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Biomedical subjects

D M Main

Publications and source records attributed to D M Main.

At least 19 recordsLinked to original sources
PubMed1996

Analysis of nine pregnancies with confined placental mosaicism for trisomy 2.

Karyotypically normal fetuses with completely trisomic or mosaic placentae may be at increased risk for intrauterine growth restriction (IUGR). Molecular and cytogenetic analyses on nine pregnancies with confined placental mosaicism (CPM) for trisomy 2 were performed at two collaborating centres. Seven cases were identified through prenatal testing of chorionic villi (CVS). Two of these seven cases demonstrated complete trisomy 2 while the remaining five cases showed various levels of trisomy 2 (33 per cent-75 per cent cells). Two cases identified after IUGR was observed in newborn infants demonstrated 65 per cent and 100 per cent trisomy 2 in cultured villi from term placentae. In all nine cases, blood chromosome analysis (n = 4), chromosome analysis of amniotic fluid cultures (n = 4), and cultured amnion (n = 5) were normal, failing to demonstrate any trisomic cells in tissues of fetal origin. Molecular studies on the fetal or newborn tissues using dinucleotide repeat polymorphisms on chromosome 2 revealed normal biparental inheritance of chromosome 2 in all nine cases. The parental origin studies of the extra chromosome 2 in the placenta showed that three cases were maternal in origin, at least two of which were consistent with a maternal meiotic non-disjunction giving rise to the trisomy 2, while in one case a paternal origin of the extra chromosome 2 was established.

Adult↗
PubMed1996

The polymorphous odontogenic cyst.

Over the years there have been sporadic reports of unusual cystic lesions of the jaws, not readily classified under conventional headings but which have been variously diagnosed as median-mandibular, glandular, sialo-odontogenic or botryoid odontogenic cyst. We present five cases which do not fit into other categories of odontogenic cyst, two of which have recurred within a few years of conservative treatment. This paper aims to alert clinicians to the propensity for regrowth of these cysts, proposes the term polymorphous odontogenic cyst for these lesions, to encompass their varied histological appearances and discusses their distinction from other cyst types with mucous and papillary formations in epithelium.

Adult↗
PubMed1994

Characteristic morphologic abnormality of harlequin ichthyosis detected in amniotic fluid cells.

We have examined cells from amniotic fluid obtained at 17 and 21 weeks' gestation and fetal skin biopsy samples from a fetus at risk of harlequin ichthyosis by light and electron microscopy. Clumps of abnormally keratinized cells that had a large number of lipid droplets in the cytoplasm were seen within both the 17- and 21-week amniotic fluid cell pellets. The cells in these clumps were similar to the thick layers of keratinized cells observed in the skin biopsy and autopsy samples. Morphologic examination of the fetal skin biopsy samples obtained at 21 weeks gestation revealed the characteristic changes of harlequin ichthyosis. The intraepidermal portions of hair canals had an excessive number of layers of keratinized cells. Normal lamellar granules were absent but abundant membrane-bound vesicles of a similar size and a number of dense bodies were observed in the cells of the upper intermediate layers of the epidermis. Autopsy skin samples of the terminated fetus at the twenty-third week of gestation showed structural changes that corresponded to those of the amniotic fluid cells and the fetal skin biopsy samples, although the periderm was gone in all the regions. Our findings of amniotic fluid indicate that the characteristic epidermal abnormality of harlequin ichthyosis has been expressed at 17 weeks gestation in some parts of the body or structures of fetal skin (e.g., hair canals) that keratinize before interfollicular epidermis. Moreover, the results suggest that harlequin ichthyosis can be detected in utero by morphologic analysis of amniotic fluid cells obtained by amniocentesis.

Adult↗
PubMed1992

Clinical differentiation of oral ulceration in Behçet's disease.

Behçet oral ulceration (BOU) is described as being indistinguishable from conventional recurrent oral ulceration (ROU). A clinical comparison between 38 Behçet patients and 38 control ROU cases was effected by completion of a standard questionnaire. Behçet patients reported an increased number of concurrent ulcers and involvement of the soft palate and oropharynx. No differences were detected with respect to duration, frequency, age of onset or family history. In addition, photographs of BOU in 15 patients revealed the concurrence of atypical aphthous and herpetiform varieties. Number, site and appearance of oral ulceration may therefore provide diagnostic features for the development of Behçet's disease.

Behcet Syndrome↗
PubMed1992

Determination of volumes of fluid in the mouth by fluoride dilution.

A dilution technique, with fluoride as a marker, has been developed to measure the volume of saliva and other fluids in the mouth. Immediately after swallowing, a small amount of fluoride solution is placed in the mouth, mixed with the oral fluids, and expelled from the mouth. The fluoride concentration of the expelled oral fluid is measured and the volume of fluid in the mouth at the time of spitting calculated from the fluoride dilution. Mean values of 0.75 +/- (SD) 0.28 ml for males and 0.72 +/- (SD) 0.16 ml for females were recorded. The accuracy of the volume determination is about +/- 0.10 ml in vivo. This technique has provided a convenient and rapid means of determining saliva volumes. It could also be used to determine rates of secretion and may prove useful in the clinic for assessing a patient's salivary competence.

Adult↗
PubMed1991

Extended longitudinal study of uterine activity among low-risk women.

Eighty-nine black women without major medical risks for preterm labor participated in this longitudinal, prospective study for the evaluation of usual prelabor uterine activity and for the assessment of how gestational age, time of day, maternal weight, age, and parity affected contraction frequency. Participants wore an ambulatory tocodynamometer for 72 consecutive hours at three points in gestation during the second and early third trimesters while engaged in usual home and work activity. Data obtained from the 81 women with uncomplicated term pregnancies demonstrated a significant increase in contraction frequency with advancing gestational age between 22 and 33 weeks. After 26 weeks, significantly more uterine activity occurred at night. Perhaps because of detection difficulties, contraction frequency was inversely related to maternal weight in women weighing greater than 112% ideal weight. Maternal age and parity did not affect contraction frequency. Contraction characteristics of eight women experiencing preterm labor or medically indicated preterm delivery are described.

Adolescent↗
PubMed1990

Differences in in vitro growth of epithelium from inflammatory and developmental odontogenic cysts.

Ninety-three odontogenic cysts, 42 of inflammatory and 51 of developmental origin, were grown in vitro from explants and/or cell suspensions. There was little difference in the success rate of culturing epithelium from explants of dentigerous cysts (N = 28) or odontogenic keratocysts (N = 23) (approximately 75% and 87%, respectively) and the dentigerous cyst grew particularly well from suspensions (N = 11) (91%) compared with the keratocyst (N = 19) (58%). Epithelium from developmental odontogenic cysts grew much better in vitro than did cysts of inflammatory origin (56 to 58% from explants and 19 to 25% from suspension). From this work there is little evidence to support previous statements that the dentigerous cyst cannot be grown from explants, or that the odontogenic keratocyst has 'aggressive' growth characteristics.

Cells, Cultured↗
PubMed1990

Risk factors for preterm premature rupture of the fetal membranes.

Preterm premature rupture of the membranes (PPROM) is a significant cause of prematurity, accounting for approximately one third of preterm births in the United States. PPROM occurs in approximately 0.7-2% of all pregnancies nationally, and has a reported recurrence rate of 21%. The elucidation of potential risk factors for PPROM could contribute to a better understanding of its etiology. To study the contributions of 20 potential risk factors, we undertook a case-control study in our clinic population, which has a 5-6% incidence of PPROM. One hundred and thirty-three patients experiencing PPROM were matched for race, age, parity and gestational age with undelivered patients. Studies performed included ultrasonographic examinations, blood levels of ascorbic acid and zinc, microbiologic assays, patient questionnaires, and chart reviews. After stratification of both groups into subgroups based on matching criteria, summary tests of significance and Mantel-Haenszel tests of odds ratios were performed. On univariate analysis the following factors achieved significance at the p less than 0.05 level with 95% confidence intervals: 1) previous history of PPROM 2) smoking (dose related) 3) fundal location of the placenta in the present pregnancy. 4) a prior history of cerclage. After regression analysis, we concluded that smoking and history of previous PPROM were found to be risk factors for PPROM in our inner city black population.

Analysis of Variance↗
PubMed1989

Acute herpetic stomatitis: referrals to Leeds Dental Hospital 1978-1987.

The clinical data of 102 patients referred to Leeds Dental Hospital from 1978 to 1987 with acute herpetic stomatitis confirmed by laboratory investigations were analysed. No gender difference was found. Differences in age distribution were marked. Only 5% of patients were aged less than 11 years, whereas the majority of cases (51%) occurred during the third decade. Statistical analysis confirmed a general trend for the mean age of patients to have increased progressively over the 10-year period.

Acute Disease↗
PubMed1989

Follicular cysts of mandibular third molar teeth: radiological evaluation of enlargement.

To test the hypothesis that follicular (dentigerous) cyst enlargement arises from impeded tooth eruption, data from standardized Orthopantomographs of 30 uninfected, wholly intracortical cysts associated with mandibular third molar teeth were analysed. Cyst areas were measured with a computer-aided image analyser (Magiscan 2, Joyce Loebl, Gateshead, UK). Two size categories, small and large, each comprising 15 cases, were distinguished. These were correlated with the radiographic variables of cyst relationships to tooth crown, and angulation and nature of impaction of associated tooth. Cyst enlargement is most active in the third and fourth decades of life. Smaller cysts were associated with teeth impacted against adjacent tooth or bone, whereas larger cysts developed predominantly from horizontally angulated teeth intruded endosteally. These findings lend support to the haemodynamic concept of follicular cyst enlargement linked with dysfunctional eruptive forces.

Adult↗
PubMed1989

Controlled trial of a Preterm Labor Detection program: efficacy and costs.

Patient education regarding the signs and symptoms of preterm labor combined with frequent clinical evaluations has been advocated as a means to reduce preterm births. Over a 3.5-year period, the risk for preterm labor was determined in 943 indigent black inner-city women using the Papiernik-Creasy scoring system. High-risk women were allocated randomly to a Preterm Labor Detection Clinic or to serve as high-risk controls. Women with lower risk scores served as low-risk controls. Women from both control groups were not informed of their risk status, and both groups received prenatal care in standard obstetric clinics. Women accepting the Preterm Labor Detection Clinic Program received comprehensive patient education and were seen weekly starting at 22 weeks' gestation. Despite this extensive outpatient program, there were no significant differences between the high-risk groups with respect to mean gestational age at delivery, mean birth weight, or percentage delivering before term as a result of preterm labor or premature rupture of membranes (PROM). Evaluations of inpatient charges revealed no significant differences due to participation in this program, although outpatient clinic utilization and charges were increased significantly for Preterm Labor Detection Clinic patients. Failure of this program to reduce preterm birth may relate to the relatively low overall rate of women presenting in preterm labor with advanced cervical dilation. In contrast, high rates of PROM and fetal death occurred in all three study groups.

Clinical Trials as Topic↗
PubMed1988

The role of ultrasound in the management of preterm labor.

Careful ultrasonographic evaluations of patients with PTL or PROM can provide critical information about estimated gestational age and birthweight. In addition, examination of FBM and perhaps objective ultrasonographic measurements of the lower uterine segment and cervix may provide valuable information to help us distinguish true preterm labor from false labor. Further research in these areas is necessary before these new approaches are widely adopted.

Anthropometry↗
PubMed1988

The epidemiology of preterm birth.

The immediate causes of preterm birth (preterm labor, PPROM, maternal complications, and fetal distress) are well-established. Similarly, the epidemiologic and medical risk factors discussed are well-known. Most risk factors, unfortunately, are not easy to modify. Furthermore, the connection between epidemiologic risks and preterm birth is often unclear. As this brief discussion of potential mediators linking risk status to preterm birth indicates, much more research is needed to define and assess potential mechanisms. It is unclear how important the five mediating factors chosen for presentation will prove to be or if other more significant mechanisms exist. However, as Eastman noted 40 years ago, "only when the factors causing prematurity are clearly understood, can any intelligent attempt at prevention be made."

Female↗