Biomedical subjects

C G Murphy

Publications and source records attributed to C G Murphy.

14 recordsLinked to original sources

PubMed1992

Outflow obstruction in pigmentary and primary open angle glaucoma.

To localize the site of outflow obstruction in glaucoma, we evaluated the trabecular meshwork tissues by morphometric methods. Thirty-three specimens from 27 patients with primary open angle glaucoma (n = 13), pigmentary glaucoma (n = 4), and pigment dispersion syndrome (n = 2), and from nonglaucomatous normal subjects (n = 8) were compared. In these specimens, the extent of aqueous channels and the area occupied by these channels where they terminate in cul-de-sacs were measured. In 32 nonglaucomatous normal specimens (six of the eight mentioned plus an additional 26), we discovered that 94% of the surface area of the cul-de-sacs is lined by trabecular cells. These measurements were used to calculate the resistance to aqueous outflow offered by cul-de-sacs. Three new concepts are advanced in this report: (1) the cul-de-sacs provide a major portion of the normal outflow resistance, (2) the cul-de-sac area is markedly reduced in pigmentary glaucoma and primary open angle glaucoma, accounting for a major portion of the increase in resistance in these conditions, and (3) macrophages are the major cell type responsible for trabecular meshwork clearance of pigment and debris. A common pathophysiologic sequence of events is proposed for the development of glaucoma in pigmentary glaucoma and primary open angle glaucoma.

Adult↗

PubMed1992

Juxtacanalicular tissue in pigmentary and primary open angle glaucoma. The hydrodynamic role of pigment and other constituents.

We tested the hypothesis that obstruction of the juxtacanalicular tissues, by melanin granules in pigmentary glaucoma and by other impermeable material in primary open angle glaucoma, leads to the development of a chronic glaucomatous condition. The distribution and concentration of melanin and other impermeable materials in the juxtacanalicular tissues and elsewhere in the trabecular meshwork was determined in 13 specimens. Six specimens were from patients with pigmentary glaucoma, two from patients with pigment dispersion syndrome, and three from patients with primary open angle glaucoma, as well as two from normal subjects. The effect of these materials on flow resistance was estimated using two hydrodynamic models. In model A, the electron-lucent spaces of the juxtacanalicular tissue were assumed to be open spaces, while in model B, these spaces and spaces filled with ground substance were assumed to be gel filled. In pigmentary glaucoma, 3.5% of the pigment was found in the juxtacanalicular tissue, while 96.5% was found in the corneoscleral and uveoscleral tissues. Permeabilities calculated according to model A were much higher than those expected from estimates of outflow facility in all groups, in agreement with the previous report of Ethier et al. The gel-filled spaces available for fluid flow, as determined by model B, showed no statistically demonstrable differences (pigmentary glaucoma, 32.9%; primary open angle glaucoma, 36.6%; pigment dispersion syndrome, 43.4%; normal, 44.1%). Furthermore, the amount of pigment present in the juxtacanalicular tissue was determined to have a negligible influence on permeability. Thus, the development of the chronic glaucomatous condition cannot be directly attributed to pigment accumulation in the juxtacanalicular tissue in pigmentary glaucoma.

Adult↗

PubMed1992

Minimizing anisometropia in bilateral pseudophakia.

One hundred twenty patients who had bilateral posterior chamber intraocular lens implantation were analyzed for postoperative anisometropia. All pairs of lenses had the same A constant and similar designs. Several parameters were analyzed to identify patients at higher risk for clinically significant anisometropia upon implantation of the second eye and determine whether the results of the first eye could be used to modify the implant power selected for the second eye to reduce the risk of anisometropia. In most cases, simply using the value of the linear regression prediction for emmetropia in the second eye without modifications minimized anisometropia.

Anisometropia↗

PubMed1992

Infection after injury: association with blood transfusion.

This study was undertaken to evaluate the association between red blood cell transfusions and infections in an easily stratified, homogenous group of injured adults. All received their initial transfusions upon arrival to the emergency department. Over 5 years, 390 uncross-matched trauma patients received type "O" red blood cells (RBCs) during initial resuscitation. One hundred fifty-four (39%) died within 7 days because of injuries sustained: 236 (61%) survived at least 7 days. Of these 236, clear differences could be seen between those receiving 6 or fewer or 7 or more units of RBCs. When adjusted for age, sex, and severity of injury (Champion Trauma Score, Injury Severity Score, TRISS), the risk of infection was higher in those receiving 7 or more units of RBCs. Similarly, risk of infection was related to units of RBCs transfused in a dose-related fashion. Blood transfusions should be avoided, if possible. Arbitrary "trigger points" for transfusions should be abandoned.

ABO Blood-Group System↗

PubMed1992

Postoperative ascitic leaks: the ongoing challenge.

BACKGROUND: The leak of ascitic fluid from surgical incisions is thought to be associated with a very high mortality rate. There have been few reports, however, focusing on the clinical characteristics, management, or mortality rates of this condition. METHODS: During a 10-year period, 18 patients with postoperative ascitic fluid leaks were treated. All patients had ascites before surgery and all had liver disease; in 13 of the 18 patients alcoholic liver disease was the cause of ascites. RESULTS: Ten of the 18 patients died (56%). Midline incisions were more often associated with recalcitrant leaks and fatal complications than were transverse incisions. CONCLUSIONS: Early consideration of fascial dehiscence and prompt repair is emphasized. The most effective predictor of survival was cessation of the leak.

Ascites↗

PubMed1991

A Bacillus subtilis dipeptide transport system expressed early during sporulation.

Two previously identified Bacillus subtilis DNA segments, dciA and dciB, whose transcripts accumulate very rapidly after induction of sporulation, were found in the same 6.2 kb transcription unit, now known as the dciA operon. Analysis of the sequence of the dciA operon showed that its putative products are homologous to bacterial peptide transport systems. The product of the fifth gene, DciAE, is similar to peptide-binding proteins from Escherichia coli and Salmonella typhimurium (DppA and OppA) and B. subtilis (OppA). A null mutation in dciAE abolished the ability of a proline auxotroph to grow in a medium containing the dipeptide Pro-Gly as sole proline source, suggesting that the dciA operon encodes a dipeptide transport system.

Amino Acid Sequence↗

PubMed1990

Treatment of candidosis in severely injured adults with short-course, low-dose amphotericin B.

Thirty-three (0.7%) of 4,818 trauma patients admitted between January 1, 1987, and July 1, 1989, developed invasive candidosis requiring IV antifungal therapy. All patients were seriously traumatized. Before developing candidosis, all patients had documented bacterial infections. These infections were generally polymicrobial and were treated with multiple broad-spectrum antibiotics (an average of 5.4 antibiotics for 17.2 days). Twenty-eight (85%) of 33 patients received enteral feedings for an average of 11 days +/- 1.5 (SEM) before developing candidosis and 24 (73%) received NG/oral nystatin for an average of 7.6 days +/- 0.9 before developing candidosis. All patients with candidosis were treated with intravenous amphotericin B: cumulative dose of 157.3 mg +/- 31.3 mg given over 10 days +/- 1.1. One patient developed recurrent candidosis despite NG/oral prophylaxis and enteral feedings. Six patients (18%) died due to sepsis and multiple organ failure. The patients who died did not objectively differ from the survivors. Candidosis is an infrequent infection in severely injured patients. Candidosis was invariably preceded by treatment with multiple broad-spectrum antibiotics for a variety of polymicrobial bacterial infections. NG/oral nystatin and enteral feedings did not prevent candidosis, in contrast to widely accepted beliefs. Amphotericin B therapy was safe. Recurrent candidosis was unusual. Candida infections had a high mortality rate associated with multiple blood transfusions and prolonged hospitalization. Candidosis represents a sign of severe injury and illness but can be amenable to prompt, aggressive treatment.

Adult↗

PubMed1989

Kinetics of phagocytosis in trabecular meshwork cells. Flow cytometry and morphometry.

Confluent human trabecular meshwork (HTM) cells from three different donors and at various stages of serial passage were fed fluorescein-labeled polystyrene beads. Phagocytosis was monitored for up to 6 days using flow cytometry, fluorescence microscopy, and morphometric calculations from comprehensive electron microscopic observations at key time points. During the first 4 hr after initiation of phagocytosis, the confluent endothelial monolayer lost its cohesiveness and became segregated into separate cells. During the first 3 days the cells underwent marked and progressive changes in shape and size. After 4 days, some cells detached from the dish, as necrotic debris and degenerative changes appeared. The kinetics of phagocytosis in this stable, confluent monolayer showed that recruitment (the percentage of cells which had ingested at least one bead) proceeded semilogarithmically, with 50% of the cells recruited by 8 hr and 97% by 96 hr. The time course of phagocytosis (ie, the average number of beads phagocytosed per cell) is described by a sigmoidlike curve, reaching half-maximum at 40 hr and maximum (about 500 beads per cell) at 96 hr. The rate of uptake (ie, the first derivative of the average number of beads per cell) reached a peak (nine beads per cell per hr) at 24 hr and then decelerated slowly over the next 5 days. Cytochalasin B treatment, as a control, reduced phagocytosis by approximately 70%. Flow cytometry, when combined with electron microscopy, should provide a useful tool to examine phagocytosis in HTM cells exposed to steroids and other hormones and drugs.

Adult↗

PubMed1989

Proteins secreted by human trabecular cells. Glucocorticoid and other effects.

The capacity of cultured human trabecular meshwork (HTM) cells to secrete an extracellular matrix was studied by indirect immunofluorescence. Synthesis of nine extracellular matrix (ECM) proteins known to be present in the normal trabecular meshwork was assessed in three HTM cell lines. Fourteen primary antibodies were used and cultures were labeled two and four weeks after confluence. The HTM cell lines showed consistent labelling patterns for the normal extracellular connective tissue constituents including collagens (types I, III, IV, V and VI), glycoproteins (laminin and fibronectin) and a basement membrane-associated proteoglycan. These antigens were localized to the basal cell surface in an extracellular reticular pattern corresponding to cell margins. Dextran addition at confluence helped to intensify the staining of these components, but ascorbate had no apparent effect. Interestingly, elastin, another normal component of the trabecular meshwork, was not identified under standard conditions, or after addition of ascorbate or dextran. However, elastin could be detected intracellularly following dexamethasone treatment for three days, and extracellularly in punctate deposits when this treatment was used for 1 or 2 weeks. Our findings indicate that HTM cells may be responsible for the secretion and maintenance of all the major ECM constituents of the trabecular meshwork. The elastin results suggest a possible mechanism contributing to obstruction of outflow in steroid glaucoma if increased amounts of elastin are also produced in vivo. This approach can also serve as a useful baseline for comparison with HTM cell lines treated with glaucoma medications or obtained from patients with glaucoma.

Antibodies↗

PubMed1987

Localization of extracellular proteins of the human trabecular meshwork by indirect immunofluorescence.

We used monospecific antibodies on semithin frozen sections to identify and localize the major tissue constituents of the nonglaucomatous human trabecular meshwork. The trabecular beams (sheets and cords) consist of a basement membrane (subendothelial extracellular matrix) surrounding an interstitial central core of connective tissue (substantia propria). The basement membrane contains collagen types III, IV, and V, the glycoproteins laminin and fibronectin, and the basement membrane-associated heparan sulfate proteoglycan. The trabecular basement membrane is unlike most subendothelial basement membranes because it contains collagen type III and a relatively disorganized structure. The central core contains collagen types I and III, and elastin. The closely linked juxtacanalicular meshwork contains collagen type III, but no collagen type I or elastin. The connective tissue composition of the trabecular meshwork appears similar to other highly compliant and resilient tissues, such as lung, blood vessels, and conjunctiva.

Adult↗

PubMed1986

Juxtacanalicular tissue in primary open angle glaucoma and in nonglaucomatous normals.

The juxtacanalicular (JXT) tissue was evaluated in 64 specimens from 36 nonglaucomatous normal persons and 28 specimens from 26 patients with primary open angle glaucoma (POAG). Morphometry was performed on more than 2000 electron micrographs taken from the entire JXT region of each of the 64 specimens studied. The concentration of three electron-dense materials (EDMs) believed to obstruct the JXT tissue in POAG was measured using precise and reproducible morphometric methods. There is a great deal of variability in the EDM concentration, but we could still measure a significant increase in EDM of about 0.2% each year in normal specimens. Specimens from patients with POAG who are younger than 40 years of age have an EDM concentration similar to that in normal specimens. After the approximate age of 40 years, a significant difference is observed in the EDM concentration between nonglaucomatous and POAG specimens. This difference represents an average increase of 23% in POAG. Such a difference is probably too small to account for the decrease in outflow facility characteristic of POAG.

Adolescent↗

PubMed1986

A BASIC program for deriving linear regression formulas for intraocular lens power prediction.

We present an original BASIC program written specifically for the ophthalmologist that allows calculation of linear regression formulas for prediction of emmetropic lens power from the surgeon's own data. The program features ongoing data storage, options for analyzing specific ranges (such as longer axial lengths), and calculation of residuals. The program is user-friendly and may be used with minimal computer knowledge. The authors will copy the program at no charge on a user's initialized diskette.

Computers↗

PubMed1986

Pathogenesis of Chandler's syndrome, essential iris atrophy and the Cogan-Reese syndrome. I. Alterations of the corneal endothelium.

Eight keratoplasty and 14 trabeculectomy specimens from Chandler's syndrome, Essential Iris Atrophy, and the Cogan-Reese syndrome were studied by electron microscopic and morphometric methods. The corneal endothelium in these conditions undergoes the most varied and complex alterations of any of the endotheliopathies so far studied. The size, shape, and density are altered, and the apical surface shows a myriad of abnormalities including alterations of the intercellular borders and junctions, and formation of numerous microvilli, filopodia, and "blebs." Whereas many cells have features indicative of metabolic activity, and others may have undergone division, still others appear to have been injured as they are disrupted and necrotic. There is also evidence for the presence of a low-grade, long-standing chronic inflammation and an associated loss of contact inhibition with formation of multiple endothelial layers. These changes do not encompass the entire endothelium, as some regions remain relatively unaffected, and each specimen presents a unique morphology. The endothelium is most affected in cases of Essential Iris Atrophy. Some changes may be related to such processes as cell migration and reparative activities. However, the presence of cell necrosis (apoptosis) and chronic inflammation (endotheliitis) may be more specifically related to the ICE syndrome endotheliopathy. The slit lamp and specular microscopy findings characteristic of this disease are correlated with the described histologic abnormalities.

Adolescent↗

PubMed1986

Pathogenesis of Chandler's syndrome, essential iris atrophy and the Cogan-Reese syndrome. II. Estimated age at disease onset.

The presence of a layer of abnormal material in Descemet's membrane in eight keratoplasty specimens served as a marker to determine whether Chandler's syndrome, Essential Iris Atrophy, and the Cogan-Reese syndrome are congenital or acquired conditions. In all eight cases of the ICE syndrome, a pattern of membrane deposition was observed, which typifies acquired disorders: a completely normal prenatal layer and both normal and abnormal portions of the postnatal layer. The thickness of the membrane deposited before the onset of abnormal secretion was used to estimate a time span for possible ages at which abnormal secretion began. The estimated age intervals for all diseased specimens had their lower limits in the postnatal period. Thus, these results led us to the conclusion that abnormal Descemet's membrane first appeared in postnatal life, years before clinical recognition of disease. The possibility of a viral etiology for this unilateral endotheliopathy resulting in an altered Descemet's membrane is discussed.

Adult↗