AN ALGORITHM TO DETERMINE THE NANODOSIMETRIC IMPACT OF GOLD NANOPARTICLES ON CELL MODELS.

High-Z nanomaterials, e.g. gold nanoparticles (GNPs), are being investigated worldwide for potential application in radiation imaging and therapy. Photon irradiation of cells containing GNP was shown to produce enhanced DNA damage which is believed to be related to the increased secondary electron (SE) yield and ionization density. In this work, an algorithm was developed for simulating the physical radiation damage inside the nucleus of a spherical cell model for the case of uniformly distributed GNPs within the cytoplasm. Previously calculated energy spectra of SE emerging from a single NP irradiated with different photon sources are used as input to obtain the SE energy spectrum at the surface of the cell nucleus. In a second step, the SE transport inside the cell nucleus is simulated with a track structure Monte Carlo code to obtain the spatial distribution of ionizations. The preliminary results presented here show that the developed algorithm allows for a fast calculation of the SE spectra at the cell nucleus surface, thus enabling a more realistic assessment of the ionization density inside the cell nucleus than that obtained by the simulation of a single GNP. Furthermore, the algorithm can be easily adapted to investigate both the effect of GNP clustering and the impact of GNP-GNP interactions on SE spectra.

Postoperative deep wound infections in adults after spinal fusion: management with vacuum-assisted wound closure.

OBJECTIVE: Vacuum-assisted wound closure (VAC) exposes the wound bed to negative pressure, resulting in removal of edema fluid, improvement of blood supply, and stimulation of cellular proliferation of reparative granulation tissue. It has been used to treat open wounds in the extremities, open sternal wounds, pressure ulcers, and abdominal wall wounds. This study retrospectively reviewed instrumented spine fusions complicated by surgical wound infection and managed by a protocol including the use of VAC in order to evaluate the efficacy of applying vacuum therapy on patients with deep spine infections and exposed instrumentation. METHODS: Twenty consecutive patients with deep wound infections after undergoing spinal fusion procedures were studied. There were 12 men and 8 women with an average age of 55 years (31-81 years). Eight patients had undergone concomitant anterior and posterior arthrodesis, nine patients had a posterior spinal fusion, and three patients had a transforaminal lumbar interbody fusion. Seven patients had a decompression with exposed dura. Sixteen patients presented with a draining wound within the first 6 weeks postoperatively (average 24 days). There were four patients who presented with back pain and temperature after 1 year postoperatively (average 3 years). All patients were taken to the operating room for irrigation and debridement followed by placement of the VAC with subsequent delayed closure of the wound. RESULTS: There was an average of 1.8 (1-8) irrigation and debridement procedures prior to placement of the VAC. Once the VAC was initiated, there was an average of 2.2 (2-3) procedures until and including closure of the wound. The wound was closed an average of 7 days (5-14 days) after the placement of the initial VAC in the wound. All patients tolerated the VAC without adverse effects. All patients were kept on a 6-week course of intravenous antibiotic therapy. The average follow-up was 10 months (6-24 months). There were no cases of uncontrolled sepsis once the VAC was initiated. All patients achieved a clean closed wound without removal of instrumentation at a minimum follow-up of 6 months. CONCLUSION: VAC therapy is an effective adjunct in closing complex deep spinal wounds with exposed instrumentation.

Organophosphate increases the sensitivity of human exocrine pancreas to acetylcholine.

Human pancreas contains two cholinesterase isoenzymes: acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE). In the present study, binding potency of two organophosphates for human cholinesterases were compared by the Ellman method. Echothiophate was found to have much greater potency than iso-OMPA for both cholinesterases. Using Karnovsky histochemical stains on human pancreatic tissue, the same results were confirmed. Dose-response studies with acetylcholine were done on viable pancreas fragments from nine human donors, without pancreatic disease (group I). Cold-preservation time was less than 30 h. Pancreas was minced into fragments, after the technique of Scheele and Palade, placed in Eagle's medium, and gassed with O2. Amylase release was measured by the Phadebas Method and corrected for basal release. There was a dose-dependent response to acetylcholine at 1 and 2 h, with a shift in peak amylase release to the left, when fragments were preincubated in 10(-4) M echothiophate. This indicated a 100-fold increase in sensitivity to acetylcholine. In three patients with chronic pancreatitis (Group II), there were variable patterns of response of amylase release to acetylcholine, and higher basal outputs. In Group III, prolonged storage conditions of over 40 h were tested for 4 pancreas donor tissues. There was no response to acetylcholine. These studies show that for up to 30 h cold storage, fragments of pancreas from human organ donors respond to acetylcholine in dose-dependent manner. An organophosphate, echothiophate (10(-4) M) which inhibits both cholinesterases, increases pancreatic sensitivity to acetylcholine, and these results are similar to findings from canine pancreas fragments, which also showed increased sensitivity.

Increased canine pancreatic acinar cell damage after organophosphate and acetylcholine or cholecystokinin.

Sublethal doses of organophosphate anticholinesterases cause acute pancreatitis in dogs within 2 h. In vitro studies using canine pancreatic fragments have also demonstrated that the peak of amylase release in response to acetylcholine is shifted far to the left after incubation with the organophosphates echothiophate (10(-4) M) or tetraisopropyl pyrophosphoramide (iso-OMPA) (10(-3) M), indicating an increased sensitivity of response. The present in vitro study examined whether there was also an increased susceptibility to acinar cell damage at the electron microscopic level after acetylcholine or cholecystokinin. Minced pieces of whole fresh canine pancreas 2-3 mm in size were placed in buffered Eagle's solution and gassed with 100% O2. After pretreatment 1 h with echothiophate or iso-OMPA, they were then incubated with acetylcholine (10(-5) M). Other tissues preincubated with echothiophate were stimulated with cholecystokinin (10(-9) M). These are submaximal doses for untreated canine pancreatic fragments. After acetylcholine and echothiophate or acetylcholine and iso-OMPA, there was extensive acinar damage with the appearance of large vacuoles and lakes, and interstitial edema. There was evidence of intense supramaximal stimulation and lateral exocytosis. Similar destructive changes were seen after echothiophate and cholecystokinin. In control sections from tissues stimulated with acetylcholine (10(-5) M) or cholecystokinin (10(-9) M, there were lumenal exocytotic patterns typical of submaximal stimulation. Other controls, organophosphate alone and unstimulated basal conditions, showed only minor changes. It is concluded that the increased sensitivity to acetylcholine after organophosphate incubation correlates with an increased susceptibility to acinar ultrastructural damage from acetylcholine and cholecystokinin.

Inhibition of acetyl- and butyrylcholinesterase and amylase release from canine pancreas.

There are two tissue-fixed cholinesterases in dog pancreas: acetylcholinesterase and butyrylcholinesterase. In the present experiments, an organophosphate that only inhibits butyrylcholinesterase (isopropylpyrophosphoramide, or iso-OMPA) was compared with echothiophate and a nonorganophosphate compound, physostigmine. The latter two agents inhibit both cholinesterases. Fresh canine pancreas from anesthetized dogs was minced into fragments and suspended in Eagle's solution gassed with 100% O2. Amylase release was measured by the Phadebas method. In 2-h dose-response studies, there was a fivefold increase in sensitivity to acetylcholine when fragments were preincubated 1 h with iso-OMPA. There was a 1,000-fold increase in sensitivity when fragments were preincubated for 1 h in echothiophate. Basal amylase release in incubates with echothiophate were also increased. In dose-response studies with CCK-8, iso-OMPA was without effect, but echothiophate treatment resulted in a greater total response to CCK-8. There was a corresponding increase in basal output with echothiophate alone. Physostigmine also potentiates the response to CCK-8. Cumulative responses up to 3 h with half-maximal acetylcholine or half-maximal CCK-8 doses showed enhanced total output in fragments preincubated with echothiophate (p less than 0.05). The enhancement effect was atropine-sensitive to hexamethonium ganglionic blockade. In calcium-free medium, the enhancement with echothiophate was greatly reduced but still present. Inhibitors of both cholinesterases in the pancreas cause a greater total amylase release to sub-maximal doses of acetylcholine and CCK-8 than agents that only inhibit butyrylcholinesterase. Though our data do not provide direct proof, the results could be explained by a greater accumulation of endogenous acetylcholine when both cholinesterases are inhibited.

Effects of insecticide, diazinon, on pancreas of dog, cat and guinea pig.

The organophosphate insecticide Diazinon has been reported to cause acute pancreatitis in dogs. Based on histochemical examination of the acinar tissue, it was suggested that pancreatic tissue-fixed butyrylcholinesterase (BuChE) is the target enzyme of organophosphate toxicity. To further evaluate this theory, we exposed dogs, cats, and guinea pigs to a single sublethal dose of the organophosphate insecticide Diazinon (75 mg/kg). In cats, which lack pancreatic BuChE, no pathological changes occurred after two, three, and six hours, whereas in the guinea pigs as in dogs, both having abundant pancreatic BuChE, vacuolization of the acinar cells, interstitial edema and vasculitis indicate acute edematous pancreatitis as early as two hours. Atropine pretreatment (0.2 mg/kg) gave complete protection against pancreatitis. It was concluded that inhibition of pancreatic BuChe leads to cholinergic hyperstimulation of the acinar cell, which results in acute pancreatitis, and that pancreatic BuChE is essential for dogs and guinea pigs to downregulate cholinergic excitation. The insecticide pancreatitis model is considered a simple, non-invasive, reproducible, and cheap and useful method to evaluate early changes and methods of treatment in acute pancreatitis. Pancreatitis in humans has also been reported after accidental insecticide exposure.

Effect of the organophosphate iso-OMPA on amylase release by pancreatic lobules of dog, guinea pig, and cat.

Organophosphates (OPs) cause irreversible inhibition of cholinesterases (ChEs) and profound cholinergic stimulation. There are major differences in the response of the dog and cat pancreas to the in vivo administration of Diazinon (O,O-diethyl O-2-isopropyl-4-methyl-6-pyrimidyl phosphothioate), a butyrylcholinesterase (BuChE) inhibitor. Acute edematous pancreatitis is found in the dog but not in the cat. The present experiments were designed to see what effect OP had in vitro on pancreatic exocrine function of dog, cat, and guinea pig, and whether the effects were consistent with an anti-ChE activity. A water-soluble OP agent, tetraisopropyl pyrophosphoramide (iso-OMPA) at 10(-3) M, which like Diazinon inhibits BuChE, was used. Minced pieces of fresh whole pancreata 3 mm in size were taken from 3 dogs, 4 guinea pigs, and 2 cats. The tissues were placed in flasks containing Eagle's solution and gassed with 100% O2. Cumulative amylase release was measured by Phadebas method up to 3 h. At half-maximal acetylcholine (ACH) concentration (10(-5) M), the canine pancreas pretreated with iso-OMPA (10(-3) M) showed a 42-87% greater release of amylase than tissues receiving ACH alone (p less than 0.001). The same potentiated response to ACH was seen in guinea pig pancreas pretreated with iso-OMPA (p less than 0.001), but iso-OMPA pretreatment did not augment the ACH response in the cat. Atropine pretreatment effectively blocked all ACH responses, and there was no effect seen with iso-OMPA alone. In the dog, iso-OMPA in combination with half-maximal carbachol (10(-6) M), or in combination with half-maximal cholecystokinin (CCK-8) stimulation (10(-9) M), provided no potentiated amylase release.(ABSTRACT TRUNCATED AT 250 WORDS)

Use of streptokinase for the salvage of a free flap: case report and review of the use of thrombolytic therapy.

This is the first case report of the clinical use of intraoperative streptokinase to promote free flap salvage. A latissimus dorsi free flap was mobilized to cover a scalping type injury. After 4 1/2 hours of ischemia and recurrent thrombosis, streptokinase was perfused into the thoracodorsal artery (7,500 units of streptokinase in 30 cc of normal saline). The free flap was exposed to this concentration of streptokinase for 10 minutes followed by drainage of the venous effluent in order to avoid possible deleterious systemic effects of the streptokinase. Good flow throughout the free flap resulted, and the flap remained viable, providing good coverage for the patient's skull. Controversies regarding the no-reflow phenomena and the use of various thrombolytic agents are discussed.

The effect of atropine and duct decompression on the evolution of Diazinon-induced acute canine pancreatitis.

Three groups of eight dogs each were studied to evaluate the early evolution of the hyperamylasemia, hyperlipasemia, and acinar cell pathology at the light and electron microscopic levels during acute Diazinon-induced pancreatitis. Two more groups of five dogs each were evaluated for the effects of cholinergic receptor blockade with atropine and ductal decompression on the evolution of serum enzyme changes and acinar cell pathology. Group I dogs received a secretin infusion of 2 units/kg/hr, and a Diazinon infusion of 75 mg/kg, and demonstrated significant increases in serum amylase and lipase at one, two and three hours. Light microscopy revealed acinar cell vacuolization and progressive interstitial edema. Electron microscopy revealed the formation of large intracytoplasmic vacuoles filled with flocculent material, the fusion of these vacuoles with basolateral membrane, and the formation of interstitial edema. In both group II dogs (that received secretin alone) and Group III dogs (that received atropine, 200 micrograms/kg IV prior to secretin and Diazinon), the serum enzyme levels and histologic results were normal. In group IV dogs, pancreatic duct cannulation to prevent hypertension prevented the hyperamylasemia and hyperlipasemia, but not the acinar cell vacuolization and interstitial edema. This model for acute interstitial pancreatitis is apparently cholinergic-receptor mediated, the serum enzyme elevations are due primarily to ductal hypertension, and the acinar cell pathology is primarily due to cholinergic stimulation and occurs independent of ductal hypertension.

Obstructing esophageal hematoma mimicking cancer: a case report and experimental study.

In this paper the 10th case of esophageal hematoma, a rare variant of the Mallory-Weiss syndrome, is reported. The radiographic study strongly suggested an obstructing neoplasm, however, this hematoma disappeared within five days and this same rapid disappearance was noted in dogs in which esophageal hematomas were induced. Fiberoptic esophagoscopy provides a clue to the diagnosis since the mural hematoma is differentiated from carcinoma by its dark color.

Clinical and secretory differences in pancreatic cancer and chronic pancreatitis.

The differential diagnosis between chronic pancreatitis and pancreatic cancer can be very difficult. In 60 patients with either of these conditions, who had satisfactory ERCP study, clinical features were correctly matched with the final diagnosis by discriminant analysis in 44 (73%). The sensitivity of ERCP radiographic findings in pancreatic cancer was 80% and sensitivity of cytology was 54%. To see if exocrine function was specific for cancer, fresh pancreatic secretions were aspirated in 27 patients at the time of ERCP. By isoelectric focusing, a pattern of extreme zymogen depletion was observed in chronic alcoholic pancreatitis (Group 1), pancreatic cancer (Group 2), and chronic nonalcoholic pancreatitis (Group 3). The three groups were not distinguishable. By contrast, significant changes in albumin, IgG and IgA concentrations were seen in Group 2. The albumin level was over ten-fold greater than in Groups 1 and 3 (p less than 0.02 and less than 0.05). The IgG was seven-fold and two-fold greater (p less than 0.01 and greater than 0.2) and the IgA was 15-fold and six-fold greater (p less than 0.002 and less than 0.05) than in Groups 1 and 3, respectively. The two groups of pancreatitis had similar concentrations of albumin and IgA. The ratio of albumin to IgG was also different in Group 2 from the other groups, suggesting different mechanisms for the appearance of proteins in pancreatic secretions. Nonzymogen protein levels can distinguish chronic pancreatitis from pancreatic cancer, and further study of them may identify useful tumor-specific markers.

Serum cholinesterase, serum lipase, and serum amylase levels during long-term echothiophate iodide therapy.

Previous studies have found increased pancreatic intraductal pressures in dogs and the development of acute pancreatitis in humans after cholinergic stimulation. However, we did not find abnormally high levels of serum lipase or serum amylase in 44 patients with glaucoma using therapeutic doses of echothiophate iodide for intraocular pressure control on a long-term basis.

Cytologic studies for the diagnosis of pancreatic cancer.

Endoscopically obtained fluid from the ampulla of Vater was subjected to cytologic examination in 141 of 159 patients with suspected pancreatic disease, most of whom were undergoing endoscopic retrograde cholangiopancreatography (ERCP) examination. Of 26 patients with proven carcinoma of the pancreas, cannulation of the ampulla was successful in 22, and in 12 of these the cytology was positive (54%). Several technical considerations are suggested to increase the yield of positive cytology. They include aspiration of 3 ml or greater, deep insertion of the cannula, collection of pure pancreatic juice, high suction, and use of a fine intraductal rasp. The diagnostic sensitivity of ERCP alone was 73% in patients with cancer, but in combination with cytology it increased to 85%. The combined evaluation yielded 100% accuracy in 22 cases of cancer in which the ampulla was successfully cannulated. In 51 patients with chronic pancreatitis, and in 75 without proven pancreatic disease, the specificity of cytology was 98% and 97% respectively. The specificity of ERCP in chronic pancreatitis was 94%. Cytology is a useful adjunct to the ERCP examination in the diagnosis of pancreatic carcinoma.

A study of the cholinesterases of the canine pancreatic sphincters and the relationship between reduced butyrylcholinesterase activity and pancreatic ductal hypertension.

Previous work from this laboratory revealed in increased canine pancreatic intraductal pressure following cholinesterase inhibitor intoxication. The pressure was negatively correlated with serum butyrylcholinesterase (BChE) activity, suggesting that BChE activity mediated the pressure rise. This study uses a histochemical technique to investigate the tissue cholinesterase activity of the canine pancreatic sphincters and the effect of a cholinesterase inhibitor (ChEI) on tissue cholinesterase activity. In five control dogs, serial sections of the major and minor spincters were stained for acetylcholinesterase (AChE) and BChE activity. Four treated dogs were given the ChEI, O,O-diethyl-O- (2-isopropyl-6-methyl-4-pyrimidinyl) phosphoro-thioate, 25 mg/kg, one hour prior to excising the ampullae. In the control dogs, BChE activity is present in the periampullary nerves and the pancreatic smooth muscle sphincters. AChE activity is present in nerves but not in smooth muscle. In the treated group, following a dose of ChEI known to cause ductal hypertension, BChE activity was absent in the pancreatic sphincters but AChE activity was preserved in the periampullary nerves. These data suggest that the pancreatic ductal hypertension that occurs following ChEI administration is due to a selective reduction in pancreatic smooth muscle BChE activity.

Ulcer perforation rate and pepsin. A study of the perfused cat esophagus.

The perforation rate of the cat esophagus varies as the log of the pepsin concentration when the esophagus is perfused in vivo with canine gastric juice at constant acidity, temperature, and pressure. The esophagus is extremely sensitive to gastric juice, frequently perforating before 60 minutes of perfusion. The maximal response is achieved with pepsin concentrations of 0.3 mg/mL, although the canine stomach is capable of concentrations as high as 1.3 mg/mL after vagal stimulation with 2 deoxy-D-glucose. These findings emphasize that peptic activity contributes significantly to initial acute esophageal ulceration induced by gastric secretions.

Sensitivity of the canine pancreatic intraductal pressure to subclinical reduction in cholinesterase acitivity.

As a continuation of work from this laboratory on anticholinesterase induced pancreatitis, a study of the relationship between reduced serum cholinesterase activity and changes in pancreatic intraductal pressure was undertaken. Pharmakokinetic studies in three dogs revealed rapid reduction in serum cholinesterase activity following an IV bolus dose of the cholinesterase inhibitor 0,0-diethyl-0-(2-isopropyl-6-methyl-4-pyrimidinyl)phosphorothioate. Following each dose of cholinesterase inhibitor, stable levels of cholinesterase inhibition were reached in 30 minutes. In four dogs the pancreatic duct was perfused from the tail of the ventral pancreas and intraductal pressures measured. A total of 25 mg/kg of the cholinesterase inhibitor was given in 5 mg/kg doses 30 minutes apart, and serum cholinesterase measured 30 minutes after each dose. Mean pressures were established over a 15 minute interval. Linear regression analysis of 23 data points revealed a significant (p < 0.001) cumulative dose-related increase in pancreatic intraductal pressure [Pressure (cm saline) = 14.2 + 1.03 x Cumulative Dose (mg/kg)] and significant (p< 0.001) negative correlation between serum cholinesterase activity and intraductal pressure [Pressure (cm saline) = 48.0 - 0.057 x Esterase Activity (mU/ml)]. These data suggest that, in dogs, reduced cholinesterase activity is directly related to increased pancreatic intraductal pressure, and it may be a factor in the pathogenesis of pancreatitis.

A study of secretory proteins, cytology and tumor site in pancreatic cancer.

Pure pancreatic fluid was aspirated at the time of endoscopic retrograde cholangiopancreatography (ERCP), after Secretin stimulation, and was analyzed for protein in eight patients with proven adenocarcinoma of the pancreas and in 16 subjects of the same sex ratio and approximately matching ages, who had normal pancreatograms and pancreatic cytology, who served as controls. The albumin concentration, IgA, IgG, were all significantly greater in the pancreatic fluid of the cancer group, and the IgM and transferrin increase was of borderline significance. Many zymogen bands present in controls were either faintly present or absent in the cancer group at matching zymogen concentration. Cytology was positive or suspicious in eight of 11 cancer patients. The secretory protein abnormalities and cytology results in the cancer group did not depend on a particular tumor site or size, the smallest being 3 cm lesions. Hence, secretory abnormalities and gross tumor size and location are independent entities to a certain extent. It is possible that secretion changes may precede the development of gross tumor. Further study will be necessary before the actual significance of these findings for early diagnosis is known.

Pancreatitis as a complication of anticholinesterase insecticide intoxication.

Severe pancreatitis and a pseudocyst occurred in a patient following accidental ingestion of an anticholinesterase insecticide, a substance not previously known to produce pancreatitis. Experiments were done to elucidate the mechanism. In one group of dogs the pancreatic duct was perfused and intraductal pressures were measured. The cholinesterase inhibitor 0,0-diethyl-0-(2-isopropyl-6-methyl-4-pyrimidinyl)phosphorothioate (25 mg/kg) caused a significant increase in the mean intraductal pressure from 12 +/- 2.4 to 27.8 +/- 5.9 cm saline. In a second group of dogs pancreatic secretory rates were measured. Anticholinesterase (75 mg/kg) in combination with secretin infusion (1 U/kg/hr) caused a significant increase in the secretin stimulated flow rate from 0.13 to 0.56 cc/min. Atropine (75 microgram/kg) abolished the anticholinesterase induced pressure and secretory rate increases. In a third group of dogs administration of cholinesterase inhibitor 75 mg/kg and secretin infusion 2 U/kg/hr resulted in acute pancreatic interstitial edema, acinar cell vacuolization, hyperamylasemia and hyperlipasemia. These results suggest that occurrence of pancreatitis as a complication of anticholinesterase insecticide intoxication is the result of hypersecretion and pharmacologic ductal obstruction.