Biomedical subjects

M L Moeschberger

Publications and source records attributed to M L Moeschberger.

At least 37 records · Page 2Linked to original sources

PubMed1997

Boron neutron capture therapy of brain tumors: enhanced survival following intracarotid injection of sodium borocaptate with or without blood-brain barrier disruption.

PURPOSE: Sodium borocaptate (Na2B12H11SH or BSH) has been used clinically for boron neutron capture therapy (BNCT) of patients with primary brain tumors. The purpose of the present study was to determine if tumor uptake of BSH and efficacy of BNCT could be enhanced in F98 glioma-bearing rats by intracarotid (i.c.) injection of the compound with or without blood-brain barrier disruption (BBB-D). METHODS AND MATERIALS: For biodistribution studies 100,000 F98 glioma cells were implanted stereotactically into the brains of Fischer rats, and 12 days later BBB-D was carried out by i.c. infusion of 25% mannitol, followed immediately thereafter by i.c. injection of BSH (30 mg B/kg body weight). Animals were killed 1, 2.5, and 5 h later, and their brains were removed for boron determination. For BNCT experiments, which were initiated 14 days after intracerebral implantation of 1000 F98 cells, BSH (30 mg B/kg b.wt. was administered intravenously (i.v.) without BBB-D, or i.c. with or without BBB-D. The animals were irradiated 2.5 h later with a collimated beam of thermal neutrons at the Brookhaven National Laboratory Medical Research Reactor. RESULTS: The mean tumor boron concentration after i.c. injection with BBB-D was 48.6 +/- 17.2 microg/g at 2.5 h compared with 30.8 +/- 12.2 microg/g after i.c. injection without BBB-D and 12.9 +/- 4.2 microg/g after i.v. injection. The best composite tumor to normal tissue ratios were observed at 2.5 h after BBB-D, at which time the tumor:blood (T:B1) ratio was 5.0, and the tumor: brain (T:Br) ratio was 12.3, compared to 1.1 and 4.6, respectively, in i.v. injected rats. The mean survival time for untreated control rats was 24 +/- 3 days, 29 +/- 4 days for irradiated controls, 33 +/- 6 days for those receiving i.v. injection of BSH, 40 +/- 8 days for rats receiving i.c. BSH without BBB-D, and 52 +/- 13 days for BBB-D followed by BNCT (p = 0.003 vs. i.v. injected BSH). CONCLUSIONS: Intracarotid administration of BSH with or without BBB-D significantly increased tumor uptake of BSH and enhanced survival of F98 glioma-bearing rats following BNCT. BBB-D may be a useful way to enhance the delivery of both low and high molecular weight boron compounds to brain tumors. Further studies are in progress to assess this approach with other boron delivery agents.

Animals↗

PubMed1997

Enhanced survival of glioma bearing rats following boron neutron capture therapy with blood-brain barrier disruption and intracarotid injection of boronophenylalanine.

Boronophenylalanine (BPA) has been used for boron neutron capture therapy (BNCT) of brain tumors in both experimental animals and humans. The purpose of the present study was to determine if the efficacy of BNCT could be enhanced by means of intracarotid (i.c.) injection of BPA with or without blood-brain barrier disruption (BBB-D) and neutron irradiation using a rat brain tumor model. For biodistribution studies, F98 glioma cells were implanted stereotactically into the brains of Fischer rats, and 12 days later BBB-D was carried out by i.c. infusion of 25% mannitol (1.373 mOsmol/ml), followed immediately by i.c. administration of 300, 500 or 800 mg of BPA/kg body weight (b.w.). At the 500 mg dose a fourfold increase in tumor boron concentration (94.5 micrograms/g) was seen at 2.5 hours after BBB-D. compared to 20.8 micrograms/g in i.v. injected animals. The best composite tumor to normal tissue ratios were observed at 2.5 hours after BBB-D, at which time the tumor: blood (T: Bl) ratio was 10.9, and the tumor: brain (T:Br) ratio was 7.5, compared to 3.2 and 5.0 respectively for i.v. injected rats. In contrast, animals that had received i.c. BPA without BBB-D had T : Bl and T:Br ratios of 8.5 and 5.9, respectively, and the tumor boron concentration was 42.7 micrograms/g. For therapy experiments, initiated 14 days after intracerebral implantation of F98 glioma cells, 500 mg/kg b.w. of BPA were administered i.v. or i.c. with or without BBB-D, and the animals were irradiated 2.5 hours later at the Brook-haven Medical Research Reactor with a collimated beam of thermal neutrons delivered to the head. The mean survival time for untreated control rats was 24 +/- 3 days, 30 +/- 2 days for irradiate controls, 37 +/- 3 days for those receiving i.v. BPA, 52 +/- 15 days for rats receiving i.c. BPA without BBB-D, and 95 +/- 95 days for BBB-D followed by i.c. BPA and BNCT. The latter group had a 246% increase in life span (ILS) compared to untreated controls and a 124% ILS compared to that of i.v. injected animals. These survival data are the best ever obtained with the F98 glioma model and suggest that i.c. administration of BPA with or without BBB-D may be useful as a means to increase the efficacy of BNCT.

Animals↗

PubMed1997

Predictors of dental use for low-income, urban elderly persons upon removal of financial barriers.

This study examines a low-income, urban elderly population of dental and medical, nondental users. A total of 1,378 medical, nondental users and 2,086 dental users were identified using longitudinal claims data (1983-1992) from a Medicare-waiver program that reimbursed for health care services at cost. Dental users were more likely to be from a younger age cohort (born after 1910, p = .0001) and were more likely to be black (63.3% vs 35.7%, P = .0001) than medical, nondental users. Medical, nondental users had more medical visits (p = .0001), higher medical and pharmacy charges (p = .0001), and more prescriptions (p = .0001) than did the dental users. These findings indicate that among this population of urban elderly, dental users were more likely to be black and have lower medical utilization than nondental users.

Aged↗

PubMed1997

Concordance of Porphyromonas gingivalis colonization in families.

Periodontitis is a widespread disease that appears to be due to a specific bacterial infection. Several species of bacteria have been investigated as potential pathogens, and particularly strong evidence links the presence of Porphyromonas gingivalis with indicators of periodontitis. Information concerning the transmission of P. gingivalis between human contacts may be important in determining risk factors for disease and developing preventive strategies. A few small studies have provided some evidence of transmission between related individuals, but no large-scale study of families that would reflect the typical transmission of this pathogen in the population has been reported. The purpose of this study was to investigate the transmission of P. gingivalis within randomly selected, extended families. The colonization status of 564 members of multigeneration families was determined, and the degree of concordance observed among members of these families was then compared to that expected to occur based on the prevalence of colonization in the population studied. A PCR assay was used for detection of P. gingivalis. Concordance in colonization was more frequently observed within entire families (P = 0.0000) and for spouses (P < 0.001), children and their mothers (P < 0.001), children and their fathers (P < 0.01), adults and their mothers (P < 0.005), and siblings (P < 0.05) than would be expected if P. gingivalis were randomly distributed in the population studied. Results showed that contact with an infected family member substantially increased the relative risk of colonization in these intrafamilial pairs. This indicates that P. gingivalis is commonly transmitted by contact with an infected family member.

Adolescent↗

PubMed1996

Enhanced delivery of boronophenylalanine for neutron capture therapy by means of intracarotid injection and blood-brain barrier disruption.

There has been increasing interest in the possible use of boronophenylalanine as a capture agent for boron neutron capture therapy of brain tumors. The purpose of the present study was to determine whether the uptake of boronophenylalanine in F98 glioma-bearing rats could be enhanced by means of intracarotid (i.c.) injection with or without blood-brain barrier disruption (BBB-D). Glioma cells (10(5)) were stereotactically implanted into the right cerebral hemisphere of Fischer rats, and 12 days later, BBB-D was performed by infusing 25% mannitol (1.373 mOsmol/ml) into the right carotid artery and then immediately injecting L-boronophenylalanine (300 mg/kg of body weight) intracarotidly. The animals were killed 0.5, 1, 2.5, and 4 hours later, and the brains were removed for boron determination by direct current plasma atomic emission spectroscopy. BBB-D was assessed by the intravenous injection of Evans blue or horseradish peroxidase, and the barrier-disrupted hemispheres and tumors showed intense staining with each. The mean tumor boron concentration after i.c. injection and BBB-D was 34.8 +/- 6.8 micrograms/g at 2.5 hours compared with 20.3 +/- 6.2 micrograms/g after i.c. injection without BBB-D and 10.7 +/- 0.7 micrograms/g after intravenous injection. No significant differences in boron concentration in muscle, skin, and eye were observed among the different groups. Boron concentrations in the ipsilateral, disrupted hemisphere increased transiently but rapidly returned to background levels by 2.5 hours after BBB-D. The tumor:brain and tumor:blood ratios were 5.2 and 5.6, respectively, compared to 3.2 and 2.1 for intravenous injection groups at 2.5 hours. The present study is the first to show that BBB-D combined with i.c. injection can enhance the tumor uptake of boron compounds for boron neutron capture therapy.

Animals↗

PubMed1996

Use of medians and "average of normals" of patients' data for assessment of long-term analytical stability.

Using results from patients, we studied several methods for long-term (years) monitoring of the analytical stability of various chemistry tests. For each test, we obtained on a bimonthly basis histograms of > or = 200 to approximately 2000 data points and determined the median, mean, and mean of those data points in the reference range ("average of normal" or AON). Examining approximately 4 years' data, we found that the medians and AON are extremely stable for most tests, and that all observed shifts in the medians or in the AON could be explained by expected or unexpected changes in the laboratory. The means and peak values of the Erlang (gamma) distribution were less useful, owing to shifts caused by extreme outliers, especially for enzymes in serum. We assumed that the underlying patient population and testing patterns were stable. We recommend the use of medians or the AON of patients' data under defined conditions for monitoring the long-term analytical stability of certain tests involving serum or whole blood.

Ammonia↗

PubMed1995

Statistical methods for dependent competing risks.

Many biological and medical studies have as a response of interest the time to occurrence of some event, X, such as the occurrence of cessation of smoking, conception, a particular symptom or disease, remission, relapse, death due to some specific disease, or simply death. Often it is impossible to measure X due to the occurrence of some other competing event, usually termed a competing risk. This competing event may be the withdrawal of the subject from the study (for whatever reason), death from some cause other than the one of interest, or any eventuality that precludes the main event of interest from occurring. Usually the assumption is made that all such censoring times and lifetimes are independent. In this case one uses either the Kaplan-Meier estimator or the Nelson-Aalen estimator to estimate the survival function. However, if the competing risk or censoring times are not independent of X, then there is no generally acceptable way to estimate the survival function. There has been considerable work devoted to this problem of dependent competing risks scattered throughout the statistical literature in the past several years and this paper presents a survey of such work.

Data Interpretation, Statistical↗

PubMed1995

Misclassification of smoking status among Southeast Asian adult immigrants.

A total of 1,403 Southeast Asian adult immigrant males (n = 783) and females (n = 620) from Cambodia, Laos, and Vietnam who currently resided in Central Ohio were interviewed to determine the self-reported smoking prevalence among them, and underwent biochemical confirmation of their smoking status. Variables having to do with the subjects' sociodemography, acculturation, and smoking history that were related to the misclassification of smoking status were also investigated. Self-reported current smoking rates were 40.9% and 5.6% for males and females, respectively. After verification of the subjects' smoking status by saliva cotinine assay (smoker status > or = 14 ng/ml), the rates of smoking were found to be greater, at 43.7% for males and 14.8% for females. Years of education, self-reported smoking status, country of origin, and method of healthcare payment were significant predictors of misclassification. These findings suggest that the prevalence of smoking is higher among Southeast Asian adult females than has been previously reported. Variables that predict misclassification with regard to smoking status are presented, and their implications for clinicians and researchers are discussed.

Acculturation↗

PubMed1994

A nude rat model for neutron capture therapy of human intracerebral melanoma.

PURPOSE: The present study was carried out to determine the efficacy of Boron Neutron Capture Therapy (BNCT) for intracerebral melanoma using nude rats, the human melanoma cell line MRA 27, and boronophenylalanine as the capture agent. METHODS AND MATERIALS: Pharmacokinetic and tissue distribution studies: MRA 27 cells (2 x 10(5)) were implanted intracerebrally, and 30 days later, 120 mg of 10B-L-BPA were injected intraperitoneally into nude rats. Therapy experiments: Thirty days following implantation, tumor bearing rats were irradiated at the Brookhaven Medical Research Reactor. RESULTS: Pharmacokinetic experiments: Six hours following administration of BPA, tumor, blood, and normal brain boron-10 levels were 23.7, 9.4, and 8.4 micrograms/g respectively. Therapy experiments: Median survival time of untreated rats was 44 days compared to 76 days and 93 days for those receiving physical doses of 2.73 Gy and 3.64 Gy, respectively. Rats that had received both 10B-BPA and physical doses of 1.82, 2.73, or 3.64 Gy had median survival times of 170, 182, and 262 days, respectively. Forty percent of rats that had received the highest tumor dose (10.1 Gy) survived for > 300 days and in a replicate experiment 21% of the rats were longterm survivors (> 220 days). Animals that received 12 Gy in a single dose or 18 Gy fractionated (2 Gy x 9) of gamma photons from a 137Cs source had median survival times of 86 and 79 days, respectively, compared to 47 days for untreated animals. Histopathologic examination of the brains of longterm surviving rats, euthanized at 8 or 16 months following BNCT, showed no residual tumor, but dense accumulations of melanin laden macrophages and minimal gliosis were observed. CONCLUSION: Significant prolongations in median survival time were noted in nude rats with intracerebral human melanoma that had received BNCT thereby suggesting therapeutic efficacy. Large animal studies should be carried out to further assess BNCT of intracerebral melanoma before any human trials are contemplated.

Animals↗

PubMed1994

Emergency department use of radiology services at a large urban teaching hospital.

RATIONALE AND OBJECTIVES: Little research has explored the use of radiologic services by emergency departments and the factors that influence use. This study aimed to identify and characterize these factors. METHODS: A total of 13,228 consecutive patient emergency charts from a large university emergency department were reviewed, and multiple parameters were entered into a database. The database was studied and statistical testing was done to identify significant parameters for patients who required imaging studies (X-ray group) and those who did not (non-X-ray group). RESULTS: Factors such as age, diagnosis, urgency of illness, and illness severe enough to require hospitalization were statistically significant in determining the need for a radiologic evaluation in the emergency setting. When these factors were equalized for the X-ray and non-X-ray groups by multivariate linear regression analysis, male sex was also found to be statistically significant. Factors such as race and presence or absence of health insurance were not statistically influential on multivariate analysis. CONCLUSIONS: Older age, diagnosis, and factors related to severity of illness affected the use of radiologic services in the emergency setting. Sex differences were also detected.

Adolescent↗

PubMed1994

Neutron capture therapy of a rat glioma using boronophenylalanine as a capture agent.

The purpose of the present study was to determine the efficacy of boron neutron capture therapy (BNCT) in treating the therapeutically refractory F98 glioma, using boronophenylalanine (BPA) as the capture agent. F98 glioma cells (10(5)) were implanted stereotactically into the brains of Fischer rats and 15 days later the animals were injected intraperitoneally with 897 mg/kg of D,L-BPA. Between 3 and 9 h after administration blood and tumor boron concentrations exhibited monoexponential decay with half-lives (t1/2) of 4.3 and 5.3 h, respectively. When 803 mg/kg of 10B-L-BPA was administered, the tumor 10B concentration was 29.4 micrograms/g and tumor-to-blood and tumor-to-brain ratios were 3.5 and 3.9, respectively. Seven days after intracerebral implantation of 10(5) F98 cells, BNCT was initiated at the Brookhaven Medical Research Reactor. The median survival time for irradiated controls (no BPA), which had received tumor physical doses of 1.7, 2.6 or 3.5 Gy, were 27, 33 and 38 days, respectively, compared to 24 days for untreated rats (P < or = 0.025-0.0001). The median survival time for BNCT-treated groups that had received 803 mg/kg of 10B-L-BPA 6 h prior to irradiation with total estimated tumor physical doses of 5.7, 8.6 and 11.5 Gy were 32, 37 and 59 days, respectively. Although the enhanced median survival times of two of the BNCT-treated group (8.6 and 11.5 Gy) were significant compared to their matched irradiated controls (P < or = 0.0175-0.0277), all BNCT-treated animals died in less than 160 days. It remains to be determined whether better survival can be achieved using higher doses of BPA and neutrons to treat a tumor, which at this time cannot be cured by any therapeutic modality.

Animals↗

PubMed1993

Boron neutron capture therapy of intracerebral melanoma using boronophenylalanine as a capture agent.

A rat brain tumor model has been developed utilizing nude rats and the human melanoma cell line MRA 27. For pharmacokinetic and tissue distribution studies, 2 10(5) MRA 27 cells were implanted intracerebrally (i.c.), and 30 days later, 120 mg of 10B-enriched L-boronophenylalanine were injected i.p. into nude rats. 10B concentrations in the tumor, blood, and normal brain were 23.7, 9.4, and 8.4 micrograms/g, respectively, 6 h following administration. For therapy experiments, tumor bearing rats were irradiated at the Brookhaven Medical Research Reactor 30 days following implantation. The median survival time was 44 days for untreated rats, 76 days for those receiving a physical dose of 2.7 Gy, and 93 days for those receiving 3.6 Gy. Animals receiving both 10B-L-boronophenylalanine and physical doses of 1.8, 2.7, or 3.6 Gy (total tumor physical doses of 5.0, 7.5, or 10.1 Gy) had median survival times of 170, 182, and 262 days, respectively. Forty % of rats that received the highest tumor dose (10.1 Gy) survived > 300 days. In a replicate experiment 21% of animals that had received L-boronophenylalanine and irradiation (total tumor physical dose of 10.1 Gy) were alive 220 days after therapy. In a parallel study, animals that were irradiated with gamma photons from a 137Cs source with 12 Gy or 2.0 Gy 9 delivered to the head had median survival times of 86 and 79 days, respectively, compared to 47 days for untreated animals. Our results indicate that boron neutron capture therapy is effective against i.c. melanoma in a rodent model and suggest that large animal studies are warranted to further assess its efficacy.

Animals↗

PubMed1993

A bivariate survival model with modified gamma frailty for assessing the impact of interventions.

Bivariate survival analysis models that incorporate random effects or 'frailty' provide a useful framework for determining the effectiveness of interventions. These models are based on the notion that two paired survival times are correlated because they share a common unobserved value of a random variate from a frailty distribution. In some applications, however, investigators may have some information that characterizes pairs and thus provides information about their frailty. Alternatively, there may be an interest in assessing whether the correlation within certain types of pairs is different from the correlation within other types of pairs. In this paper, we present a method to incorporate 'pair-wise' covariate information into the dependence parameter of the bivariate survival function. We provide an example using data from the Framingham Heart Study to investigate the times until the occurrence of two events within an individual: the first detection of hypertension and the first cardiovascular disease event. We model the dependence between these two events as a function of the age of the individual at the time of enrollment into the Framingham Study.

Adult↗

PubMed1993

A national study of periodontal assessment by dental hygienists.

PURPOSE: Periodontal examination is one of the most frequently performed dental hygiene diagnostic services. This examination is the basis for effective dental hygiene treatment throughout long-term care. The purpose of this investigation was to examine how dental hygienists across the United States assess the periodontal status of three patient types: patients new to the practice, periodontally healthy recall patients, and periodontally unhealthy recall patients. METHODS: A two-stage cluster sampling method was used to select a random sample of dental hygienists from each of two states randomly selected from four regions of the United States. Questionnaires were mailed in 1989 to 2,618 dental hygienists. Individual responses were scored according to criteria derived from dental literature for conducting seven components of a comprehensive periodontal examination. Results were calculated and analyzed for each state and region, and across regions for each patient type. RESULTS: Responses were received from 1,429 subjects, resulting in a 57.5% response rate of deliverable questionnaires. Overall mean scores (possible 0-7) across all regions were 3.68-new patients, 3.22-healthy patients, and 2.67-unhealthy patients. Of the seven assessment components, three-gingival inflammation, furcation involvement, and radiographs-were performed according to the scoring criteria for all patient types by a majority of respondents. The criterion for periodontal pockets was met by a majority for new patients only. Three assessment component criteria were met by less than 40% of the sample for all patient types-attachment levels, mobility, and plaque control. Differences in the mean scores of certain states were found to be statistically significant. CONCLUSION: Specific dental hygiene standards are recommended for initial diagnostic and recall monitoring periodontal examinations. Additionally, dental hygiene administration and management of long-term preventive and supportive periodontal therapy programs should assist in improving effectiveness of care and further delineate the profession of dental hygiene.

Dental Care↗

PubMed1993

Biological and environmental risk for poor developmental outcome of young children.

A cross-sectional retrospective study was conducted to develop and field test a state-wide screening method for identifying children at risk for developmental problems. Families of 2.5- to 3-year-old children were sampled from the Ohio birth certificate register. Standardized telephone interviews were conducted with 1,601 parents concerning home environment and demographic characteristics. Developmental delay, the outcome variable, was defined by low scores on an abbreviated Developmental Profile II, which was also administered over the telephone. Obstetric history and health status of the newborns was obtained from birth certificates. By means of logistic regression analysis, we found six independent variables representing environmental and biological determinants.

Child Development↗

PubMed1993

Dental hygienists' utilization of periodontal assessment skills and perceived collaboration with dentist-employer.

PURPOSE: As cotherapists in providing total patient care, dental hygienists must foster their pivotal role in the prevention, recognition, and initial therapy of periodontal disease. Cooperation and communication between the hygienist and dentist are necessary to assure the best possible sequence of procedures for a complete periodontal assessment. This study examined the extent of periodontal assessments performed by Ohio dental hygienists treating new patients in private practice and correlated the use of these skills to perceived collaboration with their dentist-employers. METHODS: In January 1990, self-designed mail questionnaires were sent to a cohort of 1,671 licensed dental hygienists randomly selected from the State of Ohio Dental Board Roster. Data were analyzed using standard descriptive statistical methods and the non-parametric Spearman's correlation coefficient. RESULTS: Responses were received from 1,071 subjects, an 81% response rate of deliverable questionnaires and a 64% response rate of original 1,671 subjects. Results suggest that although hygienists perceive a high level of collaboration with their dentist-employer, periodontal assessments are being performed at a minimal level. There appears to be a fairly consistent, weak positive correlation between overall periodontal assessment and perceived collaboration scores. CONCLUSION: These data indicate that continued emphasis is needed on the hygienist's role in periodontal assessment. Delineation of this role may be enhanced by the establishment of specific collaborative efforts between the hygienist and dentist in defining the practice's periodontal protocol.

Dental Hygienists↗

PubMed1992

Effects of environment and management on mortality in preweaned dairy calves.

Forty-eight herds participating in the 1988/1989 Ohio National Animal Health Monitoring System dairy project were monitored for 1 year to determine the effects of environment and management on mortality in preweaned calves. Environmental factors were evaluated by veterinarians during monthly visits to the herds. Management procedures were measured through the use of a questionnaire administered near the end of the project. Mortality in preweaned calves was calculated for each herd by using data from project records on calf mortality and animal inventory, which were collected monthly by veterinarians. Relationships between the management/environment variables and calf mortality were examined by use of analysis of covariance. Herd size, days on a nipple feeder, navel disinfection, type of housing, and whether each calf observed with diarrhea was treated with antibiotics were the variables that had an impact on herd mortality. These variables explained approximately 39% of the variation in mortality among herds.

Analysis of Variance↗

PubMed1992

Estimation of reference ranges: how many subjects are needed?

We measured Na, K, Cl, glucose, hemoglobin, erythrocytes, and hematocrit in the serum or blood from approximately 800 male and 200 female second-year medical students in an effort to define the size of an acceptable reference population. Using the data from the men and Monte Carlo simulations of 10-400 samples, each carried out 5000 times, we found that for most of the above tests, approximately 200 people are required for stable lower (2.5%) and upper (97.5%) reference limits to be obtained. This agrees with the 198 subjects required by strictly statistical criteria to define the same limits with a 99% confidence level.

Adult↗