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Biomedical subjects

D W Rogers

Publications and source records attributed to D W Rogers.

At least 19 recordsLinked to original sources
PubMed1992

Augmentation of the systemic host anti-tumor response through laser excision.

This study examines whether primary laser excision results in augmentation of the systemic host anti-tumor response to tumor rechallenge. Single R3230AC mammary tumor implants, (0.5 x 0.5 x 1.0 mm), were grown in 112 female Fisher 344 rats. The animals were randomized. Group S tumors were excised by scalpel. Group E was excised with a Surgistat electrocautery (Valley Labs, Boulder, CO). Group CS was excised with a Sharplan 1100 CO2 laser (Sharplan, Allendale, NJ) at 25 watts (W) continuous wave (CW) (0.2 mm spot size) and the wound was "sterilized" with a 5-mm spot size by gently heating the tissue without blanching. Group K was excised with a KTP/532 laser (Laserscope, San Jose, CA) at 17 W CW using a 400 microns fiber. Group Y was excised with a Sharplan 2100 Nd:YAG laser set at 15W CW using a 0.2 mm clear sapphire tip. A second tumor implant, (0.5 x 0.5 x 1.0 mm), was placed at a remote site 14 days postoperatively. An unoperated control group was implanted. Secondary tumor volumes were measured for 36 days and the mean tumor volumes (MTV) were statistically compared. The MTV in groups CS, K, Y, and E was less than control (P less than 0.01). The MTV in groups CS, K, Y, and E was less than group S, although this was not statistically different. Lasers and cautery appear to increase the host response against subsequent tumor challenge. This study corroborates earlier studies of other modalities. Further studies to determine whether this host sensitization is an immune response and to elucidate the mechanisms of this effect are warranted.

Animals↗
PubMed1992

Hepatitis C virus does not cause nonalcoholic steatohepatitis.

The pathogenesis of nonalcoholic steatohepatitis (NASH) remains poorly understood. Since inflammation and fatty changes are associated with hepatitis C (HCV) infection, we have tested the role of HCV in the genesis of NASH. Five consecutive cases of classic NASH were tested by Abbott anti-c100-3 EIA and polymerase chain reaction (PCR) to detect HCV-RNA. All serum specimens were negative for anti-c100-3 (or anti-HCV EIA) and HCV PCR. Based on this study, we conclude that HCV does not play a causative or contributing role in the pathogenesis of NASH.

Adult↗
PubMed1992

Post-cardiac surgery tamponade mimicking acute hepatitis. Report of two cases.

Two patients developed cardiac tamponade from delayed hemorrhage into the pericardial sac following open heart surgery. The initial clinical manifestations of tamponade included nausea and dramatic elevations of serum aminotransferases, simulating acute hepatitis. To our knowledge, this presentation of cardiac tamponade has not been previously reported.

Acute Disease↗
PubMed1991

Effect of argon laser and Photofrin II on murine neuroblastoma cells.

Laser-induced fluorescence (LIF) of photosensitizers is used to detect cancer. The effect of argon laser light with an average irradiance of 31 mW cm-2 and Photofrin II (Dihematoporphyrin ether, DHE) at concentrations of 1.0 and 5.0 micrograms ml-1 on C1300 murine neuroblastoma cells (MNB, NB41A3) in vitro was investigated. Growth curves and cell viability (trypan blue dye exclusion) were determined at 1, 24, 96, and 144 hr post-irradiation. Light doses of 1.8 and 9.0 J cm-2 combined with 5.0 micrograms DHE ml-1 decreased both cell numbers and viability, immediately and up to 144 hr postirradiation. Argon laser light alone at a fluence of 9.0 J cm-2 caused reversible injury to the cells. This in vitro study shows that both low energy argon laser light and low dose DHE are cytocidal to C1300 MNB cells. LIF promises to aid in the detection and destruction of neuroblastoma. Surgeons should be aware that tissue irreversible damage is likely to occur when performing LIF detection of neuroblastoma. The doses of laser light and of Photofrin II found to be toxic to neuroblastoma cells in culture may provide guidelines for photodynamic therapy ablation of neuroblastoma clinically.

Animals↗
PubMed1991

The role of Monte Carlo simulation of electron transport in radiation dosimetry.

A brief overview is given of the role in radiation dosimetry of electron transport simulations using the Monte Carlo technique. Two areas are discussed in some detail. The first is the calculation of stopping-power ratios for use in ion chamber dosimetry. The uncertainty in stopping-power ratios is discussed with attention being drawn to the fact that the relative uncertainty in restricted collision stopping powers is greater than that in unrestricted stopping powers if the major source of uncertainty is the density effect correction. Using ICRU Report 37 stopping powers and electron spectra calculated in a small cylinder of graphite, the value of the Spencer-Attix graphite to air stopping-power ratio in a 60Co beam is found to be 1.0021 for an assumed graphite density of 1.70 g/cm(3) and 0.23% less for an assumed density of 2.26 g/cm(3). The second area discussed is the feasibility of using Monte Carlo techniques to calculate dose patterns in a patient undergoing electron beam radiotherapy.

Electrons↗
PubMed1990

Methods for the endoscopic photographic and visual detection of helium cadmium laser-induced fluorescence of Photofrin II.

Endoscopic detection of small tumors is key to the early diagnosis and treatment of malignancy. This paper describes a simple, endoscopic detection system which enables tumor localization and a permanent record based on the laser-induced fluorescence of dihematoporphyrin ether (LIFD). Spectral analysis of dihematoporphyrin ether (DHE, Photofrin II) was performed with a Perkin Elmer LS-5 scanning fluorimeter. DHE at concentrations of 50 micrograms/ml and 5 micrograms/ml in 95% ethanol were tested, demonstrating fluorescence quenching at 50 micrograms/ml DHE at 406 nm excitation. This phenomenon was not observed at 442 nm excitation. Based on this data and the availability of the helium cadmium laser, a series of endoscopic detection systems was developed and tested utilizing a LiConix 4240NB helium cadmium laser (TEMoo, 442 nm, 40 mW). A fiber with a microdiverging (MDL) lens was used. Irradiance achieved at the tip of the fiber was 31.58 mW/cm2 for MDL. A Corning 34832 (550 nm) sharp cutoff barrier filter was coupled to an Olympus OES BF2T10 bronchoscope. Successful detection of LIFD was obtained. Direct observation of LIFD is possible when wearing Laserguard argon safety goggles (OD 15 at 488 nm, OD 11 at 514 nm). Photographic recording of LIFD was performed with the following cameras and parameters: Olympus OM-2S camera (OM2) with EES135 film (ISO 1600) with a 4-second exposure (method 1) and the Olympus OES SCP-10 instant camera with Polaroid 779 (ISO 640) film and a 120-second exposure (method 2). The photographic methods demonstrate the red fluorescence of DHE on filter paper disks at concentrations of 0.5 micrograms/ml (500 ng/ml). (ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Ruptured mycotic pseudoaneurysm of the gastroduodenal artery presenting with hemoperitoneum and subcapsular liver hematoma.

We report a case of a patient with mycotic pseudoaneurysm of the gastroduodenal artery who presented with hemoperitoneum and subcapsular hematoma of the liver. The diagnosis was established with contrasted abdominal CT scanning. Visceral angiography was not needed. Prompt recognition and surgical intervention led to a favorable outcome. Pseudoaneurysm of visceral vessels is an uncommon disease process, and to our knowledge, this is the first reported case that has presented with free blood in the peritoneal cavity and beneath the liver capsule. This case may also represent a rare complication of therapeutic ERCP procedures. Mycotic aneurysm or pseudoaneurysm of visceral vessels may develop from bacteremia and its dissection or rupture should be suspected in patients presenting with sepsis and abdominal pain.

Aged↗
PubMed1990

Blood contamination of anaesthetic and related staff.

The incidence of skin contamination of anaesthetic and related staff by patient's blood and saliva was studied during 270 anaesthetics in Cardiff hospitals over seven continuous days in October 1989. A survey was also made of current Hepatitis B immunisation status and glove-wearing habits of 75 anaesthetists. Blood from 35 (14%) patients caused skin contamination of 65 staff during 46 incidents. Twenty-eight (61%) of the contamination incidents occurred during vessel cannulation. Five (8%) of the 65 staff contaminated by blood already had cuts on their hands. There were nine incidents (4%) of skin contamination by saliva. Fifty-three (71%) anaesthetists were immunised against Hepatitis B. Only seven (9%) anaesthetists wear gloves for oral or nasal intubation, six (8%) for insertion of peripheral venous cannulae, 47 (63%) for insertion of arterial lines and 67 (89%) for insertion of central lines. All anaesthetic and associated staff should wear gloves on a routine basis.

Anesthesiology↗
PubMed1989

Beneficial effects following carbon dioxide laser excision on experimental neuroblastoma.

Treatment of neuroblastoma in children consists of primary excision with adjuvant radiation and chemotherapy. When the tumor invades surrounding structures that cannot be safely excised or when distant metastasis is present, the patient has a poor prognosis. Because the CO2 laser can be used to excise malignant tumors without seeding the surrounding tissue and because the defocused beam can vaporize malignant cells, we compared partial scalpel excision and partial laser excision of C1300 murine neuroblastoma to the growth rate of residual tumor. In 25 mice, 75% of the tumor was excised with a scalpel, and in another 25, the same percentage was excised with the CO2 laser (10 W). CO2 laser excision significantly decreases the growth of residual neuroblastoma (P less than .01). However, the effect appears to be a function of increased tumor immunogenicity after laser excision rather than the increased tumor kill. We conclude that CO2 laser excision of neuroblastoma may prove to be superior to scalpel excision for primary surgical treatment of neuroblastoma.

Animals↗
PubMed1989

Monoclonal antibodies for detecting bone marrow invasion by neuroblastoma.

One hundred and sixty six bone marrow aspirates from children with abdominal neuroblastoma were independently examined for the presence of neuroblastoma cells by conventional haematological staining techniques and by indirect immunofluorescence using one or more of five monoclonal antibodies. Results using the two methods were evaluated by comparison with the results of bone marrow, bone and lymph node biopsy specimens taken at the same time, and in the light of the child's clinical course. One antibody, UJ13A, was found to have 98.5% specificity and 85.7% sensitivity, compared with sensitivities for conventional staining of 50% for aspirate alone and of aspirate or trephine biopsy specimen of 71.4%. The remaining antibodies UJ127/11, UJ223/8, UJ181/4 and UJ167/11, with specificities in the range 94-99%, were found to have sensitivities in the range 47-61%, lower than the sensitivity of conventionally stained aspirate or trephine biopsy specimen. Routine immunofluorescence staining with monoclonal antibody UJ13A should increase the sensitivity of detection of metastatic neuroblastoma.

Abdominal Neoplasms↗
PubMed1988

Comparison of continuous-wave, chop-wave, and super pulse laser wounds.

Some of the latest generation of CO2 lasers incorporate features that alter the wave form. The present study was undertaken to evaluate the relative zone of coagulation in acute laser wounds created in continuous-wave (CW), chop-wave (CPW), and super pulse wave (SPW) modes. The damage from single-point impact sites and incisions was compared in a guinea pig model. Animals were anesthetized with pentobarbital, and wounds were created with a 125-mm handpiece in focus (0.2-mm spot size) on dorsal and flank skin sites with the Sharplan 743 and 1100 CO2 lasers (Sharplan, Ltd., Allendale, NJ). Point impacts of CW and CPW were compared at power levels of 5, 10, 25, 40, 60, and 80 W at time durations of 0.05, 0.1, 0.2, and 0.5 seconds. Incisions of 3.0 cm were created at 25 W in CW, CPW, and SPW modes. Histologic sections stained with hematoxylin and eosin and Van Giesen elastin stains were evaluated by a single observer (R.J.L.). Zones of coagulation for the point-impact study varied from 79 to 257 +/- 66 (SD) micron in width with no significant differences between any of the wounds. Greater thermal damage (coagulation) occurred as the time interval increased. The zones of coagulation in the incision study were 309 +/- 83 (SD) micron for CW, 238 +/- 51 (SD) micron for SPW1 (743), 260 +/- 79 (SD) micron for CPW, and 194 +/- 56 (SD) micron for SPW2 (1100). These results are significant to the P less than 0.01 level.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Comparison of local tumor recurrence following excision with the CO2 laser, Nd:YAG laser, and Argon Beam Coagulator.

This study compares the incidence of local tumor recurrence following primary excision with the CO2 laser, Nd:YAG laser (contact), Argon Beam Coagulator, or electrocautery. One hundred eight Fisher 344 rats with R3230AC mammary tumors (1.6 +/- 0.04 [SD] cm diameter) were used. All animals were randomized into groups of similar tumor size. In groups C and CS, excision was performed with a Sharplan 1060 CO2 laser (TEMoo, 25 W, continuous wave [CW], 0.2-mm spot size). Wounds in group CS were "sterilized" (0.5-mm spot size, 25 W, CW) by gently heating the wound without causing blanching or charring. In group N, a 0.4-mm contact Laser Blade and a Cooper 8000 Nd:YAG laser at 20 W CW was used. In groups SA1 and SA2, tumors were excised with the scalpel, and hemostasis and wound "sterilization" were accomplished with the Bard System 6000 Argon Beam Coagulator (ABC) at 40 W and 4 liters/min argon gas flow in SA1 and 12 liters/min in SA2. In group E, excision was accomplished at 40 W blend mode, 10 W spray mode. In group EA, excision was accomplished at 60 W cutting current, and hemostasis was achieved with the ABC. The animals were examined for evidence of recurrence for 34 days postoperatively. Mortalities were excluded from analysis. The incidence of recurrence was 11/14 (79%) in C, 6/16 (38%) in CS, 10/14 (71%) in SA1, 6/13 (46%) in SA2, 6/15 (40%) in N, 7/10 (70%) in EA, and 3/15 (20%) in E. Group E is statistically different (P less than .01) from groups EA, C, and SA1. Group C was different (P less than .01) from groups E, CS, and N. These results demonstrate an inverse relationship between tumor recurrence and local thermal effects at the surgical site. The ABC did not increase tumor recurrence. Contact YAG surgery was similar to CO2 laser excision and "sterilization." An attempt to study the influence of gas flow and pressure on local tumor recurrence and metastases should be made.

Adenocarcinoma↗
PubMed1988

Generation of photon energy deposition kernels using the EGS Monte Carlo code.

The EGS Monte Carlo code was used to generate photon energy deposition kernels which describe the energy deposited by charged particles set in motion by primary, first scattered, second scattered, multiple scattered and bremsstrahlung plus annihilation photons. These were calculated for a water medium irradiated with monoenergetic photons with energies in the range 0.1-50 MeV. In addition to the primary energy deposition kernels, primary charged particle transport was further characterised by computing the effective centre of the voxels, and the effective penetration depth, effective radius and effective lateral distance travelled by these particles. The dose per unit collision kerma for parallel monoenergetic primary photons beta' was calculated. Additional applications of the energy deposition kernels are discussed.

Computer Simulation↗
PubMed1988

Mechanisms of reduction of tumor recurrence with carbon dioxide laser in experimental mammary tumors.

This study compares local tumor recurrence after low energy CO2 laser wound sterilization with recurrence after scalpel, laser or electrocautery excision. Wound histologic changes were studied to understand the mechanism of the interaction between the laser and wound. Single implants of R3230AC mammary tumor were grown to an average diameter of 24 millimeters in the mammary ridge of 80 female fisher 344 rats. Rats were anesthesized with pentobarbital and randomized into groups, each with similar tumor size: scalpel (S), laser (L), laser with wound sterilization (LV), scalpel with sterilization (SV) and electrocautery (E). All surgical procedures were performed by the same surgeon with the same technique, with the exception of the instruments used. Tow rats from each group were sacrificed immediately and the wounds examined histologically. The Sharplan 1100 CO2 laser was used with a 125 millimeter hand piece in focus and in continuous wave for groups L and LV. Sterilization in groups LV and SV was performed with 5 millimeter spot size by heating the site gently without causing blanching of tissue. Excision in group E was performed with coagulating current from a monopolar cautery (Valley Lab). Rats were examined periodically for 30 days and those dying during this period were excluded from analysis. The incidence of wound recurrence was eight of 12 in group S; five of eight, L; four of 13, E; three of 12, LV, and two of nine, SV (p less than 0 .05). Histologic changes in the wound demonstrated viable tumor in all groups, with fewer areas present in groups E, SV and LV. Local thermal effects and the noncontact nature of the CO2 laser make it an effective adjunct in reducing local tumor recurrence by enhancing the cytoreductive capability of surgical procedures.

Adenocarcinoma↗