rats. The RNA was reverse transcribed and then amplified by PCR using two oligonucleotide primers specific for both bovine and rat bFGF. A sample of the PCR solution was size fractionated by electrophoresis in an 8% polyacrylamide gel, which was then stained with ethidium bromide and examined under ultraviolet light. When reverse transcription-PCR was performed on RNA from bovine endothelial cells, rat hypothalamus, or whole rat ovary, a single major DNA band corresponding in length to the distance between the 5'-ends of the two bFGF-specific primers (354 base pairs) was obtained. The identity of this material with the bovine and rat bFGF sequences was confirmed by restriction enzyme analysis. When RNA from isolated granulosa cells was examined, however, no bFGF mRNA was detected. These results confirm that the bFGF gene is expressed in the ovary during follicular development. Furthermore, they demonstrate that ovarian bFGF expression is cell specific, since granulosa cells do not contain detectable bFGF mRNA.

Evaluation of deoxyribonucleic acid (DNA) isolated from human bloodstains exposed to ultraviolet light, heat, humidity, and soil contamination

Abstract: This study was designed to analyze the effects of common environmental insults on the ability to obtain deoxyribonucleic acid (DNA) restriction fragment-length polymorphisms (RFLP) patterns from laboratory prepared specimens. The environmental conditions studied include the exposure of dried bloodstains to varying amounts of relative humidity (0, 33, 67, and 98%), heat (37°C), and ultraviolet light for periods of up to five days. In addition, the effect of drying over a four-day period in whole blood collected with and without ethylenediaminetetraacetate (EDTA) was examined. The results of the study showed that, under the conditions studied, the integrity of DNA is not altered such that false RFLP patterns are obtained. The only effect observed was that the overall RFLP pattern becomes weaker, but individual RFLP fragments are neither created nor destroyed.

Excess benign melanocytic naevi after chemotherapy for malignancy in childhood.

Abstract: OBJECTIVE--To see whether children who have had chemotherapy develop increased numbers of moles. DESIGN--Blind assessment of patients having chemotherapy and subsequent comparison with the first suitable patients matched for age and sex who were attending the clinic during the same period after having completed treatment. Controls were obtained the following year by taking the first suitable patients attending a routine dermatology outpatient clinic who matched the study groups for age and sex. SETTING--Referrals to a paediatric oncology clinic and a dermatology clinic at two city hospitals. PATIENTS--The group receiving chemotherapy comprised all 32 patients with acute lymphatic leukaemia, lymphoma, and rhabdomyosarcoma who were attending the paediatric oncology clinic on two mornings a week during October 1987 to March 1988. The group who had completed treatment comprised 32 patients who were attending for follow up during the same period and who matched the first group for age and sex. Thirty two other patients attending the dermatology outpatient clinic with unrelated skin conditions served as controls. END POINT--Definite increase in numbers of moles on children after a course of chemotherapy. MEASUREMENTS AND MAIN RESULTS--Moles were counted by one observer on defined areas of the body and divided into those less than 3 mm and greater than or equal to 3 mm diameter. Patients receiving chemotherapy had a similar number of moles to the control group. By contrast patients who had completed chemotherapy had significant increases both in moles less than 3 mm and greater than or equal to 3 mm and in the total number of moles. These patients were more likely to have moles on acral sites. CONCLUSIONS--Children with substantially increased numbers of moles (benign melanocytic naevi) after successful chemotherapy for malignancy may have an increased risk of melanoma. They should be offered prolonged surveillance and cautioned about exposure to ultraviolet light.

Polarized light in high-redshift radio galaxies

Abstract: HIGH-redshift radio galaxies are characterized by ultraviolet excesses1,2 associated with elongated continuum and emission-line structures aligned along their radio axes3,4. Commonly, these properties are interpreted in terms of jet-induced star formation. However, observations of a blue, polarized continuum knot in the low-redshift radio galaxy PKS2152 — 69 have suggested an alternative beaming/scattering model5,6. To test this model we have obtained imaging-polarimetry observations of two high-redshift radio galaxies: 3C277.2 (z = 0.766) and 3C368 (z = 1.132). We find that both sources are strongly linearly polarized at ultraviolet rest wavelengths, with E-vectors within 25° of perpendicular to the axis of the extended continuum and radio structures. This implies that a large proportion of the ultraviolet light in these objects does not come directly from stars and we suggest it is scattered radiation from the nucleus. These observations also have important implications for beaming models of the active nuclei and for our understanding of the evolution of the host galaxies.

Induction of cytochrome P450-mediated detoxification of xanthotoxin in the black swallowtail

Abstract: Xanthotoxin is a phototoxic allomone found in many of the host plants of the black swallowtail,Papilio polyxenes (Lepidoptera: Papilionidae). When added to the diet of final instar larvae, xanthotoxin can induce the cytochrome P450 monooxygenase (P450) activity in midgut microsomes by which it is detoxified. Induction is dose-dependent, increasing sevenfold when larvae feed on parsley treated topically with xanthotoxin at 0.5 or 1.0% fresh weight. Although xanthotoxin exerts much of its toxic effects when photoactivated by ultraviolet light, induction of P450 activity did not differ in the presence or absence of ultraviolet light. Despite a 4.7-fold induction of xanthotoxin-metabolizing P450 activity, total P450 content measured in the same microsomal samples did not increase significantly. These data indicate that multiple forms of P450 exist in the black swallowtail midgut and that they are differentially induced by xanthotoxin.

Radiation curable abrasion resistant coatings from colloidal silica and acrylate monomer

Abstract: The present invention relates to coating compositions containing multifunctional acrylate monomers, acrylic monomers and colloidal silica Silanes are absent from these coating compositions Transparent, abrasion resistant coatings result from the cure, either by ultraviolet light or electron beam radiation, of these compositions

Repair of pyrimidine dimer ultraviolet light photoproducts by human cell extracts.

Abstract: A newly developed method allows human cell extracts to carry out repair synthesis on ultraviolet light irradiated closed circular plasmid DNA [Wood, R. D., Robins, P., & Lindahl, T. (1988) Cell 53, 97-106]. The identity of the photodamage that leads to this repair replication was investigated. Removal of stable pyrimidine hydrates from irradiated plasmid pAT153 did not significantly affect the amount of repair replication in the fluence range of 0-450 J/m2, because of the low yield of these products and their short DNA repair patch size. Photoreactivation of irradiated DNA using purified Escherichia coli DNA photolyase to remove more than 95% of the cyclobutane dimers from the DNA reduced the observed repair synthesis by 20-40%. The greater part of the repair synthesis is highly likely to be caused by (6-4) pyrimidine dimer photoproducts. This class of lesions is rapidly repaired by mammalian cells, and their removal is known to be important for cell survival after ultraviolet irradiation.

Isolation of a formamidopyrimidine-DNA glycosylase (fpg) mutant of Escherichia coli K12.

Abstract: The fpg+ gene of Escherichia coli coding for formamidopyrimidine-DNA glycosylase was previously cloned on a multicopy plasmid. The plasmid copy of the fpg+ gene was inactivated by cloning a kanamycin resistance gene into the open reading frame, yielding the fpg-1:: Knr mutation. This mutation was transferred to the chromosome in the following steps: (i) linearization of the plasmid bearing the fpg-1::Knr mutation and transformation of competent bacteria (recB recC sbcB); (ii) selection for chromosomal integration of the fpg-1::Knr mutation; (iii) phage P1 mediated transduction of the fpg-1::Knr mutation in the AB1157 background. The resulting fpg- mutant exhibited no detectable Fapy-DNA glycosylase activity in crude lysates. The insertion mutation was localized by means of genetic crosses between mtl and pyrE, at 81.7 min on the E. coli linkage map. Sequence analysis confirmed this mapping and further showed that fpg is adjacent to rpmBG in the order fpg, rpmGB, pyrE. The formamidopyrimidine-DNA glycosylase defective strain does not show unusual sensitivity to the following DNA damaging treatments: (i) methylmethanesulfonate, (ii) N-methyl-N′-nitro-N-nitrosoguanidine, (iii) ultraviolet light, (iv) γ-radiation. The fpg gene is neither part of the SOS regulon nor the adaptive response to alkylating agents.

Fluorescent and skeletal density banding in Porites lutea from Papua New Guinea and Indonesia

Abstract: Shallow water Porites lutea corals were collected along two transects normal to mainland shorelines, parallel to gradients in water quality: one, 7 km long, near Motupore Island in South Papua New Guinea, the other, 70 km long, from Jakarta Bay along the Pulau Seribu chain in the Java Sea. The corals were slabbed and studies were made of skeletal density bands as revealed by X-ray photography and fluorescent bands as revealed by ultraviolet light. Water quality measurements and rain-fall data were assembled for the two areas and related to skeletal banding patterns. For both areas, with increasing distance form mainland there is a decrease in overall brightness of fluorescence in corals and an increase in the contrast between bright and dull fluorescent bands. Fluorescence is bright, but seasonal banding is obscure in corals within about 2 km of stream mouths at Motopure and about 5 km of the coast in Jakarta Bay; this suggests that, despite low freshwater run-off during dry seasons, there are sufficient organic compounds which cause fluorescence in coral skeletons, to swamp seasonal effects. During the wet seasons, deluges of freshwater consequent on mainland rainfall of greater than about 150 mm/ month extend at least 7 km offshore in the Motupore area and perhaps tens of kilometres into Java Sea, giving distinctive bright and dull fluorescent banding in off-shore corals. The fluorescent banding pattern within corals on the Motupore reefs is similar in most corals along the transect and it correlates well with the Port Moresby monthly rainfall data. This relationship suggests that the same body (or bodies) of freshwater affect all reefs of the area during the wet season. The fluorescent banding in Java Sea corals does not show a precise correlation with either mainland or island monthly rainfall data; indeed the pattern of fluorescent banding on Pulau Seribu can only be matched in corals from reefs less than about 25 km apart. This suggests that in this area discrete water bodies carrying the relevant organic acids for coral fluorescence affect the fringing reefs on the chain of islands. Comparisons of fluorescent and density banding have revealed that for these areas, in general, periods of high freshwater run-off are times of deposition of less dense skeleton in Porites lutea corals.

Laser catheter system

Abstract: A fiber optic device for remote delivery of intense ultraviolet optical signals comprising an excimer laser source and an optical fiber. The output of the pulsed, transverse discharge, high pressure laser source is coupled to an articulating reflection mechanism which directs the pulsed laser output to an input end of the optical fiber. The optical fiber serves to transmit the light from the laser source to a remote location or target. The excimer laser further comprises a segmented first elongated laser electrode and a coextensive second laser electrode which is substantially solid. The discharge is stabilized by inductors connected to each segment of the first electrode and further by preionization electrodes located adjacent and coextensive with the second electrode. The preionization electrodes comprise a central conductor surrounded by a dielectric sleeve. The laser further comprises a closed gas system for the lasing medium gas. The gas system comprises a circulating blower, a heat exchanger and a cryogenic trap. The optical fiber comprises a central core having a substantially constant index of refraction and a cladding having an index of refraction which varies as the radius of the cladding. Thus, the invention advantageously permits high intensity ultraviolet light to be generated over extended periods of time utilizing a sealed laser and furthermore delivers the high intensity ultraviolet light to a remote location through an optical fiber with minimal damage to the fiber. The system is particularly well suited for application as a percutaneously introduced laser angioplasty system for removal of vascular obstructions.