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Biomedical subjects

H M McDonald

Publications and source records attributed to H M McDonald.

16 recordsLinked to original sources
PubMed2000

Intrauterine infection and spontaneous midgestation abortion: is the spectrum of microorganisms similar to that in preterm labor?

OBJECTIVE: To determine whether microorganisms associated with intrauterine infection and preterm labor play a contributing role in midgestation abortion. METHODS: A 4 year retrospective review of spontaneous midgestation abortions for which autopsy and microbiological cultures of placental and fetal tissue were performed was conducted for a tertiary obstetrics hospital, which included a regional referral service for perinatal and fetal pathology. One hundred twenty-nine spontaneously delivered, nonmacerated, midgestation fetuses or stillbirths (of between 16 and 26 weeks' gestation) and placentas were examined and cultured for aerobic and anaerobic bacteria, yeasts, and genital mycoplasmas. RESULTS: Microorganisms were recovered in 85 (66%) cases (57% placentas, 49% fetuses). Among the culture positive cases, 81% had histological chorioamnionitis, 28% fetal pneumonitis, 38% clinical signs of infection, and 62% ruptured membranes at the time of miscarriage. These differed significantly from culture-negative cases (44%, 5%, 13%, and 34%, respectively). Group B streptococcus (GBS) was the most significant pathogen, recovered in 21 cases, 13 as the sole isolate, 94% with chorioamnionitis, and 47% in women with intact membranes. Escherichia coli and Ureaplasma urealyticum (22 and 24 cases, respectively) occurred mostly as mixed infections, with ruptured membranes. GBS, MU urealyticum, and Streptococcus anginosus group were individually associated with chorioamnionitis, Bacteroides/Prevotella and S. anginosus with fetal pneumonitis. The spectrum of microorganisms was similar to that in preterm labor at later gestations; however, GBS appeared to be the most significant pathogen in midgestation miscarriage, especially with intact membranes. CONCLUSIONS: Unsuspected intrauterine infection underlies many spontaneous midgestation abortions. GBS is a key pathogen in this setting.

Abortion, Spontaneous↗
PubMed1997

Impact of metronidazole therapy on preterm birth in women with bacterial vaginosis flora (Gardnerella vaginalis): a randomised, placebo controlled trial.

OBJECTIVE: To ascertain whether metronidazole treatment of women with a heavy growth of Gardnerella vaginalis during mid-pregnancy would reduce the risk of spontaneous preterm birth. DESIGN: A multicentre, randomised, placebo-controlled trial. SETTING: Four metropolitan hospitals. PARTICIPANTS: Eight hundred and seventy-nine singleton women with a heavy growth of G. vaginalis or Gram stain indicative of bacterial vaginosis at 19 weeks of gestation. INTERVENTIONS: Oral metronidazole (400 mg) or placebo twice daily for two days at 24 weeks of gestation, and at 29 weeks if G. vaginalis found in test-of-cure swab four weeks after treatment. MAIN OUTCOME MEASURES: Spontaneous preterm birth less than 37 weeks. RESULTS: Intention-to-treat analysis showed no difference between metronidazole and placebo groups in overall preterm birth (31/429 [7.2%] vs 32/428 [7.5%]) or spontaneous preterm birth (20/429 [4.7%] vs 24/428 [5.6%]). Among the 480 women with bacterial vaginosis treatment had no effect on spontaneous preterm birth (11/242 [4.5%] vs 15/238 [6.3%]). In the subset of 46 women with a previous preterm birth, women in the metronidazole group showed a significant reduction in spontaneous preterm birth (2/22 [9.1%] vs 10/24 [41.7%], OR 0.14, 95% CI 0.01-0.84). A treatment effect was also found in compliant women with a previous preterm birth and bacterial vaginosis (0/14 [0%] vs 6/17 [35.3%], OR 0.0, 95% CI 0.0-0.94). CONCLUSION: Metronidazole treatment of women with a heavy growth of G. vaginalis or bacterial vaginosis did not reduce the preterm birth rate. Among women with a previous preterm birth, treatment reduced the risk of spontaneous preterm birth. Further studies are required to confirm these findings.

Adult↗
PubMed1995

Prevention of early onset group B streptococcal sepsis in the newborn.

There is an urgent need for strategies to prevent early onset group B streptococcal sepsis in the newborn. The most effective mechanism is the identification of maternal carriers of the organism and interruption of transmission during labour. Vaginal culture is currently the most reliable method for the identification of carriers. Antibiotic prophylaxis for known carriers in labour has been demonstrated to be effective as standard management practice in a number of Australian institutions and is the best available strategy at this stage.

Antibiotic Prophylaxis↗
PubMed1994

Changes in vaginal flora during pregnancy and association with preterm birth.

A prospective study of the vaginal flora changes between midtrimester and labor was undertaken in 560 women; 337 had intact membranes and were in labor when swabs were taken. Of these, 45 delivered preterm. Gardnerella vaginalis, Ureaplasma urealyticum (both associated with preterm birth when present in midtrimester), and Mycoplasma hominis commonly persisted between midtrimester and labor, particularly in the preterm cohort (24 [65%] of 37 midtrimester isolates), and these organisms were seldom acquired late in pregnancy. A second group, Bacteroides species, had both a high persistence (9 [60%] of 15 midtrimester isolates) and high late acquisition rate (10 [53%] of 19 labor isolates) in the preterm cohort. These findings provide a rationale for treatment of bacterial vaginosis in pregnancy. A third group, comprising enteropharyngeal bacteria and Peptostreptococcus species, were almost all acquired late in the preterm cohort (14 [88%] of 16 labor isolates), and persistence from midtrimester was rare.

Bacteria↗
PubMed1994

Bacterial vaginosis in pregnancy and efficacy of short-course oral metronidazole treatment: a randomized controlled trial.

OBJECTIVE: To characterize the natural history of bacterial vaginosis in pregnancy and to assess the efficacy of short courses of oral metronidazole therapy for long-term suppression of bacterial vaginosis flora. METHODS: This was a randomized, double-blind, placebo-controlled study of two 2-day courses of metronidazole (400 mg twice daily) in pregnant women with bacterial vaginosis (by Gram stain) and/or heavy growth of Gardnerella vaginalis. The first course was given at 24 weeks' gestation and a second course at 29 weeks if the follow-up vaginal swab grew G vaginalis. Follow-up swabs were performed at 28, 32, and 36 weeks' gestation. RESULTS: On the basis of their G vaginalis colonization, 196 women were enrolled, and 137 were evaluable for efficacy, including 66 with bacterial vaginosis. The microbial ecology of bacterial vaginosis in 36 women in the placebo group was relatively stable, with 72% persistence at 28 weeks and 57% at 32 weeks' gestation. Metronidazole effectively suppressed bacterial vaginosis for 4 weeks after the first course in 76%, compared with 28% in the placebo group, and had a cumulative efficacy of 87% compared to 44% 4 weeks after the second course (odds ratio 0.12, 95% confidence interval 0.03-0.5). CONCLUSIONS: The microbial ecology of bacterial vaginosis in pregnant women is relatively stable. Long-term suppression of bacterial vaginosis flora for 2-3 months can be achieved by short courses of metronidazole therapy in 87% of women in mid-pregnancy. Because bacterial vaginosis has been associated with an increased risk of preterm labor, these findings provide the foundation for an intervention study of women with bacterial vaginosis in pregnancy.

Administration, Oral↗
PubMed1992

Prenatal microbiological risk factors associated with preterm birth.

OBJECTIVE: To study the vaginal flora of pregnant women at 22-28 weeks gestation to determine whether the presence of specific micro-organisms is significantly associated with preterm birth and prelabour rupture of the membranes. DESIGN: A comprehensive descriptive prospective study of the vaginal micro-flora of women between 22-28 weeks gestation comparing those who gave birth preterm (less than 37 weeks) with those who gave birth at term. Microbiological assessment included cultures for aerobic and anaerobic bacteria, yeasts, genital mycoplasmas and Trichomonas vaginalis. Multiple logistic regression analysis was used to account for confounding obstetric and demographic variables. SETTING: The Queen Victoria Hospital, Adelaide, South Australia. SUBJECTS: 135 women who gave birth preterm compared to 651 women who gave birth at term. MAIN OUTCOME MEASURE: Preterm birth and preterm prelabour rupture of membranes (PROM) RESULTS: The prevalence of Gardnerella vaginalis between 22-28 weeks was significantly higher in women who gave birth preterm compared to women who gave birth at term (23% vs 15%; multiple logistic regression odds ratio (OR) 1.8, 95% confidence intervals (CI) 1.01-3.2, P less than 0.05. Ureaplasma urealyticum was also found in a higher proportion of women who gave birth preterm (49% vs 32% OR 1.7, 95% CI 1.1-2.6, P less than 0.0005). Preterm PROM occurred in 42% of whom 60% were carriers of U. urealyticum between 22-28 weeks, compared with 32% in the term group (OR 3.2, CI 1.7-6.1, P less than 0.0005). When women who received antibiotics between the midtrimester swab and labour were excluded, G. vaginalis was also significantly associated with preterm PROM (OR 2.7, CI 1.1-6.5, P less than 0.05). The presence of vaginal enteropharyngeal bacteria (E. coli, Klebsiella spp., Haemophilus spp., Staph. aureus) in the midtrimester was not predictive of preterm birth, but when these organisms were found in labour, they appeared to have been acquired later in the pregnancy. CONCLUSION: Women carrying G. vaginalis or U. urealyticum during the midtrimester had nearly twice the risk of preterm birth, while women positive for U. urealyticum had more than a threefold risk of preterm PROM.

Adult↗
PubMed1991

Vaginal infection and preterm labour.

OBJECTIVE: To study the vaginal flora of women in preterm labour (PTL) and determine whether the presence of specific vaginal microflora is significantly associated with onset of PTL. DESIGN: A comprehensive prospective study of the vaginal microflora of women in early labour comparing women in PTL with term controls. Microbiological assessment included cultures for aerobic and anaerobic bacteria, yeasts, genital mycoplasmas and Trichomonas vaginalis. Multiple logistic regression analysis was used to adjust for confounding obstetric and demographic variables. SETTING: The Queen Victoria Hospital, Adelaide. PATIENTS: 428 Women in PTL compared to 568 women in labour at term. MAIN OUTCOME MEASURE: PTL and preterm prelabour rupture of membranes (PPROM) in relation to specific vaginal microflora. RESULTS: After multiple logistic regression analysis, two distinct bacteriological groupings were associated with PTL less than 37 weeks gestation, namely, the bacterial vaginosis group of organisms, Gardnerella vaginalis and Bacteroides spp., and a group of enteropharyngeal organisms, E. coli, Klebsiella spp., Haemophilus spp. and S. aureus. G. vaginalis was found in 12% of women in PTL compared to 6% at term [regression odds ratio (ROR) 1.8, 95% confidence intervals (CI) 1.1-3.1] whereas Bacteroides spp. were detected in 45% of women in PTL compared with 35% at term (ROR 1.6, CI 1.2-2.1). The prevalence of G. vaginalis (17%) and Bacteroides spp. (50%) was even higher in women in PTL less than 34 weeks gestation. The enteropharyngeal group of organisms were more commonly present in women in PTL less than 37 weeks (E. coli 10% vs 6%, ROR 1.4, CI 0.8-2.4; Klebsiella spp. 3% vs less than 1%, ROR 5.4, CI 1.1-26.7; Haemophilus spp. 2% vs less than 1%, ROR 5.5, CI 1.1-28.6; S. aureus 6% vs 4%, ROR 1.8, CI 0.9-3.3) and were isolated even more frequently in women in PTL less than 34 weeks (E. coli 15%; Klebsiella spp. 4%; S. aureus 7%). Bacteroides spp., Klebsiella spp., and Haemophilus spp. were all found to be associated with PPROM. CONCLUSION: There are two distinct bacteriological groupings commonly found in women in PTL, especially in PTL less than 34 weeks gestation. These bacteriological groups are women with bacterial vaginosis in pregnancy and women who demonstrate enteropharyngeal bacteria in the vagina.

Adult↗
PubMed1988

Projections of the dorsal and lateral terminal accessory optic nuclei and of the interstitial nucleus of the superior fasciculus (posterior fibers) in the rabbit and rat.

The projections of the dorsal and lateral terminal accessory optic nuclei (DTN and LTN) and of the dorsal and ventral components of the interstitial nucleus of the superior fasciculus (posterior fibers; inSFp have been studied in the rabbit and rat by the method of retrograde axonal transport following injections of horseradish peroxidase into oculomotor-related brainstem nuclei. The projections of the ventral division of the inSFp have been further investigated in rabbits with the anterograde axonal transport of 3H-leucine. The data show that the projections of the DTN, LTN, and inSFp are remarkably similar in rabbit and rat. The DTN projects heavily to the ipsilateral medial terminal accessory optic nucleus (MTN), nucleus of the optic tract, and dorsal cap of the inferior olive. The DTN projects sparsely to the ipsilateral visual tegmental relay zone and to the contralateral superior and lateral vestibular nuclei. The LTN and dorsal component of the inSFp are found to share the same basic connections; both project heavily to the ipsilateral nucleus of the optic tract and visual tegmental relay zone and send a moderately sized projection to the ipsilateral MTN. However, while the dorsal component of the inSFp sends significant ipsilateral projections to both rostral and caudal portions of the dorsal cap, only a few LTN neurons appear to follow this example and only by projecting to the rostral part of the dorsal cap. In addition, both the LTN and dorsal component of the inSFp send sparse contralateral projections to the MTN, nucleus of the optic tract, and visual tegmental relay zone; and the dorsal component of the inSFp also provides a sparse contralateral projection to both rostral and caudal portions of the dorsal cap. The ventral component of the inSFp projects heavily to the ipsilateral visual tegmental relay zone and moderately to the ipsilateral MTN and nucleus of the optic tract. The ventral inSFp projects sparsely to the contralateral MTN, the nucleus of the optic tract, and the visual tegmental relay zone. A few of its neurons target the ipsilateral dorsal cap of the inferior olive. Unlike the DTN (present study) and the MTN (Giolli et al.: J. Comp. Neurol. 227:228-251, '84; J. Comp. Neurol. 232:99-116, '85a), the LTN and the inSFp of the rabbit and rat lack projections to the superior and lateral vestibular nuclei.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1986

Physical maturity and outcome of pregnancy in primiparas younger than 16 years of age.

The association of complications and adverse outcomes of early teenage pregnancy with physical growth maturation of mothers was studied in subjects identified from review of medical records in a Pittsburgh obstetrical hospital from 1970 through 1977. Five groups were used to categorize the subjects: (1) 449 primiparas younger than 16 years of age, (2) 347 primiparas 20 to 24 years of age, pair-matched with subjects in group 1 by race, hospital service status, sex of infant, trimester of first prenatal visit, and year of delivery within 5 years, (3) 139 group 1 mothers at the time of their second delivery, (4) 104 group 1 primiparas whose postmenarcheal age was less than or equal to 2.6 years at delivery, and (5) 108 group 1 primiparas whose postmenarcheal age was greater than or equal to 4.1 years at delivery. Subjects in groups 1 and 2, first and second pregnancies of subjects in group 3, and subjects in groups 4 and 5 were compared for prepregnancy weight and height, weight gain during pregnancy, complications of pregnancy, birth weight and gestational age of infant, and perinatal morbidity and mortality. Although primiparas younger than 16 years of age had not achieved mature height and weight, no relationship between mother's physical growth maturation and adverse pregnancy course or outcome was demonstrated.

Adolescent↗
PubMed1985

GABAergic neurons comprise a major cell type in rodent visual relay nuclei: an immunocytochemical study of pretectal and accessory optic nuclei.

The enzyme glutamic acid decarboxylase (GAD) has been localized in sections of rodent brains (gerbil, rat) using conventional immunocytochemical techniques. Our findings demonstrate that large numbers of GAD-positive neurons and axon terminals (puncta) are present in the visual relay nuclei of the pretectum and the accessory optic system. The areas of highest density of these neurons are in the nucleus of the optic tract (NOT) of the pretectum, the dorsal and lateral terminal accessory optic nuclei (DTN, LTN), the ventral and dorsal subdivisions of the medial terminal accessory optic nucleus (MTNv, MTNd), and the interstitial nucleus of the posterior fibers of the superior fasciculus (inSFp). The findings indicate that 27% of the NOT neurons are GAD-positive and that these neurons are distributed over all of the NOT except the most superficial portion of the NOT caudally. The GAD-positive neurons of the NOT are statistically smaller (65.9 microns2) than the total population of neurons of the NOT (84.3 microns2) but are otherwise indistinguishable in shape from the total neuron population. The other visual relay nuclei that have been analyzed (DTN, LTN, MTNv, MTNd, inSFp) are similar in that from 21% to 31% of their neurons are GAD-positive; these neurons are smaller in diameter and are more spherical than the total populations of neurons. The data further show that a large proportion of the neurons in these visual relay nuclei are contacted by GAD-positive axon terminals. It is estimated that approximately one-half of the neurons of the NOT and the terminal accessory optic nuclei receive a strong GABAergic input and have been called "GAD-recipient neurons". Further, the morphology of the GAD-positive neurons combined with their similar distribution to the GAD-recipient neurons suggest that many of these neurons are acting as GABAergic, local circuit neurons. On the other hand, the large number of GAD-positive neurons in the NOT and MTN (20-30%) in relation to estimates of projection neurons (75%) presents the possibility that some may in fact be projection neurons. The overall findings provide morphological evidence which supports the general conclusion that GABAergic neurons play a significant role in modulating the output of the visually related NOT and terminal accessory optic nuclei.

Animals↗
PubMed1979

Malignant transformation of a Warthin tumor: case report, review of the literature, and discussion of pathology.

Papillary cystadenoma lymphomatosum (Warthin's tumor) is generally considered to be a benign tumor. However, a few well-documented cases of malignant transformation have been reported. In each case, the patient had received radiotherapy to the neck region where the tumor later developed. This paper reports a case of malignant transformation of a papillary cystadenoma lymphomatosum (PCL) in a patient who had not received radiotherapy. Light and electron microscopy documented this transformation and clearly identified the malignant portion of the tumor as having its origin in a benign PCL. The literature is reviewed and a discussion of pathology presented.

Adenolymphoma↗