Evaluation of effects of chitosan in preventing hemorrhagic cystitis in rats induced by cyclophosphamide

Hemorrhagic cystitis is a common problem following cyclophosphamide or radiation therapy. Chitosan has been shown to be an effective hemostatic agent and promoter of wound healing in animal experiments. We evaluated the safety and efficacy of intravesical chitosan in an animal model of cyclophosphamide cystitis. Hemorrhagic cystitis was induced in female F344 rats by intraperitoneal cyclophosphamide, 100 mg/kg. Chitosan solution (0.3 ml) was instilled intravesically on day 1 (Group 1), on days 1, 3, and 5 (Group 2), or 1 hour after the administration of cyclophosphamide (Group 3). The rats in group 4 were treated with chitosan diluent on day 1 after cyclophosphamide, and the rats in group 5 received intravesical chitosan without cyclophosphamide. Sequential examination revealed decreased mortality and lower incidences of severe bladder bleeding, necrosis and inflammation in Group 3. Treatment delayed until after the appearance of the cystitis, especially repeated treatments, appeared to make the cyclophosphamide-induced changes worse. Used within 1 hour of cyclophosphamide administration, before the cystitis develops, chitosan seemed to have the possibility to inhibit the appearance of hemorrhagic cystitis. In addition to the changes in the bladder, severe changes occurred in the kidneys secondary to cyclophosphamide.

Laser energy and dye fluorescence transmission through blood in vitro

PURPOSE

Because of the potential usefulness of evaluating and treating choroidal neovascularization obscured by blood, we designed this study to quantify the transmission of dye fluorescence and laser energy through blood.

METHODS

Blood preparations anticoagulated with ethylenediaminetetraacetic acid with hematocrits of 0% (plasma), 46%, and 99% were placed in open cuvettes with path lengths of 100, 200, or 500 microns and were exposed for one minute to either 100% oxygen or 100% carbon dioxide. Each cuvette was then sealed. Photographs of the cuvettes of blood in front of a flask of fluorescein or indocyanine green solution were decoded and used to calculate the percent transmission of fluorescence through blood. Cuvettes of blood were also placed in the path of argon, krypton, and diode lasers for energy transmission measurements.

RESULTS

Plasma transmission of fluorescein and indocyanine green fluorescence and argon, krypton, and diode laser energy was 89% to 100% for all samples tested. Transmission of fluorescein fluorescence and argon laser energy through 99% hematocrit samples were both less than 5%. Transmission of indocyanine green fluorescence through 100-, 200-, and 500-microns-thick cuvettes filled with 99% hematocrit blood was 57%, 34%, and 4%. Transmission of krypton laser energy was 50%, 25%, and 6%; and transmission of diode laser energy was 60%, 35%, and 12% through 99% hematocrit blood. Intermediate transmission values were obtained for 46% hematocrit samples.

CONCLUSIONS

Krypton and, to a slightly greater degree, diode laser energy penetrate a thin film of blood. Indocyanine green fluorescence also penetrates a thin film of blood. If a layer of blood appears thinner than 500 microns, then indocyanine green angiography may be useful in imaging underlying pathologic features. If a lesion can be imaged with indocyanine green, then it can probably be treated with a krypton or diode laser.

Relationship of DNA adducts derived from 2-acetylaminofluorene to cell proliferation and the induction of rodent liver and bladder tumors

Pharmacokinetic models have been developed to assist in extrapolating results from rodent bioassays. However, in numerous circumstances, it is necessary to combine such models with cellular response models to fully define interspecies and dose extrapolations. Interactions between pharmacokinetic target tissue end points (DNA adduct formation) and cellular proliferation in liver and urinary bladder carcinogenesis is illustrated with the results from the ED01 study involving 2-acetylaminofluorene administered to female mice. The interaction of genotoxic and cell proliferative effects are also illustrated in a co-carcinogenesis study with low doses of N-[4-(5-nitro-2-furyl)-2-thiazolyl]formamide and high doses of sodium saccharin. The application of such interactions to humans is illustrated for the case of cigarette smoke-induced bladder cancer.

Port site metastases after laparoscopic colorectal surgery for cure of malignancy

Laparoscopic surgery is excellent for treating benign disease of the colon and rectum, and for palliative operations for malignancy. Its application for cure of colorectal malignancy, however, must be approached with caution. Port site recurrence of tumour is a particular, and increasingly recognized, drawback. This review discusses the evidence to date to support prospective randomized trials of laparoscopic colectomy for cure of carcinoma.

Effect of sodium saccharin on the neonatal rat bladder

In a two-generation bioassay, high doses of dietary sodium saccharin (NaSac) produce bladder carcinoma in rats, whereas acid saccharin (HSac) does not effect the urothelium. NaSac and HSac administered as 5% of the diet to F0 Sprague-Dawley (SD) and F344 rats, continued through to the weaned male rats for ten additional weeks. Control 3H-thymidine labeling index (LI) was high prior to and at birth (approximately 11%), declining rapidly by weaning (to < 0.2). Neither NaSac nor HSac increased proliferation through 7 days of age. NaSac increased the proliferation rate at later times, whereas HSac did not. The LI decreased to control levels in NaSac-fed rats switched to control diet after weaning and increased in control-fed rats switched to NaSac after birth or weaning. In a second experiment, 5% NaSac did not affect urothelial morphology of SD rats through 7 days. By 21 days post-birth, urothelial hyperplasia occurred in NaSac-fed rat. The LI in treated versus control was similar through gestation, with a slight difference by 7 days. LI was significantly different by 21 days post-birth, but was similar between males and females. These results provide additional evidence for the increased cell proliferative effects of NaSac during the neonatal period, but not during gestation.

Signal transduction by cAMP-dependent protein kinase A in Drosophila limb patterning

Interaction between distinctly specified cells in adjacent compartments establishes organizing centres that control growth and specify cell fate in the developing limbs of Drosophila. Localized expression of the secreted Hedgehog protein (Hh) by cells in the posterior compartment induces expression of the secreted signalling molecules decapentaplegic (dpp) or wingless (wg) in nearby anterior cells. wg and dpp in turn organize spatial pattern in the wing and leg imaginal discs. The Hh signal is thought to act by antagonizing the ability of the patched (ptc) gene product to repress wg and dpp expression. Here we present evidence that removing activity of the gene encoding cyclic AMP-dependent protein kinase A (pka) is functionally equivalent to removing ptc activity or to providing cells with the Hh signal. These findings suggest that cyclic AMP-dependent protein kinase A is a component of the signal transduction pathway through which Hh and Ptc direct localized expression of dpp (or wg) and establish the compartment boundary organizer.

Human relevance of animal carcinogenicity studies

Extrapolation of results from rodent bioassays involving high-dose exposures to possible carcinogenic risk in humans exposed to low doses is based on the assumptions of species relevance and high- to low-dose extrapolation. For genotoxic chemicals, such as 2-acetylaminofluorene and N-[4-(5-nitro-2-furyl)-2-thiazolyl]formamide, these assumptions appear to be appropriate, although the dose response can be greatly modified by cell proliferation effects of these chemicals at high doses. In contrast, nongenotoxic chemicals, such as chemicals causing urinary calculi or sodium saccharin and related sodium and potassium salts, frequently are carcinogenic only at high doses and/or only in specific species. Consequently, for extrapolation of results for nongenotoxic chemicals these assumptions may not be appropriate.

Comparison of the effects of new specific azasteroid inhibitors of steroid 5 alpha-reductase on canine hyperplastic prostate: suppression of prostatic DHT correlated with prostate regression

Four new azasteroid inhibitors of steroid 5 alpha-reductase were compared to the benchmark compound finasteride, each at a dose level of 1 mg/kg/day, as well to placebo and to castration, in seven groups of mature male beagle dogs with enlarged prostates. Prostate volumes were measured repetitively by a volume MRI method over 15 weeks of treatment. The study probed the obverse of the familiar relation between DHT and prostate growth, and provides the first documentation of a tight negative correlation between prostate regression and the prostatic concentration of DHT across a range of treatment regimens (r = -0.982). In this first direct comparison study of structure vs. in vivo activity for several azasteroids in the dog model of BPH, relative efficacy for induction of shrinkage of the dog prostate did not correlate at all with the inhibitor's relative activity against the dog 5 alpha-reductase in vitro. On the basis of the relative IC50 values it would not have been predicted that, at the dose tested, the analogue MK-434 (17 beta-benzoyl-4-aza-5 alpha-androst-1-en-3-one) was distinguished from the other inhibitors with respect to the induction of faster and more complete regression (69%) as well as greater reduction in prostatic DHT (95%), both of which approached the castrated dog levels of 75% prostatic shrinkage and > 98% reduction in DHT. Treatment with any one of the five azasteroids induced two- to five-fold increases in prostatic testosterone. However, total androgen was conserved at the placebo control level. Despite the differences noted, each azasteroid tested induced a highly significant decrease in prostatic volume that correlated tightly with a decreased prostatic DHT level in canine spontaneous BPH.

The initial worcester experience with laparoscopic hysterectomy

STUDY OBJECTIVE

To examine three community hospital's experience with the first 108 attempted laparoscopic hysterectomies.

DESIGN

Retrospective analysis of hospital and office charts using a standardized data-collection sheet.

SETTING

All procedures were performed at the Medical Center of Central Massachusetts, St. Vincent's Hospital, or the University of Massachusetts Medical School, Worcester, Massachusetts.

PATIENTS

The first 108 patients to have a laparoscopic hysterectomy attempted. Ninety procedures were completed successfully.

MEASUREMENTS AND MAIN RESULTS

Areas that were analyzed were indications for surgery, type of laparoscopic hysterectomy, surgeons' instrument preference, failure to complete the operation, complications, and relative cost. Surgical indications, patient demographics, and complication rates were comparable with those unpublished papers. However, our data showed no improvement in estimated blood loss or operating room time with increased operator experience. Review of pathology reports indicated no cases in which an unsuspected malignancy was encountered.

CONCLUSIONS

Laparoscopic hysterectomy can be performed safely and successfully by generalists in obstetrics and gynecology. Additional study is required to know whether variables such as operating room time and expense will improve as this procedure is increasingly performed by generalists rather than specialists.

Nubbin encodes a POU-domain protein required for proximal-distal patterning in the Drosophila wing

The nubbin gene is required for normal growth and patterning of the wing in Drosophila. We report here that nubbin encodes a member of the POU family of transcription factors. Regulatory mutants which selectively remove nubbin expression from wing imaginal discs lead to loss of wing structures. Although nubbin is expressed throughout the wing primordium, analysis of genetic mosaics suggests a localized requirement for nubbin activity in the wing hinge. These observations suggest the existence of a novel proximal-distal growth control center in the wing hinge, which is required in addition to the well characterized anterior-posterior and dorsal-ventral compartment boundary organizing centers.

Bilateral radial chorioretinal folds

Chorioretinal folds are most commonly idiopathic. Radial chorioretinal folds can be a sign of choroidal neovascularization. A case of bilateral radial chorioretinal folds as a presenting sign of age-related macular degeneration is reported. This patient has maintained good visual acuity in one eye in which the only sign of occult choroidal neovascularization is the presence of chorioretinal folds and minimal leakage on fluorescein angiography.

Effect of xylene clearance of mesenteric fat on harvest of lymph nodes after colonic resection

OBJECTIVE

To find out if clearance of surgical colectomy specimens with xylene gave a higher yield of lymph nodes and more accurate staging than the traditional step-sectioning technique.

DESIGN

Consecutive open study.

SETTING

Private hospital, United States.

MATERIAL

84 specimens from colonic resections, 4 of which were total colectomies and the remaining 80 segmental resections.

INTERVENTIONS

The first 41 (2 colectomies and 39 segmental resections) were cleared by step-sectioning alone (to establish baseline values). The remainder (n = 2 and 41, respectively) were step-sectioned, the lymph nodes were removed, and then the residual tissue was cleared with xylene.

MAIN OUTCOME MEASURES

The number of lymph nodes found, and if the diagnosis was changed by the finding of additional nodes.

RESULTS

The baseline values in the two total colectomy specimens were 76 and 101, and the mean (range) after segmental colectomy was 21 (1-98). The values after total colectomy in the second group were 33 and 73, and after xylene clearance an additional 12 and 17 nodes were found. After segmental colectomy a mean (range) of 13 (0-43) was found, and an additional 4 (0-12) were found after xylene clearance. No additional nodes containing metastases were found in total colectomy specimens after xylene clearance, and only 6 additional nodes after segmental resection contained metastases. These changed the histological stage of the disease in only 2 patients.

CONCLUSIONS

Xylene clearance offers little advantage over careful traditional step-sectioning of specimens, but may be of value if the histopathologist does not do routine meticulous step-sectioning.

Cell interaction between compartments establishes the proximal-distal axis of Drosophila legs

The appendage primordia of Drosophila are subdivided into compartments by the localized expression of transcription factors. Interaction between cells in adjacent compartments establishes organizing centres responsible for generating spatial pattern and promoting cell proliferation in the developing appendages. Localized expression of hedgehog (hh) in the posterior compartment of the leg imaginal disc directs expression of wingless (wg) in ventral-anterior cells and decapentaplegic (dpp) in dorsal-anterior cells near the anterior-posterior compartment boundary; wg then acts to specify ventral cell fate and to organize the dorsal-ventral axis of the leg. Interaction between wg-expressing ventral cells and dorsal cells near the anterior-posterior compartment boundary promotes axis formation in the leg. Here we show that the combined action of wg-expressing cells in the ventral-anterior compartment and dpp-expressing cells in the dorsal-anterior compartment activates expression of Distal-less, a gene required for proximal-distal axis formation in the limbs. These results demonstrate that sequential interaction between anterior-posterior and dorsal-ventral compartments establishes the proximal-distal axis of the limbs.

31P NMR and triple quantum filtered 23Na NMR studies of the effects of inhibition of Na+/H+ exchange on intracellular sodium and pH in working and ischemic hearts

The triple quantum filtered 23Na NMR method is applied here to measure the effects of EIPA, a specific inhibitor of the Na+/H+ antiporter, on relative intracellular sodium concentrations in isolated working hearts at baseline, during ischemia, and at subsequent reperfusion. In analogy to the spectrophotometric isosbestic point, an approach is developed that defines a value of tau at which the effect of the relaxation times on the TQF signal intensities is minimized, and the signals are proportional to the sodium concentration for both ischemic and working hearts. EIPA at 1.5 microM significantly inhibited (P < 0.01) the influx of intracellular Na+ during 20 min of ischemia at 36.2 degrees C in this rat heart model. In parallel 31P NMR studies, EIPA had no effect on either the development of acidosis during ischemia or on the recovery of pHi during reperfusion despite its profound effect on intracellular Na+ influx. Thus, under our conditions the Na+/H+ antiporter did not play a critical role in the maintenance of intracellular pH. EIPA treatment resulted in improved recovery (P < 0.005) of mechanical function after 20 min of ischemia. [ATP] was higher in treated hearts during ischemia and reperfusion.

Mitogenic effects of propoxur on male rat bladder urothelium

Propoxur produces bladder tumors in rats, but not other species. The hyperplastic and tumorigenic effects do not occur if urinary pH is lowered by administering propoxur in a semi-synthetic diet or co-administering it with ammonium chloride (NH4Cl). We fed propoxur at 8000 p.p.m. in Altromin 1321 diet to male Wistar rats for 4 weeks, with or without NH4Cl as 10,000 p.p.m. of the diet. The urine of rats fed control diet with or without propoxur had a relatively high urinary pH (approximately 8); the addition of NH4Cl lowered the urinary pH by approximately 0.5-1.0 units. There was no evidence of urinary calculi or amorphous precipitate nor was there an increase in microcrystals or formation of different crystals than occur in normal rat urine. Propoxur produced hyperplasia of the urothelium, as observed by light and scanning electron microscopy, and increased the labeling index for proliferating cell nuclear antigen. These effects were significantly inhibited by co-administration with NH4Cl. There was no evidence of urothelial necrosis. Thus, the hyperplasia appears to result from a direct mitogenic effect of propoxur or a metabolite on the urothelium, rather than from toxicity and consequent regeneration. Based on the present study and previous investigations, the urothelial effects of propoxur in the rat are dependent on high urinary pH and high administered doses, factors which need to be incorporated into any mechanistic model for the chemical and into any extrapolation to potential effects in humans.

Glandular stomach hemorrhage induced by high dose saccharin in young rodents

In studies primarily designed to evaluate the effects of saccharin and silicate on the urinary bladders of rodents, hemorrhage of the glandular stomach was observed in high incidence. It occurred in young rats with high doses of saccharin (7.5% sodium saccharin; 6.3% acid saccharin), with no difference between male and female F344 rats fed during ages 5 to 15 weeks. no difference between sodium saccharin and acid saccharin, and was reversible, even with continued saccharin administration. Sodium silicate (0.38, 1.13, 2.26% of the diet) had no influence on gastric hemorrhage. Iron deficiency anemia has been observed in young rats fed high dietary levels of saccharin, and the present results suggest that gastric hemorrhage contributes to its etiology.

Development of a test of cognitive bias in medical decision making

PURPOSE

To develop an inventory to measure the influence of cognitive biases on medical decisions.

METHOD

The Inventory of Cognitive Biases in Medicine (ICBM) consists of 22 medical scenarios in which respondents choose between alternatives that represent bias-prone or statistically based decisions. In 1992 and 1993 the ICBM was administered to 102 medical students and residents and 318 physician faculty at the Wright State University School of Medicine.

RESULTS

The statistically correct decision was made in fewer than half the ICBM scenarios for both groups (students and residents, 41%; faculty, 49%); and only the faculty scored better than chance. Acceptable reliability (KR 20 = .62 for the faculty administration) and item discrimination (mean = .49) were achieved. Further, the results suggest that the ICBM has both content and construct validity.

CONCLUSION

The rather poor performances of the students and residents and the faculty on the ICBM suggest that cognitive biases constitute an important detraction from reliance on logical and statistical strategies. The ICBM shows promise for use as a tool in both instructional and research endeavors attempting to minimize and elucidate this phenomenon.

Low glutathione reductase and peroxidase activity in age-related macular degeneration

Age-related macular degeneration (ARMD) may result from events initiated by reactive oxygen species. Blood samples from 18 patients with ARMD and 18 similarly aged controls were analysed for activities of important antioxidants. Blood glutathione reductase activity was lower in patients with ARMD compared with controls (p = 0.035). The activities of glutathione peroxidase (p = 0.18) and erythrocyte superoxide dismutase (p = 0.29) were similar between the two groups by a Student's two sample t test. Logistic regression was used to determine which enzyme activities were associated with ARMD after adjusting for possible confounding variables: smoking history, age, multivitamin use, and cardiovascular disease. Glutathione reductase activity (p = 0.05) and glutathione peroxidase activity (p = 0.065) were significantly associated with ARMD by this analysis. The relation of glutathione reductase and glutathione peroxidase activity to ARMD merits further study.

Comparison of effects of angiotensin-converting enzyme inhibition with those of angiotensin II receptor antagonism on functional and metabolic recovery in postischemic working rat heart as studied by [31P] nuclear magnetic resonance

To assess the role of angiotensin II (AII) in development of myocardial injury during ischemia and reperfusion, the effects of short-term treatment with the angiotensin-converting enzyme (ACE) inhibitor lisinopril were compared with the effects of short-term treatment with L-158,338, an AII antagonist, in isolated working rat heart. Myocardial function was assessed and correlated with simultaneous measurement of high-energy phosphate metabolism and intracellular pH by [31P] nuclear magnetic resonance (NMR) before, during, and after global ischemia. Hearts from rats treated with 1 mg/kg lisinopril in vivo recovered substantially more function than those of controls (p < 0.001), whereas 50 ng/ml (0.11 microM) lisinopril in vitro had no effect on functional recovery. A dose-dependent increase in functional recovery was observed in rat heart treated with 0.3, 1, or 3 mg/kg L-158,338 in vivo (p < 0.005). Treatment with 50 ng/ml (0.12 microM) L-158,338 in vitro also resulted in increased functional recovery (p < 0.02). Significantly milder acidosis during ischemia and significantly increased coronary flow were characteristic of the improved functional recovery exhibited by the groups treated with either lisinopril or L-158,338 in vivo. Treatment with L-158,338 in vitro caused significantly increased coronary flow during reperfusion as compared with either its control group or with lisinopril treatment in vitro. High-energy phosphate metabolism was essentially unchanged by any treatment regimen. AII antagonism alone resulted in a degree of improvement in functional recovery comparable to that observed with oral ACE inhibitor treatment.

neu is not involved in N-[4-(5-nitro-2-furyl)-2-thiazolyl]-formamide-induced bladder carcinoma or 2-amino-4-(5-nitro-2-furyl)thiazole transformation of rat bladder epithelial cells

Enhanced c-erbB-2/neu expression has been linked with a poor prognosis in human bladder cancer. Previous reports have shown that a point mutation at nucleotide T2012 in the coding region of the transmembrane domain of the rat gene is sufficient to confer transformation potential on this gene. We examined the comparative levels of p185neu as well as the sequence around the hotspot (T2012) of the neu gene of rat bladder cells transformed by 2-amino-4-(5-nitro-2-furyl)thiazole (ANFT) or established in culture from N-[4-(5-nitro-2-furyl)-2-thiazolyl]formamide (FANFT)-induced rat bladder tumors. We concluded that increased p185neu expression did not correlate significantly with tumorigenicity. No alterations in nucleotide sequences of the neu gene were observed in either in vitro model.

Neu is not involved in N-[4-(5-nitro-2-furyl)-2-thiazolyl]formamide- induced bladder carcinoma or 2-amino-4-(5-nitro-2-furyl)thiazole transformation of rat bladder epithelial cells

Enhanced c-erbB-2/neu expression has been linked with a poor prognosis in human bladder cancer. Previous reports have shown that a point mutation at nucleotide T2012 in the coding region of the transmembrane domain of the rat gene is sufficient to confer transformation potential on this gene. We examined the comparative levels of p185neu as well as the sequence around the hotspot (T2012) of the neu gene of rat bladder cells transformed by 2-amino-4-(5-nitro-2-furyl)thiazole (ANFT) or established in culture from N-[-4-(-5-nitro-2-furyl)-2- thiazolyl]formamide (FANFT)-induced rat bladder tumors. We concluded that increased p185neu expression did not correlate significantly with tumorigenicity. No alterations in nucleotide sequences of the neu gene were observed in either in vitro model.

Prohibitin gene is overexpressed but not mutated in rat bladder carcinomas and cell lines

Prohibitin was isolated as a candidate antiproliferating gene in rat liver cells, and it has been suggested as a tumor suppressor gene in human breast cancer. We investigated the steady state level of prohibitin mRNA in rat bladder cell lines and in rat bladder carcinoma induced by N-[4-(5-nitro-2-furyl)-2-thiazolyl]formamide (FANFT) and sodium saccharin, as well as the protein level in rat bladder epithelial cells. We also examined the prohibitin gene for mutations using the polymerase chain reaction (PCR) single strand conformation polymorphism (SSCP) and direct sequencing methods. All rat bladder tumors investigated and several cell lines had unexpectedly increased steady state levels of prohibitin mRNA compared with that of normal rat bladder or liver. The prohibitin protein was easily detected by Western blotting in all cell lines regardless of their malignant status or growth rate. However, PCR-SSCP and direct sequencing analysis showed no mutations in the prohibitin gene. These results These results indicate that prohibitin overexpression, but not mutations, may be involved in the early stage of rat bladder carcinogenesis.

Does laparoscopic-assisted ileal pouch anal anastomosis reduce the length of hospitalization?

Previous data have suggested that laparoscopic colon and rectal surgery may shorten the length of hospitalization. These claims have been attributed to a reduction of the length of ileus. The definition of "ileus" is variable and in all cases is subjective. In this study it was defined as the length of time until the patient passed flatus or stool without nausea, vomiting or abdominal distention. This prospective study was undertaken to compare the duration of ileus and of hospitalization after laparoscopic-assisted (LAC) and standard laparotomy (SC). After restorative proctocolectomy with an ileal-pouch anal anastomosis (IPAA) in both sets of patients. Twenty-two patients underwent LAC and 20 age, sex, and diagnosis-matched controls underwent SC. Mucosal ulcerative colitis (MUC) was the diagnosis in 16 LAC and in 15 SC patients while polyposis was the diagnosis in 6 LAC and in 5 SC patients. The mean time to resolution of postoperative ileus was 4.2 (4-11) days in the LAC group and 3.3 (2-5) days in the SC group. Hospital discharge was similar in each group occurring at a mean of 8.7 (7-13) days after LAC and 8.9 (6-18) days after SC. Neither the length of time for ileus resolution nor the length of hospitalization were reduced in the LAC group. Laparoscopic-assisted IPAA conferred none of the theoretical advantages associated with other laparoscopic procedures.