Prognostic factors in infants and very young children with intracranial ependymomas

The Pediatric Oncology Group (1986-1990) conducted a study in which 48 children <3 years of age with intracranial ependymomas were treated with prolonged postoperative chemotherapy (CT) and delayed RT. Thirty-one children, 0-23 months of age at diagnosis (Gp A) received 2 years of CT followed by RT; while 17 children, 24-36 months of age at diagnosis (Gp B) received CT for 1 year followed by radiation. One-year survivals were 87% (Gp A) and 94% (Gp B) and 2-year survivals were 67% (Gp A) and 82% (Gp B). In subsequent years a significant divergence in survivals according to age has been noted (p = 0.04). Five-year survivals were 25.7% (Gp A) vs. 63.3% (Gp B). The curves began to diverge 1 year following diagnosis. Other than age, the only significant prognostic factor was degree of surgical resection: 5-year survivals were 66% (total resection) vs. 25% (subtotal resection). Neither the presence of metastases, degree of anaplasia nor the degree of surgical resection varied significantly according to age at diagnosis. The most likely reason for the difference in survivals between the two age groups relates to the timing of radiation following CT, i.e., 1-year delay in children 24-36 months of age compared to a 2-year delay in children 0-23 months of age. An alternative but less likely hypothesis is that ependymomas in the younger children have a more aggressive biology. In contrast, survivals in the 24- to 36-month group are much better than previous reports in the literature suggesting that prolonged postoperative CT may allow both a delay in CRT as well as provide improved survivals. Based on these results, future treatment trials should emphasize maximal surgical resection and a delay in radiation of no more than 1 year.

A prospective study of sealant application in navy recruits

A 3-year prospective study was designed to evaluate sealants in preventing the formation and progression of caries in a young adult military population. United States Navy dentists performed dental examinations on recruits being in-processed at the Naval Training Center, San Diego, California. Contralateral molar pairs (same arch) without caries or restorations were selected. Occlusal decalcification and lesions limited to enamel were also eligible, but teeth with proximal decalcification were disqualified. The sample consisted of 860 molar pairs in 529 Navy recruits, each contributing one or two pairs. Required annual dental examinations provided follow-up data, with results being recorded on postcards that were mailed back to the investigator. Yearly response rates were as follows: 1 year, 62.2% (483 molar pairs); 2 year, 47.8% (378 molar pairs); and 3 year, 41.4% (317 molar pairs). The response rate for pairs having at least one observation during the 3-year follow-up was 72.6% (563 molar pairs), with a caries conversion rate of 1.2% (7 teeth) on sealed teeth and 5.3% (32 teeth) on control teeth, yielding 35 discordant molar pairs on 33 recruits (30 on control teeth and 5 on sealed teeth) (p < 0.0001). These results confirm the efficacy of sealants in significantly reducing the rate caries in a young adult military population.

Pneumomediastinum during relapse of ulcerative colitis

Pneumomediastinum can be caused by gas dissecting along fascial tissue planes into the mediastinum from remote locations, including the retroperitoneum. One potential source of retroperitoneal gas is the colon. We present the third reported case of pneumomediastinum (plus pneumothorax and subcutaneous emphysema) without free intraperitoneal gas developing during an attack of ulcerative colitis. Because there was no colonic perforation noted at colectomy, the extracolonic gas was presumed to originate from a microscopic or partial thickness perforation of the colon. GI perforation must be considered not only in patients who have free intraperitoneal gas but also in those who present with symptoms, signs, or studies consistent with retroperitoneal gas, such as subcutaneous emphysema, pneumomediastinum, or pneumothorax.

The role of the Internet in medical decision making

The Internet has dramatically changed the means by which information is obtained. Accurate, up-to-date information is vital to maintain the quality of healthcare, especially as US healthcare delivery changes to a primary care-based system. The availability of this new and potentially vast source of information also affects strategies for medical decision making. In this article, use of online information in our medical center is discussed, together with the impact of a locally-developed decision support system. This system first contained components for differential diagnosis as well as computer-assisted instruction. Initially, online searching was limited to Medline literature searches. This component has now been expanded to include important new tools for accessing medical information on the Internet.

Use of shoulder flexors to achieve isometric elbow extension in C6 tetraplegic patients during weight shift

The anterior deltoid muscle has been found to be active during elbow extension in normal volunteers and in C6 tetraplegic patients lacking a functional triceps. Using surface electromyography (EMG) on normal volunteers and on patients with spinal cord injury (SCI) at the C6 motor level, we evaluated whether the anterior deltoid and biceps brachii muscles are active during closed chain elbow extension in a simulated weight shift position. Thirteen normal volunteers performed isometric contractions at 5 submaximal levels of force ranging from 4-25 kg. Six SCI patients performed isometric contractions at force levels of 20%, 40%, 60%, 80% and 100% maximum voluntary contraction (MVC). Surface EMG over the right biceps, triceps, and anterior deltoid muscles was recorded for each participant and the root mean square (rms) electromyographic activity level for each muscle was determined at each level of force. Statistical analyses using repeated ANOVA with Tukey HSD post-hoc tests were performed for each level of force. The results indicated increasing rms activity of the triceps and anterior deltoid muscles with increasing force in normal volunteers to a significant degree (P < 0.05). SCI patients showed significant increasing activity of the anterior deltoid with increasing force, but showed minimal triceps rms activity. In both groups, the biceps showed minimal rms activity. SCI patients exhibited significantly greater rms activity of the anterior deltoid at low force compared with normal volunteers. The results suggest that the anterior deltoid aids in isometric elbow extension during a simulated weight shift maneuver.

On the interpretation of microbial clusters in periodontal disease

Cluster analysis is sometimes used in periodontal research to describe patterns of microbial identifications observed among cases (subjects or sites). These patterns are assumed to define subsets of cases that are meaningful, in the sense of defining periodontal subgroups that have reliable differences in some aspect of their disease. However, cluster analysis is an exploratory, first-stage technique that does not incorporate the machinery that allows one to evaluate the statistical significance and reliability of the patterns observed. Problems inherent in drawing inferences from cluster analysis are discussed and, as one methodological example of how the statistical significance of clustering might be determined, a randomization-based test for binary scaled microbial identifications is described. The introduction of cluster analysis to the study of periodontal microbiology was important and innovative, but future work needs to incorporate validation by either statistical means or independent replication. The present rarity of such confirmatory methods in the literature suggests caution in accepting specific cluster-based hypotheses about patient-microbial patterns.

Group dynamics in forensic pretrial decision-making

This study examines how forensic evaluators' opinions that pertain to diagnosis, competency to stand trial, and criminal responsibility (Maryland's version of the not guilty by reason of insanity plea) are rendered at a state forensic hospital for defendants pleading not criminally responsible. Pretrial evaluations completed independently by a psychiatrist, a psychologist, and a social worker were presented at a forensic staff conference where psychiatrist and psychologists openly "voted" on diagnosis, competency to stand trial, and criminal responsibility. These results were then sent to the court. The purpose of this study was to assess the clinicians' level of agreement and the role that conformity played in the decision-making process. A sample of twenty court-ordered pretrial evaluations of defendants examined at the hospital between March and June 1991, with evaluators' opinions generated by a secret ballot, were compared with a matched control group from an earlier time, when opinions were generated by open ballot. The study was designed to compare the opinions of forensic evaluators in the issues of diagnosis, competency to stand trial, and criminal responsibility between the two samples. The defendants in the experimental group and the control group were matched on the basis of age, race, sex, and offense. It was hypothesized that with secret ballot voting there would be a greater disparity of agreement regarding diagnosis, competency to stand trial, and criminal responsibility opinions compared with the open method of voting. However, the results of this study did not support that hypothesis. There was little disparity on forensic opinions rated either by secret or open voting.

Strength post-spinal cord injury: myometer vs manual muscle test

This study was designed to compare changes in strength after spinal cord injury (SCI) with the use of a hand held myometer to the manual muscle test (MMT). Eighty-eight C4-C8 Frankel A-D tetraplegic subjects were tested at various times up to 2 years post-SCI. Elbow flexor strength on successive examinations were grouped according to their early and later MMT scores (3.5 with no change in MMT. 3.5 to 4.0, and 3.5 to 4.5; 4.0 with no change in MMT, 4.0 to 4.5, and 4.0 to 5.0; 4.5 with no change in MMT, and 4.5 to 5.0). For each group, later myometric measurements (MYO) were expressed as percents of their earlier MYO and were analyzed using paired Student t-tests. Later MYO were 116, 205, 232% (P > 0.05, P < 0.002, P < 0.05) of their earlier MYO for groups 3.5 with no change in the MMT, 3.5 to 4.0, and 3.5 to 4.5 respectively. Later MYO were 140, 139, 191% (P < 0.05, P < 0.02, P < 0.0001) of their earlier MYO for groups 4.0 with no change in MMT, 4.0 to 4.5, and 4.0 to 5.0 respectively. Later MYO were 127 and 126% (P < 0.01, P < 0.02) of their earlier MYO for groups 4.5 with no change in MMT and 4.5 to 5.0 respectively. In conclusion the hand held myometer detected changes in muscle strength not detected by the MMT.

Interleukin-1 beta, prostaglandin E2, and immunoglobulin G subclasses in gingival crevicular fluid in patients undergoing periodontal therapy

Determination of the presence of inflammatory products found in gingival crevicular fluid (GCF) may be of value in evaluating both periodontal disease status and the outcome of therapy. Immunoglobulin G subclasses 1 through 4 (IgGs), interleukin 1-beta (IL-1 beta), and prostaglandin E2 (PGE2) have all been shown to be present in GCF. This study monitored IgGs, IL-1 beta, and PGE2 in GCF of 18 adult patients as they progressed through periodontal treatment toward maintenance therapy. Sites were selected from the most severely affected sextant as determined by probeable crevice depth (PD) at initial examination (IE). GCF was collected on four occasions: initial examination; 4 weeks after completion of initial therapy (oral hygiene counseling, and scaling and root planing); 3 months after completion of surgery; and 7 to 9 months later at a maintenance visit. All variables were reduced to binary form (positive or negative), and break points chosen to separate the approximately symmetrical bell-shaped areas (negatives) from the skewed tails (positives). Repeated measures analyses of variance were performed to detect significant changes in all variables across time. Significant improvements were observed for all the clinical variables measured: PD, attachment level, and bleeding on probing. However, significant reductions for the GCF components only occurred in the concentrations of IL-1 beta and PGE2, but were not evident until the maintenance sampling. Surprisingly, GCF:serum ratios of IgG subclasses did not change significantly over the course of the investigation. The robustness of the levels of these components may be due to inflammation associated with the healing process, or to a further plaque induced response.

Propofol: an alternative general anesthetic for outpatient oral surgery

PURPOSE

This study compared propofol with methohexital for use in outpatient general anesthesia for oral surgery procedures.

PATIENTS AND METHODS

Fifty American Society of Anesthesia (ASA) class I or II patients undergoing elective minor oral surgery procedures were selected for inclusion in the study. Participants were randomly divided into two groups-propofol-treated and methohexital-treated. All anesthetic agents were titrated in bolus using dosages standardized by weight. After premedication with intravenous midazolam and fentanyl, general anesthesia was induced either by propofol or methohexital. The quality of the anesthesia was subjectively evaluated by the anesthetist, surgeon, and the patient. Also, a standardized battery of tests was developed to quantitatively evaluate recovery from anesthesia.

RESULTS

Propofol showed significantly less percentage increase in diastolic blood pressure and heart rate than methohexital. However, at the same time, propofol showed significantly greater percentage lowering of diastolic blood pressure. The mean low heart rate percentage of preoperative baseline were different, but both were greater than 100%. The anesthetist and patient evaluations showed no statistically significant difference in the acceptance of either agent. No patient in either group had any recollection of pain with induction or any recollection of the operation itself. There were no statistically significant effects of group in recovery test performance, although patients tended to recover more quickly in the symbol digit test and object recall test with propofol. No patient complained of any postoperative complications secondary to the anesthetic.

CONCLUSIONS

Propofol is a suitable agent for induction and maintenance of general anesthesia for outpatient oral surgery procedures. It provides a smooth induction of anesthesia with few excitatory effects.

Treatment of infants with malignant gliomas: the Pediatric Oncology Group experience

Although survivals of infants with malignant brain tumors are worse than any other age group, one possible exception to this rule are the malignant gliomas. Eighteen children less than 3 years of age with malignant gliomas (glioblastoma multiforme, anaplastic astrocytoma and malignant glioma) were treated on the Pediatric Oncology Group regimen of prolonged postoperative chemotherapy and delayed irradiation, (1986-1990). Of 10 children evaluable for neuroradiologic response, 6 had partial responses (> 50% reduction) to two cycles of cyclophosphamide and vincristine. Progression free survivals at 1,3 and 5 years were 54.25% +/- 12, 43% +/- 16 and 43% +/- 23 respectively. Survivals at 5 years were 50% +/- 14. Four children were not irradiated after 24 months of chemotherapy due to parental refusal and none have developed recurrent disease. Neither degree of surgical resection, presence or absence of metastases, nor pathology influenced survival but this may reflect small sample size. This study suggests that some malignant gliomas in infants are chemotherapy sensitive and may be associated with a good prognosis. Why infants with these high-grade gliomas fare better than adults is not clear. It is likely that there is something intrinsically different about them that cannot be identified on routine pathologic examination.

Brush border phosphatidylinositol 3-kinase mediates epidermal growth factor stimulation of intestinal NaCl absorption and Na+/H+ exchange

In terminally differentiated ileal villus Na+-absorptive cells, epidermal growth factor (EGF) stimulates NaCl absorption and its component brush border Na+/H+ exchanger, acting via basolateral membrane receptors, and as we confirm here, a brush border tyrosine kinase. In the present study we show that brush border phosphatidylinositol 3-kinase (PI 3-kinase) is involved in EGF stimulation of NaCl absorption and brush border Na+/H+ exchange. In rabbit ileum studied with the Ussing chamber-voltage clamp technique, EGF stimulation of active NaCl absorption is inhibited by the selective PI 3-kinase inhibitor wortmannin. PI 3-kinase, a largely cytosolic enzyme, translocates specifically to the brush border of ileal absorptive cells following EGF treatment. This translocation occurs as early as 1 min after EGF treatment and remains increased at the brush border for at least 15 min. EGF also causes a rapid (1 min) and large (4-5-fold) increase in brush border PI 3-kinase activity. Involvement of PI 3-kinase activity in intestinal Na+ absorption is established further by studies done in the human colon cancer cell line, Caco-2, stably transfected with the intestinal brush border isoform of the Na+/H+ exchanger, NHE3 (Caco-2/NHE3 cells). Brush border Na+/H+ exchange activity was measured using the pH-sensitive fluorescent dye 2'7'-bis(carboxyethyl)5-(6)-carboxyfluorescein. EGF added to the basolateral surface but not apical surface of Caco-2/NHE3 cells increased brush border Na+/H+ exchange activity. The EGF-induced increase in brush border Na+/H+ exchange activity was completely abolished in cells pretreated with wortmannin. EGF treatment caused increased tyrosine phosphorylation of PI 3-kinase in both ileal brush border membranes and Caco-2/NHE3 cells, suggesting that a tyrosine kinase upstream of the PI 3-kinase is involved in the EGF effects on Na+ absorption. In conclusion, the present study provides evidence in two separate intestinal models, the ileum and a human colon cancer cell line, that PI 3-kinase is an intermediate in EGF stimulation of intestinal Na+ absorption.

Perfusion liquid chromatography of whey proteins

A perfusion reversed-phase (RP) HPLC method was developed for the rapid separation of the main bovine whey proteins: alpha-lactalbumin (alpha-LA), serum albumin (BSA) and the genetic variants of beta-lactoglobulin (A and B) (beta-LG A and beta-LG B). For the method development, the influence of factors favouring structural changes of proteins (temperature and organic acid concentration in the mobile phase), gradient and other chromatographic conditions and the mass of protein injected was examined. The optimized method allowed the separation of proteins in about 1.5 min (cycle time 3.5 min) with resolution around 1.0 for the beta-lactoglobulins. The method was applied to the determination of proteins in a whey from raw bovine milk. The precision of the determinations was < or = 3.75 mg per 100 ml (S.D.). With respect to the accuracy, errors < or = 7.0% in the determination of alpha-LA, beta-LG A and beta-LG B were obtained, compared with an RP-HPLC reference method. However, higher errors in the quantification of BSA were found owing to the lack of purity of the peak assigned. In addition, the proposed method has proved to be very useful in the detection of homologous whey proteins from different species (cow, sheep and goat) in milk mixtures.

Tobacco use habits of naval personnel during Desert Storm

This study examined availability and usage of tobacco products, and their potential impact on the oral health of naval personnel deployed to Desert Storm. Of 4,200 surveys mailed to a randomly selected sample, 45.6% were returned (N = 1,915). The respondents included 55.9% who reported a present or former smoking habit, 34.1% who identified themselves as current smokers (SM), and 23.8% who were smokeless tobacco (ST) users. Tobacco products were easily and inexpensively accessible through ship stores, exchange, or military support organizations (USO). While in the Persian Gulf, 7.0% started SM and 9.3% started ST, resulting in an overall 4.7 and 6.1% increase in SM and ST, respectively. Of those who were already tobacco users, 29.2% reported more SM use and 19.0% used ST more often. Stress (35.1%) and boredom (21.4%) were the most frequently cited reasons to start or increase use. Although 30.5% of respondents reported military personnel have encouraged them to quit, 77.2% reported that anti-smoking efforts have been unsuccessful in influencing them to quit. Since the tobacco usage rate is higher in the military than in the civilian sector, greater emphasis on preventive efforts in warranted to promote health and wellness.

Long term survivors of childhood brain stem gliomas treated with hyperfractionated radiotherapy. Clinical characteristics and treatment related toxicities. The Pediatric Oncology Group

BACKGROUND

Over the past decade, the principal focus of research in pediatric brain stem gliomas has been on the use of hyperfractionated radiotherapy (HRT). The purpose of this study was to evaluate the clinical characteristics and treatment related toxicities of long term survivors of HRT treatment.

METHODS

Of the 130 children with brain stem tumors treated with escalating doses of HRT on Pediatric Oncology Group (POG) #8495, there are only 9 long term survivors. Prospectively collected data, including flow sheets and all pretreatment and follow-up radiologic studies, were reviewed for these patients. Additional information was requested from the treating institutions with regard to sequelae of treatment.

RESULTS

Clinical characteristics (including age, sex, duration of symptoms, and presenting signs) for the nine surviving patients were not different from the total population of patients treated on POG #8495. Pretreatment imaging, however, revealed that only four of the nine patients had typical diffuse intrinsic pontine lesions and, conversely, that at least three of the nine patients had lesions that would now be considered relatively favorable. Complete information regarding treatment related toxicity was available for eight patients, only one of whom is without sequelae. Seven have schooling difficulties, two have a seizure disorder, five have hearing loss, and two have required growth hormone replacement. Follow-up imaging findings were striking in four of the eight patients because of white matter changes consistent with leukoencephalopathy (two patients), diffuse microhemorrhages (one patient), and dystrophic calcification (one patient) in the radiation field.

CONCLUSIONS

The high frequency of treatment related sequelae in long term survivors of HRT suggests a need for caution in the use of HRT, particularly in patients who have brain stem tumors with a more favorable prognosis.

Asymmetric signal transduction in polarized ileal Na(+)-absorbing cells: carbachol activates brush-border but not basolateral-membrane PIP2-PLC and translocates PLC-gamma 1 only to the brush border

In ileal Na+ absorptive cells, carbachol inhibits NaCl absorption and its component brush-border Na+/H+ exchanger, acting via basolateral membrane (BLM) receptors. This carbachol effect involves brush-border but not BLM protein kinase C. In the present work we describe another asymmetric aspect of signal transduction in these epithelial cells, this time involving phosphatidylinositol 4,5-bisphosphate (PIP2)-specific phospholipase C (PLC). Thirty seconds and 1 min after carbachol treatment, brush-border PIP2-specific PLC activity increased, returning to control levels by 2.5 min. Involvement of brush-border tyrosine kinase(s) in this effect was suggested by inhibition of the carbachol effect on NaCl absorption by the tyrosine kinase inhibitor genistein, added to the mucosal but not the serosal surface. Luminal genistein pretreatment also prevented the carbachol-induced increase in brush-border PLC activity. In contrast, carbachol exposure did not change the BLM PIP2-specific PLC activity. Western analysis and immunoprecipitation demonstrated that PLC-gamma 1 is present in the brush border and that carbachol increases the PLC-gamma 1 amount in the brush border. Both the brush border and BLM contain PLC-beta 3 and a small amount of PLC-delta 1 but no PLC-beta 1, whereas BLM lacks detectable PLC-gamma 1. No change in PLC-beta 3 or PLC-delta 1 amount in the brush border occurred with carbachol exposure. No change in tyrosine phosphorylation of brush-border PLC-gamma 1 occurred with carbachol treatment. The Ca2+ ionophore A23187 did not alter PIP2-specific PLC activity in either the brush border or the BLM. These studies demonstrate that carbachol but not Ca2+ ionophore effects on brush-border NaCl absorption are associated with increases in brush-border but not BLM PIP2-specific PLC activity and in the amount of brush-border PLC-gamma 1, and involve tyrosine phosphorylation. This asymmetric aspect of epithelial signal transduction, together with the previous demonstration of localization of high-sensitivity IP3 stores to the apical membrane area in intestinal epithelial cells, shows that different aspects of signal transduction occur at the apical and basolateral membranes in epithelial and requires studies in both domains to define mechanisms of intracellular signalling.

NHE2 and NHE3 are human and rabbit intestinal brush-border proteins

Rabbit NHE2 and NHE3 are two epithelial isoform Na+/H+ exchangers (NHE), the messages for which are found predominantly and entirely, respectively, in renal, intestinal, and gastric mucosa. The current studies used Western analysis and immunohistochemistry to identify and characterize the apical vs. basolateral membrane distribution of NHE2 and NHE3 in intestinal epithelial cells. Based on Western analysis, NHE2 and NHE3 both are present in brush-border but not basolateral membranes of small intestine. Both NHE2 and NHE3 are 85-kDa proteins. Consistent with Western analysis, NHE2 and NHE3 are immunolocalired to the brush-border but not basolateral membranes of villus epithelial cells, but not goblet cells, in human jejunum and ileum and in surface epithelial cells in the ascending and descending colon and rectum. In addition, NHE2 and NHE3 are present in small amounts in the crypt cell brush border of human jejunum, ileum, ascending and descending colon, and rectum. In rabbit jejunum, ileum, and ascending colon, NHE2 and NHE3 are present in the brush border of epithelial and not goblet cells, again much more in the villus (small intestine)/ surface cells (colon) than the crypt. NHE2 but not NHE3 is present in the brush border of rabbit descending colon surface cells and in small amounts in crypt cells. NHE2 and NHE3 are both human and rabbit small intestinal and colonic epithelial cell brush-border Na+/H+ exchanger isoforms that colocalize in all intestinal segments except rabbit descending colon, which lacks NHE3.

Effect of model fitting artifacts on the stepwise approach to identifying patterns of attachment loss

The stepwise approach to the determination of periodontal attachment loss involves fitting linear, logarithmic, and exponential models to individual site data and concluding that the form of loss is consistent with the model that has the greatest r-value, provided that the model predicts loss in excess of a site-specific threshold. Logarithmic and exponential fits are considered to define early and late bursts, respectively, while linear fit describes loss at a constant rate. In a recently published study, the stepwise approach was applied to 6,935 sites in patients with established periodontitis and, of 581 loss detections, 195 (33.6%) were linear, 224 (38.6%) logarithmic, and 162 (27.9%) exponential. However, curvilinear patterns may occur by chance and regression algorithms that can fit such curvature may have an advantage unrelated to the true mechanism(s) [correction of mchanism(s)] of periodontal destruction. To investigate the implications of this possibility, proportions of linear, logarithmic, and exponential fit were estimated by simulation under four different conditions. These conditions incorporated random or random plus linear change, but no nonlinear effects. The relative proportions of model fits described in the published study were approximated in all of these conditions. It would appear that the observed proportions are ubiquitous to the modelling approach itself, and do not constitute evidence of a causal non-linear biological mechanism. The stepwise approach may be useful for detecting change but relevance to causal processes seems problematic.

Necrotizing ulcerative gingivitis, periodontitis, and stomatitis: clinical staging and predisposing factors

Necrotizing ulcerative gingivitis (NUG), necrotizing ulcerative periodontitis (NUP), and necrotizing stomatitis (NS), collectively termed necrotizing gingivostomatitis (NG), represent a dramatic, but rare oral infection associated with diminished systemic resistance, including HIV infection. Over a 5-year period, 68 consecutive NG patients from a population with known HIV status were evaluated and treated. Lesions were staged (modified Pindborg), and clinical findings and predictor variables were compared to 68 random control subjects without NG. Most cases (52%) were stage 1, with necrosis of the tip of the interdental papilla only; 19% were stage 2, with the entire papilla affected; 22% had necrosis of marginal (stage 3) or attached gingiva (stage 4); and 7% were more advanced, with mucosal necrosis or bone exposure. Attachment loss was a feature of stage 2 or greater NG. Beside HIV infection, significant predisposing factors included poor oral hygiene, unusual life stress, inadequate sleep, Caucasian race, age 18 to 21 years, and recent illness. Ten of 68 NG patients were HIV-positive. These patients were older than seronegative patients, less likely to be Caucasian, and maintained better oral hygiene and sleep. HIV-positive NG cases were clinically indistinguishable from HIV-negative cases in this series.

A comparison of three statistics for detecting differences in digitized dental radiographs: a simulation study

OBJECTIVES

Because of methodology-induced structural differences in dental radiographs, determination of change has always depended upon expert interpretation. However, new methods should be able to considerably reduce structured error in digitized subtracted images. Once true change in density is obscured only by random variation in pixel density, statistical methods may be brought to bear on the problem of detecting change. The most appropriate statistic is not obvious, however, since density change can be quantified with respect to both magnitude and dimensional extent. Whereas mean density loss is often intuitively defined as the average density of those pixels losing density (to preclude gaining pixels from offsetting losing pixels), the extent of change may be defined in a variety of ways. In this study, extent was defined as either (a) the total number of pixels losing density, or (b) the size of the largest cluster of losing pixels. The object was to evaluate the comparative statistical power of three possible statistics (based on mean density, number of losing pixels, and size of largest losing cluster) for detecting change.

METHODS

In a series of simulations of comparative clinical trials, density was reduced in the centre of 1600-pixel square regions of interest by either one or 10 grey-scale units, and t-tests, based on the three statistics, were then compared for their ability to detect differences.

RESULTS

Each of the three statistics was shown to exhibit superior relative power under particular conditions of loss magnitude, loss distribution, and pixel threshold for change.

CONCLUSION

Selection of the appropriate statistic for identifying change between radiographs will require further information about the anticipated distribution of density changes for the different disease processes under investigation.

Lack of efficacy of postoperative chemotherapy and delayed radiation in very young children with pineoblastoma. Pediatric Oncology Group

Eleven infants with pineoblastomas were treated with prolonged postoperative chemotherapy in an attempt to delay radiation and reduce neurotoxicity. These infants were part of the Pediatric Oncology Group infant brain tumor study but the outcome of infants with pineoblastomas was not previously reported. Ages ranged from 1 month to 35 months, with eight of 11 < or = 12 months at diagnosis. Four had + cytology and three had + myelograms at diagnosis. The majority had partial surgical resection (25-75% reduction in tumor) and 10 had shunts. Chemotherapy consisted of two 28-day cycles of cyclophosphamide plus vincristine, followed by one 28-day cycle of cisplatin plus etoposide. Craniospinal radiation was planned following completion of either 2 years of chemotherapy (children less than 24 months at diagnosis) or following one year (children 24-36 months at diagnosis). Neuroimaging results following two cycles of cyclophosphamide and vincristine were one partial response, five stable disease, and five progressive disease. There were no responders in the leptomeninges. All children ultimately failed chemotherapy (2 months-11 months). Nine failed in the primary site. Of those eight children in whom a metastatic workup was performed at time of progression, all had evidence of leptomeningeal disease. Six received radiation following failure on chemotherapy. All failed either in the primary site, leptomeninges or extraneurally (peritoneal cavity). All children died. Survival following diagnosis ranged from 4 months to 13 months. This chemotherapy regimen was neither effective in controlling tumor in the primary site nor in treating or preventing leptomeningeal spread.

Alternative splicing and differential targeting of fibroblast growth factor receptor 1 in the pregnant rat uterus

Recent studies suggest that steroid effects on uterine cell proliferation may be moderated by polypeptide growth factors. We now provide evidence that high affinity fibroblast growth factor (FGF) receptors are present temporally and spatially in the pregnant rat uterus (days 4-6) to support the idea that basic FGF action occurs via binding to its high affinity FGF receptor 1 (FGFR1). Reverse transcription-polymerase chain amplification indicates that both the full-length transcript and an alternatively spliced messenger RNA are present in the uterus. Western immunoblot analysis confirms that rat uterine membrane proteins contain two receptor isoforms, and these receptors bind basic FGF with high affinity and specificity. Immunolocalization of FGFR1 revealed receptor-positive cells in both the uterine stroma and epithelia on days 4-6 of pregnancy. However, the receptor was differentially localized in the disparate cell types. The nuclei of stromal cells were positive for FGFR1, whereas epithelial cell nuclei were negative. Together, these results suggest that FGF signal transduction in uterine stromal cells is mediated by activation of FGFR1.

Elbow extension using anterior deltoids and upper pectorals in spinal cord-injured subjects

OBJECTIVE

Surface electromyography was used to identify muscles active in isometric elbow extension in spinal cord-injured (SCI) patients.

DESIGN

Tetraplegic subjects participated in this cohort study aimed at identifying some of the muscles that are active during isometric elbow extension.

SETTING

Regional Spinal Cord Injury (SCI) Center.

PATIENTS

The patients had to have a C6 motor level on the right side (wrist extensor > or = 3/5) with 0/5 or 1/5 elbow extensor muscle power. Of 32 patients who could be contacted by telephone, 6 eventually were able to make it to the SCI center for testing.

MEASUREMENTS

The patients performed a series of isometric elbow extension contractions of 25%, 50%, and 75% of maximum voluntary contraction (MVC) as measured by a force transducer. Surface electromyography (EMG) of the right elbow extensor, anterior deltoid, and upper pectoral muscles was measured using the root mean square (rms) of the amplitude of the motor unit activity as the parameter of muscle activity. Statistical analyses were performed using a repeated analysis of variance (ANOVA) with Tukey post-hoc HSD for each percentage of MVC.

RESULTS

For each muscle tested, there was significantly (p < 0.05) greater rms activity for each percentage of MVC except between 50% and 75% MVC of the elbow extensor muscle. However, the elbow extensor muscle had minimal EMG activity when compared with the amplitude of the rms activity of the anterior deltoid and upper pectoral muscles for each percentage of MVC.

CONCLUSION

The results of the study suggest that the anterior deltoid and the upper pectoral muscles exert an isometric elbow extension force for C6 quadriplegic patients.

Effects of gender-related factors on the incidence of localized alveolar osteitis

Numerous literature references have suggested increased risk for localized alveolar osteitis associated with female gender, use of oral contraceptives, and point in menstrual/contraceptive cycle. However, the available information has not been systematically considered with the intent to accurately estimate the magnitude of these effects. The present review suggests that under certain conditions, some of which may be avoidable, females may have at least a two to threefold increase in osteitis risk compared with males. It appears that this greater risk may be reduced by considering hormonal cycles when scheduling elective exodontia.

Detection of periodontal probing change by analysis of distribution mean and skew

A problem associated with probing measurement is that important site-specific change may be obscured by measurement variability. Furthermore, if many sites are monitored there is an increasing likelihood that any particular "detected change" might be the result of this measurement error. Since error and multiplicity effects would tend to increase mouth-wise false positive rate, demanding decision thresholds are often set. However, imposition of difficult criteria, increases site-wise false negative rate and therefore reduces utility in the clinical setting. Evaluation of mean change might sometimes be a useful alternative, but also problematic as a few dramatic site-level losses can be inconsequential among many stable or improving sites. A strategy is proposed for evaluating probing changes in a single patient, which is based on the statistical evaluation of two attributes of the change distribution. (1) Disease progression is concluded when mean probing loss increases over time, and (2) a clinically relevant asymmetry is concluded when the distribution tail corresponding to loss is skewed. Computerized simulation was used to determine alpha-error for tests of mean and skew, for three different distributions of probing change. Actual alpha-error was shown to be near nominal levels. Power was estimated as a function of the number and magnitude of sites with probing loss and as a function of whether there was change in both mean and skew or in skew alone. Under most conditions studied, simultaneous tests for skew and mean provided enhanced power relative to a test for loss alone and would appear to offer the clinician an additional statistical context for appraising disease status.

Treatment of blue nevi with the Q-switched ruby laser

The common blue nevus is a benign, localized collection of dermal melanocytes. To date, removal required excisional surgery to eliminate pigment that usually extends into the reticular dermis. We report the successful long-term elimination of common blue nevi on the nasal skin of two patients whose lesions were treated with the laser emission of 694 nm energy from the Q-switched ruby laser.

Wrist strength measured by myometry as an indicator of functional independence

The purpose of this study was to show that independence of self care activities of motor complete quadriplegic patients related better to the force of contraction of the wrist extensor (WE) muscles measured by a hand held myometer than to the manual muscle test (MMT) for grades 3 to 5. The patients (n = 24), identified by having unilaterally or bilaterally functional WE muscle (MMT > or = 3/5) with bilateral elbow extensor (EE) muscles < 3/5, were evaluated at 2 to 6 months after injury for four feeding activities utilizing the Quadriplegia Index of Function (QIF). We found 54% were independent drinking from a cup, 58% using a spoon or fork, 13% cutting food, and 23% pouring liquids. Comparisons were made between right, left, and bilateral mean myometry scores and median MMT scores for each of the QIF activities. The independent group of patients had myometry scores 54 to 140% greater (p < 0.05) than those patients dependent in the self care activity except when the right or left WE myometric score was analyzed for cutting food (p = 0.1). MMT comparisons showed no significant median score differences in any activity performed. There were no patients with only one WE muscle > or = 3/5 (n = 9) who were able to cut food or pour liquids independently. In conclusion, myometry appeared to be a better indicator than the MMT for some self care activities evaluated utilizing the Quadriplegia Index of Function.

Postoperative chemotherapy and delayed radiation in infants and very young children with choroid plexus carcinomas. The Pediatric Oncology Group

Eight infants with choroid plexus carcinomas were treated with surgery, prolonged postoperative chemotherapy and delayed radiation. The results suggest that some infants with choroid plexus carcinomas can be successfully treated with multimodality therapy, even allowing children with less than a gross total resection to have prolonged disease-free intervals.

Etiologies of central diabetes insipidus in children

The last major review of the etiologies of central diabetes insipidus in children was performed a quarter century ago, prior to the development of modern neuroimaging techniques. We retrospectively reviewed the records of children with central diabetes insipidus identified at Children's Hospital of Buffalo from 1979 to 1992. Of the 35 patients identified, 27 were males and 8 were females. Their ages ranged from 3 weeks to 20 years. Nineteen children had brain tumors, 7 had cerebral malformations, 3 had central nervous system infections, 1 had traumatic brain injury, and 5 were considered idiopathic. Patients with brain death were excluded from the review. Thirty-one of 35 patients developed diabetes insipidus in conjunction with other endocrinopathies. Brain tumor and its treatment account for the most common cause. Cranial magnetic resonance imaging has improved the identification of structural lesions and the understanding of the pathophysiology of central diabetes insipidus.

Proposed guidelines for American Dental Association acceptance of products for professional, non-surgical treatment of adult periodontitis. Task Force on Design and Analysis in Dental and Oral Research

Guidelines are suggested for determining efficacy of products to supplement scaling and root planing in professional, non-surgical treatment of adult periodontitis. They result from an extended process including a conference on clinical trials in gingivitis and periodontitis, a subsequent workshop, and commentary from industrial, academic, professional and governmental members of the periodontal research community on two drafts. Recommendations are made in the broad areas of basic study design, subject and periodontal site selection, clinical management, choice of outcome variables, statistical summarization and analysis, and criteria for acceptance. Prominent dissenting views, with justifications for positions taken here, are also provided. Groundwork is laid for possible future guidelines addressing products for primary prevention or over-the-counter uses, or for determining superiority or equivalence of competing products. However, issues are identified which require further exploration before responsible and widely acceptable recommendations can be made in these areas. The guidelines suggested here are meant to form the basis of an evolving document rather than a static standard. It is suggested that they be reviewed frequently in the light of improvement in the technology available for periodontal research, and the emergence of products representing new approaches to periodontal therapy.

Lung volume specificity of inspiratory muscle training

We examined the extent to which training-related increases of inspiratory muscle (IM) strength are limited to the lung volume (VL) at which the training occurs. IM strength training consisted of performing repeated static maximum inspiratory maneuvers. Three groups of normal volunteers performed these maneuvers at one of three lung volumes: residual volume (RV), relaxation volume (Vrel), or Vrel plus one-half of inspiratory capacity (Vrel + 1/2IC). A control group did not train. We constructed maximal inspiratory pressure-VL curves before and after a 6-wk training period. For each group, we found that the greatest improvements in strength occurred at the volume at which the subjects trained and were significantly greater for those who trained at low (36% for RV and 26% for Vrel) than at high volumes (13% for Vrel + 1/2IC). Smaller increments in strength were noted at volumes adjacent to the training volume. The range of vital capacity (VC) over which strength was increased was greater for those who trained at low (70% of VC) than at high VL (20% of VC). We conclude that the greatest improvements in IM strength are specific to the VL at which training occurs. However, the increase in strength, as well as the range of volume over which strength is increased, is greater for those who trained at the lower VL.

Pressure-flow specificity of inspiratory muscle training

The inspiratory muscles (IM) can be trained by having a subject breathe through inspiratory resistive loads or by use of unloaded hyperpnea. These disparate training protocols are characterized by high inspiratory pressure (force) or high inspiratory flow (velocity), respectively. We tested the hypothesis that the posttraining improvements in IM pressure or flow performance are specific to training protocols in a way that is similar to force-velocity specificity of skeletal muscle training. IM training was accomplished in 15 normal subjects by use of three protocols: high inspiratory pressure-no flow (group A, n = 5), low inspiratory pressure-high flow (group B, n = 5), and intermediate inspiratory pressure and flow (group C, n = 5). A control group (n = 4) did no training. Before and after training, we measured esophageal pressure (Pes) and inspiratory flow (VI) during single maximal inspiratory efforts against a range of external resistances including an occluded airway. Efforts originated below relaxation volume (Vrel), and peak Pes and VI were measured at Vrel. Isovolume maximal Pes-VI plots were constructed to assess maximal inspiratory pressure-flow performance. Group A (pressure training) performed 30 maximal static inspiratory maneuvers at Vrel daily, group B (flow training) performed 30 sets of three maximal inspiratory maneuvers with no added external resistance daily, and group C (intermediate training) performed 30 maximal inspiratory efforts on a midrange external resistance (7 mm ID) daily. Subjects trained 5 days/wk for 6 wk. Data analysis included comparison of posttraining Pes-VI slopes among training groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Recommended revisions to American Dental Association guidelines for acceptance of chemotherapeutic products for gingivitis control. Report of the Task Force on Design and Analysis in Dental and Oral Research to the Council on Therapeutics of the American Dental Association

This paper presents suggested revisions to the American Dental Association's 1985 guidelines for acceptance of anti-gingivitis chemotherapeutic agents. The areas of study design, choice and quality control of clinical gingivitis measurements, statistical analysis, and minimum strength of effect, are addressed. The revisions articulate certain aspects of study design which were implicit in the 1985 guidelines, clarify language on cross-over designs and independence of studies, and recommend use of a United States population in at least one trial supporting a product. Separate recording and analysis of a product's effect on gingival bleeding is proposed, and quality control of clinical measurements receives enhanced emphasis. Modestly elaborated statistical reporting guidelines and strengthened approval criteria, based on size of estimated effect as well as statistical significance, are advocated.

Brush-border tyrosine phosphorylation stimulates ileal neutral NaCl absorption and brush-border Na(+)-H+ exchange

The drug genistein, a tyrosine (Tyr) kinase inhibitor, was used to define a role for Tyr phosphorylation in regulation of basal and stimulated neutral NaCl absorption in rabbit ileum. Brush-border vesicles contain Tyr-phosphorylated peptides. Genistein freeze-thawed into the vesicles caused a concentration-dependent inhibition of at least three peptides with M(r) 111,000, 83,000, and 80,000. Studied with the Ussing chamber-voltage clamp technique, genistein added to the ileal mucosal surface inhibited neutral NaCl absorption. Direct addition of genistein to brush-border vesicles made from ileal villus cells inhibited brush-border Na(+)-H+ exchange but not D-glucose-stimulated Na+ uptake. These effects were not duplicated by genistin, a drug with similar structure to genistein but lacking Tyr kinase inhibiting properties. Serosal but not mucosal epidermal growth factor (EGF) stimulated NaCl absorption. Mucosal genistein but not genistin also altered second-messenger regulation of neutral NaCl absorption, inhibiting the effect of Ca2+ ionophore A-23187 and of serosal EGF but not affecting the transport changes caused by 8-bromoadenosine 3',5'-cyclic monophosphate (8-BrcAMP). In contrast, the Cl secretory effects indicated by the increase in short-circuit current for all three agents, A-23187, EGF, and 8-BrcAMP, were inhibited by mucosal genistein. These results suggest that 1) a Tyr kinase is involved in basally stimulating ileal neutral NaCl absorption and brush-border Na(+)-H+ exchange; 2) EGF stimulates NaCl absorption by an effect exerted from the serosal surface, but the effect also involves a brush-border Tyr kinase; 3) brush-border Tyr kinase is involved in the ability of Ca2+ ionophore A-23187 to inhibit neutral NaCl absorption but is not involved in the transport effects of cAMP. This study suggests that Tyr kinase(s) acting over short time periods is involved in stimulation of neutral NaCl absorption and brush-border Na(+)-H+ exchange and also in Ca(2+)-induced inhibition of NaCl absorption. These studies represent the first example of a brush-border Tyr kinase being involved in short-term signal transduction in intestinal epithelial cells.

Desmoplastic infantile gangliogliomas: an approach to therapy

Desmoplastic infantile gangliogliomas are massive cystic tumors, typically occurring in the cerebral hemispheres of infants. They are remarkable pathologically for a prominent desmoplasia and, in some cases, for a cellular mitotically active component that can be readily interpreted as a malignant neoplasm. Four children less than 1 year of age were diagnosed with desmoplastic infantile gangliogliomas in the Pediatric Oncology Group infant brain tumor study (Protocol number 8633). All had been diagnosed by their respective institutions as having malignant tumors, i.e., Grade III astrocytoma, malignant meningioma, leptomeningeal fibrosarcoma, and gliosarcoma. All had increased intracranial pressure, and two had seizures. The tumors were extremely large, with one measuring 12 x 9 x 9 cm. None had evidence of metastatic disease. One patient had a gross total resection, and the other three had debulking procedures. All four children were treated with chemotherapy (cyclophosphamide, vincristine, cisplatinum, etoposide) for periods ranging from 12 to 24 months. Of those with postoperative measurable disease, one child had a complete response, one a partial response, and one had stable disease at the conclusion of chemotherapy. No child received radiation therapy. All children are alive with progression-free survivals after diagnosis of more than 36, 42, 48, and 60 months, respectively. Although desmoplastic infantile gangliomas are rare, recognition of this tumor type is essential because, despite their massive size and pathologically malignant appearance, they may have a relatively benign clinical course. If total surgical resection can be achieved, further therapy may not be indicated. In those patients in whom residual disease is present, chemotherapy appears to be an effective form of therapy.(ABSTRACT TRUNCATED AT 250 WORDS)

Information integration in a decision support system

Electronic medical records pose a challenge because of the complex types of data which are included. Decision support systems must be able to deal effectively with these data types. In the expert system demonstrated here, a diversity of data types are included. These data are processed by three different methods. However, the different methods of processing are transparent to the user. An overall rule-based interface integrates the different methods into one comprehensive system.

Bursts of periodontal destruction and remission, percolation phase shifts, and chaos

Bursts of periodontal destruction are modelled as percolation-driven phase shift events. Percolation theory, though widely used to study the flow of liquids through porous nonliving materials (e.g., soils and rocks), can be applied to bacterial or toxicological penetration of living tissue in only an approximate sense. However, it seems necessary that some mechanism, fundamentally similar to the percolation phase shift, is required to adequately account for bursts. Percolation theory is therefore offered as a framework for considering such events. A principal finding of percolation theory is the existence of percolation thresholds, such that when P, the independent probability that a subregion is susceptible to an invading substance, is above the threshold, the region will percolate or allow flow through, and when P is below the threshold the region will not percolate. This instantaneous transition, from a structure that will permit percolation to one that will not, is described as a phase shift. In addition, the value of P is postulated to depend on multiple factors which might constitute a chaotic system. The nonproportionality of a percolation phase shift and the nonpredictability of any specific chaotic event suggest that reliable burst predictors may, in theory, not be possible at the level of the individual site.

Configural frequency analysis for exploring bacterial sets in periodontal health and disease

Periodontal research has been concerned with identifying bacterial sets in oral health and disease. Configural frequency analysis (CFA) is a taxonomical method used to test the statistical significance of patterns of elementary cell frequencies in cross-tabulated data, and may therefore be used to evaluate interactions among occurrences and non-occurrences of periodontal microorganisms. CFA patterns may exist as configural types or anti-types depending on whether observed cell frequencies are greater or less than expected frequencies, respectively, based on table marginals. CFA was applied to two published data sets. In the first, the occurrence of Bacteroides (Porphyromonas) gingivalis (Bg) and Treponema denticola (Td) was studied in military subjects. Analysis of individual cells of the resultant two-by-two contingency table revealed the existence of a single anti-type (Td in the absence of Bg) suggesting a sequential phenomenon. The second, more complex, data set was based on reported occurrence of Actinobacillus actinomycetemcomitans (Aa), Bg, and Bacteroides (Prevotella) intermedius (Bi) in sites with and without progressive periodontitis. CFA based on all data identified three statistically significant configural types and two anti-types. However, a somewhat different configurational picture emerged when disease progression status was considered a stratification variable for separate analysis. All these analyses, which were undertaken for expository purposes, assumed independence of observations. Methodological procedures are suggested for CFA when observations are not independent.

Final results of a study of escalating doses of hyperfractionated radiotherapy in brain stem tumors in children: a Pediatric Oncology Group study

PURPOSE

In September 1984, the Pediatric Oncology Group began accrual to a Phase I/II study designed to assess the efficacy and toxicity of sequentially escalated doses of hyperfractionated (twice daily) radiotherapy in children with poor-prognosis brain stem tumors. Pediatric Oncology Group Study #8495 closed in June 1990 with a total of 136 patients on study. We report here the outcome of patients treated at the third and final dose level (75.6 Gy), and compare the results to those obtained at the 66 and 70.2 Gy dose levels.

METHODS AND MATERIALS

Patients eligible for study were those between 3 and 21 years of age with previously untreated tumors arising in the midbrain, pons or medulla. Histological confirmation of diagnosis was not mandatory provided that the clinical and radiological findings were typical for brain stem glioma. Treatment consisted of radiotherapy delivered to local fields. At the third dose level, fraction sizes of 1.26 Gy were given twice daily, with a minimum interfraction interval of 6 hr to a dose of 75.6 Gy in 60 fractions over 6 weeks. Between 5/89 and 6/90, 41 patients were accrued to the study. Two were excluded from analysis leaving 39 evaluable patients, 21 male and 19 female, whose ages ranged from 3 to 15 years (median 7.5 years).

RESULTS

Following treatment, neurological improvement was reported in 30/39 (77%) of the patients. On central review of imaging studies in 29 patients, one patient was found to have had a complete response to radiotherapy, five a partial (> 50% response), and only three had non-responding or progressive disease. The median time to disease progression was 7 months; median survival time was 10 months; survival at 1 year was 39.9% (SE 8.3%) and at 2 years, 7% (SE 4.8%). The pattern of failure was local in all patients; in addition six had evidence of leptomeningeal seeding. Morbidity of treatment included an enhanced skin reaction (21%), otitis media and/or externa (26%), and steroid use > 3 months (62%). Intralesional necrosis was a frequent finding (45%) on imaging studies performed at a median time of 6 weeks post treatment.

CONCLUSION

The results of treatment in terms of progression-free survival and overall survival are not significantly different (at p = .55 and p = .46, respectively) from those obtained at the two previous dose levels. There is no evidence that higher doses of hyperfractionated radiotherapy given as in this study improve the outlook of patients with poor-risk brain stem gliomas.

Mammographic parenchymal patterns in Asian and Caucasian women attending for screening

The breast parenchymal patterns were assessed and compared on the screening mammograms of 200 Asian and 400 Caucasian women, matched for age and between 50 and 64 years of age. The breast patterns were allocated according to Wolfe's classification. The results show a significant excess of Asians in the P1 and N1 groups and a deficit in the P2 group. Taking N1 and P1 as a low risk group and P2 and DY as a high risk group, there is a highly significant excess of Asians in the low risk group. These findings are considered in relation to the low incidence of breast cancer in Asian women and their poor acceptance of breast screening.

Effect of dietary vitamin E supplementation and rotational stress on alveolar bone loss in rice rats

The effect of this supplementation on bone loss (distance from the cementum-enamel junction to the alveolar crest measured at the midline of the lingual aspect of each of the mandibular molar roots) was studied in rats that were either not stressed or stressed on a rotational device for 90 days. In the first study, neither vitamin E nor stress condition had statistically significant effects but there was substantial bone loss and bone-loss variability in all groups. Before the start of the second study, to reduce differences in bone loss that might otherwise exist before introduction of the treatments, rats received an antibiotic in their drinking water. In addition, rotational stress was introduced more abruptly than in the first study to reduce the likelihood of adaptation. Bone loss and bone-loss variability were substantially reduced in the second study. Analysis of these data indicated that vitamin E supplementation had a statistically significant protective effect, which was most pronounced at sites most susceptible to loss. Stressed subjects tended to lose more bone, but this effect was not significant. These findings suggest some role for vitamin E supplementation in the maintenance of periodontal health but also a sensitivity in this effect to initial periodontal status.

Postoperative chemotherapy and delayed radiation in children less than three years of age with malignant brain tumors

BACKGROUND

Among patients with malignant brain tumors, infants and very young children have the worst prognosis and the most severe treatment-related neurotoxic effects. Therefore, in 1986, the Pediatric Oncology Group began a study in which postoperative chemotherapy was given in order to permit a delay in the delivery of radiation to the developing brain.

METHODS

Children under 36 months of age with biopsy-proved malignant brain tumors were treated postoperatively with two 28-day cycles of cyclophosphamide plus vincristine, followed by one 28-day cycle of cisplatin plus etoposide. This sequence was repeated until the disease progressed or for two years in 132 children 24 months of age at diagnosis and for one year in 66 children 24 to 36 months of age at diagnosis. After this, the patients received radiation therapy. The response to the first two cycles of chemotherapy was measured in 102 patients with residual postoperative disease.

RESULTS

The first two cycles of cyclophosphamide and vincristine produced complete or partial responses in 39 percent of the 102 patients who could be evaluated. The response rates were highest among patients with medulloblastomas, malignant gliomas, or ependymomas. Patients with brain-stem gliomas or embryonal tumors (primitive neuroectodermal tumors) had little or no response. The progression-free survival rate was 41 percent at one year for children who were 24 to 36 months old at diagnosis and 39 percent at two years for those under 24 months of age at diagnosis. Multivariate analysis identified embryonal tumors as a significant adverse prognostic feature (relative risk, 2.2; 95 percent confidence interval, 1.4 to 3.4) and complete resection as a favorable feature (relative risk, 0.33; 95 percent confidence interval, 0.20 to 0.54). Complete responses to chemotherapy were associated with a progression-free survival rate approaching that achieved with gross total resection. A comparison of cognitive evaluations obtained at base line and after one year of chemotherapy revealed no evidence of deterioration in cognitive function.

CONCLUSIONS

Chemotherapy appears to be an effective primary postoperative treatment for many malignant brain tumors in young children. Disease control for one or two years in a large minority of patients permitted a delay in the delivery of radiation and, on the basis of preliminary results, a reduction in neurotoxicity. For patients who had undergone total surgical resection or who had a complete response to chemotherapy, the results are sufficiently encouraging to suggest that radiation therapy may not be needed in this subgroup of children after at least one year of chemotherapy.

Simulation study of methods to detect periodontal associations when they are inconsistent among subjects

Most statistical methods used to evaluate associations between indices of clinical periodontal diseases and purported prognostic markers test for effects across subjects. If associations exist within only a subset of subjects, however, associations may be masked, particularly in small studies. This issue was explored by using simulation to study four methods for detecting periodontal associations. Built into the simulations was the possible biological reality that a non-zero association between the two variables of interest (squared correlation coefficients, rho 2, ranged from 0.1 to 0.9 depending on simulation), measured at 16 sites per subject, did not exist in all of 10 hypothetical subjects. The four methods for testing the null hypothesis that rho = 0, or a related hypothesis; were: (1) Sites, analysis based on 160 sites incorrectly considered independent observations; (2) Subjects, analysis based on one score for each of 10 subjects; (3) Each subject, separate analyses based on sites within each of 10 subjects, family-wise type I (alpha) error corrected for multiplicity, and (4) the Each Subject method where P-levels were estimated using permutation procedures rather than t-distributions. Each Subject methods were found to have greater relative power (although there are differences in null hypotheses) under conditions of heterogeneity in rho and are considered to be particularly relevant in exploratory periodontal research when the primary interest is establishing the existence of a relationship, even if in only a subset of subjects.

Glucocorticoid stimulation of ileal Na+ absorptive cell brush border Na+/H+ exchange and association with an increase in message for NHE-3, an epithelial Na+/H+ exchanger isoform

Methylprednisolone stimulates rabbit ileal neutral NaCl absorption; and aminoglutethimide, which decreases glucocorticoid levels, decreases NaCl absorption. Studies were carried out to determine the mechanism of these effects and to determine which members of the gene family of mammalian Na+/H+ exchangers were involved. Rabbits were treated subcutaneously with methylprednisolone (40 mg daily for 24 or 72 h), aminoglutethimide (100 mg twice daily for 72 h), or saline as a control. Ileal brush border membranes were prepared by magnesium precipitation, and brush border Na+/H+ exchange was determined by 22Na+ uptake over 3-8 s. The 22Na+ uptake experiments were performed in the presence of a voltage clamp using either valinomycin/potassium or tetramethylammonium/nitrate to eliminate potential contributions by other electrogenic transport processes. Methylprednisolone treatment approximately doubled ileal brush border Na+/H+ exchange, whereas aminoglutethimide led to a 50% decrease in Na+/H+ exchange. These effects were specifically on Na+ uptake with an acid inside pH gradient, whereas diffusive Na+ uptake (no pH gradient), glucose-dependent Na+ uptake, and glucose and Na+ equilibrium volumes were not affected. To determine if the increase in Na+/H+ exchange was associated with an increase in message expression, mRNA levels were measured by ribonuclease protection assay. Methylprednisolone stimulated the NHE-3 mRNA level by 4-6-fold at 24 h, which remained increased at 72 h. In contrast, messages for NHE-1 and NHE-2 were not affected by methylprednisolone. In summary, 1) methylprednisolone stimulation of rabbit ileal Na+ absorption is due to stimulation of ileal villus cell brush border Na+/H+ exchange; 2) basal ileal brush border Na+/H+ exchange is dependent on glucocorticoid levels; and 3) an increase in NHE-3 message, but not in NHE-1 or NHE-2 message, correlates with the stimulation of ileal brush border Na+/H+ exchange. It is likely that NHE-3 is an Na+/H+ exchanger that is involved in ileal Na+ absorption.