Prefrontal cortex astroglia modulate anhedonia-like behavior

Reductions of astroglia expressing glial fibrillary acidic protein (GFAP) are consistently found in the prefrontal cortex (PFC) of patients with depression and in rodent chronic stress models. Here, we examine the consequences of PFC GFAP+ cell depletion and cell activity enhancement on depressive-like behaviors in rodents. Using viral expression of diphtheria toxin receptor in PFC GFAP+ cells, which allows experimental depletion of these cells following diphtheria toxin administration, we demonstrated that PFC GFAP+ cell depletion induced anhedonia-like behavior within 2 days and lasting up to 8 days, but no anxiety-like deficits. Conversely, activating PFC GFAP+ cell activity for 3 weeks using designer receptor exclusively activated by designer drugs (DREADDs) reversed chronic restraint stress-induced anhedonia-like deficits, but not anxiety-like deficits. Our results highlight a critical role of cortical astroglia in the development of anhedonia and further support the idea of targeting astroglia for the treatment of depression.

Prefrontal Cortex Astroglia Modulate Anhedonia-like Behavior

Reductions of astroglia expressing glial fibrillary acidic protein (GFAP) are consistently found in the prefrontal cortex (PFC) of patients with depression and in rodent chronic stress models. Here, we examine the consequences of PFC GFAP+ cell depletion and cell activity enhancement on depressive-like behaviors in rodents. Using viral expression of diphtheria toxin receptor in PFC GFAP+ cells, which allows experimental depletion of these cells following diphtheria toxin administration, we demonstrated that PFC GFAP+ cell depletion induced anhedonia-like behavior within 2 days and lasting up to 8 days, but no anxiety-like deficits. Conversely, activating PFC GFAP+ cell activity for 3 weeks using designer receptor exclusively activated by designer drugs (DREADDs) reversed chronic restraint stress-induced anhedonia-like deficits, but not anxiety-like deficits. Our results highlight a critical role of cortical astroglia in the development of anhedonia and further support the idea of targeting astroglia for the treatment of depression.

Retrospective study of the incidence of sarcoidosis-like reaction in patients treated with immunotherapy

AIM

To assess the frequency of radiographically evident drug-induced sarcoidosis-like reaction (DISR) in patients treated with anti-cytotoxic T-lymphocyte-associated antigen-4 (CTLA-4) therapy, anti-programmed cell death protein 1 (PD-1) therapy, or a combination of both in a single centre.

MATERIALS AND METHODS

The images and medical records of 457 patients with metastatic melanoma or head and neck cancer treated with either anti-CTLA-4 therapy, anti-PD-1 therapy, or a combination of both at University of California medical centre were reviewed retrospectively and the incidence of radiological manifestations of DISR was assessed among these treatment groups.

RESULTS

Radiological manifestations of DISR were found in 19/457 patients (4.1%). The mean interval from the initiation of immunotherapy to development of DISR was 5.5 months (range 2.3-13.5 months). Mean interval from radiological detection of DISR to imaging evidence of resolution was 5.8 months (range 1.6-18.3 months). Three patients out of 81 (3.7%), 11/297 (3.7%), and 5/79 (6.3%) developed sarcoidosis-like reaction after treatment with anti-CTLA-4 antibody, anti-PD-1 antibody, and a combination of both, respectively. Most patients with DISR were asymptomatic and did not require systemic therapy. Most patients did not demonstrate concomitant increased maximum standardised uptake value (SUVmax) in other organs on their integrated 2-[¹⁸F]-fluoro-2-deoxy-d-glucose (FDG) positron-emission tomography (PET)/computed tomography (CT).

CONCLUSIONS

In the present retrospective study of patients treated with immune checkpoint inhibitors (ICIs), DISR occurred in approximately 3.7% of patients treated with either anti-CTLA-4 or anti-PD-1 antibody and 6.3% of patients treated with a combination of both.

1147 Sleep Correlates With Improved Functional Outcome In The Intensive Care Unit

Introduction

Disruption of sleep may have significant implications in acute brain injury, functional recovery, and critical illness. Few data exist characterizing sleep architecture in patients admitted to an intensive care unit (ICU). We aim to describe sleep and clinical characteristics in patients with acute brain injury and critical illness.

Methods

Retrospective analysis was performed in ICU patients who underwent continuous electroencephalographic (EEG) monitoring from 2018-2019. Sleep was scored based on AASM-defined EEG criteria. Clinical variables, EEG characteristics, and modified Ranking Scale (mRS) were collected. Good outcome was defined as mRS<3. Differences were assessed using chi-square analysis and t-test.

Results

205 patients were reviewed with a mean age of 57 years (range 18-91) and a majority (57%) were male. Patients carried a primary neurologic/neurosurgical (61%) or medical/surgical (39%) diagnosis. Status epilepticus, subdural hemorrhage, traumatic brain injury, encephalopathy and cardiac arrest accounted for the majority of diagnoses encountered. Only 58 patients (28%) achieved N1 sleep; of these 76.4% achieved N2, 2.8% N3, and none achieved REM. Of those achieving any sleep, 43% had good outcomes versus only 23% in those who did not (t=-7.45, p<0.001). Neurological patients were more likely to attain sleep compared to those with other primary diagnoses (χ 2 (1)=7.08, p=0.008). Centrally acting anesthetics did not account for sleep differences between neurologic and non-neurologic patients (χ² (1)=2.01, p=0.16). However, those with primary brain injury reached sleep more often in the absence of anesthetic use (χ 2 (1)=4.82, p=0.03). The overall mortality was 32% in this cohort.

Conclusion

Most critically ill patients do not achieve electrophysiologic sleep. Of those who do, N1/N2 stages are seen most often. Neurological patients were more likely to sleep, and achieving any sleep was associated with improved functional outcome. Further studies are needed to determine whether sleep augmentation in the critically ill impacts functional outcome.

Support

N/A.

Direct and Indirect Effects of Fibroblast Growth Factor (FGF) 15 and FGF19 on Liver Fibrosis Development

Farnesoid X receptor (FXR) induces fibroblast growth factor 15 (FGF15; human ortholog FGF19) in the gut to potently inhibit bile acid (BA) synthesis in the liver. FXR activation in hepatic stellate cells (HSCs) reduces liver fibrosis (LF). Fgf15^-/- mice develop attenuated LF, but the underlying mechanisms for this protection are unclear. We hypothesized that FGF15/19 functions as a profibrotic mediator or mitogen to HSCs and increased BAs in Fgf15^-/- mice leads to enhanced FXR activation in HSCs, subsequently reducing fibrogenesis. In this study, complimentary in vivo and in vitro approaches were used: (1) CCl₄ -induced LF model in wild type (WT), Fgf15^-/- , and Fgf15 transgenic (TG) mice with BA levels modulated by feeding cholestyramine- or cholic acid-containing diets; (2) analysis of primary HSCs isolated from WT and Fgf15^-/- mice; and (3) treatment of a human HSC line, LX-2, with FXR activators and/or recombinant FGF19 protein. The results showed that Fgf15^-/- mice had lower basal collagen expression, which was increased by BA sequestration. CCl₄ induced fibrosis with similar severity in all genotypes; however, cholestyramine increased fibrosis severity only in Fgf15^-/- mice. HSCs from Fgf15^-/- mice showed increased FXR activity and reduced expression of profibrotic mediators. In LX-2 cells, FXR activation increased peroxisome proliferator-activated receptor gamma activity and reduced proliferation. FGF19 activated both signal transducer and activator of transcription 3 and c-Jun N-terminal kinase pathways and reduced nuclear factor kappa-light-chain-enhancer of activated B cells signaling without increasing fibrogenic gene expression or cell proliferation. Conclusion: FGF15/19 does not act as a direct profibrotic mediator or mitogen to HSCs in our models, and the protection against fibrosis by FGF15 deficiency may be mediated through increased BA activation of FXR in HSCs.

Knowledge, opinions and factors influencing practices regarding sugar in oral paediatric medications: a survey of Dunedin pharmacy staff

BACKGROUND AND OBJECTIVES

Sugar, a known aetiological factor in dental decay, has been used in paediatric medications as a bulking agent, preservative and to improve taste. Although artificial sweeteners have largely replaced sugar, some prescribed and over-the-counter (OTC) paediatric medications and supplements containing sugar are still available in New Zealand. Little is currently known about the knowledge, opinions and practices of staff in NZ pharmacies regarding sugar-containing paediatric medications. This study was carried out to investigate these factors.

METHODS

After ethical approval was obtained, questionnaires were delivered to all staff members at pharmacies in the greater Dunedin area. Quantitative statistical analysis was carried out using SPSS version 22.0 with the alpha value set at 0.05. Qualitative data were analysed using a general inductive technique.

RESULTS

A total of 58 questionnaires were returned giving a pharmacy response rate of 63.0%. Some 29.9% of respondents thought the inclusion of sugar in medications necessary and 77.6% agreed that sugar in paediatric medications can contribute to dental decay. Most of the 67.2% who reported that they do not give advice to customers regarding sugar in medications and oral health, felt it was not a priority. Parental request was the main factor determining provision or recommendations regarding sugar-free options (87.9%).

CONCLUSION

Although choice of a sugar-free medication can be limited by many factors, inter-professional collaboration and knowledge sharing on this topic would be advantageous. In addition, the provision of more formalised education, either as part of undergraduate pharmacy curricula or as part of continuing education, should be considered.

Canadian experience with the pipeline embolization device for repair of unruptured intracranial aneurysms

BACKGROUND AND PURPOSE

Flow-diverting stents, such as the PED, have emerged as a novel means of treating complex intracranial aneurysms. This retrospective analysis of the initial Canadian experience provides insight into technical challenges, clinical and radiographic outcomes, and complication rates after the use of flow-diverting stents for unruptured aneurysms.

MATERIALS AND METHODS

Cases were compiled from 7 Canadian centers between July 2008 and December 2010. Each center prospectively tracked their initial experience; these data were retrospectively updated and pooled for analysis.

RESULTS

During the defined study period, 97 cases of unruptured aneurysm were treated with the PED, with successful stent deployment in 94 cases. The overall complete or near-complete occlusion rate was 83%, with a median follow-up at 1.25 years (range 0.25-2.5 years). Progressive occlusion was witnessed over time, with complete or near-complete occlusion in 65% of aneurysms followed through 6 months, and 90% of aneurysms followed through 1 year. Multivariate analysis found previous aneurysm treatment and female sex predictive of persistent aneurysm filling. Most patients were stable or improved (88%), with the most favorable outcomes observed in patients with cavernous carotid aneurysms. The overall mortality rate was 6%. Postprocedural aneurysm hemorrhage occurred in 3 patients (3%), while ipsilateral distal territory hemorrhage was observed in 4 patients (3.4%).

CONCLUSIONS

Flow-diverting stents represent an important tool in the treatment of complex intracranial aneurysms. The relative efficacy and morbidity of this treatment must be considered in the context of available alternate interventions.

Delayed ipsilateral parenchymal hemorrhage following flow diversion for the treatment of anterior circulation aneurysms

BACKGROUND AND PURPOSE

The PED is a flow-diverting stent designed for the treatment of cerebral aneurysms. We report 4 cases of delayed ipsilateral IPH following the technically successful treatment of anterior circulation aneurysms with the PED.

MATERIALS AND METHODS

Clinical and imaging data from all patients undergoing aneurysm treatment with the PED at 2 institutions were analyzed to assess the incidence of delayed IPH after treatment with the PED.

RESULTS

A total of 66 patients (47 anterior circulation) with cerebral aneurysms underwent treatment with a PED between January 2008 and November 2010. Four patients experienced delayed periprocedural IPH, all after the treatment of anterior circulation aneurysms (8.5%, 4/47). The aneurysm size ranged from 5 to 21 mm. All IPHs occurred within the cerebral hemisphere, ipsilateral to the treated aneurysm, and were anatomically remote from the treated aneurysms. All procedures were uncomplicated, and patients emerged from general anesthesia at neurologic baseline. The hemorrhages became clinically evident between 1 and 6 days after the procedure. Two patients had unfavorable outcomes (mRS scores, 4 and 6).

CONCLUSIONS

Delayed IPH may occur after the treatment of anterior circulation aneurysms with flow diverters. This complication does not seem to be restricted to a specific aneurysm subtype and does not seem to be related to an intraprocedural complication or solely attributable to DAT.

Delayed spontaneous rupture of a posterior inferior cerebellar artery aneurysm following treatment with flow diversion: a clinicopathologic study

In this report, we present the fatal spontaneous delayed rupture of a previously unruptured large PICA aneurysm following treatment with the PED. Pathology at postmortem examination has supported the theory that intra-aneurysmal thrombus may acutely destabilize the aneurysm wall. Aneurysms with an anatomic arrangement that promote continued flow into the neck may not be optimal candidates for the flow-diversion treatment strategy.

A novel treatment of distal cerebral vasospasm. A case report

SUMMARY

A 22-year-old woman had an aneurysmal SAH due to a ruptured anterior communicating artery aneurysm and was treated successfully with endovascular coiling. The patient subsequently developed severe clinical and angiographically distal vasospasm. After failure of both medical treatment and proximal balloon angioplasty, the NeuroFlo device was tried and the patient showed substantial clinical recovery. We demonstrated an excellent outcome using a novel treatment for distal cerebral vasospasm with the NeuroFlo device.

Comparison of transendocardial and retrograde coronary venous intramyocardial catheter delivery systems in healthy and infarcted pigs

We compared two routes for myocardial delivery of therapeutics, transendocardial (TE) delivery with an intramyocardial injection catheter, and retrograde coronary venous (RCV) delivery with a balloon occlusion catheter in the interventricular vein.

METHODS

TE and RCV injection of 15 microM, neutron-activatable microspheres was compared in healthy pigs (Group I, n = 3), pigs with a 1-week-old myocardial infarction (MI; group II, n = 5), and pigs with a 2-weeks-old MI (group III, n = 4). The MI was induced by a 1-hr balloon occlusion in the LAD. Both methods were compared in the same animal using different microspheres. The RCV catheter allowed for continuous measurement of distal pressure and 2.5 x 10(6) microspheres were injected in 10 ml at 300 mmHg above balloon occlusion pressure. The TE injections were targeted to the infarct zone and 2.5 x 10(6) microspheres were distributed over 10 injections of 200 microl.

RESULTS

The retention of microspheres decreased with increase in MI age, but was comparable between devices within the groups. RCV delivery resulted in (14.3 +/- 0.9)% microsphere retention in Group I, (10.3 +/- 0.2)% in Group II, and (6.4 +/- 0.1)% in group III (P < 0.05 versus group I). Microsphere retention after TE was (15.1 +/- 0.7)% in group I, (18.9 +/- 0.6)% in group II, (4.1 +/- 0.1)% in Group III (P < 0.05 versus groups I and II). The RCV catheter delivered primarily to midventricular, antero-septal segments, whereas TE targeted apical areas predominantly.

CONCLUSIONS

Delivery efficacy was comparable between devices in each group however RCV targeted midventricular areas whereas TE targeted apical areas.

A review of prednicarbate (Dermatop)

Prednicarbate is a nonhalogenated corticosteroid that is used in the treatment of inflammatory skin diseases, for example atopic dermatitis. It has a favorable benefit-risk ratio, with an inflammatory action similar to that of a medium potency corticosteroid, but with a low potential to cause skin atrophy. Thus, prednicarbate may be a consideration in the treatment of atopic dermatitis in children, and other inflammatory disorders in children and adults.

Pimecrolimus: a review

Pimecrolimus (SDZ ASM 981), an ascomycin derivative, is one of the new classes of immunomodulating macrolactams and was specifically developed for the treatment of inflammatory skin diseases. The interest in pimecrolimus has been substantial because of its significant anti-inflammatory activity and immunomodulatory capabilities and its low systemic immunosuppressive potential. The mechanism of action of pimecrolimus is the blockage of T cell activation. Pimecrolimus (like all ascomycins) is an immunophilin ligand, which binds specifically to the cytosolic receptor, immunophilin macrophilin-12. This pimecrolimus-macrophilin complex effectively inhibits the protein phosphatase calcineurin, by preventing calcineurin from dephosphorylating the nuclear factor of activated T cells (NF-AT), a transcription factor. This results in the blockage of signal transduction pathways in T cells and the inhibition of the synthesis of inflammatory cytokines, specifically Th1- and Th2-type cytokines. Pimecrolimus has also been shown to prevent the release of cytokines and pro-inflammatory mediators from mast cells. Several studies have evaluated the effectiveness of pimecrolimus as a treatment for skin diseases. In animal models of allergic contact dermatitis, topical pimecrolimus was found to be effective. In human studies of allergic contact dermatitis pimecrolimus demonstrated significantly more efficacy than the control treatment. As well, the effectiveness of pimecrolimus 0.6% cream was comparable to 0.1% betamethasone-17-valerate; however, pimecrolimus was not associated with any of the side effects characteristic of a topical steroid. Topical application of pimecrolimus is not associated with skin atrophy. Pimecrolimus is effective and safe in both children and adults with atopic dermatitis. When pimecrolimus 1% cream has been applied to adult atopics, improvement has been observed as early as the first week, with a 72% reduction in severity after 3 weeks. Pharmacokinetic studies have shown very low blood levels of pimecrolimus following topical application, with no accumulation after repeated applications. Following application of pimecrolimus cream occasional transient irritation may be experienced at the application site. Similar results have also been found in children aged 3 months and older following application of pimecrolimus 1% cream. Topical pimecrolimus in psoriasis appears to exhibit a dose-dependent therapeutic effect under semi-occlusive conditions. Pimecrolimus has an enormous potential as a new treatment of inflammatory skin diseases. It has been shown to be effective in atopic and allergic contact dermatitis, with a favorable adverse-effects profile, which includes little effect on the systemic immune response.

Hospital prescribing errors: epidemiological assessment of predictors

AIMS

To demonstrate an epidemiological method to assess predictors of prescribing errors.

METHODS

A retrospective case-control study, comparing prescriptions with and without errors.

RESULTS

Only prescriber and drug characteristics were associated with errors. Prescriber characteristics were medical specialty (e.g. orthopaedics: OR: 3.4, 95% CI 2.1, 5.4) and prescriber status (e.g. verbal orders transcribed by nursing staff: OR: 2.5, 95% CI 1.8, 3.6). Drug characteristics were dosage form (e.g. inhalation devices: OR: 4.1, 95% CI 2.6, 6.6), therapeutic area (e.g. gastrointestinal tract: OR: 1.7, 95% CI 1.2, 2.4) and continuation of preadmission treatment (Yes: OR: 1.7, 95% CI 1.3, 2.3).

CONCLUSIONS

Other hospitals could use our epidemiological framework to identify their own error predictors. Our findings suggest a focus on specific prescribers, dosage forms and therapeutic areas. We also found that prescriptions originating from general practitioners involved errors and therefore, these should be checked when patients are hospitalized.

Tacrolimus: a review of its use for the management of dermatoses

The newly developed immunomodulator tacrolimus (FK506) is the first of a new class of agents that have enormous potential to change the way that dermatoses are treated and managed. Tacrolimus has been found to be active in a topical formulation with the latter exerting its effects by acting on the signal transduction pathways inside T cells and inhibiting gene transcription. The result is decreased responsiveness of T cells to antigens. Percutaneous absorption of tacrolimus is higher in diseased skin as opposed to healthy skin and, therefore, the drug will be taken in at progressively lower quantities as lesions heal. There is limited systemic absorption of tacrolimus over the course of therapy. The most extensive experience with tacrolimus has been in treating atopic dermatitis. In numerous trials, tacrolimus ointment 0.03-0.3% has shown to be effective in reducing the symptoms and severity of atopic dermatitis in adults and the paediatric population. Furthermore, there have been no significant toxic effects associated with topical therapy with tacrolimus. The most common complaint is that of local irritation after applying the ointment. This is generally transient and the patient is able to continue with therapy. The other dermatoses where tacrolimus has been used include contact dermatitis, psoriasis and pyoderma gangrenosum.

High-performance liquid chromatographic method for simultaneous determination of hawthorn active components in rat plasma

A simple HPLC method with photodiode-array (PDA) ultraviolet detection was developed for the simultaneous determination of four active polyphenol components of hawthorn (Crataegus), chlorogenic acid, epicatechin, hyperoside and isoquercitrin, in rat plasma. Following extraction from the plasma samples with ethyl acetate-methanol (2:1, v/v), these four compounds were successfully separated using a C18 column with a gradient elution of 5 and 25% acetonitrile in 25 mM phosphate buffer (pH 2.4). The flow-rate was set at 1 ml/min and the eluent was detected at 325 nm for chlorogenic acid, 278 nm for epicatechin, and 360 nm for both hyperoside and isoquercitrin. Narignin (0.82 microg) was used as the internal standard and was detected at 278 nm. The method is linear over the studied range of 0.16-40, 0.63-160, 0.13-32 and 0.13-30 microg/ml for chlorogenic acid, epicatechin, hyperoside and isoquercitrin, respectively. The correlation coefficient for each analyte was greater than 0.995. The intra-day and inter-day precision of the analysis was better than 4 and 7%, respectively. The extraction recoveries at low to high concentration were greater than 85% for both epicatechin and chlorogenic acid, and greater than 94% for both hyperoside and isoquercitrin. The detection limits were 0.04, 0.20, 0.03 and 0.03 microg/ml for chlorogenic acid, epicatechin, hyperoside and isoquercitrin. The developed method was used to analyze the plasma concentrations of the four analytes after the intravenous administration of hawthorn polyphenol extract to rats.

An evaluation of the hemostatic effects of hydrophilic, alcohol, and lipophilic extracts of notoginseng

STUDY OBJECTIVE

To compare the hemostatic effects of hydrophilic, alcohol, or lipophilic extract of notoginseng with those of the control and placebo.

DESIGN

Hemorrhagic rat model.

SETTING

Hartford Hospital, Hartford, Connecticut; animals were housed at the Hartford Hospital animal facility.

ANIMALS

Sixty-two male Wistar rats. Intervention. Administration of placebo (wheat flour), and alcohol, hydrophilic (water), and lipophilic (hexane) extracts of notoginseng.

METHODS

Rats were divided into five groups, and their tails were transected 5 mm from the tip. Group 1 received no treatment (control), group 2 received placebo, group 3 received alcohol extract, group 4 received hydrophilic extract, and group 5 received lipophilic extract. Total bleeding time was determined and compared among the groups.

MAIN RESULTS

Bleeding time was shorter for the placebo group than the control group (p=0.035). The alcohol extract group had the shortest bleeding time, which was significantly shorter than that of the control (p<0.0001), placebo (p=0.0124), and lipophilic extract groups (p=0.002). The hydrophilic extract group had a shorter bleeding time than the control group (p=0.0058) and showed a trend toward shorter bleeding time than the lipophilic extract group (p=0.068).

CONCLUSIONS

The alcohol extract of notoginseng results in the shortest bleeding time and provides better hemostatic effects than no treatment, placebo treatment, and treatment with lipophilic extract.

Meningeal melanocytoma of the planum sphenoidale. Case report and review of the literature

Meningeal melanocytoma is a rare benign primary melanotic tumor of the meninges, most commonly found in the spinal canal and the posterior fossa. The authors report the 19th published case of a supratentorial meningeal melanocytoma and the first reported case in which the tumor arose from the planum sphenoidale. The patient's presenting symptoms were characteristic of a large bifrontal lesion and included headaches, personality change, lethargy, and urinary and fecal incontinence. Computerized tomography and magnetic resonance imaging studies revealed an extraaxial lesion arising from the planum sphenoidale. The patient underwent successful gross total removal of the tumor without neurological sequelae. Based on the findings shown in this case report, meningeal melanocytoma should be included in the differential diagnosis of extraaxial lesions arising from the area of the planum sphenoidale.

Short-term effects of a progestational contraceptive drug on food intake, resting energy expenditure, and body weight in young women

BACKGROUND

Studies showed that hormonal fluctuations that occur over the human menstrual cycle affect energy intake and expenditure. However, little is known about the possible effects on body weight regulation that may arise when these cyclic changes are suppressed with hormonal contraceptives.

OBJECTIVE

The aim of this study was to examine how a progestational contraceptive drug (depot medroxyprogesterone acetate) affects food intake, resting energy expenditure (REE), and body weight in young women.

DESIGN

Twenty normal-weight women were tested in a single-blind, placebo-controlled experiment. Body weight, REE, and 3-d food intake (food provided) were measured in the follicular and luteal phases of 2 menstrual cycles before a single injection of depot medroxyprogesterone or saline solution was administered. Measurements were also taken 4 times after injection: in the luteal and follicular phases of 2 cycles in the placebo group and 2 wk apart (to mimic timing of the menstrual phases) in the drug group.

RESULTS

Before injection, the phase of the menstrual cycle affected both energy intake and REE. The study participants consumed more energy (4.3%; P = 0.02) and expended more energy at rest (4.3%; P = 0.0002) in the luteal phase than in the follicular phase. Comparison of pre- and postinjection means showed that treatment with the contraceptive drug had no significant effects on energy intake, REE, or body weight.

CONCLUSIONS

This study showed that, although phases of the menstrual cycle affected energy intake and REE, depot medroxyprogesterone acetate did not alter energy intake or expenditure or cause weight gain in young women.

Clonal selection versus genetic instability as the driving force in neoplastic transformation

Recent clonal studies of spontaneous neoplastic transformation in cell culture indicate that it develops at confluence in a small minority of individual clonal populations before it does in the uncloned parental culture. Either preferential selection of spontaneous variants or genetic destabilization in clones can be inferred to explain the result. In the present experiments, using a subline of NIH 3T3 cells that is relatively refractory to transformation, we demonstrate unequivocally that transformed foci appear under selective conditions in some clones long before there is any sign of neoplastic change in the polyclonal culture from which they were derived. Because the transformed cells that appear in the susceptible clones are not inhibited in the size or number of foci formed on a confluent background of the uncloned parental population, the genetic events underlying transformation must occur much less frequently in the latter. This disparity can be accounted for by the much larger number of selectable cells in the susceptible clones at confluence than in the parental culture, where such cells are a minority. The preferential transformation exhibited by experimental isolation and expansion of susceptible clones accords with evidence from various sources that neoplastic transformation in culture is a multistep process dependent primarily on selection of spontaneously occurring genetic variants. There is no necessity to posit a significant role for genetic destabilization in neoplastic transformation. These considerations bolster computer models of human cancer that implicate selective expansion of rogue clones rather than genetic instability as the driving force in the origin of most tumors. Both the genetics of the selected clone and the epigenetics of the selective environment would then contribute to tumor development.

An evaluation of the hemostatic effect of externally applied notoginseng and notoginseng total saponins

No effective hemostatic agents are available for external use. This project was conducted to evaluate the hemostatic effects of notoginseng using a hemorrhagic rat model. Rats (n = 40) were divided into four groups, and their tails were transected 5 mm from the tip. Group 1 received no treatment (control), while the other groups received external powder applied to the wound. Group 2 received placebo (flour), group 3 received ground notoginseng, and group 4 received a saponin extract of notoginseng. The total bleeding time was determined and compared between groups. The notoginseng group had lower bleeding times (9.60 +/- 1.50 min) than the control group (19.23 +/- 4.09 min, p < 0.001) or the placebo group (15.18 +/- 2.24 min, p < 0.001). Likewise, the saponin extract group had significantly lower bleeding times (11.70 +/- 2.53 min) than the control and placebo groups (p < 0.001 for both comparisons). No differences were found between the notoginseng and the saponin extract groups (p = 0.35). Notoginseng and a saponin extract from notoginseng provide hemostatic effects when applied externally.

Is the 135S poliovirus particle an intermediate during cell entry?

Poliovirus binding to its receptor (PVR) on the cell surface induces a conformational transition which generates an altered particle with a sedimentation value of 135S versus the 160S of the native virion. A number of lines of evidence suggest that the 135S particle is a cell entry intermediate. However, the low infection efficiencies of the 135S particle and the absence of detectable 135S particles during infection at 26 degrees C by the cold-adapted mutants argue against a role for the 135S particle during the cell entry process. We show here that binding of 135S-antibody complexes to the Fc receptor (CDw32) increases the infectivity of these particles by 2 to 3 orders of magnitude. Thus, the low efficiency of infection by 135S particles is due in part to the low binding affinity of these particles. In addition, we show that there is an additional stage in the entry process that is associated with RNA release. This stage occurs after formation of the 135S particle, is rate limiting during infection at 37 degrees C, but not at 26 degrees C, and is PVR independent. The data also demonstrate that during infection at 26 degrees C, the rate-limiting step is the PVR-mediated conversion of wild-type 160S particles to 135S particles. This suggests that during infection at 26 degrees C by the cold-adapted viruses, 135S particles are formed, but they fail to accumulate to detectable levels because the subsequent post-135S particle events occur at a significantly faster rate than the initial conversion of 160S to 135S particles. These data support a model in which the 135S particle is an intermediate during poliovirus entry.

Stabilization of poliovirus by capsid-binding antiviral drugs is due to entropic effects

When poliovirus attaches to its receptor or is heated in hypotonic buffers, the virion undergoes an irreversible conformational transition from the native 160 S (or N) particle to the 135 S (or A) particle, which is believed to mediate cell entry. The first-order rate constants for the thermally induced transition have been measured as a function of temperature for virus alone and for complexes of the virus with capsid-binding drugs that inhibit the receptor and thermally mediated conversion. Although the drugs have minimum inhibitory concentrations (MIC) that differ by almost three orders of magnitude, the activation energies for the N to A transition for the drug complexes (145 kcal/mol) were indistinguishable from each other or from that of the virus alone. We conclude that the antiviral activity of these drugs derives from a novel mechanism in which drug-binding stabilizes the virions through entropic effects.

Coculturing diverse clonal populations prevents the early-stage neoplastic progression that occurs in the separate clones

Most human cancers are of monoclonal origin and display many genetic alterations. In an effort to determine whether clonal expansion itself could account for the large number of genetic alterations, we compared spontaneous transformation in cloned and uncloned populations of NIH 3T3 cells. We have reported that progressive transformation of these cells, which is driven by the stress of prolonged contact inhibition at confluence, occurs far more frequently in cultures of recent monoclonal origin than in their uncloned progenitors. In the present work we asked how coculturing six clones at early and late stages of progression would affect the dynamics of transformation in repeated rounds of confluence. When coculture started with clones in early stages of transformation, marked by light focus formation, there was a strong inhibition of the progression to the dense focus formation that occurred in separate cultures of the individual clones. In contrast, when coculture started after the individual clones had progressed to dense focus formation, there was selection of transformants from the clone producing the largest and densest foci. Mixing the cells of a single clone with a large excess of uncloned cells from a subline that was refractory to transformation markedly decreased the size of dense foci from clones in transit from light to dense focus formation, but had much less effect on foci from clones with an established capacity for dense focus formation. The major finding of protection against progression by coculturing clones in early stages of transformation suggests that the expansion of a rogue clone in vivo increasingly isolates many of its cells from genetically stabilizing interactions with surrounding clones. Such clonal isolation might account for the increase in mutation rates associated with the dysplasia in colorectal adenomas that signifies the transition between benign and malignant growth.

Poliovirus mutants at histidine 195 of VP2 do not cleave VP0 into VP2 and VP4

The final stage of poliovirus assembly is characterized by a cleavage of the capsid precursor protein VP0 into VP2 and VP4. This cleavage is thought to be autocatalytic and dependent on RNA encapsidation. Analysis of the poliovirus empty capsid structure has led to a mechanistic model for VP0 cleavage involving a conserved histidine residue that is present in the surrounding environment of the VP0 cleavage site. Histidine 195 of VP2 (2195H) is hypothesized to activate local water molecules, thus initiating a nucleophilic attack at the scissile bond. To test this hypothesis, 2195H mutants were constructed and their phenotypes were characterized. Consistent with the requirement of VP0 cleavage for poliovirus infectivity, all 2195H mutants were nonviable upon introduction of the mutant genomes into HeLa cells. Replacement of 2195H with threonine or arginine resulted in the assembly of a highly unstable 150S virus particle. Further analyses showed that these particles contain genomic RNA and uncleaved VP0, criteria associated with the provirion assembly intermediate. These data support the involvement of 2195H in mediating VP0 cleavage during the final stages of virus assembly.

Relation of the slow growth phenotype to neoplastic transformation: possible significance for human cancer

Deletions are widely distributed over the genome in the most frequently occurring human cancers and are the most abundant genetic lesion found there. Deletions are highly correlated with the slow growth phenotype of mutated animal and human cells and result in chromosomal transposition when the retained ends are joined. Transpositions are only a minor source of mutation in rapidly multiplying bacteria but are a major cause of mutations in stationary bacteria. The NIH 3T3 line of mouse cells undergoes neoplastic transformation during prolonged incubation in a stationary state and expresses the slow growth phenotype on serial subculture at low density, suggesting a relation between transformation and chromosomal deletions. To further explore the relation between neoplastic transformation and the slow growth phenotype as a surrogate for deletions, two sublines of the NIH 3T3 cells with differing competence for transformation were serially subcultured in the stationary state at confluence and tested at each subculture for transformation and growth rate. Cell death in a fraction of the population and a heritable slowdown in proliferation of most of the survivors became increasingly pronounced with successive rounds of confluence. The reduction in growth rate was not proportional to the degree of transformation of the cultures, but all of the transformed cultures were slow growers at low density. All of the discrete colonies from cloning transformed cultures developed at a lower initial rate than control colonies under optimal conditions for growth, but they continued to grow at later stages, forming multilayered colonies under conditions that inhibited the further growth of the control colonies. The results suggest that prolonged incubation of NIH 3T3 cells in the stationary state results in growth-impairing deletions over a wide range of sites in the genome, but more restricted subsets of such lesions are responsible for neoplastic transformation. These findings provide dynamic, functional support in culture for the histopathological evidence that the quiescent state of cells associated with atrophy and fibrosis plays a significant role in the origin of some cancers in experimental animals and human beings.

Quantitative aspects of the selective killing of transformed cells by methotrexate in the presence of leucovorin

A quantitative study was made of the cytotoxicity of methotrexate (MTX) for nontransformed and transformed NIH 3T3 cells in the presence and absence of leucovorin. The study was preceded by an analysis of the growth rates of the cells at low and high population density combined with low and high concentrations of calf serum (CS). The reduced maximal growth rates of the transformed cells at low population densities relative to the nontransformed cells reinforced earlier evidence that heritable damage involving chromosome aberrations drives the process of transformation. When small numbers of transformed cells are cocultured with a large excess of nontransformed cells in the assay for transformed foci, the transformed cells were more readily killed by MTX than the nontransformed cells. The selectivity was increased when leucovorin (folinic acid) was present in the medium. The selective killing of the transformed cells actively multiplying in foci was most pronounced when the background of nontransformed cells had become confluent and their growth was inhibited. However, selectivity has also been demonstrated when transformed and nontransformed cells are growing at their maximum rates at low density despite the lower growth rate of the transformed cells under these conditions. The sensitivity of transformed cells in pure culture to MTX was lower during the first 3 d of subculture than in the following 6 d but decreased to zero a few d after net growth had ceased. The nontransformed cells were more susceptible to killing by MTX in Dulbecco's modified Eagle's medium (DMEM) than in MCDB 402, but the transformed cells were sensitive to MTX in both media. The high selectivity of MTX for transformed over nontransformed cells in MCDB 402 results from the presence of 1.0 microM leucovorin (5-formyltetrahydrofolate), a reduced form of the folic acid present in most other culture media. When leucovorin was added to DMEM with its high concentration of folic acid, the resistance to MTX of both nontransformed and transformed cells was greatly increased, but the selectivity of MTX for transformed cells was almost entirely lost. The results indicate that leucovorin protects nontransformed cells against concentrations of MTX that kill transformed cells, but the protection is dependent on the relative amounts of leucovorin to folic acid in the medium. The relative sensitivities of transformed and nontransformed cells in our system to MTX when both cell types are exhibiting their characteristic differential in growth behavior is similar to that described for tumor and normal cells in vivo. Since the unregulated growth behavior of the transformed, tumor-producing cells is efficiently and quantitatively measured in this system, it can be used to develop general principles of treatment and resolve questions of cytotoxic mechanism.

Clonal dynamics of progressive neoplastic transformation

In a recent study, we found that newly isolated clones of NIH 3T3 mouse cells undergo neoplastic transformation more readily than uncloned cultures from which they were derived. After eleven low-density passages (LDPs), most of the 29 clones produced lightly stained early-stage transformed foci when grown to confluence in a primary assay for transformation, and one of them consistently produced a few tiny dense foci. In the present work, six of the clones were kept in LDPs for 56 passages and assayed for focus formation at confluence at six passage levels. The clone that produced tiny dense foci switched to light foci during the LDPs, four others produced light foci at different passage levels, and one progressed from light to dense foci after the last passage. By contrast, all the clones progressed to dense focus formation in five or fewer serial repetitions of the assay at confluence. Because all but one of the clones underwent about half as many total divisions at each LDP as they did when grown to the stationary state at confluence, the latter is more efficient in eliciting progression than the exponential growth of the LDPs. Extension of the period at confluence of uncloned cultures results in the appearance of dense foci within light foci. Because the latter are localized clonal populations, the intrafocal progression reinforces the conclusion that clonal expansion favors transformation. We discuss the significance of these results for the clonal origin of human cancer and the increased incidence of cancer with age.

Energy density but not fat content of foods affected energy intake in lean and obese women

BACKGROUND

Studies have shown that energy intake increases when both the fat content and energy density of the entire diet increases. When the fat content and energy density vary independently of one another, however, energy density, but not fat content, influences intake.

OBJECTIVE

The present study examined whether energy intake in lean and obese women is affected when either the energy density or the fat content of a portion of the diet is manipulated and palatability is held constant.

DESIGN

In a within-subjects design, 17 lean and 17 obese women consumed meals in the laboratory for four, 4-d test periods. In 3 of these test periods the energy density (4.4 and 6.7 kJ/g) or the fat content (16% and 36% of energy) of compulsory entrees representing 50% of each subject's usual energy intake was manipulated. Additional self-selected foods were consumed ad libitum at meals and as snacks.

RESULTS

There were no systematic differences in palatability of the manipulated foods across conditions. Obese and lean participants responded similarly to the dietary manipulations. Intake of self-selected foods at meals was reduced significantly by 16% for both lean and obese subjects in the low- compared with the high-energy-density condition. The fat content of the compulsory foods had no significant effect on energy intake. Ratings of hunger did not differ between diets.

CONCLUSION

These results indicate that when a portion of the diet was manipulated, the energy density, but not the fat content, of the foods affected total energy intake at meals in both lean and obese women.

The cellular ecology of progressive neoplastic transformation: a clonal analysis

A comparison was made of the competence for neoplastic transformation in three different sublines of NIH 3T3 cells and multiple clonal derivatives of each. Over 90% of the neoplastic foci produced by an uncloned transformed (t-SA') subline on a confluent background of nontransformed cells were of the dense, multilayered type, but about half of the t-SA' clones produced only light foci in assays without background. This asymmetry apparently arose from the failure of the light focus formers to register on a background of nontransformed cells. Comparison was made of the capacity for confluence-mediated transformation between uncloned parental cultures and their clonal derivatives by using two nontransformed sublines, one of which was highly sensitive and the other relatively refractory to confluence-mediated transformation. Transformation was more frequent in the clones than in the uncloned parental cultures for both sublines. This was dramatically so in the refractory subline, where the uncloned culture showed no overt sign of transformation in serially repeated assays but increasing numbers of its clones exhibited progressive transformation. The reason for the greater susceptibility of the pure clones is apparently the suppression of transformation among the diverse membership that makes up the uncloned parental culture. Progressive selection toward increasing degrees of transformation in confluent cultures plays a major role in the development of dense focus formers, but direct induction by the constraint of confluence may contribute by heritably damaging cells. In view of our finding of increased susceptibility to transformation in clonal versus uncloned populations, expansion of some clones at the expense of others during the aging process would contribute to the marked increase of cancer with age.

Selective killing of preneoplastic and neoplastic cells by methotrexate with leucovorin

Three sublines of NIH 3T3 cells had the properties of non-neoplastic, preneoplastic, and neoplastic cells, respectively. The closer the cells were to neoplastic behavior, characterized by continuing growth at high density, the slower they multiplied at lower density. Under the conditions of high population density and low calf serum concentration used in the assay for transformed focus formation, the transformed or neoplastic cells were much more sensitive to killing by methotrexate (MTX) than were non-neoplastic cells in the same culture. This differential sensitivity of neoplastic cells was far more pronounced in molecular, cellular, and developmental biology medium 402 (MCDB 402) than in DMEM. It is associated with the presence in MCDB 402 of folinic acid, known clinically as leucovorin, which is a reduced form of the folic acid present in DMEM. Although leucovorin had been shown to selectively spare normal bone marrow and intestine in animals from the killing effect of MTX on tumor cells, we demonstrate the preferential killing of neoplastic over non-neoplastic cells of the same derivation. Neither neoplastic nor non-neoplastic cells were killed once they had stopped multiplying at their respective saturation densities. The development of the light foci characteristic of the preneoplastic cells was less sensitive to MTX than the formation of the dense foci produced by the fully neoplastic cells. The system should serve as a valuable model to establish basic principles and optimal conditions for selective killing of neoplastic cells by chemotherapeutic drugs.

Random population-wide genetic damage induced in replicating cells treated with methotrexate

Low lethality treatment of the NIH 3T3 mouse cell line with methotrexate (MTX) during exponential multiplication results in heterogeneous, heritable reduction in growth rate of most if not all the replicatively surviving cells. The effective concentrations of MTX are 10 to 100 times higher in molecular, cellular and developmental biology medium 402 (MCDB 402) than in Dulbecco's modification of Eagle's medium (DMEM) medium because of the folate-sparing presence of adenine, thymidine and, particularly, of folinic acid in MCDB 402 medium. The reduced growth rates are detectable during early passages of surviving populations before the faster growing cells dominate them. The heritable effect is most clearly demonstrated by sequestered cloning of many individual cells immediately after drug treatment, and repeatedly measuring the growth rates of the clones in serial passages. After 7-10 passages of the clones, there is an increase in growth rate of some of the slow growing clones presumably due to the generation and selection of faster growing cells. Evidence from mutagenic studies at a single genetic locus in other cell lines suggests that heritable reductions in growth rate arise from chromosome aberrations although point mutations may also contribute to the effect. Clastogenic changes can be induced by a wide variety of mutagens and carcinogens, many of which are used in chemotherapy of cancer and other chronic diseases. The population-wide, heritable damage to cells may be the source of, or may contribute to, late-occurring side effects of treatment in cancer and other chronic diseases.

Poliovirus 2C region functions during encapsidation of viral RNA

We have been exploring the mechanism of action of 5-(3,4-dichlorophenyl) methylhydantoin (hydantoin), an antiviral drug that inhibits the replication of poliovirus in culture. By varying the time of drug addition to infected cells, we found that the drug acts at a stage which is late in the replication cycle and subsequent to the step inhibited by guanidine. Furthermore, we detected normal levels of full-length plus-strand virion RNA in hydantoin-treated cultures. A new assembly intermediate in addition to the expected assembly intermediates was detected in drug-treated cultures. This intermediate has properties consistent with that of a packaging intermediate. Drug-resistant mutants were readily isolated. Sequence analysis of three independent drug-resistant mutants identified amino acid substitutions in the 2C coding region. Reconstruction by site-directed mutagenesis confirmed that these single mutations were sufficient to confer drug resistance. Taken together, these data suggest that the poliovirus 2C region is involved in virus encapsidation and that hydantoin inhibits this stage of replication.

Unmasking large and persistent reductions in proliferation rate of aging cells

We have reported that nontransformed sublines of NIH 3T3 cells that are incubated under the growth constraint of confluence for 10 d or longer exhibit heritable reductions of growth rate upon serial subculture at low density, which simulate the effects of aging in vivo on cell growth. There is also a marked increase in the likelihood of neoplastic transformation. After switching to a new batch of calf serum (CS), we found the reduced growth rate was no longer produced within the previously established timeframe. However, substitution of fetal bovine serum (FBS) for CS during the period of recovery from confluence or the following tests of growth rate resulted in profound inhibition of growth in cells serially subcultured from confluent cultures. In some cases, fewer than one in a thousand cells from subcultures of confluent cultures formed colonies in FBS although they cloned at relatively high efficiency in CS. The reduced growth in FBS was retained in the postconfluent subcultures after many generations of multiplication at low density in CS. Generally, similar results with individual variations were obtained with three other batches of FBS. The numbers of cells per 3-d colony initiated from subcultures of confluent cultures were lower than those of control cultures that had never been confluent. Supplementation of FBS-containing medium with CS fully restored the growth of the postconfluent subcultures to the rate in CS medium, indicating that there is a deficiency of growth factor(s) in FBS rather than the presence of an inhibitor. The results show that prolonged incubation at confluence induces a populationwide heritable increase in requirement for growth factor(s) in short supply in FBS. Because clonal studies have shown that the reduction in growth rate is irreversible and varies in degree from clone to clone, we propose it arises from damage to DNA at any of many different genetic loci or from chromosome aberrations. Such genetic damage is also consistent with the increased tendency for neoplastic transformation in subcultures from the long-term confluent cultures.

Ubiquitous, heritable damage in cell populations that survive treatment with methotrexate

A permanent line of mouse embryo fibroblasts was treated with concentrations of the anticancer drug methotrexate (MTX) that left 20-50% surviving colonies. The surviving population initially multiplied at a much slower rate than controls after subculture in the absence of the drug, and required 9-12 days of serial subculture, with selective growth of the faster growing cells, to approximate the control rate. To determine the distribution of growth rates of cells in the original posttreatment populations, many single cells were isolated in multiwell plates immediately after the treatment period, and the resulting clones were serially subcultured. Most of the control clones underwent about 2 population doublings per day (PD/D). Almost all the survivors of MTX treatment multiplied at heterogeneously reduced rates, ranging from 0.6 PD/D to as high as control rates for a very few clones. They maintained the reduced rates through many subcultivations. The heritability of the reduced growth rates indicates that most cells that retain proliferative capacity after treatment with MTX carry random genetic damage that is perpetuated through many divisions of their progeny. Similar results have been described for cells that survive x-irradiation, and suggest random genetic damage is a common occurrence among cells in rapidly growing tissues that survive cytotoxic treatment. It also occurs in serial subcultures of cells that had been held under the constraint of confluence for extended periods, which suggests that the accumulation of random genetic damage to somatic cells during aging of mammals underlies the reduction of growth rate and function of the cells that characterizes the aging process.

Inhibition of intracellular multiplication of human strains of Chlamydia trachomatis by nitric oxide

It was previously shown that murine T cell clones could inhibit the intracellular growth of the mouse strain of Chlamydia trachomatis by cytokine-mediated induction of the inducible nitric oxide synthase (iNOS) system in epithelial cells, an effect enhanced by direct epithelial-T cell interaction via specific adhesion molecules. These findings and other recent reports showing that human mucosal epithelial cells secrete nitric oxide (NO) via iNOS expression would suggest that mucosal epithelial-derived NO may be involved in mucosal defense against Chlamydia and other pathogens that infect epithelial cells. As an initial approach to investigating whether NO contributes to chlamydial control in humans, the present studies evaluated the susceptibility of human isolates of C. trachomatis to NO delivered by chemical donors or via induction of the epithelial iNOS system by a cytokine-secreting T cell clone. It was found that a chlamydial-specific, cytokine-secreting, murine T lymphocyte clone (clone 2.14-0) could inhibit the intraepithelial growth of human strains of Chlamydia trachomatis (serovar E and H, and Lymphogranuloma venerum type L2) via the iNOS pathway when the clone was co-cultured with chlamydial-infected epithelial cells. Furthermore, treatment of infected epithelial cells with 50 microM of the NO donor, S-nitroso-L-glutathione, resulted in significant inhibition (approximately 70%) of chlamydial multiplication, while the NO scavenger, myoglobin plus ascorbate, could reverse the effect, demonstrating that NO could directly inhibit human strains of Chlamydia. The results are consistent with the hypothesis that the IFN-gamma-inducible iNOS pathway can contribute to chlamydial control in humans.

Characterization of the ion channels formed by poliovirus in planar lipid membranes

The steps in poliovirus infection leading to viral entry and uncoating are not well understood. Current evidence suggests that the virus first binds to a plasma membrane-bound receptor present in viable cells, leading to a conformational rearrangement of the viral proteins such that the virus crosses the membrane and releases the genomic RNA. The studies described in this report were undertaken to determine if poliovirus (160S) as well as one of the subviral particles (135S) could interact with membranes lacking poliovirus receptors in an effort to begin to understand the process of uncoating of the virus. We report that both forms of viral particles, 160S and 135S, interact with lipid membranes and induce the formation of ion-permeable channels in a manner that does not require acid pH. The channels induced by the viral particles 160S have a voltage-dependent conductance which depends on the ionic composition of the medium. Our findings raise the possibility that viral entry into cells may be mediated by direct interaction of viral surface proteins with membrane lipids.

The poliovirus 135S particle is infectious

The molecular mechanism of cell entry by unenveloped viruses is poorly understood. The picornaviruses poliovirus, human rhinovirus, and coxsackievirus convert to an altered form (the 135S or A particle) upon interaction with receptors on susceptible cells at 37 degrees C. The 135S particle is thought to be a necessary intermediate because it accumulates inside susceptible cells soon after infection and drugs which inhibit conversion of the virus to this form also prevent infection. However, since a variable fraction of the altered 135S particles is reported to elute unproductively from the surface of susceptible cells, their precise role remains unclear. We have found that poliovirus 135S particles can infect Chinese hamster ovary (CHO) and murine L cells, neither of which are susceptible to infection by native poliovirus. The infectivity of the particles in tissue culture appears to be between 10(3) to 10(5) times less than that of poliovirus on HeLa cells. The 135S particle infectivity was not sensitive to RNase but was greatly reduced by proteolytic treatment. Proteolysis specifically removed the newly exposed N terminus of VP1, a feature which has previously been shown to mediate interactions of the particle with lipid membranes. These results demonstrate that although the infectivity of the 135S particle appears to be receptor independent, it nonetheless requires some property associated with the protein coat. In particular, the N terminus of VP1 plays an important role in the infection process. Our findings are consistent with the hypothesis that the 135S particle is an intermediate in the normal cell entry pathway of poliovirus infection.

Vitellogenin induction and reduced serum testosterone concentrations in feral male carp (Cyprinus carpio) captured near a major metropolitan sewage treatment plant

Endocrine disrupting chemicals can potentially alter the reproductive physiology of fishes. To test this hypothesis, serum was collected from common carp (Cyprinus carpio) at five riverine locations in Minnesota. Male fish collected from an effluent channel below the St. Paul metropolitan sewage treatment plant had significantly elevated serum egg protein (vitellogenin) concentrations and significantly decreased serum testosterone concentrations compared to male carp collected from the St. Croix River, classified as a National Wild and Scenic River. Carp collected from the Minnesota River, which receives significant agricultural runoff, also exhibited depressed serum testosterone concentrations, but no serum vitellogenin was apparent. These data suggest that North American rivers are receiving estrogenic chemicals that are biologically active, as has been reported in Great Britain.