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Biomedical subjects

M E Cohen

Publications and source records attributed to M E Cohen.

At least 91 records · Page 5Linked to original sources
PubMed1993

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.

Adaptation, Physiological↗
PubMed1993

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.

Asia↗
PubMed1993

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.

Biomarkers↗
PubMed1993

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.

Aggregatibacter actinomycetemcomitans↗
PubMed1993

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.

Disease Susceptibility↗
PubMed1993

Predicting percent body fat from circumference measurements.

All U.S. Navy service members are required to meet percent body fat (%BF) standards as a condition of military service. Naval personnel who exceed standards for %BF can be separated from active duty. Currently, %BF predictions are determined by circumference measurements and a prediction equation (circumference equation = CEQ). In view of the importance these prediction results have for personnel retention, a validation study was undertaken to determine the accuracy of %BF prediction for a population determined to be overfat by the CEQ. The population for the validation study comprised men with 22%BF or greater and women with 30%BF or greater. Values for %BF were determined for 49 men and 50 women by hydrostatic weighing (HW) and circumference measurements at the Naval Submarine Medical Research Laboratory (NSMRL) using a regression equation developed at the Naval Health Research Center (NHRC), San Diego, California. The HW and CEQ values were compared to a superset of the original NHRC population. The correlation coefficients for the NSMRL validation group were lower than those reported in the original NHRC group. The results are attributed to the restricted range of NSMRL data and greater error of prediction at extreme ranges of values. A medical diagnostic model was used to evaluate the sensitivity, specificity, and predictive value of CEQ. It shows that the Navy's current procedures produce a 6.8 to 18% false positive rate for individuals declared as having excess body fat. The data suggest that caution should be utilized when using the CEQ method for individual career decisions.

Adipose Tissue↗
PubMed1992

CFTR protein expression in primary and cultured epithelia.

The gene responsible for the lethal disorder cystic fibrosis encodes a 1480-amino acid glycoprotein, CFTR. Using polyclonal antibodies directed against separate phosphorylation sites in the pre-nucleotide-binding fold (exon 9) and the R domain (exon 13), we have identified a 165-kDa protein in Xenopus laevis oocytes injected with recombinant CFTR cRNA transcribed from the full-length CFTR plasmid pBQ4.7. A protein of the same mobility was also detected with Western blotting techniques in whole cell extracts of cells that express CFTR mRNA (T84, FHTE, HT-29), including biopsied human nasal and bronchial tissue. Immunodetectable 165-kDa protein was concentrated in the apical membrane fraction of ileal villus tissue. We also report that the 165-kDa protein levels can be modulated pharmacologically, and these levels are appropriately correlated with second-messenger-regulated Cl- efflux. Thus, native or recombinant CFTR can be recognized by these anti-CFTR peptide polyclonal antibodies.

Animals↗
PubMed1992

Patterns of breast calcification in patients on renal dialysis.

Patients on renal dialysis are prone to form areas of metastatic calcification in soft tissues. In this study we have analysed the mammograms of 16 women on renal dialysis and compared them with a control group of 32 women attending for routine mammographic screening. We found a significant increase in vascular and parenchymal calcifications in the women on renal dialysis. Ductal calcifications were no more prevalent in the patients on dialysis, and in no case did the calcification simulate malignancy.

Breast Diseases↗
PubMed1992

Changes in the approach to central nervous system tumors in childhood.

Current approaches to children with brain tumors are in a state of evolution. Currently, 50% of children with all types of brain tumors may be expected to survive 5 years. Therefore, the goals of neuro-oncology have broadened to include improved survival and improved quality of life. This article reviews changes in therapy that have altered survival as well as changes in therapy as a consequence of increasing recognition of complications and toxicity of treatment.

Brain↗
PubMed1992

Motor power differences within the first two weeks post-SCI in cervical spinal cord-injured quadriplegic subjects.

The purpose of this study was to confirm the clinical impression that motor power significantly changed within the first 2 weeks after a spinal cord injury (SCI) and to determine the time for motor power assessment within the first 2 weeks post injury that best correlated with motor power determined 6 months post-SCI. Our hypothesis was that within the first 2 weeks postinjury, the manual muscle test (MMT) scores would change significantly from the < or = 24 h examination and that the post-24 h evaluations of strength would have a higher correlation with the 6 month measure of motor outcome than the evaluation of strength performed < or = 24 h after SCI. The biceps, extensor carpi radialis, triceps, flexor digitorum profundus, and interosseous muscle strength was measured in 40 subjects using the MMT (muscles graded 0/5 to 5/5) at < or = 24 h, 72 h, 1 week, 2 weeks, 3 months, and 6 months post-SCI. Upper extremity motor index scores (MIS) obtained at the four testing periods within 2 weeks of injury were analyzed using a Friedman analysis of variance with Duncan's post-hoc tests to identify significant differences. Separate analyses were performed on subgroupings of the total sample based on the strength of the most rostral key muscle having less than antigravity strength. There were three groups evaluated: initial MMT 0/5 (n = 22), initial MMT 1-1.5/5 (n = 17), and initial MMT 2-2.5/5 (n = 13).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1992

The role of computerized information systems in quality assurance in hospital social work departments.

Computerized information systems can be valuable tools in the total quality assurance program of hospital social work departments. This paper presents a matrix of potential roles for the information system at various levels of assessment-structural, process, and outcome. It then illustrates these roles, based on examples from a country-wide information system developed for hospital social work departments in Israel.

Data Interpretation, Statistical↗
PubMed1992

Issues in the development of social work information systems: the case of hospital social work departments.

Information systems have been proposed as a valuable resource for promoting the efficient and effective operation of hospital social service departments. However, the development and implementation process must overcome the tensions inherent to collection and utilization of structured information by social work practitioners. These include the need for quantified data about qualitative phenomena, compatibility with existing work routines, compatibility with norms and perceptions of information needs at different levels, and potential versus actual utilization of the data. The authors examine these issues and present strategies for dealing with them, in the context of a project to develop a country-wide information system for social work departments in general hospitals in Israel.

Communication Barriers↗
PubMed1992

Treponema denticola and Porphyromonas gingivalis as prognostic markers following periodontal treatment.

Subgingival plaque samples were collected from individuals with advanced periodontitis before and 3 to 11 weeks after scaling and root planing periodontal treatment. The plaque levels of Treponema denticola and Porphyromonas gingivalis antigens were measured before and after treatment by a quantitative immunoassay procedure using monoclonal antibodies specific for these oral bacteria. A decrease in mean levels of T. denticola (P less than .05) and P. gingivalis antigens (P less than .09) were observed following periodontal therapy. Improved health, as measured by a decrease in probing depth, was associated with a decrease in T. denticola antigen (P less than .05). These results suggest that the T. denticola levels of successfully treated sites decreased, while non-responding sites had levels of this microbial marker which were equal to or greater than the pre-treatment levels. These results provide additional evidence that T. denticola is associated with human adult severe periodontal disease, and can serve as a prognostic marker for disease recurrence.

Adult↗
PubMed1992

Risk indicators for periodontitis in a military treatment population.

The association between the periodontal diagnosis and a variety of subject characteristics was studied in a group of 1,783 patients examined at a large military dental clinic. In order of importance, age greater than 30, smoking, male sex, and Filipino racial background were all found to be statistically significant risk indicators for the presence of moderate or advanced periodontitis. A logistic regression equation serving as a predictive model employing these four variables was presented. The strong association found between smoking and advanced periodontitis is consistent with the hypothesis that smoking has cumulative detrimental effects on periodontal health. While these and other risk indicators are neither causative, diagnostic, nor prognostic, they may be helpful in alerting the clinician to more carefully evaluate other clinical signs or laboratory findings of disease.

Adolescent↗
PubMed1992

Relationship between two measures of upper extremity strength: manual muscle test compared to hand-held myometry.

One hundred and twenty-two individuals with spinal cord injuries at levels C4-6, Frankel classifications A through D, were evaluated to determine the relationship between the manual muscle test (MMT) and hand-held myometry as accurate methods for measuring muscular strength. More specifically, this study attempted to define a range of myometry scores that could be correlated with discrete MMT grades. It also investigated which of the two modalities (MMT or hand-held myometry) is the best reflection of improvement in muscle strength over time. Sequential motor strength examinations using both modalities were performed at 72 hours, one week, and two weeks post SCI and then one, two, three, four, six, 12, 18, and 24 months post injury. The data analyses included calculations of Spearman ranked correlations, analyses of variance, and linear regressions. Results showed that 22 of 24 correlations between MMT and myometry were significant at p values less than .001. The range of myometry measurements for a particular MMT grade appears to be most specific for MMT scores less than 4 (ie, poor-plus to good), and less specific for MMT scores greater than or equal to 4. The results of this study also indicate that myometry measurements detect increases in strength over time, which are not reflected by changes in MMT scores.

Adolescent↗
PubMed1991

Hyperfractionated radiation therapy in brain stem tumors. Results of treatment at the 7020 cGy dose level of Pediatric Oncology Group study #8495.

Between May 1986 and February 1988, 57 patients were accrued to the second dose level of a Phase I/II Pediatric Oncology Group (POG) study exploring the use of hyperfractionated radiation therapy (HRT) in children with high-risk brain stem tumors. Local fields were treated with fraction sizes of 117 cGy given twice daily, with a minimum interfraction interval of 6 hours, to a total dose of 7020 cGy in 60 fractions over 6 weeks. Information regarding clinical status during HRT was available for 55 patients (44 [80%] improved, 6 remained stable, and 5 deteriorated). Results of initial and follow-up computed tomography (CT) scan and/or magnetic resonance imaging (MRI) were available for review for 52 patients. One patient had a complete response (CR) to treatment, 3 had a partial response (PR) (more than 50% response), and 40 remained stable, for a total response rate (CR + PR + stable) of 77%. Median time to disease progression was 6 months. Median survival time was 10 months. Survival rate was 39.6% (standard error [SE] = 6.6%) at 1 year and 23% (SE = 5.8%) at 2 years. Complications of treatment included an enhanced skin reaction in six patients and otitis media and/or externa in nine. One patient bled into tumor shortly after completion of HRT, and three had intralesional necrosis. Five patients continued taking steroids for protracted periods in the face of improved clinical and/or radiologic findings. Complications related to the use of steroids included opportunistic infections, impaired glucose tolerance, hypertension, osteoporosis, and significant mood changes. In no patient was there evidence of any late injury attributable to HRT. When compared with results of treatment with HRT at a lower dose level (6600 cGy), there appears to be a trend toward improved survival at 7020 cGy despite a less favorable patient population at the higher dose level. A second dose escalation to 7560 cGy in 60 fractions over 6 weeks has been implemented as planned.

Adolescent↗