Multiple rainfall event pollution transport by sustainable drainage systems: the fate of fine sediment pollution.

A key design criterion of sustainable urban drainage systems is to mitigate urban stormwater pollution. Current research defines sustainable urban drainage systems (SuDS) pollutant treatment efficiency through the detention of total suspended solids, urban nutrients and heavy metal pollutants within the system during a design flow event, with research focusing on sand (>2 mm) sediment movement. The impact of multiple rainfall-runoff events on the fine sediment (<2 mm) treatment efficiency of SuDS is not yet well defined, and the temporal movement of detained sediment has not been investigated in detail. The field research presented in this paper addresses this research gap, monitoring ongoing fine sediment transport through a best-practice-designed SuDS network over 12 months through the use of a novel rare earth oxide trace methodology. Through time-stepped monitoring of the fine sediment pollution across three SuDS treatment trains (networks), the following key conclusions have been drawn. (1) That fine sediment becomes re-suspended and re-deposited within SuDS assets and the network as a result of ongoing multiple rainfall-runoff events. (2) That this re-suspension continues for over 52 weeks. (3) That by area, linear wetlands (within the monitored networks) outperform wetland and swale assets in multiple event fine sediment detention. And (4) that multiple event monitoring and analysis of fine sediment within a SuDS network highlights the under-performance of SuDS assets against current design event expectations.

Sudden unexpected death from an undiagnosed histiocytic sarcoma in an adolescent female.

A previously well 15-year-old female who was awaiting medical investigations for a proptosed right eye collapsed and died suddenly while walking. Postmortem examination revealed diffuse distortion and infiltration of multiple organs by a suspected neoplastic process. Histology confirmed the invasion of multiple organs by atypical cells and myocardial infiltration was the likely cause of death. An extensive panel of immunohistochemistry established the diagnosis of a histiocytic sarcoma. Sudden unexpected death due to a clinically undiagnosed neoplasia in childhood and adolescence is uncommon. This is the first report of a histiocytic sarcoma causing sudden unexpected death and highlights the importance of considering undiagnosed hematological malignancies when examining a case of sudden death at postmortem.

Thrombus formation in a dilated torcula following aneurysmal subarachnoid haemorrhage.

A case of thrombus formation occurring within a dilation of the dural venous sinuses following aneurysmal sub-arachnoid haemorrhage is presented. Acute neurological deterioration accompanied propagation of the thrombus. The patient was anticoagulated on day 5 post-SAH with no haemorrhagic complications and made a full recovery. The optimum time to commence anticoagulation is not clear and is discussed.

IDH mutation analysis in gliomas as a diagnostic and prognostic biomarker.

INTRODUCTION: There is a high rate of IDH1/2 mutations in low grade gliomas and in high grade gliomas deriving from them. IDH analysis of gliomas is a novel method of classification and an independent prognostic marker. We compared antibody and sequencing methods for the detection of IDH mutations. METHOD: 88 samples from 74 patients were identified. For immunohistochemistry: sections were stained with anti-IDH1R132H antibody. For sequencing: DNA was extracted from fresh, frozen tissue. RESULTS: 28% (20/71) of cases were positive for the R132H IDH1 mutation by antibody. An IDH1 mutation was detected by molecular genetics in 37% (21/57) of cases and no IDH2 mutations were detected. 24% (5/21) had rare IDH1 mutations not detected by immunohistochemistry. Where sufficient tissue was available, immunohistochemistry and DNA analysis were fully concordant for the p.Arg132His mutation. Both Grade II gliomas and anaplastic astrocytomas showed a statistically different distribution of IDH1 mutation load compared to GBMs (p < 0.0001; p = 0.0021 respectively). CONCLUSION: A rationalised combined approach involving R132H antibody testing and sequencing of negative cases would be ideal for the detection of IDH1 mutations--antibody testing is cheaper than sequencing but sequencing demonstrates rare IDH1 mutations not detected by immunohistochemistry.

Treatment of heavy metals by iron oxide coated and natural gravel media in Sustainable urban Drainage Systems.

Sustainable urban Drainage Systems (SuDS) filter drains are simple, low-cost systems utilized as a first defence to treat road runoff by employing biogeochemical processes to reduce pollutants. However, the mechanisms involved in pollution attenuation are poorly understood. This work aims to develop a better understanding of these mechanisms to facilitate improved SuDS design. Since heavy metals are a large fraction of pollution in road runoff, this study aimed to enhance heavy metal removal of filter drain gravel with an iron oxide mineral amendment to increase surface area for heavy metal scavenging. Experiments showed that amendment-coated and uncoated (control) gravel removed similar quantities of heavy metals. Moreover, when normalized to surface area, iron oxide coated gravels (IOCGs) showed poorer metal removal capacities than uncoated gravel. Inspection of the uncoated microgabbro gravel indicated that clay particulates on the surface (a natural product of weathering of this material) augmented heavy metal removal, generating metal sequestration capacities that were competitive compared with IOCGs. Furthermore, when the weathered surface was scrubbed and removed, metal removal capacities were reduced by 20%. When compared with other lithologies, adsorption of heavy metals by microgabbro was 10-70% higher, indicating that both the lithology of the gravel, and the presence of a weathered surface, considerably influence its ability to immobilize heavy metals. These results contradict previous assumptions which suggest that gravel lithology is not a significant factor in SuDS design. Based upon these results, weathered microgabbro is suggested to be an ideal lithology for use in SuDS.

Quantifying the tensile strength of microbial mats grown over noncohesive sediments.

Biofilms in marine and fluvial environments can comprise strong bacterial and diatom mats covering large areas of the bed and act to bind sediments. In this case the bed material becomes highly resistant to shear stresses applied by the overlying fluid motion and detachment, when it does occur, is manifest in patches of biofilm of the order cm(2) being entrained into the flow. This article is the first to report tensile test data specific to the centimeter scale using moist biofilm/sediment composite materials; the strain (ε)-stress (σ) relationships permit quantification of the elasticity (Young's modulus, E) and cohesive strength of each specimen. Specifically, we compare the mechanical strength of cyanobacterial biofilm-only samples to that of biofilm cultured over sediment samples (glass beads or natural sands of d ~ 1 mm) for up to 8 weeks. The range of tensile strength (1,288-3,283 Pa) for composite materials was up to three times higher than previous tensile tests conducted at smaller scale on mixed culture biofilm [Ohashi et al. (1999) Water Sci Technol 39:261-268], yet of similar range to cohesive strength values recorded on return activated sludge flocs [RAS; Poppele and Hozalski (2003) J Microbiol Methods 55:607-615]. Composite materials were 3-6 times weaker than biofilm-only samples, indicating that adhesion to sediment grains is weaker than cohesion within the biofilm. Furthermore, in order to relate the tensile test results to the more common in-situ failure of bio-mats due to shear flow, controlled erosion experiments were conducted in a hydraulic flume with live fluid flow. Here, the fluid shear stress causing erosion was 3 orders of magnitude lower than tensile stress; this highlights both the problem of interpreting material properties measured ex-situ and the need for a better mechanistic model of bio-mat detachment.

Convection enhanced delivery of panobinostat (LBH589)-loaded pluronic nano-micelles prolongs survival in the F98 rat glioma model.

BACKGROUND: The pan-histone deacetylase inhibitor panobinostat is a potential therapy for malignant glioma, but it is water insoluble and does not cross the blood-brain barrier when administered systemically. In this article, we describe the in vitro and in vivo efficacy of a novel water-soluble nano-micellar formulation of panobinostat designed for administration by convection enhanced delivery (CED). MATERIALS AND METHODS: The in vitro efficacy of panobinostat-loaded nano-micelles against rat F98, human U87-MG and M059K glioma cells and against patient-derived glioma stem cells was measured using a cell viability assay. Nano-micelle distribution in rat brain was analyzed following acute CED using rhodamine-labeled nano-micelles, and toxicity was assayed using immunofluorescent microscopy and synaptophysin enzyme-linked immunosorbent assay. We compared the survival of the bioluminescent syngenic F98/Fischer344 rat glioblastoma model treated by acute CED of panobinostat-loaded nano-micelles with that of untreated and vehicle-only-treated controls. RESULTS: Nano-micellar panobinostat is cytotoxic to rat and human glioma cells in vitro in a dose-dependent manner following short-time exposure to drug. Fluorescent rhodamine-labelled nano-micelles distribute with a volume of infusion/volume of distribution (Vi/Vd) ratio of four and five respectively after administration by CED. Administration was not associated with any toxicity when compared to controls. CED of panobinostat-loaded nano-micelles was associated with significantly improved survival when compared to controls (n=8 per group; log-rank test, P<0.001). One hundred percent of treated animals survived the 60-day experimental period and had tumour response on post-mortem histological examination. CONCLUSION: CED of nano-micellar panobinostat represents a potential novel therapeutic option for malignant glioma and warrants translation into the clinic.

Phase I trial of the somatostatin analog octreotide acetate in the treatment of fluoropyrimidine-induced diarrhea.

PURPOSE: Diarrhea is one of the dose-limiting toxicities for administration of fluorouracil (5FU) in patients with gastrointestinal malignancies and can result in severe morbidities or mortality. The somatostatin analog octreotide acetate has been used in the treatment of 5FU-induced diarrhea with promising results. A phase I trial was initiated to determine the maximum-tolerated dose of octreotide acetate that could be administered in this setting. PATIENTS AND METHODS: Patients were required to have National Cancer Institute Common Toxicity Criteria > or = grade 2 diarrhea or watery diarrhea secondary to treatment with 5FU or a modulated 5FU regimen. At least three patients were treated at each dose level; after satisfactory completion of this dose level (zero of three or one of six patients with < or = grade 2 toxicity), additional patients were added at the next dose level. Doses of octreotide acetate studied were 50 to 2,500 micrograms subcutaneously three times daily for 5 days. RESULTS: A total of 35 patients received 49 courses of therapy. The only significant toxicities occurred at 2,500 micrograms. At this dose level, one patient developed an allergic reaction with flushing, nausea, and dizziness after each of the first two injections. A second patient developed asymptomatic hypoglycemia with a serum glucose level of 26 mg/dL. The maximum-tolerated dose was 2,000 micrograms. The efficacy of the treatment correlated significantly (P = .01) with the dose of octreotide administered, and more patients completed the course of therapy at the higher doses. CONCLUSION: Octreotide acetate can be safely administered for the treatment of fluoropyrimidine-induced diarrhea in patients with gastrointestinal malignancies. The dose-limiting toxicities were allergic (nausea, rash, and light-headedness) and endocrine (hypoglycemia). There was a significant correlation between complete response to therapy and octreotide dose.

Phase II/pharmacodynamic trial of dose-intensive, weekly parenteral hydroxyurea and fluorouracil administered with interferon alfa-2a in patients with refractory malignancies of the gastrointestinal tract.

PURPOSE: Combined depletion of pyrimidine and purine DNA precursors has resulted in therapeutic synergism in vitro. The aims of the current study were to test this strategy in patients with refractory tumors and to assess its effects on selected nucleotide pools. PATIENTS AND METHODS: A single-institution phase II trial was initiated in patients with advanced carcinomas of the stomach and pancreas. Patients had measurable disease and had no prior chemotherapy except adjuvant fluorouracil (5FU) or gemcitabine. 5FU was administered by CADD + pump at 2.6 g/m(2) intravenously by 24-hour infusion on days 1, 8, 15, 22, 29, and 36. Parenteral hydroxyurea (HU) was administered at 4.3 g/m(2) as a 24-hour infusion concurrently with 5FU. Interferon alfa-2a (IFN-alpha2a) was administered at 9 million units subcutaneously on days 1, 3, and 5 each week. No drug was administered in weeks 7 and 8. Pharmacodynamic studies were performed to assess drug effects on levels of deoxyuridine triphosphate (dUTP) and thymidine triphosphate (TTP) pools in peripheral-blood mononuclear cells (PBMCs) before and 6 hours after treatment using a highly sensitive DNA polymerase assay. RESULTS: There were 53 patients enrolled onto the study (gastric carcinoma, 31; pancreatic carcinoma, 22). The median age was 61 years, with 22% of patients > or = 70 years old. The predominant grade 3 to 4 toxicities were leukopenia (49%), granulocytopenia (55%), and thrombocytopenia (22%). Severe diarrhea occurred in 12%, mucositis in 0%, and vomiting in 10% of patients. Patients > or = 70 years had no greater incidence of toxicities. Among the 30 assessable patients with gastric carcinoma, there were two (7%) complete responders and 11 (37%) partial responders (median duration, 7 months). Among the 21 assessable patients with pancreatic carcinoma, there was one responder. Median survival among all patients with gastric carcinoma was 10 months and 13 months for patients with pancreatic carcinoma. Twenty-three patients had samples studied for levels of dUTP and TTP. There was no change in the levels of TTP before and after treatment. Furthermore, dUTP was detected in only five of 28 samples after treatment with no increase in the dUTP/TTP ratio. CONCLUSION: Combination therapy with high-dose, weekly infusional HU and 5FU with IFN-alpha2a modulation was well-tolerated with activity in gastric cancer. Patients > or = 70 years tolerated therapy as well as younger patients. This was the first study to correlate levels of TTP and dUTP after treatment with clinical outcome. In PBMCs used as a surrogate tissue, HU abrogated the 5FU-induced increase in dUTP levels without reversing the overall efficacy of the regimen.

Pilot trial of cisplatin, radiation, and WR2721 in carcinoma of the uterine cervix: a New York Gynecologic Oncology Group study.

PURPOSE: A phase I trial of WR2721 was initiated to determine the maximal safe dose for incorporation into a consecutive 5-day schedule of cisplatin administered concurrently with radiation therapy in patients with cervical cancer. PATIENTS AND METHODS: WR2721 was administered at 340 to 910 mg/m2/d immediately before cisplatin. Cisplatin was administered at 20 mg/m2/d for 5 days every 3 weeks in combination with external-beam radiation therapy and at 100 mg/m2 after each brachytherapy treatment. Pelvic radiation consisted of external-beam therapy to a dose of 39.6 Gy, followed by brachytherapy with cesium 137 tandem and ovoid insertions to deliver 80 Gy to point A and 55 Gy to point B. RESULTS: Twenty patients were enrolled; 19 were assessable. The dose-limiting toxicity of WR2721 was hypotension. No patients developed serious sequelae, but hypotension required a reduction in the dose of WR2721 at the highest dose level tested. The major grade 3 or 4 toxicities included transient azotemia (five of 19), leukopenia (nine of 19), vomiting (four of 19), and neurotoxicity (two of 19). One patient experienced an anaphylactic reaction to cisplatin. CONCLUSION: The recommended dose of WR2721 administered in conjunction with cisplatin on a daily x 5 schedule plus radiation therapy is 825 mg/m2/d for 5 days.

Management of hypocalcemic effects of WR2721 administered on a daily times five schedule with cisplatin and radiation therapy. The New York Gynecologic Oncology Group.

PURPOSE: To determine the effects of the chemoprotective agent, WR2721, administered on a daily x 5 schedule with cisplatin and radiation therapy, on calcium and parathyroid hormone (PTH) levels. PATIENTS AND METHODS: Twenty women with cervical cancer were enrolled in a clinical trial to determine the maximal safe dose of WR2721 plus radiation therapy and cisplatin on a novel daily x 5 schedule. Detailed studies of the effects of WR2721 on calcium and PTH levels were initiated after a patient developed symptomatic hypocalcemia. RESULTS: Treatment with WR2721 resulted in a rapid decline in serum PTH levels within 4 hours, which fell below the lower limits of normal at 24 hours, then returned to within normal limits at 48 hours. In contrast, serum levels of ionized calcium were not affected acutely, and declined by only 7% within 24 hours. However, this small decrease persisted for the 5 days of treatment. Hypocalcemic effects were successfully managed with oral calcium carbonate and calcitriol supplements. In one patient, particularly sensitive to the effects of WR2721, serum levels of ionized calcium decreased to less than 3.0 mg/dL despite oral calcium supplements. CONCLUSION: The effects of WR2721 on serum ionized calcium levels are mediated by direct inhibition of PTH activity; other effects such as inhibition of renal tubular calcium reabsorption cannot be excluded. We recommend that patients treated with WR2721, cisplatin, and radiation therapy receive routine oral calcium and calcitriol supplementation and that serum ionized calcium levels be monitored frequently.

Interferon induces thymidine phosphorylase/platelet-derived endothelial cell growth factor expression in vivo.

The enzyme/cytokine thymidine phosphorylase/platelet-derived endothelial cell growth factor (TP/PD-ECGF) has diverse functions within cells, including the regulation of steady-state thymidine levels, the conversion of the cancer chemotherapeutic agent 5-fluorouracil (FUra) to an active metabolite, and the mediation of angiogenesis in normal and malignant cells. Although the levels of TP/PD-ECGF vary substantially among different tissues and are generally found to be elevated in tumors, little is known about the control of its expression in vivo in humans. In this study, peripheral blood mononuclear cells were obtained from patients prior to and during treatment with IFN and FUra and analyzed for TP/PD-ECGF expression. Sixteen of 21 patients (76%) exhibited an average 3-4-fold increase of TP/PD-ECGF protein levels after treatment with either IFN-alpha or-beta, with the remaining patients having either a decrease (four patients) or no change (one patient) at the sampling times examined. Expression in vivo increased rapidly within 1-2 h of IFN treatment and remained elevated for up to 48 h after its administration. The increase in TP/PD-ECGF protein was accompanied by a concomitant increase in TP/PD-ECGF mRNA levels. TP/PD-ECGF mRNA expression in cells in vitro was induced by IFN but not by pharmacologically relevant concentrations of FUra, suggesting that the IFN was responsible for the induction seen in the patients. This study demonstrates that IFN induces TP/PD-ECGF expression in vivo by regulation of the level of mRNA expression.

Prolonged ultraviolet light-induced erythema and the cutaneous carcinoma phenotype.

A considerable amount of evidence exists in support of the role of ultraviolet radiation as a major etiologic factor in human skin cancer, both melanoma and carcinoma types. On the basis of epidemiologic studies a phenotype has been described which helps to identify the persons who are more susceptible to skin cancer. In an attempt to further define this population, patients with cutaneous carcinoma and a normal control group were exposed to artificial ultraviolet light (UVL) and the erythema and tanning responses of each group were measured over a 21-day period. UVL-induced erythema was prolonged in a significantly higher percentage of patients with skin cancer than in control patients, lasting two to three weeks after single exposures to 6 and 8 times the patient's minimal erythema dose. The presence of prolonged erythema correlated with this history of previous skin cancer but did not correlate with other established risk factors for cutaneous carcinoma, i.e., fair skin, light hair and light eyes, easy sunburning and poor tanning, and Celtic ancestry. Prolonged erythema following UVL radiation may therefore represent an additional risk factor and help to identify the skin cancer-susceptible population.

Phase II trial of N-(phosphonacetyl)-L-aspartate (PALA), 5-fluorouracil and recombinant interferon-alpha-2b in patients with advanced gastric carcinoma.

The aspartate transcarbamoylase inhibitor, N-(phosphonacetyl)-L-aspartate (PALA), synergistically enhanced the cytotoxicity of a combination of 5-fluorouracil (5-FU) and interferon-alpha (IFN) against human colon cancer cell lines in vitro. To test the efficacy of this combination in the clinical setting, patients with locally advanced or advanced gastric carcinoma were treated with the combination of PALA, 5-FU and IFN (PFI). Patients were required to have biopsy-proven disease beyond the scope of surgical resection, measurable disease, no prior chemotherapy, adequate bone marrow, renal and hepatic function, to be fully ambulatory and to have given informed consent. Drug was administered as follows: PALA, 250 mg/m2, 15 min i.v. infusion, days 1, 15, 22, 29, and then weekly; 5-FU, 750 mg/m2 daily x 5 as a continuous i.v. infusion beginning day 2, then at 750 mg/m2 days 16, 23 and 30, then weekly; IFN, 9 MU subcutaneously three times per week beginning day 2. There were 22 patients enrolled. The major toxicities were fatigue and associated neurotoxicity, with acceptable gastrointestinal and haematological toxicities. There was one complete responder (5%) and 3 partial responders (14%); two of these responses were durable (> 3 years). Despite this modest clinical activity, other regimens for advanced gastric cancer such as FAMTX and ELF appear to have greater activity with comparable toxicity.

The potential role of amifostine in conjunction with cisplatin in the treatment of locally advanced carcinoma of the cervix.

The treatment of locally advanced carcinoma of the cervix with radiation therapy as a single modality is inadequate, specifically for stage III and IVA disease. While chemotherapy as single-modality therapy is ineffective in advanced cervical cancer, there is some evidence of efficacy when used in combination with radiation therapy. A recently conducted phase II trial from the Albert Einstein College of Medicine used standard whole pelvic radiation therapy with concurrent cisplatin 20 mg/m(2)/d X 5 days for four courses in women with stage IB to IVA cervical cancer. Toxicities, mainly hematologic and soft tissue, were acceptable in this trial. There was only a modest impact on disease-free survival among women with stage III disease. A subsequent phase I trial conducted by the New York Gynecologic Oncology Group tested the addition of amifostine to the combination of cisplatin plus radiation therapy using the Albert Einstein College of Medicine regimen. Amifostine at doses escalated from 340 to 910 mg/m(2) was administered immediately before cisplatin. The dose-limiting toxicity was hypotension. Amifostine should be tested in future clinical trials either as a cytoprotective agent in patients receiving cisplatin plus radiation therapy or, alternatively, to assess dose intensification of cisplatin in combination with radiation therapy.

Cutaneous lesions in disseminated candidiasis mimicking ecthyma gangrenosum.

Cutaneous nodules are recognized as a manifestation of disseminated candidiasis. We describe skin lesions clinically identical to ecthyma gangrenosum that, on microscopic examination, were due to Candida emboli rather than Pseudomonas sepsis. Thus, the appearance of necrotic pustules and ulcerative plaques in the immunocompromised patient would raise the possibility of Candida as well as Pseudomonas sepsis, and illustrates the diagnostic importance of skin biopsy in such cases.

Uveitis, poliosis, hypomelanosis, and alopecia in a patient with malignant melanoma.

Bilateral uveitis, poliosis, hypomelanosis, and alopecia (Vogt-Koyanagi-Harada syndrome) developed spontaneously in a 57-year-old woman following operation for metastatic malignant melanoma. She has been disease-free for 8 1/2 years in spite of a highly unfavourable prognosis. Within the framework of current concepts of cell-mediated and humoral immunity in patients with malignant melanoma, activity of the host's immune system is postulated for the destruction of normal melanocytes in the skin, hair follicle, and uveal tract, as well as for the favorable outcome.

Off-label dermatologic therapies. Usage, risks, and mechanisms.

Off-label refers to the prescribing of Food and Drug Administration-approved drugs for a use not indicated on the package insert. The prescribing of off-label drugs may benefit patients with many dermatologic diseases including angiogenesis-related conditions. We surveyed 55 dermatologists from a single large academic program to assess their use of particular drugs for specific skin conditions, their perception of such use as being for Food and Drug Administration-approved or for off-label indications, and their attitudes towards off-label therapies. The practice of prescribing off-label drugs was common among the respondents, many of whom had misperceptions about which conditions are Food and Drug Administration-approved indications and about the legal ramifications of off-label therapies. We suggest that understanding the principles of off-label prescribing in conjunction with the mechanisms of drug action in diseases may help clinicians exercise their judgment in finding innovative therapies for their patients.

Phosphorylation of synapsin I and dynamin in rat forebrain synaptosomes: modulation by sigma (sigma) ligands.

The effects of sigma (sigma) ligands on protein phosphorylation were examined in crude, rat forebrain synaptosomes. Synaptosomes were prelabelled with 32P(i) and incubated with the sigma ligands 1,3-di-o-tolylguanidine (DTG), (+)pentazocine and (-)pentazocine (3, 10, 30, 100, 300 microM), or haloperidol, reduced haloperidol, and (+)SKF 10,047 (100 microM). Aliquots were then incubated for 10 s in control (5 mM K+) or depolarising buffer (41 mM K+). All the sigma ligands increased basal phosphorylation of synapsin Ib and other proteins including dynamin, and inhibited the depolarisation-dependent increase in phosphorylation of synapsin Ib in synaptosomes. The effects of these ligands are not directly on protein kinases or protein phosphatases. This indicates that the sigma ligands are mediating their effects via interaction with sigma binding sites, and suggest, for the first time, that protein phosphorylation may be one mechanism through which sigma ligands produce their biological effects.

Mediation of serotonin-induced analgesia by the 5HT2 receptor in the pentobarbital anesthetized mouse model.

Serotonin can induce analgesia when injected directly into the brain, but analgesia after peripheral administration has been more difficult to show. The pentobarbital anesthetized mouse (PAM) model, developed to alleviate some of the problems involved in the measurement of tail flick latency, was used to assess the action of peripherally administered serotonin. Mice were anesthetized with about 65 mg/kg of sodium pentobarbital IP and their tail flick latencies measured while they were in stage III anesthesia. In these anesthetized mice, IP serotonin induced a significant analgesia that was much more robust than that found in awake mice. The analgesic effect was dose-dependent from 0.25 mg/kg to 10 mg/kg but was not blocked by the antiopiate naltrexone. Of several psychotropic agents tested, only amitriptyline, mianserin, and trazodone had significant effects on analgesia in the PAM model. The analgesic effect of serotonin was reproduced by the 5HT2 agonist DOI and totally blocked by the 5HT2 antagonist NPP. These results show the utility of the PAM model in studying nonopiate analgesia and suggest that the analgesic action of serotonin is mediated primarily through the 5HT2 receptor.