Increased risk of occurrence of neuroleptic malignant syndrome on combined treatment with lithium and neuroleptic

Whether there is an increased risk of occurrence of neuroleptic malignant syndrome (NMS) on combined treatment with lithium and neuroleptic is a controversial issue. Patients seen in a general psychiatry unit of a university hospital in India were prospectively screened for NMS over a 2 year period. Diagnosis of NMS was made on operational criteria and the details of treatment at the time of occurrence of NMS were collected systematically. Eight cases of NMS were identified during the period of the study, out of which 5 (62.5%). were taking lithium and a neuroleptic together at the time of occurrence of NMS. The high prevalence of patients on lithium and neuroleptic concomitantly in our sample of NMS, and the similar findings in many of the earlier prospective studies, makes it possible to speculate whether there is an association between combined use of lithium and neuroleptic and occurrence of NMS. Findings are discussed.

The role of antioxidant enzymes in the control of opossum sphincter of Oddi motility

Superoxide rapidly oxidizes nitric oxide (NO) to form peroxynitrite, thus terminating the biological activity of NO. The aims of our study were to determine if superoxide alters the motor function of the sphincter of Oddi and to localize the antioxidant enzymes in the sphincter of Oddi. Immunostaining was performed and enzyme activities were measured in the sphincter of Oddi. In physiological experiments, force-displacement transducers recorded tension in the spontaneously contracting sphincter of Oddi and after electrical field stimulation (EFS) of precontracted sphincter of Oddi. Superoxide was generated by the addition of xanthine with xanthine oxidase, superoxide radicals were scavenged by the addition of superoxide dismutase (SOD), and catalase or SOD was inhibited by diethyldithiocarbamic acid. Immunostaining demonstrated SOD and catalase immunoreactivity in ganglia situated at the serosal surface of the circular muscle. Total SOD activity was 202 +/- 12 U/mg. Generation of superoxide or inhibition of SOD increased the contractile frequency and decreased relaxation after EFS. We conclude that superoxide alters sphincter of Oddi motor function, and the presence of superoxide scavenging enzymes in enteric plexuses suggests that they may regulate sphincter of Oddi neuromuscular function by clearing endogenous superoxide.

Carcinoids of the jejunum and ileum: an immunohistochemical and clinicopathologic study of 167 cases

BACKGROUND

Carcinoid tumors of the gastrointestinal tract differ in their clinical and histopathologic features, depending on the site of origin. There are few clinicopathologic studies that specifically describe jejunoileal carcinoid tumors.

METHODS

One hundred sixty-seven ileal and jejunal carcinoids were retrospectively studied with emphasis on clinical, pathologic, immunohistochemical, and prognostic features.

RESULTS

The mean age of patients at the time of presentation was 62 +/- 12 years (range, 13-93 years). Eight patients had carcinoid syndrome (5%) and 1 had Zollinger-Ellison syndrome. Twenty-six percent of tumors were multiple, and 77% were transmurally invasive; 31% had regional lymph node metastases only, and 32% had liver or mesenteric metastases. Ninety-three percent of tumors had an insular growth pattern. Serotonin was expressed in 86% of tumors (86 of 102), chromogranin in 92%, and neuron specific enolase in 95%. Twenty percent of tumors (10 of 51) expressed prostatic acid phosphatase; 96% were argyrophil, and 98% argentaffin. Of 80 cases with follow-up data (mean follow-up, 52 +/- 5 months), 21% were dead of disease, 16% were dead of other causes, 19% were alive with disease, and 44% had no evidence of disease at last follow-up. The 5-year Kaplan-Meier survival estimate for all cases was 58%. By univariate analysis, survival was negatively correlated with distant metastases at the time of surgery (P = 0.002), mitotic rate (P = 0.01), tumor multiplicity (P = 0.01), the presence of carcinoid syndrome (P = 0.02), depth of invasion (P = 0.03), and female gender (P = 0.05); by multivariate analysis, survival was negatively associated with distant metastasis (P = 0.002), carcinoid syndrome (P = 0.01), and female gender (P = 0.03).

CONCLUSIONS

Jejunoileal carcinoid tumors have a relatively high rate of transmural invasion and aggressive clinical behavior. They are usually insular and largely argentaffin, with a high rate of chromogranin and serotonin positivity. These features differentiate jejunoileal carcinoids from other gastrointestinal carcinoids.

Carcinoids of the jejunum and ileum: an immunohistochemical and clinicopathologic study of 167 cases

BACKGROUND

Carcinoid tumors of the gastrointestinal tract differ in their clinical and histopathologic features, depending on the site of origin. There are few clinicopathologic studies that specifically describe jejunoileal carcinoid tumors.

METHODS

One hundred sixty-seven ileal and jejunal carcinoids were retrospectively studied with emphasis on clinical, pathologic, immunohistochemical, and prognostic features.

RESULTS

The mean age of patients at the time of presentation was 62 +/- 12 years (range, 13-93 years). Eight patients had carcinoid syndrome (5%) and 1 had Zollinger-Ellison syndrome. Twenty-six percent of tumors were multiple, and 77% were transmurally invasive; 31% had regional lymph node metastases only, and 32% had liver or mesenteric metastases. Ninety-three percent of tumors had an insular growth pattern. Serotonin was expressed in 86% of tumors (86 of 102), chromogranin in 92%, and neuron specific enolase in 95%. Twenty percent of tumors (10 of 51) expressed prostatic acid phosphatase; 96% were argyrophil, and 98% argentaffin. Of 80 cases with follow-up data (mean follow-up, 52 +/- 5 months), 21% were dead of disease, 16% were dead of other causes, 19% were alive with disease, and 44% had no evidence of disease at last follow-up. The 5-year Kaplan-Meier survival estimate for all cases was 58%. By univariate analysis, survival was negatively correlated with distant metastases at the time of surgery (P = 0.002), mitotic rate (P = 0.01), tumor multiplicity (P = 0.01), the presence of carcinoid syndrome (P = 0.02), depth of invasion (P = 0.03), and female gender (P = 0.05); by multivariate analysis, survival was negatively associated with distant metastasis (P = 0.002), carcinoid syndrome (P = 0.01), and female gender (P = 0.03).

CONCLUSIONS

Jejunoileal carcinoid tumors have a relatively high rate of transmural invasion and aggressive clinical behavior. They are usually insular and largely argentaffin, with a high rate of chromogranin and serotonin positivity. These features differentiate jejunoileal carcinoids from other gastrointestinal carcinoids.

Effects of oxygen radicals and radical scavenging on opossum lower esophageal sphincter

Nitric oxide mediates esophageal peristalsis and lower esophageal sphincter (LES) relaxation. Superoxide produced with inflammation inactivates nitric oxide. Superoxide is cleared in biological systems by superoxide dismutase. We tested the hypothesis that superoxide and the superoxide scavenging system modulate LES function. Transverse strips of muscle from the opossum LES relaxed when stimulated by an electrical field. Diethyldithiocarbamite was used to inhibit copper/zinc superoxide dismutase. Xanthine and xanthine oxidase were used to generate superoxide. Xanthine with xanthine oxidase or diethyldithiocarbamite alone had no effect on the LES. However, xanthine/xanthine oxidase and diethyldithiocarbamite reduced LES relaxation 34.1% and increased its resting tone 71.2%. Superoxide dismutase did not affect LES function, but protected the tissue from the effects of diethyldithiocarbamite and xanthine/xanthine oxidase. These studies are consistent with the hypothesis that superoxide acts by inactivating nitric oxide and suggest that these antioxidant enzyme systems may play a role in the maintenance of LES function.

An artificial HIV enhancer-binding peptide is dimerized by the addition of a leucine zipper

A 42 residue artificial peptide that binds to the HIV-1 enhancers has been described previously. The specificity of interaction of the peptide with its target DNA sequence has been demonstrated by a variety of techniques. Naturally occurring regulatory proteins frequently bind to DNA as dimers, thereby increasing the strength and specificity of the interaction, the dimer interface often being provided by a leucine zipper type coiled coil. As a suitable binding site for this kind of system is located to the 5' end of the HIV enhancer region, it was decided to design and synthesize a fusion peptide that not only contained the DNA binding sequence of the original 42 residue peptide but also incorporated a leucine zipper based on that of the GCN4 transcriptional activator, that should, therefore, be capable of dimerizing. The resultant peptide, LZ66, has now been shown to be fully active in band shift and in vitro transcription assays and to exhibit about double the inhibitory activity of the parent 42 residue peptide. Preliminary CD measurements revealed that the peptide has a high alpha-helical content and that it adopts a stable conformation down to the low micromolar peptide concentration range. Sedimentation equilibrium studies confirmed that the principles involved in the design of the peptide are valid and that the peptide is indeed dimeric in solution.

A trimeric, alpha-helical, coiled coil peptide: association stoichiometry and interaction strength by analytical ultracentrifugation

Alpha-helical coiled coils are proving to be almost ideal systems for the modelling of peptide and protein self-association processes. Stable oligomeric systems, in which the stoichiometry is well defined, can be produced by the careful selection of the appropriate amino acid sequence, although the principles behind this are still not fully understood. Here we report on a 35 residue peptide, FZ, synthesized by the solid phase method, which was originally designed to form a dimer, but which, in fact, associates to the trimeric state. A detailed characterization of the associative properties of the peptide has been performed by circular dichroism spectroscopy and, in particular, by sedimentation equilibrium in the analytical ultracentrifuge. The presence of the trimeric state, which is stable even at low peptide concentrations, has been confirmed by various independent methods of analysis for molar mass. The effects of both temperature and of guanidinium chloride on the peptide have been investigated and both found to be peptide-concentration dependent. The unfolding induced by the denaturant cannot be adequately described by a simple, two state monomer-trimer equilibrium.

Occurrence of neurolepric malignant syndrome on trihexphenidyl discontinuation

The neuroleptic malignant syndrome (NMS) commonly occurs on treatment with neuroleptics, it is also reported in patients who suddenly stop drugs like levodopa, amitriptyline and imipramine. We report a case of NMS, which occurred in a patient on lithium, haloperidol and trihexyphenidyl (THP) after sudden discontinuation of THP. The cholinergic system, through its effect on the dopaminergic system, may play a role in the genesis of NMS. Alternatively, anticholinergic withdrawal may produce extrapyramidal symptoms (EPS), and the consequent alteration in food and fluid intake may produce electrolyte imbalance which increases the risk for NMS.

The role of ultraviolet light in the induction of cellular DNA damage by a spark-gap lithotripter in vitro

PURPOSE

The purpose of this study was to investigate the mechanisms for DNA damage induced by a spark-gap lithotripter.

MATERIALS AND METHODS

Cultured Chinese hamster ovary cells suspended in phosphate buffered saline were exposed in small chambers placed at the focus of a lithotripter in a 37C water bath. Viability was checked by trypan blue exclusion, and DNA strand breaks were evaluated with the comet assay after exposure.

RESULTS

About 50% cell lysis and significant DNA damage in surviving cells were found after 500 discharges. The strand break effect, but not the lysis, could be eliminated by blocking the light emitted by the discharge. The exposure chamber material influenced the results, and use of nutrient medium with serum reduced the observed effects. The DNA damage was eliminated by added novobiocin and enhanced by added aphidicolin, as expected for strand breaks associated with repair of ultraviolet light damage. The DNA strand-break effect of 500 spark-gap discharges approximated that obtained from a positive control treatment with 38 J/m2. of 254 nm. ultraviolet light.

CONCLUSIONS

Thus, the observed DNA damage appears to result from exposure of cells to the ultraviolet light emissions of the spark-gap discharge, rather than to the shockwaves or shockwave induced cavitation, which causes the cell lysis. Exposure of the skin to this ultraviolet light during lithotripsy might have some clinical implications for prolonged or repeated treatment.

Contrast-agent gas bodies enhance hemolysis induced by lithotripter shock waves and high-intensity focused ultrasound in whole blood

Fresh canine whole blood was exposed in 1.3-mL disposable pipette bulbs with or without added Albunex contrast agent to lithotripter shock waves (rate: 2 Hz; mean pressure amplitude: 14.8 MPa) or 1.28-MHz high-intensity focused ultrasound up to a mean pressure amplitude of 17.8 MPa. Significant shock-wave-induced hemolysis up to about 10% was detected after 500 or more shock waves without added agent, after 200 with 1% added agent and after 100 with 10% added contrast agent. Hemolysis was increased somewhat with added contrast agent, but this enhancement was not statistically significant. For ultrasound exposure, significant hemolysis approaching 100% was detected for 100-ms continuous exposure at 17.8 MPa without added gas bodies. Addition of 1% contrast agent enhanced the hemolysis by reducing the apparent threshold to 10 MPa. Burst mode exposure with a 100-ms total on-time (20 microseconds, 100 microseconds and 1-ms bursts) also yielded hemolysis enhancement with added contrast agent, with results similar to the 100-ms continuous exposure. The added gas bodies appear to lower cavitation thresholds by serving as cavitation nuclei in the blood.

Antioxidant enzymes in intramural nerves of the opossum esophagus

Superoxide radical (O2-.) combines with nitric oxide (NO) to form peroxynitrite, thereby nullifying the biological activity of NO. Superoxide dismutase (SOD) prevents this reaction by converting O2-. to H2O2. We tested the hypotheses that the antioxidant enzymes catalase (CAT), Mn SOD, and Cu/Zn SOD are present in enteric neurons of the opossum esophagus, and that O2-. alters esophageal motor function. Immunostaining demonstrated CAT, Mn SOD, and Cu/Zn SOD immunoreactivity in interganglionic nerve bundles and ganglia of the myenteric and submucosal plexuses. Western blot analysis confirmed the presence of these enzymes in homogenates of esophageal muscularis propria, and enzyme assays demonstrated Cu/Zn SOD and Mn SOD activities of 262 and 73 U/mg protein, respectively. Both diethyldithiocarbamic acid, an inhibitor of Cu/Zn SOD, and xanthine (X) with xanthine oxidase (XO), which generate O2-., shortened the latency of the nerve-mediated contraction of circular esophageal muscle, the off response, by 20.2 and 23.4%, respectively. SOD alone did not affect the latency, but it inhibited the effect of X with XO on the latency. Antioxidant enzymes found in intramural esophageal nerves may play a role in regulating NO-mediated neuromuscular communication in the esophagus.

The role of cavitation in the induction of cellular DNA damage by ultrasound and lithotripter shock waves in vitro

The induction of DNA strand breaks in Chinese hamster ovary cells was measured with the comet assay after continuous wave ultrasound or lithotripter shock wave exposure. Cell lysis and hydrogen peroxide production were measured to gauge the level of inertial cavitation activity. Significant DNA damage was found after 2.17-MHz ultrasound exposure at 37 degrees C to 0.82 MPa for 2 min or 4 min, and to 0.58 MPs for 4 min. A significant portion of the damage induced at the 0.82-MPa level was repaired by the cells when warmed. Neither exposure to 500 or 1000 shock waves at 37 degrees C in a thin-walled tube, nor exposure to 1000, 1500 or 2000 shock waves at 25 degrees C in a polyethylene pipette bulb produced a significant effect, when the flash of light from the spark-gap discharge was blocked. This finding was consistent with the generally lower lysis and hydrogen peroxide production by the shock wave exposure.

Characterization of leucine zipper complexes by electrospray ionization mass spectrometry

The development of "soft" ionization methods has enabled the mass spectrometric analysis of higher-order structural features of proteins. We have applied electrospray ionization mass spectrometry (ESI-MS) to the analysis of the number and composition of polypeptide chains in homomeric and heteromeric leucine zippers. In comparison with other methods that have been used to analyze leucine zippers, such as analytical ultracentrifugation, gel chromatography, or electrophoretic band shift assays, ESI-MS is very fast and highly sensitive and provides a straightforward way to distinguish between homomeric and heteromeric coiled-coil structures. ESI-MS analyses were carried out on the parallel dimeric leucine zipper domain GCN4-p1 of the yeast transcription factor GCN4 and on three synthetic peptides with the sequences Ac-EYEALEKKLAAX1EAKX2QALEKKLEALEHG-amide: peptide LZ (X1, X2 = Leu), peptide LZ(12A) (X1 = Ala, X2 = Leu), and peptide LZ(16N) (X1 = Leu, X2 = Asn). Equilibrium ultracentrifugation analysis showed that LZ forms a trimeric coiled coil and this could be confirmed unequivocally by ESI-MS as could the dimeric nature of GCN4-p1. The formation of heteromeric two- and three-stranded leucine zippers composed of chains from LZ and LZ(12A), or from GCN4-p1 and LZ, was demonstrated by ESI-MS and confirmed by fluorescence quenching experiments on fluorescein-labeled peptides. The results illustrate the adaptability and flexibility of the leucine zipper motif, properties that could be useful to the design of specific protein assemblies by way of coiled-coil domains.

Co-localization of manganese superoxide dismutase and NADH diaphorase

Manganese superoxide dismutase (Mn SOD), mitochondrial enzyme, defends against the toxic effects of superoxide radical (O2.-) in pathological processes by catalyzing the conversion of O2.- to hydrogen peroxide (H2O2). The activity of another enzyme, NADH diaphorase, forms the basis for a histochemical method used commonly to demonstrate nerve cell bodies in the enteric plexuses. We found identical patterns of localization of Mn SOD immunoreactivity and NADH diaphorase activity in brain, esophagus, stomach, colon, liver, and kidney. NADH diaphorase enzymatic activity co-migrated with complexes of Mn SOD on a non-denaturing gel. This suggests that the NADH diaphorase may in some way be related to Mn SOD.

Kinetics of folding of leucine zipper domains

Leucine zippers are short coiled coils frequently found in transcription factors where they serve as dimerization domains. The basic features contributing to the thermodynamic stability of leucine zippers are well understood, but very little is known about their folding kinetics. Leucine zippers have a simple and well defined structure and are, therefore, excellent models for the study of the concerted folding and assembly of polypeptide chains. Here we report on a fluorescence stopped flow investigation of the kinetics of association and dissociation of a series of model leucine zippers based on the common sequence Xzero-EYEALEKKLAAX1EAKX2QALEKKLEALEHG-amide (Xzero = N alpha-acetyl, N alpha-fluorescein-GGG, or N alpha-dimethylaminocoumarin-GGG; Xl = Leu or Ala; X2 = Leu, Ala, or Asn). When Xzero is fluorescein, self-quenching between adjacent fluorophores leads to a decrease in fluorescence emission intensity whereas unfolding of the coiled coil leads to an increase. In a heteromeric coiled coil containing both fluorophores, resonance energy transfer between the donor coumarin and the acceptor fluorescein is observed, and the mixing of labeled and nonlabeled peptides allows the measurement of the rates of strand exchange between leucine zippers. Exchange rates do not depend on peptide concentration, indicating that strand exchange is governed by the rate of dissociation of the coiled coil. Strand exchange between leucine zippers with X1 and X2 = Leu occurs with a half-time of approximately 30 min. A single Leu/Ala substitution at X1 or X2 decreases the half-time to approximately 1 s. Folding was also studied in a relaxation experiment in which a preexisting equilibrium between monomeric chains and coiled coils was rapidly disturbed by dilution with buffer, and the relaxation to the new equilibrium was followed by the increase in fluorescence. In peptides with X1, X2 = Ala or X1 = Ala, X2 = Asn the folding process can be described by a simple two-state monomer<-->dimer equilibrium with k(on) approximately 4 x 10(6) M-1 s-1 and k(off) approximately 10 s-1. Kd = k(off)/k(on) approximately 2.5 microM is in good agreement with the value of Kd obtained from equilibrium measurements. The peptides with a single Ala at X1 or X2 exhibit biphasic folding kinetics. One phase is concentration dependent and the other apparently concentration independent. This behavior can be interpreted as a monomer<-->dimer equilibrium coupled to an equilibrium between different conformational isomers. Leu to Ala and Leu to Asn substitutions in the hydrophobic core alter the folding kinetics in a position-dependent manner.(ABSTRACT TRUNCATED AT 400 WORDS)

Induction of base damage in DNA solutions by ultrasonic cavitation

Ultrasound can damage macromolecules by the mechanical (shearing) and sonochemical (free radical generating) action of ultrasonic cavitation. Attributing macromolecular damage to either direct mechanical stress or to indirect mechanisms involving free radicals or other sonochemicals is a challenging problem. DNA damage induced by ultrasound was evaluated by measuring the formation of purine and pyrimidine products using combined gas chromatography-mass spectrometry with selected ion monitoring. Samples of DNA were prepared in 10 mmol dm-3 phosphate buffered saline (pH 7.4) and saturated with a mixture of argon:oxygen (3:1). Continuous 2.17 MHz ultrasound exposures at 0.82 mPa spatial peak negative pressure amplitude were performed in a 60 rpm rotating tube exposure system. Hydrogen peroxide yields were measured after each exposure to quantify the cavitation activity and ranged up to 350 mumol dm-3 for 1-h exposures. Purine and pyrimidine products identified were those typically observed following exposure of DNA to hydroxyl radical-generating systems, such as ionizing radiation, hypoxanthine/xanthine oxidase, or hydrogen peroxide in the presence of transition metal ions. The yields of these products were directly correlated with cavitation activity as measured by residual hydrogen peroxide concentrations. The yields of DNA products increased in the following order: thymine glycol approximately cytosine glycol > 8-oxoAde > FAPyAde approximately 5-HMU approximately 5,6-diOHCyt > FAPyGua. Unexpectedly, 8-oxoguanine did not exhibit a dose-dependent increase above background levels, and this observation is inconsistent with processes involving metal ion-dependent formation of hydroxyl radicals from hydrogen peroxide. In addition, the product yields were far too large to result from the residual hydrogen peroxide. Thus, ultrasonic cavitation appears to have a mode of action distinct from either ionizing radiation or formation of hydroxyl radicals via Fenton-like reaction with transition metals.

Gastrointestinal cancer

BACKGROUND

There are great differences in incidence and prognosis of cancer among the component sites of the digestive tract. Furthermore, a number of the histologic types of tumors at these sites differ in their incidence and prognosis.

METHODS

The SEER data from 1973 to 1987 on frequency, incidence, staging, and survival for the various histologic types of 194,452 cancers of the esophagus, stomach, and intestines were studied.

RESULTS

There was an increased incidence of adenocarcinomas of esophagus, gastric cardia, small intestine, and colon; incidence rates for rectal adenocarcinoma and esophageal squamous cell carcinoma remained stable; and rates for gastric adenocarcinoma decreased. Blacks had higher incidence rates than whites for gastric adenocarcinoma; squamous cell carcinoma of the esophagus; carcinoids of the small intestine, colon, and rectum; and gastric sarcomas. Whites, especially males, had higher incidence rates for adenocarcinomas of the esophagus and gastric cardia than did blacks. Blacks had lower rates for rectal adenocarcinomas than did whites, but slightly higher rates than whites for rectal mucinous carcinomas and colonic adenocarcinomas. Data on race, sex, survival, and time trends indicate that mucinous colorectal carcinomas are biologically different from other adenocarcinomas. Males had poorer overall survival than did females for most histologic types of digestive tract tumors. Appendiceal mucinous adenocarcinomas with distant metastases were associated with a high (50%) 5-year survival. The poor prognosis of cases diagnosed as colonic carcinoid raises the possibility that some of these actually may be carcinomas.

CONCLUSION

Studies of digestive tract cancer require analysis by histologic type for adequate assessment.

Gastrointestinal cancer

BACKGROUND

There are great differences in incidence and prognosis of cancer among the component sites of the digestive tract. Furthermore, a number of the histologic types of tumors at these sites differ in their incidence and prognosis.

METHODS

The SEER data from 1973 to 1987 on frequency, incidence, staging, and survival for the various histologic types of 194,452 cancers of the esophagus, stomach, and intestines were studied.

RESULTS

There was an increased incidence of adenocarcinomas of esophagus, gastric cardia, small intestine, and colon; incidence rates for rectal adenocarcinoma and esophageal squamous cell carcinoma remained stable; and rates for gastric adenocarcinoma decreased. Blacks had higher incidence rates than whites for gastric adenocarcinoma; squamous cell carcinoma of the esophagus; carcinoids of the small intestine, colon, and rectum; and gastric sarcomas. Whites, especially males, had higher incidence rates for adenocarcinomas of the esophagus and gastric cardia than did blacks. Blacks had lower rates for rectal adenocarcinomas than did whites, but slightly higher rates than whites for rectal mucinous carcinomas and colonic adenocarcinomas. Data on race, sex, survival, and time trends indicate that mucinous colorectal carcinomas are biologically different from other adenocarcinomas. Males had poorer overall survival than did females for most histologic types of digestive tract tumors. Appendiceal mucinous adenocarcinomas with distant metastases were associated with a high (50%) 5-year survival. The poor prognosis of cases diagnosed as colonic carcinoid raises the possibility that some of these actually may be carcinomas.

CONCLUSION

Studies of digestive tract cancer require analysis by histologic type for adequate assessment.

Thresholds for hemorrhages in mouse skin and intestine induced by lithotripter shock waves

In vivo biological effects of ultrasound should be characterized as thermal or cavitational to understand their etiology and significance. A spark-gap shock-wave lithotripter was built and used to compare cavitation-induced hemorrhages to the heat-induced petechial hemorrhages caused by continuous-wave ultrasound in mouse intestine. Intestinal hemorrhages induced in anesthetized hairless mice by the lithotripter pulses involved tissue destruction with bleeding into the lumen of the intestine, and were associated with intestinal gas bubbles. Skin hemorrhages were also observed, which appeared to be contusions, with no actual breakage of the skin. Administration of 100 shock waves with peak positive amplitude of 18.5 MPa produced an average of 7.6 (standard error [SE] 3.1, n = 6) intestinal hemorrhages and 45 (SE 11) skin hemorrhages. The counts and severity of hemorrhages increased with increasing numbers (3 to 300) of shock waves. Absorbers of varying thickness were used to reduce the pressure amplitude of the shock waves, which were thereby modified into low frequency ultrasound pulses. For 100 pulse exposures, apparent thresholds for effects occurred between 1.6 and 4.0 MPa for the intestinal hemorrhages and between 0.6 and 1.6 MPa for the skin hemorrhages. The low 1-Hz pulse repetition frequency precluded significant heating, and so these effects were the result of cavitation, which probably occurred inside the intestines or in the surrounding water. Compared to the previously observed thermal petechia, the cavitation-induced hemorrhages could be distinguished on the basis of their appearance upon histological examination, and also by the relative values of the thermal and mechanical exposure indices associated with the two different exposure modes.

Gastrointestinal cancer

BACKGROUND

There are great differences in incidence and prognosis of cancer among the component sites of the digestive tract. Furthermore, a number of the histologic types of tumors at these sites differ in their incidence and prognosis.

METHODS

The SEER data from 1973 to 1987 on frequency, incidence, staging, and survival for the various histologic types of 194,452 cancers of the esophagus, stomach, and intestines were studied.

RESULTS

There was an increased incidence of adenocarcinomas of esophagus, gastric cardia, small intestine, and colon; incidence rates for rectal adenocarcinoma and esophageal squamous cell carcinoma remained stable; and rates for gastric adenocarcinoma decreased. Blacks had higher incidence rates than whites for gastric adenocarcinoma; squamous cell carcinoma of the esophagus; carcinoids of the small intestine, colon, and rectum; and gastric sarcomas. Whites, especially males, had higher incidence rates for adenocarcinomas of the esophagus and gastric cardia than did blacks. Blacks had lower rates for rectal adenocarcinomas than did whites, but slightly higher rates than whites for rectal mucinous carcinomas and colonic adenocarcinomas. Data on race, sex, survival, and time trends indicate that mucinous colorectal carcinomas are biologically different from other adenocarcinomas. Males had poorer overall survival than did females for most histologic types of digestive tract tumors. Appendiceal mucinous adenocarcinomas with distant metastases were associated with a high (50%) 5-year survival. The poor prognosis of cases diagnosed as colonic carcinoid raises the possibility that some of these actually may be carcinomas.

CONCLUSION

Studies of digestive tract cancer require analysis by histologic type for adequate assessment.

Ultrasound contrast agents nucleate inertial cavitation in vitro

Some ultrasound contrast agents contain stable bodies of gas, and this study was undertaken to determine if these agents could provide nuclei for inertial cavitation. Inertial cavitation was detected and assessed by the measurement of the sonochemical hydrogen peroxide after exposure to 2.17-, 2.95- or 3.8-MHz ultrasound. A noncavitating system was obtained by removing cavitation nuclei from the rotating tube exposure chambers by vacuum degassing, and from the phosphate-buffered saline medium by filtering. Albunex added at 10-2, 10-3 or 10-4 dilutions, or Levovist added at 2 mg mL-1, 0.2 mg mL-1 or 0.02 mg mL-1 all initiated significant H2O2 production for 2.17-MHz ultrasound at 0.41 MPa or higher spatial peak pressure amplitude for 5 min exposure gated at 0.25 s on and off with 60-rpm rotation. Not rotating the tube virtually eliminated H2O2 production. For 2.5-min continuous exposure, both agents initiated significant H2O2 production for 2.95-MHz exposure at 0.58 MPa or higher, but not for 3.8-MHz exposure up to 1.16 MPa. Bubble-based ultrasound contrast agents therefore appear to be able to provide nuclei for inertial cavitation in the rotating tube exposure system.

Comet assay reveals DNA strand breaks induced by ultrasonic cavitation in vitro

The induction of DNA strand breaks in cultured Chinese hamster ovary (CHO) cells was investigated in suspensions directly exposed to 2.17-MHz ultrasound. Production of hydrogen peroxide, a DNA-damaging sonochemical, by inertial cavitation was enhanced by the use of argon-and-oxygen-bubbled media and cell survival was improved by establishing standing waves and minimizing tube rotation. Viable cells were separated from the suspension after exposure and kept on ice for evaluation with the single-cell gel electrophoresis (comet) assay. With this assay, DNA damage from as little as 2-mumol/L hydrogen peroxide treatment for 30 min could be detected, and cell survival as low as 2-5% after ultrasound exposure was adequate for assay. An ultrasound dose-response trend was noted for increasing pressure amplitude up to 0.82 MPa (free field) and increasing exposure duration up to 4 min. The cells were able to repair some of the strand breaks when warmed to 28 degrees C for 30 min. The effect was not eliminated by addition of catalase, which indicates that the DNA damage was not due to the action of residual H2O2 alone. The results confirm the hypothesis of DNA damage in cells surviving inertial cavitation.

The effects of gestation on circulating progenitor cells

The frequency of BFU-E in second-trimester fetal blood (484 +/- 104/10(5)) falls progressively during gestation to a value of 69 +/- 41/10(5) in cord bloods of 36 weeks gestation and beyond, but this is still significantly greater than adult blood values of 14 +/- 8 (P < 0.01). BFU-E obtained from unfractionated peripheral blood mononuclear cells from fetuses/neonates less than 36 weeks gestation were more sensitive to erythropoietin than adult BFU-E, but the sensitivity of highly purified BFU-E obtained from second-trimester fetal liver was similar to that in adult cells. Almost maximal growth of BFU-E from purified fetal progenitor cells could be achieved with erythropoietin alone, whereas adult cells required the presence of other factors with 'burst-promoting activity'.