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R A Doherty

Publications and source records attributed to R A Doherty.

At least 37 records · Page 2Linked to original sources
PubMed1984

Rare-event analysis methods for detection of fetal red blood cells in maternal blood.

Methods for analyzing very small subpopulations of cells ("rare-event analysis methods") are of interest in many areas of biology. In this paper we demonstrate the ability to detect one Rh-positive erythrocyte per 100,000 Rh-negative erythrocytes. This is the level needed to detect human fetal red blood cells in the maternal circulation in the case of fetal-maternal Rh-incompatibility. Erythrocytes stained with fluorescent immunobeads are more than 100 times as bright as the same cells stained by indirect immunofluorescence (or almost 40 times as bright as cells stained by the biotin-avidin technique). More importantly there is greater than a sevenfold increase in signal-to-noise (S/N) ratio, which proves critical in detecting very low frequency ("rare event") cell subpopulations. Although equal mixtures of positive and negative cells can easily be detected, positives cannot be easily distinguished from negatives when they are present in relative frequencies of 1:1000 or less as measured by either indirect immunofluorescence or biotin-fluorescent avidin labeling of D antigens. However, use of fluorescent immunobeads and high-speed flow cytometry allows detection of subpopulations of the same cells at relative frequencies of less than 1:100,000. Based on calibrations using free-fluorescent immunobeads, the average Rh-positive cell (when present in a relative frequency of 1:100,000) labeled with 36 +/- 19 fluorescent immunobeads. Rh-positive cells of relative frequencies 1:10,000 and 1:100,000 can be detected above background (Rh-negative red blood cells treated with the same amount of fluorescent immunobeads). Using defined mixtures of Rh-positive and negative cells, the expected numbers of positive cells were observed over a range of 1:100 to 1:100,000 relative Rh-positive cell frequencies. These methods should prove of general use in applications where original frequency information about rare cell subpopulations is important and would be lost if enrichment procedures were to be used.

Centrifugation, Density Gradient↗
PubMed1983

Interaction of methylmercury with microtubules in cultured cells and in vitro.

The effects of methylmercury (MeHg) on cytoplasmic microtubules in cultured fibroblasts and on the in vitro polymerization of microtubules were examined. MeHg caused disruption of cellular microtubules in a concentration- and time-dependent manner. Addition of the metal-chelating agent, dimercaptosuccinic acid (DMSA), both prevented and reversed the effect of MeHg. Comparisons of the cellular levels of mercury and microtubule integrity indicated that microtubules dissociated at levels higher than 0.6 microgram Hg/mg protein. In vitro polymerization was also directly inhibited by MeHg; this effect was prevented by the addition of DMSA.

Cells, Cultured↗
PubMed1983

Reassurance through prenatal diagnosis and willingness to bear children after age 35.

This study reports on a survey of 2,209 women age 25-45; most were married. Respondents were asked about their reproductive plans and whether prenatal reassurance might influence their reproductive intentions. For almost two-thirds of the age 35-45 respondents, either the woman or her husband had already chosen sterilization; of those able to bear children, but with uncertain plans, 25 per cent of 35-39 year olds and 12.8 per cent of 40-45 year olds indicated an increased willingness to have children if they were reassured that their baby had none of the birth defects detectable by amniocentesis.

Adult↗
PubMed1981

Methylmercury poisoning in the Iraqi suckling infant: a longitudinal study over five years.

In a five-year longitudinal study of mothers and infants exposed to methylmercury during the Iraq epidemic of 1972, the frequencies of signs and symptoms exhibited by the mothers were typical of methylmercury poisoning. When blood concentrations of mercury are corrected to 1 March 1972, mothers with the most severe signs and symptoms had an average blood mercury concentration significantly higher (p less than 0.01) than either the milder or asymptomatic groups. Analytical data indicate that the predominant route of exposure for the infant was through breast milk in which approximately 60% of total mercury was determined, by cold vapor atomic absorption, to be organic mercury. Abnormal neurological signs in these infants became more obvious with time: hyperreflexia was observed in 8 of 22 infants at first examination, and in 17 of 22 at second examination. Delayed motor development became evident at the second and third examinations. The frequency of pathological reflexes and delayed motor developmental milestones was so high as to be considered significant even in the absence of a controlled study. There was no increase in mortality as compared to a control group.

Female↗
PubMed1981

Hormonal and cytogenetic studies in phenotypically female patients with gonadal dysgenesis.

In 4 cases of gonadal dysgenesis the clinical, hormonal, cytogenetic, and histological findings were correlated. There were 2 patients with 46,XY karyotype, one patient with 45,X Turner's syndrome and one patient with a 46,XX chromosome complement. All patients had streak gonads with ovarian stroma. In one phenotypically female 46,XY individual an involuted gonadoblastoma was found. Her testosterone was four-fold higher in gonadal vein blood compared to peripheral blood. Cytogenetic analysis of multiple tissues in both cases with the 46,XY karyotype greatly reduced the probability of mosaicism. In the patient with 45,X Turner's syndrome and in the one with 46,XX gonadal dysgenesis only peripheral blood cells were karyotyped and mosaicism was not further excluded by analysis of other tissues. The concentrations of steroid hormones in gonadal vein blood were low. The levels ranged as follows: estrone 41-98 pg/ml, estradiol 18-90 pg/ml, testosterone 37-294 ng/100 ml, dihydrotestosterone 13-22 ng/100 ml, and progesterone 0.3-1.5 ng/ml. It was concluded that gonadal streaks were similarly deficient in biosynthesis of steroid hormones despite different chromosomal complements.

Adolescent↗
PubMed1980

Amniotic fluid secretor typing: validation for use in prenatal prediction of myotonic dystrophy.

Use of the well-established linkage of the secretor locus (Se) to the myotonic dystrophy locus (Dm) as an indirect means for prenatal prediction of myotonic dystrophy requires that the phenotypic expression of the fetal secretor locus be accurately and reliably assessed in amniotic fluid. Secretor status determinations on 89 amniotic fluids obtained by second trimester amniocentesis were compared with results of postnatal secretor typing of saliva samples collected from the resulting 89 offspring. The secretor types of the paired amniotic fluid-saliva samples were in agreement in all cases. The only unusual typing result was on an amniotic fluid from a blood group O secretor fetus in which the level of soluble H antigen was estimated to be about one-third that observed for other H secretors. Though it is possible that rare secretor fetuses with very low titers of soluble antigen at the time of amniocentesis could be mistyped as non-secretors, our results indicate that such an erroneous typing result would only occur in about 1-2% of all amniotic fluids tested. Constructed mixtures of 10% heparinized blood in non-secretor amniotic fluid or of 10% serum in amniotic fluid derived from secretor fetuses did not introduce sufficient levels of soluble antigen or of antibody to interfere with accurate secretor typing, thus providing reassurance that maternal and/or fetal blood contamination of amniotic fluid does not compromise accuracy of fetal secretor typing. This study documents the accuracy and reliability of amniotic fluid secretor typing for prenatal prediction of fetal risk for later development of myotonic muscular dystrophy.

ABO Blood-Group System↗
PubMed1980

An improved DEAE-cellulose filter assay for colchicine binding protein (during mouse brain development).

A DEAE-cellulose filter assay for colchicine binding protein (CBP) has been modified to include 1 M-sucrose in the incubation medium (single-point assay). Due to the much greater stability of colchicine binding capacity under the conditions described, multiple time-point assays (time-decay method) were not necessary for accurate determination of CBP in brain samples, as shown by the agreement of results obtained using the two methods to measure CBP in C129F1 hybrid mouse brains at different stages of development. In this study, the highest concentrations of CBP (millimoles of colchicine bound per milligram of total protein) were observed in the 160,000 g supernatant and pellet of newborn-brain homogenate. The CBP concentrations in these two fractions were approximately twice those observed in the earliest stage measured (13.5 days gestation) and in the 11-month-old adult. However, CBP concentration, in terms of millimoles of colchicine bound per gram of brain wet weight, reached a maximum at the end of the 1st week after birth. Between 17.5 days gestation and the end of the 1st postnatal week, more CBP accumulated in the pellet fraction than in the supernatant.

Animals↗
PubMed1980

Lead and calcium distributions in blood, plasma and milk of the lactating mouse.

Although it has been established that lead is transferred in milk from mother to suckling offspring, the physiological processes and parameters involved are not well understood. Single i.v. doses (0.2 mg/kg) or p.o. doses (2 mg/kg) of radiolabeled lead were administered to lactating and nonlactating female mice, and lead concentrations in blood, plasma, and milk were determined during a 21-day period. Large differences in lead elimination were observed between lactating and nonlactating mice. A significant fraction (25%) of the initial maternal dose ("absorbed" dose) was transferred to the suckling pups. The ratio of lead concentration in milk to lead concentration in plasma was found to be nearly constant over time. However, the milk-to-blood concentration ratios decreased during the same period. Furthermore, the concentration of lead in milk exceeded the plasma concentration by a factor of approximately 25, indicating that there is a physiological process(es) which established a large milk-to-plasma concentration ratio. A similar calcium concentration ratio was also observed. It is concluded that plasma lead concentration is a more accurate index for the estimation of milk lead concentration than is whole blood lead concentration.

Animals↗
PubMed1979

Amniotic fluid cell culture II. Evaluation of a red blood cell lysis procedure for culture of cells from blood-contaminated amniotic fluid.

Second trimester amniotic fluid samples obtained transabdominally for genetic analysis not infrequently are contaminated with blood. There has been disagreement as to whether blood contamination interferes with the efficiency of culture of amniotic fluid cells for genetic diagnosis. A procedure using ammonium chloride to lyse contaminating red blood cells has been recommended to increase culture success. In this report we document that cultures derived from blood-contaminated amniotic fluids form fewer cell colonies than cultures from clear amniotic fluids. We also show that a recommended procedure using ammonium chloride to lyse red blood cells is ineffectual in improving the efficiency of cell culture, and may be detrimental to successful culturing of cells from bloody amniotic fluids. A hypothesis concerning the mechanism of interference with culture of amniotic fluid cells by contaminating blood is presented and a means of preventing this complication is suggested.

Ammonium Chloride↗
PubMed1979

Prenatal methylmercury poisoning. Clinical observations over five years.

Thirty-two infants prenatally exposed to methylmercury and their mothers were examined over a five-year period after the Iraqi methylmercury epidemic. Severity of poisoning in mothers was related to the peak mercury concentration in their hair and in the infants to the maximum concentration in maternal hair during pregnancy. In nine cases of cerebral palsy, methylmercury exposure occurred only during the last trimester. All infants except three (two were orphaned soon after birth and one was bottle-fed) were exposed postnatally via suckling. Whereas the mother's symptoms usually improved, the damage to the fetal nervous system appears to be permanent. Milder cases previously not identified in other studies are reported. The syndrome consists of varying degrees of developmental retardation in addition to exaggerated tendon reflexes and the pathologic extensor plantar reflex (minimal brain damage syndrome).

Abnormalities, Drug-Induced↗