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G R Mason

Publications and source records attributed to G R Mason.

At least 19 recordsLinked to original sources
PubMed1999

Pancreatogastrostomy as reconstruction for pancreatoduodenectomy: review.

A summary of 733 reported cases of pancreatogastrostomy (PG) as a reconstructive procedure following pancreatoduodenectomy and the traumatically severed pancreas indicates an aggregate leakage rate of 4% over a 52-year period. Although mortality rates have declined over this period, the reported high correlation of leak with mortality seems to indicate the greater safety of PG over other methods for treating the residual pancreatic duct. The lower rate of complications related to pancreatocutaneous fistula from PG should correlate with shorter and less expensive hospital stays for patients treated with this technique. Several questions regarding technique must await further investigation.

Gastrostomy↗
PubMed1998

Appropriate background correction for DTPA aerosol clearance.

Measurement of the clearance rate of inhaled aerosols of 99mTc-diethylenetriamine pentaacetic acid (DTPA) from distal airway to pulmonary capillary is a sensitive technique for the detection of lung injury. As the solute diffuses across the blood-gas barrier, the concentration in circulating blood increases, giving rise to a background signal superimposed on the signal from residual DTPA in the airway. Background subtraction is conventionally based on the thigh, but this tissue has the disadvantage in that its composition, in terms of the relative volumes of its extracellular extravascular and intravascular compartments (a ratio of approximately 4:1), is quite different from that of the lung (<1:6). With comparison to the thigh, we examined alternative regions for background, liver, and cranium, which have extravascular-to-intravascular compartment ratios much closer to these for the lung, to determine the most appropriate background for correction of the pulmonary signal. From 1 min after intravenous injection of 99mTc-DTPA, the time-activity curves recorded by a gamma camera over the liver and lung in a group of otherwise normal cigarette smokers decreased up to 30 min after injection, with time courses that could essentially be superimposed on each other; the curve recorded over the thigh with a separate scintillation probe continued to increase. The curve recorded over the cranium had a time course similar to that for the liver and lung. Following aerosol inhalation, the lung clearance rates over the initial 7 min when background subtraction was used, based on the liver, cranium, and thigh were, respectively, 4.9 +/- 2.9, 4.7 +/- 2. 6, and 5.4 +/- 3.4 (SD) %/min, compared with 4.1 +/- 2.2%/min without subtraction. The corresponding values based on 30 min of data were 3.3 +/- 1.4, 3.4 +/- 1.4, 4.2 +/- 2.3, and 2.8 +/- 1. 0%/min. When the liver was used for background, the lung clearance curves were clearly multiexponential, whereas thigh correction tended to give curves that were monoexponential or even convex upward on semilogarithmic axes. With an appropriate region for background, the true shape of a lung curve can be identified, which permits the study of an intervention on the clearance while it is in progress. The intravenous DTPA, required for calibrating the background regions, can be given before inhalation of the tracer.

Adolescent↗
PubMed1997

Single-tube, nested, reverse transcriptase PCR for detection of viable Mycobacterium tuberculosis.

Several problems remain before molecular biology-based techniques, such as PCR, are widely accepted for the detection of infectious agents. Among the most formidable of these problems are the inability of the tests to distinguish between viable and nonviable organisms. We approached this problem by using the fact that bacterial mRNA has an extremely short half-life, averaging only a few minutes. We reasoned that by targeting bacterial mRNA by a reverse transcriptase PCR (RT-PCR), a positive signal would indicate the presence of a recently viable organism. To test our hypothesis, we chose to target the mRNA coding for the ubiquitous 85B antigen of mycobacteria. After partially sequencing the gene coding for 85B, we developed primers that were specific for Mycobacterium tuberculosis. In a single-tube, nested, RT-PCR (STN RT-PCR), these primers detected fewer than 40 CFU in spiked sputum samples and as few as 12 CFU in clinical sputum specimens. The sensitivity of STN RT-PCR with smear-negative samples was as good as that of culture. The specificity was 100%. More importantly, when M. tuberculosis was cultured with and without 1 microgram of isoniazid per ml, this assay could distinguish between those cultures which contained the antibiotic and those which did not. Subcultures on Lowenstein-Jensen agar confirmed the viability assessments of the STN RT-PCR. Control experiments demonstrated that isoniazid did not inhibit the RT-PCR. In addition, when an IS6110-targeted, DNA PCR was used to examine the same samples, all samples though 13 days (the last sample) continued to be positive, irrespective of whether isoniazid was present, thereby demonstrating the superiority of an mRNA target in the detection of mycobacterial viability.

Bacterial Typing Techniques↗
PubMed1995

Current experience with pancreatogastrostomy.

BACKGROUND: The reconstruction technique for the pancreatic remnant remaining after pancreatoduodenectomy has most frequently been pancreatojejunostomy. Although the mortality rate has been reduced to rather low levels in many centers, the leakage rate from this anastomosis remains high, in the range of 10% or greater. An alternative reconstruction, pancreatogastrostomy, has been known for almost 50 years and has been performed on small numbers of patients. The leakage rate for this anastomosis is less than 1% in literature reports in more than 200 patients. The purpose of this report was to add to the previously reported experience with this technique and to compare it with standard reconstruction as performed in a major American medical center by experienced surgeons. METHODS: The medical records of all patients operated on at the Loyola University Medical Center and the Edward Hines, Jr., Veteran's Affairs Hospital from August 1986 to May 1993, with a procedure code relating to the pancreas, were reviewed. RESULTS: A total of 58 Whipple procedures were identified, including 34 pancreatogastrostomies, 23 pancreatojejunostomies and 1 stapled pancreatic stump. No leaks in any pancreatogastrostomies were observed in the 38 patients so treated, whereas 4 leaks and 2 deaths related to the anastomosis occurred in the group of 23 patients with pancreatojejunostomies. The average length of stay was 14.2 days for the pancreatojejunostomy group and 15.5 days for the pancreatogastrostomy group, excluding duration data from those who died or experienced leakage. There was no significant difference in the length of stay between pancreatojejunostomy and pancreactogastrostomy; there was a statistically significant lengthening of stay for those patients whose anastomosis leaked versus those whose did not leak. The 10 patients having a pylorus-sparing operation had an average postoperative stay of 16 days, including both types of reconstruction. CONCLUSIONS: The gradual adoption of this procedure at a major medical center has led to the abandonment of pancreatojejunostomy as a reconstruction technique for the pancreatic remnant remaining after pancreatoduodenectomy.

Anastomosis, Surgical↗
PubMed1995

The effect of inhalation of platelet-activating factor on the pulmonary clearance of 99mTc-DTPA aerosol.

Platelet-activating factor (PAF) is a short-acting, lipid-soluble autocoid, inhalation of which causes an immediate pulmonary vascular sequestration of granulocytes and a peripheral neutropenia. We investigated the effect of PAF inhalation on the pulmonary clearance rate of inhaled 99mTc-DTPA in order to test the hypothesis that the pulmonary sequestration of granulocytes results in acute lung injury. In nine normal nonsmoking adults, the rate of clearance of DTPA, corrected for background activity, was 1.5 (SD 0.7) %/min over the first 10 min after inhalation. Inhalation of 4.8 micrograms PAF abruptly increased the clearance rate to a mean value of 2.3 (1.4) %/min (p < 0.05). No increase in clearance was observed in four nonsmoking subjects who inhaled vehicle only. The mean overall increase after PAF was 87% of the baseline clearance, significantly different (p < 0.05) from the corresponding change in the control group, which was -17%. After PAF, the clearance rate returned to baseline values within 10 min in all subjects. In all subjects who inhaled PAF, but in none who inhaled vehicle, there was an immediate neutropenia of 51 (SD 25) % of the baseline value (p < 0.01). This neutropenia persisted longer than the corresponding accelerated DTPA clearance and was still 74 (36) % of the baseline value at 10 min. Furthermore, there was no correlation between the increase in DTPA clearance induced by PAF inhalation and the decrease in peripheral blood granulocyte count. We conclude that PAF inhalation results in an increase in pulmonary DTPA clearance, probably not mediated by pulmonary vascular granulocyte sequestration.

Administration, Inhalation↗
PubMed1995

Pentamidine aerosol versus trimethoprim-sulfamethoxazole for Pneumocystis carinii in acquired immune deficiency syndrome.

Pneumocystis carinii pneumonia remains one of the most common opportunistic infections in patients with acquired immune deficiency syndrome (AIDS). Treatment with either intravenous pentamidine or trimethoprim-sulfamethoxazole (TMP-SMX) is frequently complicated by serious adverse reactions. This study was a prospective, blinded comparison of 600 mg/d of pentamidine as an aerosol versus 15 mg/kg/d of trimethoprim plus 75 mg/kg/d of sulfamethoxazole for patients with mild or moderately severe P. carinii pneumonia (alveolar arterial oxygen difference of less than 55 mm Hg). Of 367 participants who were randomized to receive study therapies, 287 had proven and 16 had presumed Pneumocystis pneumonia. There were 29 deaths within 35 d of study initiation: 12 in the aerosolized pentamidine group and 17 in the TMP-SMX groups (log rank p = 0.28). The difference in mortality was 3.4% (95% CI = -3.5, 10.8%). Ninety-four patients treated with aerosolized pentamidine had to have their study therapy changed because of lack of efficacy, compared with 22 patients treated with TMP-SMX (p = 0.002). In addition PaO2 improved faster in patients treated with TMP-SMX. However, aerosolized pentamidine was discontinued less often than TMP-SMX because of toxicity (9.4 versus 40% p < 0.001). Rash (0.6 versus 14.9%), nausea and vomiting (1.7 versus 12.2%), and abnormalities of liver function tests (1.7 versus 12.2%) were the most common adverse effects necessitating treatment discontinuation. During 6-mo. follow-up there was no difference in mortality.(ABSTRACT TRUNCATED AT 250 WORDS)

AIDS-Related Opportunistic Infections↗
PubMed1995

111-indium-DTPA-IgG lung imaging in patients with pulmonary and HIV infection.

111-Indium-DTPA-IgG (111In-IgG) is a new radiopharmaceutical that has been evaluated for the detection of infection without the need for in vitro cell labeling. We prospectively studied this agent in 33 patients suspected of having lung infections, most of whom also had HIV infection, and three patients with HIV infection and diarrhea without lung disease. Anterior and posterior lung images in the upright position were obtained within 24 h after intravenous administration of 2 mCi of 111In-IgG and were read in a blinded fashion by two nuclear medicine physicians. Of 29 patients suspected to have Pneumocystis carinii pneumonia (PCP), the diagnosis was confirmed by bronchoalveolar lavage in 18. Diffusely increased lung uptake of 111In-IgG was found in 17 of 18 patients who had PCP and was normal in 10 of 11 patients without PCP. The intensity of 111In-IgG uptake was related to sever gas exchange abnormality. Two patients with apparent bacterial lung infections had focal accumulation of 111In-IgG while two patients with minor radiographic abnormalities had no increased uptake. Normal lung uptake also occurred in two of three HIV-positive patients who had diarrhea and no lung disease. 111In-IgG appears to be useful in the detection of PCP and other pulmonary infections.

AIDS-Related Opportunistic Infections↗
PubMed1994

Indium-111 labelled pooled human immunoglobulin imaging to monitor the efficacy of specific therapy for Pneumocystis carinii pneumonia.

Functional imaging is ideally suited to monitoring the effect of specific therapy on disease processes. In this pilot study five patients with AIDS and Pneumocystis carinii pneumonia (PCP) were imaged with Indium-111 labelled pooled human immunoglobulin (111In-HIG) during infection and after therapy for PCP. The lung activity of 111In-HIG, measured as a lung/heart ratio, was calculated in a study performed during infection with PCP and after therapy. In all five patients the lung/heart ratio of 111In-HIG was reduced after treatment. The mean reduction in heart/lung ratio was 27% (range 12%-53%). If these results are confirmed by a larger study, 111In-HIG will be useful in monitoring the response of PCP to therapy in patients with AIDS.

AIDS-Related Opportunistic Infections↗
PubMed1993

Additive effects of exposure to silica dust and smoking on pulmonary epithelial permeability: a radioaerosol study with technetium-99m labelled DTPA.

BACKGROUND: Increased pulmonary epithelial permeability evaluated by the rate of clearance from lung to blood of the radioaerosol solute technetium-99m labelled diethylenetriamine pentaacetate (99mTc-DTPA) has been reported in smokers and in workers exposed to silica dust. A study was carried out to determine whether there are additive effects of cigarette smoke and exposure to silica dust on clearance rates of 99mTc-DTPA in ceramic workers. METHODS: Thirty one subjects with silicosis were studied, of whom 18 smoked cigarettes and 13 were non-smokers. They had similar histories of exposure to silica dust, and radiological alterations consistent with silicosis. The results from these patients were compared with those from normal subjects and smokers previously studied by the authors. RESULTS: Pulmonary function values were normal in most patients and not significantly different among groups. The median (range) rate of clearance of 99mTc-DTPA in smokers with silicosis was 4.1 (1.9-12.7) %/minute, which was higher than the rates in non-smoking patients with silicosis of 2.2 (1.1-6.6) %/minute and in smokers without exposure to silica dust of 2.9 (1.6-4.5) %/minute. These differences were more evident and significant when the clearance rates of the lower lobes of the three groups were compared. Clearance rates higher than 3%/minute were much more frequent in smokers with silicosis (85%) than in non-smoking patients with silicosis (15%) and in smokers (40%). CONCLUSION: In ceramic workers with radiographic changes resulting from exposure to silica dust, there is an additive effect of inhalation of silica dust and cigarette smoking on clearance rates of 99mTc-DTPA.

Adult↗
PubMed1991

Perspectives a century later on the "Ansa en Y" of César Roux.

During the last 100 years, since César Roux began utilizing his "Ansa-en-Y" procedure for gastric outlet obstruction, the procedure at first fell into disuse but was later adapted for other applications. This article discusses the background of the procedure and compares the original indications with the author's current experience. Current applications in this series were for chronic pancreatitis (26 patients), alkaline gastritis (22 patients), biliary duct obstruction (7 patients), pancreatic pseudocyst (3 patients), and gastric substitution (3 patients).

Anastomosis, Roux-en-Y↗
PubMed1991

Experimental cholelitholysis with the pulsed tunable dye laser.

This study evaluates the pulsed tunable dye laser with wavelength 504 nm, frequency 10 Hz, and pulse width 1.2 microseconds for cholelitholysis. Power of 10-40 kW was directed through a 250-microns quartz fiber optic to ablate 55 gallstones (removed from 14 patients). The fiber was positioned in direct contact with the stones under saline. Power delivery was begun at 10 kW and increased in 10-kW increments until litholysis began. The range of power and energy necessary to fragment the gallstones was evaluated on four common bile ducts (fresh autopsy specimens). Following fragmentation, all stones were analyzed. There were 35 cholesterol stones (3 calcified) and 20 bilirubin stones (4 calcified). Size ranged from 0.012 to 7.56 cm3 (mean 0.96 +/- 1.41 cm3). Energy necessary for fragmentation ranged from 0.4 to 11.2 J (exposure time 1.0-28 s). Power necessary for fragmentation was 20 kW for 2/55 stones and 40 kW for 53/55 stones. At 40 kW (40 mJ/pulse), common bile duct perforation occurred within 1.1 +/- 0.1 s (0.44 +/- 0.04 J). The pulsed tunable dye laser can fragment gallstones of all compositions. The threshold for fragmentation is 40 kW, but common bile duct perforation occurs at this power. We conclude that laser radiation sufficient to fragment gallstones can injure the common bile duct.

Cholelithiasis↗
PubMed1990

Initial trial of argon ion laser endarterectomy for peripheral vascular disease.

In the initial of open laser endarterectomy, 16 patients underwent 18 reconstructions for claudication (13 patients), rest pain (3 patients), and gangrene (2 patients). The mean (+/- SD) preoperative ankle arm index was 0.53 +/- 0.18. The laser endarterectomies were aorto-bi-iliac (1 patient), iliac (1 patient), superficial femoral (7 patients), profunda femoral (7 patients), and popliteal-posterior tibial (2 patients). All operations included surgical exposure, vascular control, administration of heparin, and an arteriotomy. Atheromas were dissected from arteries with argon ion laser radiation (power, 1.0 W). End points were welded with laser light. Arteries were closed primarily. The laser endarterectomies were 6 to 60 cm long and required 168 J to 2447.5 J. All patients had symptomatic relief, with a postoperative ankle arm index of 0.97 +/- 0.10. There were no arterial perforations from laser radiation. Surgical complications included early thrombosis requiring thrombectomy (3 patients) and hematoma requiring evacuation (1 patient). The laser endarterectomies have an 88% patency at 1 year. Open endarterectomy can be performed with laser radiation. A larger clinical trial is necessary to define the indications for laser endarterectomy in peripheral vascular disease.

Adult↗
PubMed1990

Application of nuclear medicine techniques to the study of ARDS.

Radionuclide techniques used for the diagnosis and study of ARDS include the routine clinical procedures of perfusion lung scanning, gallium and white-cell imaging, as well as PET, indicator dilution methods for measuring extravascular lung water, and means of measuring protein accumulation, protein flux, and solute transfer. The techniques that reflect the rate of protein leak from the microvasculature and sensitive measures of rapidly reversible alveolar injury appear most promising. While clinical usefulness remains to be documented, these methods may ultimately assist with the diagnosis of ARDS and with the evaluation of prognosis and therapy.

Humans↗
PubMed1990

Effect of mechanical ventilation and barotrauma on pulmonary clearance of 99mtechnetium diethylenetriamine pentaacetate in lambs.

We studied the effect of positive pressure mechanical ventilation on the pulmonary clearance (k) of 99mtechnetium diethylenetriamine pentaacetate (99mTc-DTPA) in lambs. Twelve lambs were anesthetized and ventilated with air at 25 breaths/min and with end expiratory airway pressure at 2 cm H2O for a minimum period of 8 h. Four lambs received normal pressure ventilation with peak airway pressure at 17 +/- 3 cm H2O and eight received high pressure ventilation with peak airway pressure at 41 +/- 2 cm H2O. Three 99mTc-DTPA clearance studies were done in each lamb; at the start and after 4 and 8 h of mechanical ventilation. All clearance measurements were made at normal peak airway pressure 16 +/- 3 cm H2O. Baseline clearance rate, k, (n = 12) was 1.2 +/- 0.5% (SD). During normal pressure ventilation, k increased from 1.0 +/- 0.5 to 2.2 +/- 0.8% after 4 h and to 2.7 +/- 0.8% after 8 h. During high pressure ventilation, k increased from 1.4 +/- 0.4 to 3.6 +/- 1.3% after 4 h and to 4.8 +/- 1.2% after 8 h. To see if 8 h of mechanical ventilation was associated with other evidence of lung epithelial injury, we determined the movement of I125 labeled albumin from the interstitium into the airspace, lung water content, lung histology, and lung lavage constituents in the lambs at the end of the study. All variables were similar between ventilated and four unventilated lambs, except the percentage of alveolar macrophages recovered by lavage, which was more in the ventilated lambs.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Initial clinical evaluation of carotid artery laser endarterectomy.

Clinical study of carotid artery laser endarterectomy began April 15, 1988. This report describes the first 10 cases that were performed in nine patients (five men and four women, mean age 70 years). Indications were asymptomatic stenosis (5), transient ischemic attacks (4), and stroke in evolution (1). There were two emergency cases and eight elective cases (including one reoperative case). Surgical exposure, systemic heparinization, vascular control, and a longitudinal arteriotomy were used. The cleavage plane between atheromas and media was developed with argon ion laser radiation (488 and 514.5 nm) directed through a 300 microns quartz fiber at power 1.0 W. Laser radiation was used to cut the atheromas out of the arteries and weld the end points. Residual atheromatous debris were vaporized with individual laser exposures. Arteriotomies were closed with sutures, and blood flow was restored. The endarterectomies were 3.9 +/- 1.1 cm long and required 330 +/- 97 joules. Mean clamp time was 22.5 +/- 7.9 minutes. Shunts were used in two cases. There were no arterial perforations or injuries as a result of laser light. Complications were hematoma (1), respiratory arrest (1), and transient neurologic deficit (1). Carotid endarterectomy is technically feasible with argon ion laser radiation. In the present series, postoperative observations, averaging 12 months and ranging from 5 to 19 months, have shown satisfactory results. No angiographic follow-up examinations were carried out.

Aged↗