Different prognostic effect of postoperative chemoradiation therapy on diploid and nondiploid high-risk rectal cancers

PURPOSE

DNA ploidy has been shown to play a role in the response to cytotoxic therapy in a variety of malignancies, including breast cancer and melanoma. However, the importance of DNA ploidy in rectal cancer is unknown. The aim of the present study was to determine whether ploidy status might be associated with response to postoperative chemoradiation in TNM Stages II to III rectal cancer.

METHODS

This retrospective study analyzed data from 229 patients with TNM Stages II to III rectal cancer who underwent resection between 1979 and 1984. The ploidy status and treatment modalities in relation to outcome were assessed.

RESULTS

The recurrence-free ten-year survival rate was 52.2 percent for patients with diploidy and 50.5 percent for patients with nondiploidy (P = 0.99). The ten-year survival rates for patients with diploidy and patients with nondiploidy were 55 and 19 percent (P = 0.016) in the chemoradiation group, and 51 and 60 percent (P = 0.15) in the nonchemoradiation group, respectively. In the chemoradiation group, DNA nondiploidy was associated with an increased recurrence rate (83.3 vs. 50.0 percent; P = 0.001). The interaction between DNA nondiploidy and chemoradiation remained important in predicting outcome in the Cox regression model. Factors independently correlated with a worse outcome included Stage IIIb (relative risk, 2.9; 95 percent confidence interval, 1.7-5; P = 0.0001), perineural invasion (relative risk, 2.5; 95 percent confidence interval, 1.6-4, P = 0.0001), distal tumor (relative risk, 1.7; 95 percent confidence interval, 1.1-2.7, P = 0.014), and nondiploidy with chemoradiation (relative risk, 2.9; 95 percent confidence interval, 1.2-7.2, P = 0.0213).

CONCLUSIONS

These findings suggest that DNA nondiploidy is inversely correlated with long-term outcome among patients with high-risk rectal cancer receiving chemoradiation.

Silicone oil tamponade to seal macular holes without position restrictions

OBJECTIVE

The authors performed a study to determine the effectiveness and safety of silicone oil as a substitute for gas to fill the vitreous cavity to treat macular holes.

DESIGN

Multicenter, nonrandomized, interventional trial.

PARTICIPANTS

Thirty-seven consecutive patients chose vitrectomy with silicone tamponade instead of gas to treat 40 eyes with stage-2 to stage-4 idiopathic age-related macular holes. Stage-2 holes constituted 40% of the holes, and stage-3 and stage-4 holes made up 60%.

INTERVENTION

All eyes were treated with vitrectomy, manual detachment of the posterior vitreous face (not done for stage-4 holes), autologous serum instillation, and silicone fill of the vitreous cavity. After insertion of the oil, the patients resumed normal activity with no restriction of head or eye position except to avoid faceup position. The oil was removed after approximately 6 weeks.

MAIN OUTCOME MEASURES

The authors considered the seal of the macular hole and the preoperative and postoperative logarithm of the minimum angle of resolution (logMAR) visions the most significant measures for comparison to other studies.

RESULTS

Eighty percent of all holes and 86% of holes not treated previously were sealed with a single silicone tamponade of the vitreous cavity. The logMAR value of visual acuity improved an average of 0.26 (2.6 lines) to 0.61 (20/81) for all eyes and 0.34 (3.4 lines) to 0.52 (20/66) when the macular hole sealed. Completeness of fill of the vitreous cavity with silicone affected seal of the macular hole. Three of eight eyes in which open holes developed after oil removal had less than 90% fill of the vitreous cavity by silicone. Sixty-nine percent of lenses increased opacity one grade or were removed after silicone tamponade. There were no significant adverse effects arising from silicone tamponade.

CONCLUSIONS

Silicone oil tamponade of macular holes is effective and safe. Silicone may be optimal for the treatment of macular holes in persons who must travel, who cannot maintain facedown positioning, or who have monocular vision. The most important factor in the successful closure of the macular hole was the completeness of fill of the vitreous cavity with silicone oil.

Persistent baculovirus infection results from deletion of the apoptotic suppressor gene p35

Infection with the wild-type baculovirus Autographa californica multiple nuclear polyhedrosis virus (AcMNPV) results in complete death of Spodoptera frugiperda (Sf) cells. However, infection of Sf cells with AcMNPV carrying a mutation or deletion of the apoptotic suppressor gene p35 allowed the cloning of surviving Sf cells that harbored persistent viral genomes. Persistent infection established with the virus with p35 mutated or deleted was blocked by stable transfection of p35 in the host genome or by insertion of the inhibitor of apoptosis (iap) gene into the viral genome. These artificially established persistently virus-infected cells became resistant to subsequent viral challenge, and some of the cell lines carried large quantities of viral DNA capable of early gene expression. Continuous release of viral progenies was evident in some of the persistently virus-infected cells, and transfection of p35 further stimulated viral activation of the persistent cells, including the reactivation of viruses in those cell lines without original continuous virus release. These results have demonstrated the successful establishment of persistent baculovirus infections under laboratory conditions and that their establishment may provide a novel continuous, nonlytic baculovirus expression system in the future.

Factors influencing the functional outcome of patients with acute epidural hematomas: analysis of 200 patients undergoing surgery

OBJECTIVE

To determine the prognostic factors of the functional outcome of patients surgically treated for acute epidural hematomas.

METHODS

Two hundred patients who consecutively underwent neurosurgery for acute epidural hematomas over the past 9-year period were studied. Clinical characteristics, radiologic findings, and the time intervals with regard to treatment course were investigated to determine the interactions between all these factors and functional outcome.

RESULTS

Functional outcome showed a significant correlation with preoperative consciousness state, Glasgow Coma Scale score, pupillary sizes, and motor posturing (chi2 test, p < 0.05). Functional outcome correlated with the period of brain herniation, the length of time of the operation, as well as the period of hospitalization (chi2 test, p < 0.05), but not with the length of time of craniotomy decompression relative to the length of time from the injury until admission. The radiologic findings of the associated brain injury, the size and the density of the clot, the degree of the brain shift, and the obliteration of the basal cisterns significantly correlated with functional outcome (chi2 test, p < 0.05), whereas no significance was attributable to skull fracture. Multivariate analysis indicated that the following four factors independently correlated with functional outcome: (1) associated brain injury, (2) best motor response, (3) hematoma volume, and (4) period of hospitalization (chi2 test, p < 0.05). A combination of the four factors led to the prediction of the functional outcome with 91% accuracy (1.5 % falsely pessimistic predictions and 7.5 % falsely optimistic prediction) and 82.1% at over 90% confidence level. These four parameters correlated significantly with preoperative neurologic deterioration (chi2 test, p < 0.05).

CONCLUSION

This study identifies the risk factors involved in the functional outcome of patients who underwent surgical treatment for acute epidural hematomas. Our results indicate that associated brain injury plus best motor response are the optimal set of two prognostic indicants, with 87% correct predictions and 70.1% at over a 90% confidence level. Prevention of in-hospital neurologic deterioration would improve the patients' functional outcome with a resultant unfavorable recovery rate ranging from 11.5% to 17%.

Cerebral blood flow velocity and vasomotor reactivity before and after shunting surgery in patients with normal pressure hydrocephalus

The purpose of this study was to evaluate pre- and post-shunting haemodynamic changes and their correlation with the clinical results in normal pressure hydrocephalus (NPH). Accordingly, eleven demented patients with clinical signs suggestive of NPH received examinations of cerebral blood flow velocity (BFV) and vasomotor reactivity (VMR) by transcranial Doppler sonography with carbogen testing before and after shunt treatment. Computerized tomography (CT), clinical assessment and neuropsychological grading were performed prior to and at 3 months following surgery. A control group consisting of 10 patients was included to establish baseline data. The pre-operative CBF studies in the anterior cerebral artery (ACA) and the middle cerebral artery (MCA) revealed the NPH patients did not have significant decreases of BFVs, but had significant decreases of carbogen VMR (P < 0.05). After shunting, there were no significant changes of the BFVs as compared with the pre-shunting data. The post-shunting VMR of the ACA was significantly higher than the pre-shunting one (p < 0.05), but there was no variation in that of the MCA. Both the values of post-shunting VMR in ACA and the post-shunting increase in VMR in MCA of the 7 shunt-responsive patients who improved mentally and in other symptoms were significantly higher than those of patients without improvement (p < 0.05). In addition, the five patients with gait improvement showed significantly higher values of post-shunting VMR of ACA and the post-shunting increase of VMR for both ACA and MCA when compared with those patients without gait improvement (p < 0.05, respectively). Our study supports the view that patients with NPH had various degrees of impaired VMR in both the ACA and the MCA, but showed insignificant reduction in BFVs, indicating a compensatory mechanism of CBF over time to accommodate the subnormal state of cerebral perfusion pressure. Shunt placement would improve the VMR in responsive patients. Postoperatively, an increase of VMR tends to accompany improvement of the functional state: that in the MCA alone is associated with symptomatic improvement in mental function and that increase in VMR in both the ACA and the MCA with improvement in gait, respectively.

Estimating sensitivity and sojourn time in screening for colorectal cancer: a comparison of statistical approaches

The effectiveness of cancer screening depends crucially on two elements: the sojourn time (that is, the duration of the preclinical screen-detectable period) and the sensitivity of the screening test. Previous literature on methods of estimating mean sojourn time and sensitivity has largely concentrated on breast cancer screening. Screening for colorectal cancer has been shown to be effective in randomized trials, but there is little literature on the estimation of sojourn time and sensitivity. It would be interesting to demonstrate whether methods commonly used in breast cancer screening could be used in colorectal cancer screening. In this paper, the authors consider various analytic strategies for fitting exponential models to data from a screening program for colorectal cancer conducted in Calvados, France, between 1991 and 1994. The models yielded estimates of mean sojourn time of approximately 2 years for 45- to 54-year-olds, 3 years for 55- to 64-year-olds, and 6 years for 65- to 74-year-olds. Estimates of sensitivity were approximately 75%, 50%, and 40% for persons aged 45-54, 55-64, and 65-74 years, respectively. There is room for improvement in all models in terms of goodness of fit, particularly for the first year after screening, but results from randomized trials indicate that the sensitivity estimates are roughly correct.

Neutral endopeptidase inhibition potentiates the natriuretic actions of adrenomedullin

Adrenomedullin (ADM) is a potent renal vasodilating and natriuretic peptide possessing a six amino acid disulfide ring. Neutral endopeptidase 24.11 (NEP) is localized in greatest abundance in the kidney and cleaves endogenous peptides like atrial natriuretic peptide, which also possesses a disulfide ring. We hypothesized that NEP inhibition potentiates the natriuretic actions of exogenous ADM in anesthetized dogs (n = 6). We therefore investigated renal function in which one kidney received intrarenal infusion of ADM (1 ng . kg-1 . min-1) while the contralateral kidney served as control before and during the systemic infusion of a NEP inhibitor (Candoxatrilat, 8 microg . kg-1 . min-1; Pfizer). In response to ADM, glomerular filtration rate (GFR) in the ADM kidney did not change, whereas renal blood flow, urine flow (UV), and urinary sodium excretion (UNaV) increased from baseline. Proximal and distal fractional reabsorption of sodium decreased in the ADM-infused kidney. In response to systemic NEP inhibition, UNaV and UV increased further in the ADM kidney. Indeed, DeltaUNaV and DeltaUV were markedly greater in the ADM kidney compared with the control kidney. Plasma ADM was unchanged during ADM infusion but increased during NEP inhibition. In conclusion, the present investigation is the first to demonstrate that NEP inhibition potentiates the natriuretic and diuretic responses to intrarenal ADM. This potentiation occurs secondary to a decrease in tubular sodium reabsorption. Lastly, the increase in plasma ADM during systemic NEP inhibition supports the conclusion that ADM is a substrate for NEP.

Effect of sensory neuropeptides on mucus secretion from cultured goblet cells

BACKGROUND

Airway goblet cell secretion is under the control of capsaicin-sensitive sensory nerves. Administration of capsaicin or antidromic stimulation of nerves can stimulate goblet cell secretion and also induce plasma exudation and smooth muscle contraction via a release of neuropeptides from sensory nerve endings in the airway. This study was designed to explore whether the effect of capsaicin or neuropeptides on goblet cell secretion is direct or secondary to other airway responses.

MATERIALS AND METHODS

We examined the effects of sensory neuropeptides including substance P (SP), neurokinin A (NKA) and neurokinin B (NKB), as well as capsaicin on cultured guinea pig tracheal goblet cells by measuring the rate of mucus discharge visually under a microscope and the release of 35SO4 radiolabeled mucin-like glycoconjugates.

RESULTS

Goblet cells in culture spontaneously secreted intracellular granules at a mean rate of about 3 times/min. SP and NKA increased secretion in a dose-dependent manner. SP was more potent than NKA with maximum responses of 52% and 37% at 10(-8) M, respectively. Quantitative measurements of 35SO4 radiolabeled mucin-like glycoprotein (MLGP) secreted by goblet cells also revealed an increase (109.2%) in mucin secretion caused by SP (10(-8) M) compared with the vehicle control. Neither capsaicin nor NKB caused any significant change in the goblet cell secretory rate. The effects of SP on the secretory rate or release of radiolabeled mucin were not potentiated by an enkephalinase inhibitor, thiorphan (10(-5) M).

CONCLUSION

Sensory neuropeptides SP and NKA directly stimulate goblet cell secretion, probably through the tachykinin receptor of the NK-1 subtype as suggested by a greater potency of SP. There was no direct effect of capsaicin on goblet cell secretion.

Markov models of breast tumor progression: some age-specific results

Researchers have noted that mammographic screening has a reduced effect on breast cancer mortality in women in their forties compared to older women. Explanations for this include poorer sensitivity in younger women due to denser breast tissue, as well as more rapid tumor progression, giving a shorter mean sojourn time (the average duration of the preclinical screen-detectable period). To test these hypotheses, we developed a series of Markov-chain models to estimate tumor progression rates and sensitivity. Parameters were estimated using tumor data from the Swedish two-county trial of mammographic screening for breast cancer. The mean sojourn time was shorter in women aged 40-49 compared to women aged 50-59 and 60-69 (2.44, 3.70, and 4.17 years, respectively). Sensitivity was lower in the 40-49 age group compared to the two older groups (83%, 100%, and 100%, respectively). Thus, both rapid progression and poorer sensitivity are associated with the 40-49 age group. We also modeled tumor size, node status, and malignancy grade together with subsequent breast cancer mortality and found that, to achieve a reduction in mortality commensurate with that in women over 50, the interscreening interval for women in their forties should be less than two years. We conclude that Markov models and the use of tumor size, node status, and malignancy grade as surrogates for mortality can be useful in design and analysis of future studies of breast cancer screening.

Recent results from the Swedish Two-County Trial: the effects of age, histologic type, and mode of detection on the efficacy of breast cancer screening

The effect of mammographic screening in reducing mortality from breast cancer is known to be smaller and more delayed in women aged 40-49 than in women over 50. In this study, we investigated how these phenomena relate to histology-specific breast cancer incidence and mortality. The data are from 2,468 women with breast cancer who participated in the Swedish Two-County Trial. The overall relative breast cancer mortality of invited to noninvited women aged 40-49 was 0.87, and the relative mortality from poorly differentiated (grade 3) ductal carcinoma was 0.95. These results were not statistically significant. The corresponding relative risks for invited women aged 50-74 were a statistically significant 0.65 and 0.61. We conclude that in this trial, with a two-year interscreening interval, the smaller and later effect of invitation to screening on breast cancer mortality in women 40-49 years old is due to the failure of screening to reduce mortality from grade 3 ductal carcinoma in this age group.

Segmental colectomy in the management of colonic inertia

Subtotal colectomy with ileorectostomy has been proposed for the management of colon inertia-type constipation. However, many patients experience frequent bowel movements, watery diarrhea, or both after such a treatment. The purpose of this study is to determine the proper colectomy with which to treat colon dysmotility constipation without the negative side effects of frequent bowel movements, watery diarrhea, or both. Forty idiopathic constipation patients were studied. All of the patients showed a prolonged right or left colon transit time and normal transit time of the sigmoid and rectum. They received different types of colectomies (left, right, and subtotal) according to the distribution or accumulation of markers in the colon. Within 3 months of surgery, all of the patients experienced a dramatic improvement of their symptoms without frequent bowel movements or watery diarrhea. No significant complications developed after surgery. All the patients were followed up for at least 2 years. Most of them (37 cases) still had satisfactory bowel movements and no other constipation symptoms. However, 3 of the 40 cases developed symptoms of constipation 1 1/2 to 2 years after surgery. They all received subtotal colectomy with ileorectal anastomosis subsequently. They reobtained satisfactory bowel movements and experienced a subsidence of other constipation symptoms 3 months later. These results suggest that directed segmental colectomy can improve colonic inertia constipation without the consequence of frequent bowel movements and diarrhea.

Transcription factor RTEF-1 mediates alpha1-adrenergic reactivation of the fetal gene program in cardiac myocytes

Alpha1-adrenergic receptor stimulation induces cardiac myocytes to hypertrophy and reactivates many fetal genes, including beta-myosin heavy chain (betaMyHC) and skeletal alpha-actin (SKA), by signaling through myocyte-specific CAT (M-CAT) cis elements, binding sites of the transcriptional enhancer factor-1 (TEF-1) family of transcription factors. To examine functional differences between TEF-1 and related to TEF-1 (RTEF-1) in alpha1-adrenergic reactivation of the fetal program, expression constructs were cotransfected with betaMyHC and SKA promoter/reporter constructs in neonatal rat cardiac myocytes. TEF-I overexpression tended to transactivate a minimal betaMyHC promoter but significantly interfered with a minimal SKA promoter. In contrast, RTEF-1 transactivated both the minimal betaMyHC and SKA promoters. TEF-1 and RTEF-I also affected the alpha1-adrenergic response of the betaMyHC and SKA promoters differently. TEF-1 had no effect. In contrast, RTEF-1 potentiated the alpha1-adrenergic responses of the SKA promoter and of a -3.3-kb betaMyHC promoter. To determine why the promoters responded differently to TEF-1 and RTEF-1, promoters with mutated M-CAT elements were tested in the same way. The betaMyHC promoter required an intact M-CAT element to respond to TEF-1 and RTEF-1, whereas the SKA promoter M-CAT was required for the TEF-1 response but not for the RTEF-1 response, suggesting that SKA promoter-specific cofactors may be involved. By competition gel shift assay, the M-CAT of the minimal betaMyHC promoter had a lower affinity than that of the SKA promoter, which partly explains the different responses of these promoters to TEF-1. These results highlight functional differences between TEF-1 and RTEF-1 and suggest a novel function of RTEF-1 in mediating the alpha1-adrenergic response in hypertrophic cardiac myocytes.

Excitatory amino acids and lead-induced neurotoxicity

The NMDA receptor non-competitive antagonist, [3H]MK-801, was used as a ligand for an autoradiographic study to determine the effects of lead on NMDA receptor in rat brain. Adult male rats were given lead acetate, 100 mg/kg, or sodium acetate, 36 mg/kg (control), by i.p. for 7 days. Lead levels were detected in blood (41.1 micrograms/dl) and brain (16.7-29.4 micrograms/g). Concentrations of lead in various brain regions did not differ. [3H]MK-801 binding was heterogeneous throughout the brain with the following order of binding densities: hippocampal formation > cortex > caudate-putamen > thalamus > brainstem. Lead exposure caused a decrease in [3H]MK-801 binding to NMDA receptors in the hippocampal formation including CA2 stratum radiatum, CA3 stratum radiatum and presubiculum, and in the agranular insular, cingulate, entorhinal, orbital, parietal and perirhinal areas of cerebral cortex. In another experiment, female rats were exposed pre- and post-natally from the 4th +/- 1 post conception day with 1,000 ppm lead in their drinking water. This treatment continued after weaning. No effects of lead on [3H]MK-801 binding were found at postnatal day (PM) 28. However, lead caused a significant increase in [3H]MK-801 binding in the hippocampus including CA1 and CA2, and in the occipital and temporal cortical areas at PN 56 and at PN 112. Increases in [3H]MK-801 binding were also found in entorhinal cortex and dentate gyrus at PN 112. The hippocampal formation is a critical neural structure for learning and memory processes, whereas cortical and subcortical regions are involved in the modulation of complex behavioral processes. NMDA receptors have been shown to play a key role in synaptic plasticity underlying learning and memory. Therefore, lead-induced alterations of ligand binding to NMDA receptors in the hippocampal formation and cortical areas may play a role in lead-induced neurotoxicity.

Economy of donor site incisions: multiple free flaps of the subscapular family for extensive extremity wounds and bilateral foot defects

One of the most important goals of modern microsurgical reconstruction is to decrease donor site morbidity as much as possible. With free flaps for lower limb reconstruction, economy of donor sites was designed and performed in 39 patients. Among these 39 patients, 17 had multiple flaps raised from a single incision for reconstruction of multiple defects in one or both lower extremities. Microvascular reconstruction of multiple defects is a challenging problem, particularly if it is to be performed simultaneously. The patients were followed for more than 3 years. Immediate complications and long-term disabilities were analyzed. From the data we conclude that this method has the following advantages: (1) economy of donor site incisions, (2) less harvest time, and (3) availability of any composite tissue for transfer. Donor site morbidity can be reduced by good planning, careful dissection, meticulous hemostasis, and adequate postoperative management.

Evaluation by Markov chain models of a non-randomised breast cancer screening programme in women aged under 50 years in Sweden

STUDY OBJECTIVE

To apply Markov chain models that have previously been used on data in randomised trials of breast cancer screening to data from an uncontrolled service screening programme; to compare results with those from a randomised trial.

DESIGN

A service screening programme in Uppsala county, Sweden, inviting 25,660 women aged 39-49 to mammographic screening every 20 months, and the Swedish Two-County Trial inviting 19,844 women aged 40-49 to two yearly screening, compared with 15,604 women of the same age in an unscreened control group. Data were analysed using Markov chain models and quasi-likelihood estimation procedures.

MAIN RESULTS

The results with respect to parameters of disease progression were very similar between the two studies. Use of estimated progression rates to predict the effect on mortality ranged from a 10% to a 17% reduction in breast cancer mortality in the Two-County Study and predicted a 15% reduction in the Uppsala programme. These compare well with the observed mortality reduction of 13% in the Two-County Trial.

CONCLUSIONS

The screening in the Uppsala programme is likely to have a similar effect to that observed in the Two-County Trial. It is feasible to evaluate non-randomised service screening programmes using Markov chain models.

An SRRC elliptically polarizing undulator prototype to examine mechanical design feasibility and magnetic field performance

In this work, a 1 m long Sasaki-type elliptically polarizing undulator (EPU) prototype with 5.6 cm period length is used to examine the mechanical design feasibility as well as magnetic field performance. The magnetic field characteristics of the EPU5.6 prototype at various phase shifts and gap motion are described. The field errors from mechanical tolerances, magnet block errors, end field effects and phase/gap motion effects are analysed. The procedures related to correcting the field with the block position tuning, iron shimming and the trim blocks at both ends are outlined.

Advanced field-measurement method with three orthogonal Hall probes for an elliptically polarizing undulator

A three-orthogonal-Hall-probe assembly with an 'on the fly' mapping method has been developed to characterize an elliptically polarizing undulator (EPU). The underlying design concept is that it can measure the three real field components without any field correction under a reliable and synchronization measurement method. Therefore, the relative central position shift, orthogonal angle and the planar Hall effect error between the three Hall probes should be calibrated and readjusted. Experimental results demonstrate that this method can yield an r.m.s. reproducibility of 10 G cm for the three field components and 2 G for the peak field strength. Under precision conditions this system can completely measure the three on-axis field components within 2 min for a 4 m-long EPU.

Developmental lead exposure alters the distribution of protein kinase C activity in the rat hippocampus

Chronic low-level lead (Pb) exposure in children is known to cause a deficit in learning and memory. In vitro studies have demonstrated that Pb altered protein kinase C (PKC) activity. Especially, hippocampal PKC has been correlated with performance in several learning tasks. The effects of Pb exposure on hippocampal PKC were investigated during development at various postnatal ages: postnatal day (PN) 7, 14, 28, and 56. Two-tenth % Pb acetate was administered to pregnant and lactating dams and then administered to weanling rats in drinking water. PKC activity was measured in both membrane and cytosolic fractions from the hippocampi of the controls and Pb-exposed animals. Pb-induced increase in PKC activity in the cytosolic fraction was observed in the PN56 rats. In contrast, PKC activity was decreased by Pb at PN7 in the membrane fraction. Furthermore, a significant decrease in the ratio of membrane to cytosolic PKC activity which is representative of PKC distribution was observed in the PN28 and PN56 Pb-exposed rats relative to the same-age controls. This study indicates that chronic Pb exposure during development influences hippocampal PKC activity and distribution. These changes may be involved in the subclinical neurotoxicity of chronic Pb exposure in young children.

A 2.9-kilobase noncoding nuclear RNA functions in the establishment of persistent Hz-1 viral infection

Differential viral gene expression during both productive and persistent infections of Hz-1 virus in insect cells was elucidated. Despite more than 100 viral transcripts being expressed during productive viral infection, massive viral gene shutoff was observed during viral persistency, leaving the 2.9-kb persistence-associated transcript 1 (PAT1) as the only detectable viral RNA. Persistence-associated gene 1 (pag1), which encodes PAT1, was cloned and found to contain no significant open reading frames. PAT1 is not associated with the cellular translation machinery and is located exclusively in the nucleus. Further experiments showed that PAT1 is functional in the establishment of persistent Hz-1 viral infection in the cells. All the evidence collectively indicates that PAT1 is a novel nuclear transcript of viral origin. Our results showed that although PAT1 and XIST RNA, a mammalian X-inactive specific transcript, are transcribed by different genes, they have interesting similarities.

Acute and subacute toxicity study of water-soluble polyalkylsulfonated C60 in rats

Polyalkylsulfonated C60, or FC4S, a highly water-soluble caged fullerene derivative, is believed to be a free radical remover or an antioxidant in biological systems. A 50 mg/ml aqueous solution was prepared as a master solution and administered to female Sprague-Dawley CD(Crl:CD(SD)BR) rats in a single-dose acute toxicity study or a 12-day subacute toxicity study where rats were given the solution daily. In a study of the median lethal dose (LD50), no rats died after oral administration, and thus FC4S was considered to be nontoxic if administered orally. In an LD50 intraperitoneal injection study, rats died within 30 hr after injection; the LD50 was determined to be approximately 600 mg per kilogram of body weight. Rats injected with the compound intraperitoneally or intravenously immediately eliminated the compound through the kidney; the kidney appeared to be the primary target organ. The compound induced a distinct lysosome-overload nephrosis, a phagolysosomal nephropathy characterized by a tinctorial difference between the outer cortex and the inner cortex and the medulla. The affected outer cortex showed a diffuse degeneration, with the presence of numerous large vacuoles and cytoplasmic aggregates in the tubular epithelium. The phagolysosomal nephropathy was detected in rats after acute exposure as well as in the surviving rats following 1 intraperitoneal injection of 500 mg/kg or intravenous injection of 100 mg/kg. Ultrastructural investigation revealed numerous membranous conglomerates characteristic of phagolysosomal and/or lysosomal inclusions in the cytoplasm of the renal tubular epithelium. These conglomerates were confined to the vacuole, electron-dense, and unevenly stained. They varied in size and shape and were fused or aggregated. Occasional phagolysosomes were also observed in the endothelial cells of the peritubular plexus. A preliminary study of microsomal enzyme activity analysis revealed a suppression effect of liver cytochrome P-450-dependent monooxygenase activities, including cytochrome P-450, cytochrome b5, and benzo(a)pyrene hydroxylase, but an increased level of kidney cytochrome P-450-dependent monooxygenase activities, including NADPH-cytochrome P-450 reductase. The significance of these enzyme alterations was not well determined. Further study is needed to clarify the correlation between the alterations of microsomal enzyme activity and the nephropathy of lysosomal overload-induced changes. These changes may serve as a biological marker in toxicity screening tests for this class of compound.