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Biomedical subjects

D B Brown

Publications and source records attributed to D B Brown.

At least 37 records · Page 2Linked to original sources
PubMed1998

Occlusive ligature and standardized fenestration of a Baerveldt tube with and without antimetabolites for early postoperative intraocular pressure control.

OBJECTIVE: To determine the effectiveness of a surgical modification for a nonvalved aqueous tube shunt in controlling intraocular pressure (IOP) in the early postoperative period. The effect of antimetabolite use on IOP also was studied. DESIGN: A retrospective study of consecutive patients who underwent modified Baerveldt 350-mm2 implant with varied, nonrandomized, exposure to antimetabolites. PARTICIPANTS: Fifty-one eyes of 46 patients with uncontrolled glaucoma were examined. INTERVENTION: Identical surgical modification of a Baerveldt 350-mm2 tube was performed in all cases and consisted of placement of an occlusive 7-0 polyglactin suture just anterior to the plate followed by a through-and-through penetration of the tube just anterior to the occlusive ligature with a standardized 15 degrees blade. Seventeen eyes were not exposed to antimetabolite, while 2 groups of 17 eyes had 3 minutes' episcleral exposure to either 5-fluorouracil 50 mg/ml or mitomycin C 0.4 mg/ml at the location corresponding to the fenestration. The Tenon's layer and conjunctiva were not exposed because of concerns regarding conjunctival erosion over the device. MAIN OUTCOME MEASURE: Intraocular pressure and number of antiglaucoma medications required were analyzed. RESULTS: For the group, mean IOP before surgery and on postoperative days 1, 4, 10, 21, 42, 63, 84, and 112 was (in millimeters of mercury) 34.6, 20.1, 17.0, 17.2, 22.0, 17.3, 18.7, 17.4, and 15.6, respectively. There was an elevation of IOP at day 21 relative to fibrotic blockage of the fenestration before suture autolysis. This was temporized with antiglaucoma medication until suture autolysis occurred or treated with laser suture lysis (8 eyes). On day 1, hypotony occurred in 3 (6%) eyes whereas IOP greater than 30 mmHg was observed in 13 (26%) eyes. By day 10, the frequency had decreased to one (2.1 %) eye and three (6.4%) eyes, respectively. The use of antimetabolites did not result in lower IOP or less medication needed for any group at any interval (analysis of variance). CONCLUSION: This modification of a nonvalved glaucoma tube shunt device provides adequate IOP control in the early postoperative period with a low rate of hypotony and surgical complications. If elevation of IOP occurs before suture autolysis, it generally is well controlled by antiglaucoma medications or laser suture lysis. Antimetabolite exposure did not influence early postoperative IOP in this study.

Aged↗
PubMed1998

Treatment of spider veins with the 595 nm pulsed-dye laser.

BACKGROUND: Previous attempts to treat spider veins with the conventional 585 nm pulsed-dye laser with a 0.5-ms pulse duration have been relatively ineffective. Recently, a new pulsed-dye laser that is tunable from 585 to 600 nm with a pulse duration 3 times longer than previously available lasers has preliminarily been shown to be effective for treatment of spider veins. OBJECTIVE: Our purpose was to evaluate the effectiveness of multiple treatments with the tunable long-pulse dye laser in treatment of spider veins of the lower extremity. METHODS: Ten female volunteers were treated in two separate areas containing blue or red linear spider veins less than 1.5 mm in diameter. Treatments were administered with the pulsed-dye laser with a 1.5-ms pulse duration and 595-nm light at fluences of 15 and 20 J/cm2, and each subject received a total of 3 treatments at each site, administered at 6-week intervals. Photographs were taken before and 6 weeks after the last treatment. RESULTS: Computer-based image analysis showed clearing of more than three fourths of veins after 3 treatments with 15 or 20 J/cm2. Side effects were minimal and the treatments were well tolerated. CONCLUSION: The 595 nm, 1.5 ms pulse duration, pulsed-dye laser is safe and effective for treating blue or red spider veins of the lower extremities less than 1.5 mm in diameter in nontanned patients with Fitzpatrick skin types I and II. Multiple treatments improve on the results obtained after a single treatment.

Adult↗
PubMed1997

Evaluation of sunscreens with various sun protection factors in a new transgenic mouse model of cutaneous photoaging that measures elastin promoter activation.

BACKGROUND: Long-term sun exposure can cause major alterations in the papillary dermis, resulting in the deposition of massive amounts of abnormal elastic material, termed solar elastosis. Previous work has demonstrated that this type of photodamage is accompanied by an increase in elastin and fibrillin messenger RNAs and elastin promoter activity. OBJECTIVE: Our purpose was to develop a rapid and sensitive in vivo method for evaluating compounds offering protection against cutaneous photodamage. METHODS: Using a line of transgenic mice that expresses the human elastin promoter linked to a chloramphenicol acetyltransferase reporter gene, we applied sunscreens with various sun protection factors to 5-day-old mice followed by 30 minimal erythema doses of solar simulating radiation for three consecutive days. RESULTS: Solar simulating radiation alone resulted in a fivefold increase in elastin promoter activity. Sun protection factors of 2, 4, 8, and 15 yielded a reduction in promoter activity by 2.8%, 42.5%, 58.1%, and 70.3%, respectively. CONCLUSION: These results confirm the use of this system as a rapid and sensitive in vivo model for evaluating compounds that protect against photodamage.

Animals↗
PubMed1996

Long-term sun exposure alters the collagen of the papillary dermis. Comparison of sun-protected and photoaged skin by northern analysis, immunohistochemical staining, and confocal laser scanning microscopy.

BACKGROUND: Long-term solar irradiation produces both morphologic and functional changes in affected skin. Because collagen is the major structural component of skin, any alteration in its production or degradation could have profound effects on cutaneous functional integrity. OBJECTIVE: Our purpose was to investigate alterations in the production and morphology of collagen fibers brought about by long-term sun exposure. METHODS: We compared collagen and collagenase gene expression and collagen immunohistochemical staining and used confocal laser scanning microscopy for morphologic examination of dermal collagen fibers in photodamaged compared with sun-protected skin from the same persons. RESULTS: Despite a large increase in elastin messenger RNA in sun-damaged skin, collagen and collagenase gene expression remained essentially unchanged. However, striking alterations in the papillary dermis of photoaged skin were found, which revealed large, abnormally clumped elastic fibers and deformed collagen fibers of various diameters, replacing the normal architecture of the papillary dermis. CONCLUSION: Our data provide evidence for normal collagen gene expression in sun-damaged skin and suggest that degradation and remodeling of collagen take place in the papillary dermis accompanied by deposition of other matrix components, predominantly abnormal elastic fibers.

Blotting, Northern↗
PubMed1996

Chronic sun exposure alters both the content and distribution of dermal glycosaminoglycans.

Chronic sun exposure leads to structural and functional alterations in exposed skin. Photoageing is a process distinct from the changes taking place due to chronological ageing. Unique alterations in the dermal extracellular matrix occur as a result of photoageing and are responsible for many of these physiological changes taking place in sun-damaged skin. Accompanying the deposition of abnormal elastic tissue, or solar elastosis, are significant alterations in dermal glycosaminoglycans (GAGs). Accumulation of GAGs as a result of photoageing, as demonstrated in both humans and animal models of photoageing, seems almost paradoxical in view of the large amounts of GAGs present in the skin of newborns, making their skin well hydrated and supple, in sharp contrast to the weathered appearance of photoaged skin. We investigate the relative GAG content of photoaged skin using immunoperoxidase stains specific for hyaluronic acid and chondroitin sulphate, and determine the location of these GAGs using confocal laser scanning microscopy. Our results demonstrate significant increases in GAG staining in sun-damaged vs. sun-protected skin from the same individuals, as measured by computer-based image analysis. Furthermore, confocal laser scanning microscopy reveals that the increased dermal GAGs in sun-damaged skin are deposited on the elastotic material of the superficial dermis of photodamaged skin, and not between collagen and elastic fibres as in normal skin. The abnormal location of GAGs on these fibres may explain the apparent paradoxical weathered appearance of photodamaged skin despite increased GAGs.

Chondroitin Sulfates↗
PubMed1996

8-methoxypsoralen and ultraviolet a radiation activate the human elastin promoter in transgenic mice: in vivo and in vitro evidence for gene induction.

Treatment of skin diseases with the combination of 8-methoxypsoralen and ultraviolet A radiation (PUVA) results in clinical alterations in treated skin that resemble those observed in chronically photodamaged skin. The PUVA-treated patients develop nonmelanoma skin cancers, pigmentary alterations and wrinkling characteristic of sun-induced changes. The major alteration in the dermis of sun-damaged skin is the deposition of abnormal elastic fibers, termed solar elastosis. Up-regulation of elastin promoter activity in dermal fibroblasts explains the excess elastic tissue but not the reason for the aberrant morphology of the elastotic material. In order to study photoaging in an experimental system, we utilized a transgenic mouse line that expresses the human elastin promoter/chloramphenicol acetyltransferase construct in a tissue-specific and developmentally regulated manner. Although UVB radiation has been demonstrated to increase promoter activity in vitro, UVA fails to demonstrate a similar effect at the doses utilized. In this study, we demonstrate the ability of PUVA treatment to up-regulate elastin promoter activity both in vitro and in vivo. These data help to explain the development of photoaging in sun-protected PUVA-treated skin. We attribute the up-regulation of elastin promoter activity in response to PUVA to the formation of DNA photoadducts, which do not occur in response to UVA radiation alone.

Animals↗
PubMed1996

Severe carbon monoxide poisoning in the pediatric patient: a case report.

A 10-yr-old female presented at Deaconess Medical Center, Spokane WA, comatose after being rescued from a house fire. Her carboxyhemoglobin was 48%. An 11-yr-old playmate presented with a carboxyhemoglobin level of 51% and later expired. Our patient was treated with hyperbaric oxygen therapy and manual artificial ventilation for 2.5 h. She recovered fully, and 7 mo later has had no neurologic deficits. Carbon monoxide bonds to the hemoglobin more tightly than oxygen, displacing the oxygen hemoglobin dissociation curve to the left and resulting in tissue hypoxia and hypotension. Carbon monoxide also exerts a negative influence on the electron transport chain, may lead to delayed neurologic sequelae because of free radical formation, and produces profound changes in the myocardium. Once seen as a capricious treatment for many symptoms, hyperbaric oxygen therapy is now an accepted treatment for carbon monoxide poisoning. The outcome suggests that in a patient whose prognosis is grave, a good outcome may be achieved with aggressive HBO therapy.

Carbon Monoxide Poisoning↗
PubMed1995

Some cases of human male infertility are explained by abnormal in vitro human sperm activation.

OBJECTIVE: To determine if a human sperm activation assay can be used to evaluate males exhibiting otherwise unexplained infertility. DESIGN: Sperm from age-matched fertile and idiopathic infertile males were assayed in the human sperm activation assay and the results were compared. A portion of the sperm from the idiopathic infertile males also was used in assisted reproductive technology (ART) attempts at pregnancy. PATIENTS: Idiopathic infertile couples who had extensive fertility testing with no identified problems that would explain their infertility. Fertile males that had fathered one or more children. MAIN OUTCOME MEASURES: Sperm nuclear decondensation-recondensation and DNA synthesis. Pregnancies resulting from ART using semen from a male whose sperm responded abnormally in the human sperm activation assay. RESULTS: Thirteen (22%) of 59 idiopathic infertile males produced sperm that responded abnormally in the human sperm activation assay. Only 1 (1.7%) of 59 fertile males produced sperm that responded abnormally in the human sperm activation assay. The percentage of abnormal responders in the patient group exhibiting unexplained infertility was significantly higher than in the fertile male group. No sperm samples that responded abnormally in the human sperm activation assay resulted in pregnancies when used in ART. CONCLUSIONS: The human sperm activation assay is a new and independent indicator for some cases of infertility that otherwise would be unexplained. The human sperm activation assay appears to have utility in determining a sperm sample's efficacy for fertilization in ART attempts at pregnancy.

Cell Nucleus↗
PubMed1995

Ultraviolet radiation activates the human elastin promoter in transgenic mice: a novel in vivo and in vitro model of cutaneous photoaging.

The major alteration in photoaged skin is the deposition of massive amounts of abnormal elastic material, termed solar elastosis. In previous work, it has been shown that solar elastosis is accompanied by increased abundance of elastin and fibrillin mRNAs and upregulation of elastin promoter activity. Using a transgenic mouse line, which expresses the human elastin promoter, linked to a chloramphenicol acetyltransferase reporter gene, in a tissue-specific and developmentally regulated manner, we investigated the effects of ultraviolet A radiation and ultraviolet B radiation on human elastin promoter activity in vivo and in vitro. Irradiation of mice with a single dose of ultraviolet B radiation (491.4 mJ/cm2) resulted in an increase up to 8.5-fold in promoter activity, whereas a more modest increase of 1.8-fold was measured with ultraviolet A radiation (38.2 J/cm2). In addition, in vitro studies revealed over a thirtyfold increase in elastin promoter activity in response to ultraviolet B radiation (5.5 mJ/cm2), whereas no change was measured in response to ultraviolet A radiation (2.2 J/cm2). These results confirm the role of ultraviolet B radiation in elastin promoter activation in photoaging, and identify ultraviolet A radiation as a contributing factor. This system should serve as a useful in vivo and in vitro model to study cutaneous photoaging, and for testing compounds that may protect against cutaneous photodamage.

Animals↗
PubMed1994

Use of chromosome microdissection, the polymerase chain reaction, and dot blot hybridization to analyze double minute chromosomes.

The potential usefulness of chromosome microdissection, the polymerase chain reaction (PCR), and dot blot hybridization as a quick screening method for determining the genetic composition of double minute chromosomes (DMs) was evaluated. DMs or abnormally banding regions (ABRs) were microdissected from multidrug-resistant hamster cell lines and amplified with PCR using primers specific for the hamster multidrug-resistance (MDR) gene, pgp 1. The microdissected-PCR-amplified products were shown to (a) hybridize to a 32P-labeled pCHP1 probe for the hamster MDR gene by using dot blot or Southern blot analysis and also (b) hybridize back to the chromosome region from which they were originally dissected by using fluorescent in situ hybridization. Microdissected/PCR-amplified DMs were also shown to hybridize to ABRs. When microdissected DMs and ABRs were amplified using hamster specific Alu primers, the resulting material was shown to hybridize with probes for hamster MDR and Alu. These results suggest that the DMs contained in these MDR hamster cell lines contain Alu-like sequences and the chromosome microdissection-PCR-hybridization approach might be used as a quick screening method for identifying genes amplified in DMs and ABRs in cell lines and human tumor samples.

Animals↗
PubMed1994

Corneal ablations produced by the neodymium doped yttrium-lithium-fluoride picosecond laser.

This study examines corneal ablations produced by the neodymium doped yttrium-lithium-fluoride (Nd:YLF) picosecond laser. The laser delivers a 1-KHz, 40-ps pulsed, 1,053-nm wavelength beam (with energy measured in microjoules) to a 15-microns diameter spot size. The ablation mechanism is by plasma formation, which generates acoustic shock waves. Using enucleated rabbit (n = 25) and human donor eyes (n = 29), corneas were examined after tissue ablation at energies ranging from 40 to 300 microJ per pulse with various programmed ablation depths and patterns. The histologic data were collected using light microscopy and transmission electron microscopy. The tissue effects and Nd:YLF laser functions studied were ablation thresholds, cutting ability, programmed ablation depth accuracy, and acute endothelial effects. Our study showed histologic ablation thresholds for the following human corneal layers: epithelium = 7.15 +/- 0.05 x 10(11) W/cm2 (34.1 +/- 8.1 J/cm2 per pulse, 50 microJ per pulse); Bowman's layer = 1.33 +/- 0.29 x 10(12) W/cm2 (58.5 +/- 3.3 J/cm2 per pulse, 100-110 microJ per pulse); stroma and endothelium = 7.10 x 10(11) W/cm2 (28.4 J/cm2 per pulse, 50 microJ per pulse). Depth of corneal ablation was found to be directly related to energy and independent of programmed ablation depth. This study shows the endothelial loss in rabbit corneas by energy beams (50 microJ per pulse) focused 100 microns from this layer.

Animals↗
PubMed1994

The mechanism of ablation of corneal tissue by the neodymium doped yttrium-lithium-fluoride picosecond laser.

This study examines the structural changes in cornea resulting from plasma formation and propagated acoustic shock waves produced by the neodymium doped yttrium-lithium-fluoride (Nd:YLF) picosecond laser. Human donor eyes and enucleated rabbit eyes were subjected to various ablation patterns at energies ranging from 40 to 300 microJ per pulse. Two distinctly different patterns were produced depending on the location of initial plasma formation. Plasmas initiated at the corneal surface produced smooth, straight-edged ablations of corneal tissue that consisted of collagen fibril fragmentation, fibril organizational disruption, and possible thermal effect observed along the lateral borders and wound apex. The extent of lateral damage was directly related to the energy applied. The range of acute collagen disorganization observed at the ablation edge in rabbit corneas at various pulsed energies was as follows: 50 microJ = 1.0-12 microns, 150 microJ = 3.8-12.5 microns, 250 microJ = 6.2-23.7 microns, and 300 microJ = 7.5-45.0 microns. Plasma formation initiated within the stroma at or above threshold energies (50-150 microJ per pulse) produced an inter- or intralamellar separation effect with little evidence of ablation or collagen fibril fragmentation. Intrastromal plasmas generated from higher energies (200-300 microJ per pulse) produced tissue ablation, along with ablation or disruption of tissue anterior to the intrastromal target area.

Animals↗
PubMed1993

Community psychiatry training for general psychiatry residents: results of a national survey.

Through its residency training committee, the American Association of Community Psychiatrists (AACP) surveyed residency training programs throughout the country with the goal of discovering what training is currently in place to prepare psychiatrists for work in "community" or "public" settings which serve traditionally underserved populations. The authors summarize the results of the survey and offer suggestions for further steps needed to improve residency training curricula and to address the need for well qualified psychiatrists to choose careers in community psychiatry.

Career Choice↗
PubMed1993

Training residents for community psychiatric practice: guidelines for curriculum development.

There is a critical need to recruit and retain more psychiatrists with the required skills and interest to work with seriously mentally ill and/or socially disadvantaged patients within organized programs in community settings. More residency training programs having the capacity to prepare psychiatrists for community practice can help to meet this need. A consensus definition of the clinical, administrative, consultative and academic areas of contemporary community psychiatric practice developed by the American Association of Community Psychiatrists is used to determine the goals of the training curriculum described in this paper. A comprehensive list of knowledge, skill, and attitude objectives, as well as suggestions for structuring clinical training assignments are provided as guidelines for curriculum development.

Adult↗
PubMed1992

Hyperbaric oxygen treatment for carbon monoxide poisoning in pregnancy: a case report.

Carbon monoxide (CO) poisoning is one of the most common forms of poisoning in the United States. When CO poisoning occurs in the pregnant patient, it is extremely toxic to the mother and fetus in terms of central nervous system disorders and delayed central nervous system sequelae. Controversy exists in treating the pregnant patient with hyperbaric oxygen (HBO) because of the unknown effects of high partial pressures of oxygen on the fetus. HBO therapy is beneficial in CO poisoning because of its effect of first increasing oxygen concentration and causing a shift in the oxygen dissociation curve from the left to the right. Second, by causing a diminished CO interaction with cytochrome oxidase, HBO allows mitochondria to use oxygen more effectively. Third, HBO may reduce lipid peroxidation which may be responsible for neurological deterioration and delayed central nervous system sequelae. Fourth, decreased CO influence through HBO may reduce changes in the myocardium as a result of CO poisoning, if cardiovascular disease is already present. A case study of successful HBO therapy used during pregnancy is presented and effects of CO on the fetus are discussed.

Adult↗
PubMed1991

Partial purification of Xenopus laevis egg extract factor(s) that induce swelling in permeabilized human sperm.

A combination of adsorption (protamine-agarose) and gel filtration (Sephacryl S-300) chromatography was used to enrich for factor(s) in Xenopus laevis frog egg extract that induce nuclear swelling-chromatin decondensation in permeabilized human sperm. It was determined that a 70-fold purification of the factor(s) that induce human sperm nuclear swelling has resulted from the purification scheme. The reduced, active factor(s) have a Kav of 0.12 and an approximate molecular weight of 290,000 daltons. The extract nuclear swelling activity is sensitive to temperatures of 50 degrees C and above, as well as proteolytic treatment. RNase and cycloheximide treatments of the extracts have no effect on the nuclear swelling activity. These data suggest that the egg extract factor(s) that induce nuclear swelling in permeabilized human sperm are protein(s) that are present in the unfertilized frog egg.

Animals↗
PubMed1991

A community-based study into the possible reasons for the high incidence of cardiovascular disease in the west Highland District of Lochaber.

Cardiovascular screening of 726 males in a Fort William group practice was undertaken in an effort to determine possible causes for the high incidence of cardiovascular disease in the area. Sixty-four per cent of those sampled were born outside the area. The mean fasting plasma cholesterol level was surprisingly low at 5.4 mmol/l. Forty-three per cent of the sample were smokers and 22% had diastolic blood pressures above 90 mm Hg, 24% were clinically obese and 29% had a history of ischaemic heart disease amongst first degree relatives. Public awareness of cardiovascular risk factors was found to be low. A local health education programme could prove to be of great benefit.

Adult↗