Prospective, randomized comparison of disposable and reusable biopsy forceps in gastrointestinal endoscopy

We prospectively compared biopsy specimens obtained with reusable and disposable stainless steel biopsy forceps of varying sizes and configurations. Six types of forceps were used: (1) jumbo reusable forceps, (2) jumbo disposable forceps with a Teflon sheath, (3) regular reusable forceps, (4) regular disposable forceps with a Teflon sheath, (5) regular long-jaw disposable forceps, and 6) regular long-jaw disposable forceps with a Teflon sheath. "Jumbo" forceps were those requiring an endoscopic biopsy channel of at least 3.3 mm. "Regular" forceps were those requiring only a 2.8-mm channel. Two biopsy specimens were obtained with each of the six forceps from normal-appearing stomach, duodenum, and sigmoid colon (25 sets at each location). Mixed and coded specimens were scored by a single pathologist for volume (height, width, and length) and histologic depth. Reusable and disposable jumbo forceps yielded biopsy specimens of similar volumes (30 +/- 1 mm3 and 33 +/- 1 mm3, respectively) and histologic depth (grades of 3.3 +/- 0.1 and 3.5 +/- 0.1, respectively). In comparison, the regular-sized biopsy forceps gave specimens with half the volume of those obtained by the jumbo forceps (reusable, 13 +/- 1 mm3; disposable with Teflon sheath, 15 +/- 1 mm3; long-jaw, 16 +/- 1 mm2; and long-jaw with Teflon sheath, 17 +/- 1 mm3). However, the histologic depths of specimens obtained with the regular disposable forceps were the same as those of specimens obtained with the jumbo forceps. Regular reusable biopsy forceps yielded specimens with the smallest overall volume and histologic depth. We conclude that disposable forceps are equivalent to reusable forceps and that the two types can be used interchangeably in gastrointestinal endoscopy. We recommend the use of jumbo forceps whenever possible because they provide biopsy specimens that are double the size of those obtained with regular forceps.

Protection against rat endotoxic shock by p55 tumor necrosis factor (TNF) receptor immunoadhesin: comparison with anti-TNF monoclonal antibody

The protective efficacy of a p55 tumor necrosis factor receptor immunoadhesin (TNFR-IgG) was compared with that of an anti-TNF monoclonal antibody (MAb) in a rat endotoxic shock model. TNFR-IgG (5 mg/kg), given 30 min before endotoxin (LPS), attenuated LPS induction of hypotension and tachycardia and eliminated LPS induction of serum TNF activity. In contrast, anti-TNF MAb (5 mg/kg) had little effect on LPS-induced hemodynamic changes and neutralized only partially the excessive serum TNF activity. The 6-day survival was 1 of 10 controls; 6 of 11, 5 of 7, and 8 of 9 rats receiving 0.2, 1.0, or 5.0 mg/kg TNFR-IgG, respectively; and 3 of 8 rats receiving 5 mg/kg anti-TNF MAb. These results indicate that TNFR-IgG is more potent than anti-TNF MAb at neutralizing excessive TNF activity in vivo.

Heterologous expression of the cytotoxin restriction in Aspergillus nidulans and Aspergillus niger

The cDNA clone of restrictocin was placed under the control of the glucoamylase promoter from Aspergillus awamori and was transformed into Aspergillus nidulans and Aspergillus niger. Site-specific changes were introduced into cDNA constructs and these were transformed into A. nidulans. The secretion signal sequence was deleted from one form of the gene and three mutations introduced single amino acid substitutions into the protein. Culture conditions were optimized for maximum expression levels of restrictocin. The activities of the expressed proteins were characterized with an in vitro rabbit reticulocyte assay. Protein synthesis in this assay was inhibited 50% by 2.5 ng/ml wild-type restrictocin, 3.5 ng/ml E95G, 30 ng/ml E95C, and 600 ng/ml H136L. Toxic effects of restrictocin were observed in the A. nidulans expression system with reduced levels of cellular protein and messenger RNA upon induction of restrictocin expression as well as the formation of the alpha-fragment product of ribosomal RNA cleavage. Toxic effects were most highly pronounced in strains expressing restrictocin without the signal sequence, less so in strains expressing native restrictocin, and absent in strains expressing H136L restrictocin.

Analysis of the pediocin AcH gene cluster from plasmid pSMB74 and its expression in a pediocin-negative Pediococcus acidilactici strain

The 3,500-bp pap operon in the 8,877-bp plasmid pSMB74 contains a cluster of four genes, papABCD, of which papA encodes prepediocin (A. M. Motlagh, M. Bukhtiyarova, and B. Ray, Lett. Appl. Microbiol. 18:305-312, 1994). The cluster without the promoter was cloned in the shuttle vector pHPS9. An Escherichia coli strain and a pediocin-sensitive Pediococcus acidilactici strain transformed with the recombinant plasmid, pMBR1.0, produced pediocin AcH. Deletion analysis by introducing mutations in the four genes in pMBR1.0 revealed that only papA and papD were required for pediocin AcH production and that the gene product of papD has both translocation and processing functions. In the transformed minicells of E. coli chi 925 the proteins of the pap cluster were synthesized, indicating no polar effect due to deletion.

Intestinal venous drainage through the liver is a prerequisite for oral tolerance induction

One feature of enteric mucosal immunity is oral tolerance (OT), a state of diminished systemic immune responsiveness to an antigen induced by previous oral feeding of that antigen. Because OT induction requires an interaction between the intestinal and systemic immune systems, the authors plan to use it as a method in experimental small bowel transplantation (SBT) to evaluate the ability of the intestinal allograft to cooperate immunologically with the host. Two different methods have been used in experimental SBT to establish graft venous drainage: anastomosis of the graft mesenteric vein to the recipient portal vein or to the inferior vena cava. This experiment was designed to examine the role of the intestinal venous drainage routes in OT induction. Rats with a surgically created mesenterico-caval shunt (MCS) and their sham controls received an immunization protocol to induce OT to ovalbumin. The results showed that OT was readily induced in the sham animals, but not in the animals with MCS. These results indicate that intestinal venous drainage through the liver plays a central role in OT induction. Therefore, future analyses of OT in allogeneic SBT will require an animal model with portal venous drainage of the intestinal graft.

Lack of graft-versus-host disease after fetal intestine transplantation

Clinical small bowel transplantation has often been complicated by lethal graft-versus-host disease (GVHD), attributed to the numerous allogeneic immunocompetent lymphocytes contained in the graft. Because the fetal immune system is relatively immature, the authors hypothesized that the risk of GVHD after small bowel transplantation might be diminished by using the fetal intestine as the donor organ. This experiment tested this hypotheses in a rat model. Jejunoileal segments harvested from Lewis (LEW) rat fetuses were transplanted subcutaneously into adult recipients of either syngeneic LEW or semiallogeneic LEW x Brown-Norway F1 (LBNF1) strains. The recipients had follow-up for 21 days after transplantation to assess the growth of the intestinal grafts ("neogut") and evaluate for GVHD. Growth of the intestinal grafts was observed in 65% (53 of 82) of the recipients, with a neogut weight of 4.5 +/- 3.7 g and length of 2.8 +/- 2.1 cm. No significant difference in graft survival rate or neogut weight and length was found between the LEW and LBNF1 recipients. Histopathologic examination of the neogut showed a mature intestinal architecture similar to that of normal adult rat intestine, with well-developed enteric lymphoid tissues including Peyer's patches. However, no clinical or histopathologic evidence of GVHD was found in any of the LBNF1 recipients. These results are consistent with the author's hypothesis and suggest that the use of fetal donor intestine for small bowel transplantation might have some immunologic advantages over the adult (immunologically mature) donor intestine.

Genetic diversity and multilocus associations in Cunninghamia lanceolata (Lamb.) Hook from The People's Republic of China

Open-pollinated seeds were assayed for allozyme polymorphisms at 24 loci to assess genetic diversity and multilocous associations in 16 populations of Cunninghamia lanceolata (Lamb.) Hook in the People's Republic of China. On average, the percentage of polymorphic loci was 88.0, the number of alleles per locus was 3.0, and the expected heterozygosity was 0.394. The distribution of genetic diversity was not correlated with the geographic and climatic variables of the populations. However, allele frequencies correlated linearly with the mean annual temperature of the populations at Mdh-1, Mdh-2, Mnr-2, Pgi-1, and Skdh-1 and with the altitude of the populations at Aph-4 and 6Pg-2. Of the total gene diversity 6% was attributed to among-population differentiation; 94% resided within populations. Two-locus gametic disequilibria were found in 15 of the 16 populations, and higher-order gametic disquilibria were significant in most populations. The gametic disequilibria did not correlate with geographic and climatic variables. The results suggest that population subdivision, founder effect, occurrence across diverse environments, a mating system dominated by inbreeding, and historical events from 2000 years of cultivation are contributing factors in the generation and maintenance of the multilocus genetic structure in this conifer.

Effect of electroacupuncture on the level of preproenkephalin mRNA in rat during penicillin-induced epilepsy

Our previous studies have shown that seizure induced by injecting penicillin (0.24 mg/2 microliters) into hippocampus could be inhibited by electroacupuncture (EA) probably via decreasing enkephalin content in hippocampus. To determine whether this change reflected the peptide synthesis, preproenkephalin (PPE) mRNA was detected in hippocampus and some other limbic structures during seizure and after EA treatment by in situ hybridization. Four hours after injecting penicillin into hippocampus, PPE mRNA levels were significantly increased by 10 folds in entorhinal cortex, subiculum, CA1 area of hippocampus, amygdaloid nucleus and piriform cortex, whereas EA treatment apparently attenuated the seizure-induced increase of PPE mRNA in the areas mentioned above. The results indicated that EA may regulate the biosynthesis of PPE in hippocampus during seizure by an alteration in gene transcription.

[Effects of beta-endorphin on blood pressure and heart rate in rats]

The present work was undertake to investigate the mechanism of changes of blood pressure and heart rate induced by beta-endorphin (beta-End) after microinjection into the Nucleus Amygdaloideus Centralis (AC) of anaesthetized rats. The results were as follows: (1) beta-End (100, 250 pg/microliters) injected into AC decreased both blood pressure and heart rate. (2) Both these effects could be antagonized by naloxone and beta-End anti-serum. (3) The effects of beta-End could also be reversed by phentolamine and propranolol. The results showed that the cardiovascular effects on beta-End were mediated by opioid receptors and through the intervention of adrenergic neurons.

Experimental high-frequency ultrasound can detect graft rejection after small bowel transplantation

Early diagnosis of graft rejection after small bowel transplantation (SBT) can allow prompt institution of vigorous immunosuppressive therapy, with resultant reversal of the rejection process. The current method for graft monitoring is random mucosal biopsy from a stomal site or through an endoscope. However, because early rejection often has a patchy distribution, it could be missed by random biopsy. We hypothesized that the pathological process of rejection would alter acoustic impedance of the tissue and thus change the ultrasonic patterns of the graft intestinal wall. If this hypothesis is correct, then high-frequency endoscopic ultrasound (US) could be used to monitor the entire transplanted bowel and guide the biopsy, with improved yields. This hypothesis was tested in a rat orthotopic SBT model. Sixty-two intestinal specimens (9 isografts, 12 allografts treated with cyclosporine A [CsA], 22 untreated allografts, and 19 intestines from normal rats) were collected for in vitro transluminal US imaging (30 MHz) and histopathologic study. The echo pattern of normal rat intestinal wall consisted of five echo layers that correlated spatially with the histological layers: the innermost hyperechoic layer 1, plus hypoechoic layer 2, corresponded to the mucosa; hyperechoic layer 3, the submucosa; anechoic layer 4, the muscularis propria; and hyperechoic layer 5, the serosa. The isografts and CsA-treated allografts were identical histologically and ultrasonically to normal intestine. However, the echo patterns of the untreated allografts had progressive loss of architectural stratification, with worsening rejection. The change began with patchy indistinctness and disruption of hyperechoic layers 1, 3 and 5, and progressed to total obliteration of the layers, with the intestinal wall becoming a nonstratified hypoechoic structure.(ABSTRACT TRUNCATED AT 250 WORDS)

[Pingyangmycin-induced chromosome damage in lymphocytes of laryngeal cancer patients]

Lymphocytes from 28 untreated laryngeal cancer patients and 23 healthy controls were cultured in vitro and exposured to pingyangmycin (bleomycin A5), a clastogen. The lymphocytes were arrested in metaphase and analyzed. The total chromosome aberration rate, mean chromatid break rate per cell and cell aberration rate were 1.98% +/- 0.05%, 0.57% +/- 0.35%, and 42.8% +/- 12% respectively for laryngeal cancer patients. However, for healthy controls these values were 0.94% +/- 0.04%, 0.28% +/- 0.12%, and 27% +/- 12% respectively. Statistical analysis showed there are significant differences between the two groups. The data indicate that under our experimental conditions chromatid break rate 0.40 can be considered to be a borderline value, 0.80 hypersensitive value. For any individual, if the chromatid break rate is 0.40 or more, one should be ranked as having cancer risk. If 0.80 or more, then, highly cancer risk.

Hydroxyl radicals generated in vivo kill neurons in the rat spinal cord: electrophysiological, histological, and neurochemical results

We have used microdialysis to establish an experimental model to characterize mechanisms whereby released substances cause secondary damage in spinal cord injury. We use this model here to characterize damaging effects of the hydroxyl radical (OH.) in vivo in the spinal cord. OH. was generated in vivo by pumping H2O2 and FeCl2/EDTA through parallel microdialysis fibers inserted into the spinal cord. These agents mixed in the tissue to produce OH. by Fenton's reaction. Two types of control experiments were also conducted, one administering only 5 mM H2O2 and the other only 0.5 mM FeCl2/0.82 mM EDTA. During administration of these chemicals, electrical conduction was recorded as one test for deterioration. OH. blocked conduction completely in 2.5-5 h and Fe2+/EDTA partly blocked conduction, but H2O2 alone did not cause detectable blockage. Histological examination supported the hypothesis that neurons were killed by OH., as Fe2+/EDTA and H2O2 alone did not destroy significant numbers of neurons. OH., H2O2, and Fe2+ all caused gradual increases in extracellular amino acid levels. These results are consistent with Fe(2+)-catalyzed free radical generation playing a role in tissue damage upon spinal cord injury.

Randomized, prospective trial of direct current versus bipolar electrocoagulation for bleeding internal hemorrhoids

Fifty patients with bleeding internal hemorrhoids unresponsive to 6 weeks of standard medical therapy were randomly assigned to receive treatment with direct current or bipolar electrocoagulation. Treatment groups were similar in bleeding severity and internal hemorrhoid grade. Treatment sessions were significantly longer for direct current electrocoagulation (8.8 +/- 0.2 minutes) than for bipolar electrocoagulation (0.1 +/- 0.03 minutes) (p < 0.001). When compared to the bipolar electrocoagulation group, direct current electrocoagulation patients had more procedural pain that terminated therapy (5 of 25 patients [20%] versus 0 of 25 [0%], for a difference of 20% [95% confidence interval, 4% to 36%]; p = 0.05) and prolonged pain after the procedure (4 of 25 patients [16%] versus 1 of 25 [4%], for a difference of 12% [95% confidence interval, -4% to 28%]; p = 0.35). However, more post-treatment rectal ulcerations were seen in the bipolar electrocoagulation-treated group (6 of 25 patients [24%] versus 1 of 25 [4%], for a difference of 20% [95% confidence interval, 2% to 38%]; p = 0.10). Treatment groups did not differ in number of treatment sessions or months of follow-up. The rates of success, defined as obliteration of the hemorrhoids or cessation of bleeding with reduction of the hemorrhoids to grade 1 or less, for the direct current electrocoagulation and the bipolar electrocoagulation groups were 88% and 92%, respectively. Failures in the direct current electrocoagulation group were uncontrollable bleeding (n = 1) and refusal to continue therapy because of pain (n = 2).(ABSTRACT TRUNCATED AT 250 WORDS)

(2,3)-alpha-Methylenepenams: synthesis and in vitro activity

A series of alpha-methylene penicillins was synthesized and SAR were studied. The alpha-isomers were found to be chemically reactive and biologically active in contrast to the beta-isomers. In addition, the alpha-isomers have broader spectrum of in vitro activity than the corresponding penicillins. Generally, the alpha-isomers are more active against gram-negative bacteria than the corresponding penicillins, but slightly weaker in potency towards gram-positive organisms.

Sonographic and computed tomography characteristics of liver ablation lesions induced by high-intensity focussed ultrasound

RATIONALE AND OBJECTIVES

The authors have previously demonstrated the ability of high-intensity focused ultrasound (HIFU) to extracorporeally induce selective tissue destruction in the liver without causing damage to the intervening abdominal wall. The potential usefulness of HIFU as a noninvasive therapy for liver cancer has been suggested. This study observes sonographic and computed tomography (CT) characteristics of HIFU-ablated liver tissue in an attempt to assess the possibility of using these imaging methods to monitor the therapeutic results.

METHODS

A sonoablated lesion was induced in the liver in each of 20 rabbits with a HIFU therapeutic system. Sequential imaging of the hepatic sonolesions with sonography and CT was performed up to 8 days after treatment, and the imaging patterns were correlated with the histopathology.

RESULTS

Hepatic sonoablated tissue could be clearly visualized by sonography as a hypoechoic lesion. On contrast-enhanced CT, the sonolesions were depicted as nonenhanced low-density regions. There was good correlation among the sizes of sonography- and CT-depicted lesions and pathologic specimens.

CONCLUSION

In this model, sonography and contrast-enhanced CT were useful imaging modalities for monitoring sonolesion evolution after HIFU treatment.

NTP technical report on the toxicity studies of a Chemical Mixture of 25 Groundwater Contaminants Administered in Drinking Water to F344/N Rats and B6C3F(1) Mice

Toxicity studies were performed with a chemically defined mixture of 25 groundwater contaminants, using dose levels considered to have environmental relevance. The mixture contained 19 organic compounds and six metals (shown below); the selection of these compounds was based primarily on the frequency of their occurrence in United States Environmental Protection Agency surveys of groundwater contamination in the vicinity of hazardous waste disposal sites. This report focuses primarily on 26-week drinking water toxicity studies with male and female F344/N rats and B6C3F(1) mice. The endpoints evaluated included histopathology, clinical pathology, neurobehavioral studies, and reproductive toxicity. Additional studies using this same chemical mixture are briefly reviewed in this report and include an evaluation of spermatogenesis in B6C3F(1) mice exposed to the chemical mixture for 13 weeks, a continuous breeding study with Sprague-Dawley rats and CD-1(R) Swiss mice, studies of myelotoxicity in B6C3F(1) mice exposed to the chemical mixture for up to 31.5 weeks, studies of immunosuppression in B6C3F(1) mice exposed for up to 13 weeks, in vitro mutagenicity assays in Salmonella typhimurium and Escherichia coli, and measures of genetic damage in bone marrow and peripheral blood of F344/N rats and B6C3F(1) mice in 2-week drinking water studies. In a 26-week drinking water study in which rats were administered the chemical mixture at composite contaminant concentrations of 0, 11, 38, 113, or 378 ppm, no deaths occurred and the body weight gain of high-dose males was slightly less than that of the controls. Water consumption decreased with dose and was 24% to 28% less than that of the controls at the highest concentration. Changes in organ weights occurred primarily in high-dose rats and included increased absolute and relative liver and kidney weights in females, increased relative kidney weight in males, and decreased absolute and relative thymus weights in males and females. Hematologic assessments indicated that rats receiving 378 ppm developed a microcytic anemia consistent with that accompanying iron depletion. Multiple foci of inflammation occurred in the liver of exposed rats. In high-dose females, these liver lesions were especially prominent and included bile duct and oval cell hyperplasia. Inflammation also occurred in the mesenteric lymph nodes, the adrenal gland, and the spleen. The amount of hemosiderin in the spleens of rats receiving the higher concentrations of the chemical mixture was less than normal. Components of a chemical mixture of 25 groundwater contaminants include acetone, aroclor 1260, arsenic, benzene, cadmium, carbon tetrachloride, chlorobenzene, chloroform, chromium, 1,1-dichloroethane, 1,2-dichloroethane, 1,1-dichloroethylene, 1,2-trans-dichloroethylene, di(2-ethylhexyl) phthalate, ethylbenzene, lead, mercury, methylene chloride, nickel, phenol, tetrachloroethylene, toluene, 1,1,1-trichloroethane, trichloroethylene, xylenes. In a 26-week study in which mice were exposed to the chemical mixture at concentrations of 0, 11, 38, 113, and 378 ppm in drinking water, there were no clear adverse effects noted in survival, weight gain, clinical pathology parameters, or histopathologic evaluations. Water consumption decreased with increasing dose, and water consumption by high-dose mice was approximately 40% less than that by the controls. In neurobehavioral assessments, no clear treatment-related effects were observed in measures of forelimb and hindlimb grip strength, hindlimb footsplay, motor activity, response to a thermal stimulus, or startle response in rats or mice evaluated at 6-week intervals throughout the 26- week drinking water studies. There were no effects on sperm morphology or motility or on estrous cycle length in rats or mice receiving the chemical mixture during the 26-week studies. Sperm concentration was decreased in F(1) CD-1(R) Swiss mice during continuous breeding studies, although there were no clear adverse effects on the fertility of Sprague-Dawley rats or CD-1(R) Swiss mice in th CD-1&reg; Swiss mice in these studies. Pup weight, the number of live males, and the number of male pups per litter were slightly decreased in dosed rats in the continuous breeding study in rats; the number of live female mouse pups in litters born of the F(0) and F(1) generations was decreased in the 378 ppm group. The significance of these observations, if any, is not known. F(1) mice receiving 378 ppm had increased incidences of hepatic inflammation compared to the controls. In female B6C3F(1) mice that received the chemical mixture in drinking water at concentrations as high as 756 ppm for 2 weeks or 378 ppm for 13 weeks, assessments of immune function showed suppression of hematopoietic stem cells and antigen-induced antibody-forming cells. This was manifested by impaired resistance to challenge with a nonlethal strain of mouse malaria, Plasmodium yoelii. Additional evidence of an adverse effect on hematopoietic stem cells was demonstrated by decreases in the in vitro colony-forming ability of granulocyte-macrophage progenitor cells and erythroid precursor cells isolated from female mice that had received the chemical mixture at a concentration of 378 or 756 ppm in 31.5 week studies. Potential genotoxic effects of the chemical mixture to the bone marrow of F344/N rats and B6C3F(1) mice were assessed in 2-week drinking water studies with concentrations as high as 756 ppm. Small increases in sister chromatid exchanges and micronucleated polychromatic erythrocytes occurred in the bone marrow of dosed male mice, and micronucleated polychromatic erythrocytes were also increased in dosed female mice. The chemical mixture did not induce mutations in Salmonella typhimurium strains TA98 and TA100 and did not induce DNA damage in Escherichia coli with or without metabolic activation. In summary, rats receiving drinking water containing a mixture of 25 common groundwater contaminants at levels of potential environmental relevance developed inflammatory lesions in the liver, spleen, lymph nodes, and adrenal gland, as well as evidence of an iron deficiency anemia. The inflammatory lesions could not be predicted based on the known toxic effects of the individual components of the chemical mixture. Mice exposed to similar concentrations of the chemical mixture did not show adverse effects in a standard toxicity study but developed deficits in bone marrow function, evidence of genetic damage, hepatic inflammation, and immunosuppression in other studies that generally included exposures to higher concentrations or exposures of longer duration. A no-observed-adverse-effect level for histologic injury (granulomatous inflammation of the liver) was 11 ppm in rats; however, no clear evidence for histologic injury was seen in mice exposed to concentrations of the chemical mixture as high as 378 ppm in a standard 26-week study. NOTE: These studies were supported in part by funds from the Comprehensive Environmental Response, Compensation, and Liability Act trust fund (Superfund) by an interagency agreement with the Agency for Toxic Substances and Disease Registry, U.S. Public Health Service.

NTP technical report on the toxicity studies of Pesticide/Fertilizer Mixtures Administered in Drinking Water to F344/N Rats and B6C3F1 Mice

Toxicity studies were performed with pesticide and fertilizer mixtures representative of groundwater contamination found in California and Iowa. The California mixture was composed of aldicarb, atrazine, 1,2-dibromo-3-chloropropane, 1,2- dichloropropane, ethylene dibromide, simazine, and ammonium nitrate. The Iowa mixture contained alachlor, atrazine, cyanazine, metolachlor, metribuzin, and ammonium nitrate. The mixtures were administered in drinking water (with 512 ppm propylene glycol) to F344/N rats and B6C3F1 mice of each sex at concentrations ranging from 0.1x to 100x, where 1x represented the median concentrations of the individual chemicals found in studies of groundwater contamination from normal agricultural activities. This report focuses primarily on 26-week toxicity studies describing histopathology, clinical pathology, neurobehavior/neuropathology, and reproductive system effects. The genetic toxicity of the mixtures was assessed by determining the frequency of micronuclei in peripheral blood of mice and evaluating micronuclei and sister chromatid exchanges in splenocytes from female mice and male rats. Additional studies with these mixtures that are briefly reviewed in this report include teratology studies with Sprague-Dawley rats and continuous breeding studies with CD-1 Swiss mice. In 26-week drinking water studies of the California and the Iowa mixtures, all rats (10 per sex and group) survived to the end of the studies, and there were no significant effects on body weight gains. Water consumption was not affected by the pesticide/fertilizer contaminants, and there were no clinical signs of toxicity or neurobehavioral effects as measured by a functional observational battery, motor activity evaluations, thermal sensitivity evaluations, and startle response. There were no clear adverse effects noted in clinical pathology (including serum cholinesterase activity), organ weight, reproductive system, or histopathologic evaluations, although absolute and relative liver weights were marginally increased with increasing exposure concentration in both male and female rats consuming the Iowa mixture. In 26-week drinking water studies in mice, one male receiving the California mixture at 100x died during the study, and one control female and one female in the 100x group in the Iowa mixture study also died early. It could not be determined if the death of either of the mice in the 100x groups was related to consumption of the pesticide/fertilizer mixtures. Water consumption and body weight gains were not affected in these studies, and no signs of toxicity were noted in clinical observations or in neurobehavioral assessments. No clear adverse effects were noted in clinical pathology, reproductive system, organ weight, or histopathologic evaluations of exposed mice. The pesticide/fertilizer mixtures, when tested over a concentration range similar to that used in the 26-week studies, were found to have no effects in teratology studies or in a continuous breeding assay examining reproductive and developmental toxicity. The California and Iowa pesticide mixtures were tested for induction of micronuclei in peripheral blood erythrocytes of female mice. Results of tests with the California mixture were negative. Significant increases in micronucleated normochromatic erythrocytes were seen at the two-highest concentrations (10x and 100x) of the Iowa mixture, but the increases were within the normal range of micronuclei in historical control animals. Splenocytes of male rats and female mice exposed to these mixtures were examined for micronucleus and sister chromatid exchange frequencies. Sister chromatid exchange frequencies were marginally increased in rats and mice receiving the California mixture, but neither species exhibited increased frequencies of micronucleated splenocytes. None of these changes were considered to have biological importance. In summary, studies of potential toxicity associated with the consumption of mixtures of pesticides and a fertilizer representative of groundwater contamination in agriculturative of groundwater contamination in agricultural areas of Iowa and California failed to demonstrate any significant adverse effects in rats or mice receiving the mixtures in drinking water at concentrations as high as 100 times the median concentrations of the individual chemicals determined by groundwater surveys. NOTE: These studies were supported in part by funds from the Comprehensive Environmental Response, Compensation, and Liability Act trust fund (Superfund) by an interagency agreement with the Agency for Toxic Substances and Disease Registry, U.S. Public Health Service.

Changes of hepatoma echo patterns with tumor growth. A study of the microanatomic basis in a rat model

OBJECTIVES

The echo patterns of human hepatoma vary considerably as the tumors grow. This sonographic study investigates the microanatomic basis of the echo-pattern changes in an animal model.

METHODS

ACI rats (n = 35) with intrahepatically implanted Morris hepatoma 3924A were imaged with 10-MHz ultrasound from days 7 to 28 after tumor implantation. The sonograms were precisely correlated with the histologic sections and microangiograms obtained from the same section plane.

RESULTS

Small hepatomas (size = 6.6 +/- 1.6 mm) without necrosis demonstrated a low-echo pattern. Medium-sized tumors (size = 11.7 +/- 3.3 mm) had a low-echo periphery and a high-echo center. The low-echo periphery corresponded to viable tumor and the high-echo core corresponded to central coagulation necrosis. Large tumors (size = 20.9 +/- 7.5 mm) with extensive necrosis revealed an irregular mixed-echo pattern.

CONCLUSIONS

The trend of increasing echogenicity of the hepatomas with tumor growth is due to the progression of coagulation necrosis.

Liver cancer ablation with extracorporeal high-intensity focused ultrasound

Recent animal studies have demonstrated the capacity of high-intensity focused ultrasound (HIFU) to extracorporeally ablate selective tissue targets in the liver without requiring surgical exposure of the liver or insertion of instruments into the liver. The potential value of HIFU as a noninvasive local treatment for human hepatic cancers has attracted considerable interest. This report reviews the current status of HIFU research and sets forth questions for future study.

Ganglion atrial natriuretic peptide in NaCl sensitive spontaneously hypertensive rats

Reports from other laboratories have shown that atrial natriuretic peptide (ANP) stores in sympathetic ganglia are increased during dietary NaCl supplementation in normotensive rats. We have previously demonstrated that dietary NaCl supplementation in NaCl sensitive spontaneously hypertensive rats (SHR-S) exacerbates hypertension and enhances peripheral sympathetic nervous system activity, while NaCl resistant Wistar-Kyoto (WKY) rats show neither response. Since endogenous ANP may inhibit ganglion transmission, an inability of SHR-S to increase ganglion ANP appropriately in response to high NaCl feeding could contribute to the NaCl induced increase in sympathetic nervous system activity and blood pressure in this model, while an increase in ganglion ANP in NaCl supplemented WKY would tend to prevent sympathetic activity and blood pressure from rising. The current study tested the hypothesis that ganglion ANP levels increase in WKY but not in SHR-S during dietary NaCl supplementation. Male SHR-S and WKY rats were placed on 1% or 8% NaCl diets at 7 weeks of age. The rats were decapitated without prior anesthesia 3 weeks later, and the superior cervical and celiac ganglia were removed for the measurement of ANP by radioimmunoassay. Dietary NaCl supplementation produced significant increases in blood pressure in SHR-S, but not in WKY rats; the high NaCl diet was associated with significant increases in the ANP content of superior cervical and celiac ganglia in WKY rats, but not in SHR-S.(ABSTRACT TRUNCATED AT 250 WORDS)

Extracorporeal liver ablation using sonography-guided high-intensity focused ultrasound

RATIONALE AND OBJECTIVES

High-intensity focused ultrasound (HIFU) is the only radiation beam that can remotely destroy deep-seated tissue targets without causing damage to the intervening tissues. This study evaluates the ability of sonography-guided HIFU to extracorporeally induce liver ablation in a rabbit model.

METHODS

Under sonographic guidance, the HIFU beam was transcutaneously focused at the target tissue in the liver through a subcostal approach. A computer controlled the HIFU exposure and transducer movement to destroy a preselected tissue volume. Simultaneous sonography monitored the tissue response. Ten insonated rabbits were killed from days 0 to 10, and the liver and intervening tissues were examined histologically.

RESULTS

A sharply demarcated sonolesion of coagulation necrosis was produced in the liver in 9 of 10 animals. No damage was found in the intervening tissues (n = 6) when adequate acoustic coupling and proper beam path was applied.

CONCLUSION

Sonography-guided HIFU might be a potential new modality for extracorporeal inducement of liver cancer ablation without resorting to laparatomy.