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Biomedical subjects

L M James

Publications and source records attributed to L M James.

At least 37 records · Page 2Linked to original sources
PubMed1988

Plaque-media rewelding with reversible tissue optical property changes during receptive cw Nd:YAG laser exposure.

Laser dosimetry for thermal fusion of plaque-wall separations during laser balloon angioplasty (LBA) is dependent upon the optical properties of the atheromatous arterial wall during one or more exposures to cw Nd:YAG laser radiation. An integrating sphere technique was used to measure relative transmission and reflection continuously during irradiation of human postmortem atheromatous aortic sections. Tissue luminal surface temperature was recorded continuously with a thermographic video imager during repetitive 20-30-sec, 8-15-watt exposure of a 3-mm nominal spot. In all specimens, transmission fell progressively during each exposure by 10-70% of baseline values. This effect was reversible with normalization of transmission during the initial phase of each subsequent exposure. Changes in transmission were inversely related to temperature over a 50-170 degrees C range, whereas relative reflection remained constant. Accompanying reversible transmission changes was the observation that the weld strength of plaque-aortic wall separations was unchanged by repetitive laser welding and tissue separation of individual sections. In conclusion, temperature-dependent reversible optical and physical properties of plaque occur during exposure to 1.06 microns cw laser radiation.

Angioplasty, Balloon↗
PubMed1984

Vietnam veterans' risks for fathering babies with birth defects.

Vietnam veterans' risks for fathering babies with major structural birth defects were assessed using a case-control study. Information regarding military service in Vietnam was obtained from interviews with mothers and fathers of babies in case and control groups and from review of military records. Vietnam veterans, in general, did not have an increased risk of fathering babies with defects (all types combined; relative risk estimate, 0.97). Vietnam veterans who had greater estimated opportunities for Agent Orange exposure did not seem to be at greater risk for fathering babies with all types of defects combined. However, for a few specific types of defects the estimated risks were higher for subgroups of Vietnam veterans that may have had a greater likelihood of exposure to Agent Orange. These seemingly higher risks could be chance events, the result of some experience in the Vietnam service of the father, or the result of some other unidentified risk factor.

2,4,5-Trichlorophenoxyacetic Acid↗
PubMed1984

Clinical interpretation of maternal serum alpha-fetoprotein concentrations.

Concentrations of maternal serum alpha-fetoprotein provide the basis for decisions to proceed to ultrasonography and amniocentesis in the multistaged screening/diagnostic process used for the prenatal detection of open neural tube defects, abdominal wall defects, and twins. The concentration of maternal serum alpha-fetoprotein at or above which women should be advised that amniocentesis is available (cutoff levels for amniocentesis) varies, depending upon a number of factors, such as maternal weight, race, residence, and gestational age. We briefly describe a methodology for computing the predicted risks of fetal conditions associated with a given concentration of maternal serum alpha-fetoprotein adjusted for important variables. This adjustment methodology provides a straightforward means for clinical laboratories to report results of assays of maternal serum alpha-fetoprotein in terms of predicted risks, to facilitate understanding by the physician and patient of the clinical meaning of the results of maternal serum alpha-fetoprotein testing.

Amniocentesis↗
PubMed1984

Paternal effects on the human sex ratio at birth: evidence from interracial crosses.

The effects of interracial crossing on the human sex ratio at birth were investigated using United States birth-certificate data for 1972-1979. The sex ratio was 1.059 for approximately 14 million singleton infants born to white couples, 1.033 for 2 million born to black couples, and 1.024 for 64,000 born to American Indian couples. Paternal and maternal race influences on the observed racial differences in sex ratio were analyzed using additional data on approximately 97,000 singleton infants born to white-black couples and 60,000 born to white-Indian couples. After adjustment for mother's race, white fathers had significantly more male offspring than did black fathers (ratio of sex ratios [RSR] = 1.027) and Indian fathers (RSR = 1.022). On the other hand, after adjustment for father's race, white mothers did not have more male offspring than did black mothers (RSR = 0.998) or Indian mothers (RSR = 1.009). The paternal-race effect persisted after adjustment for parental ages, education, birth order, and maternal marital status. The study shows that the observed racial differences in the sex ratio at birth are due to the effects of father's race and not the mother's. The study points to paternal determinants of the human sex ratio at fertilization and/or of the prenatal differential sex survival.

Black People↗
PubMed1983

Estimates of birth prevalence rates of spina bifida in the United States from computer-generated maps.

A computer-generated mapping procedure was developed to estimate geographic and race-specific birth prevalence rates of open spina bifida. The estimates are based on birth certificate data adjusted for underascertainment. Separate maps were produced for white births and black births. For both races there is a general decreasing rate of spina bifida from east to west. The highest rates are eight per 10,000 total births for whites in Southern Appalachia, and the lowest rates are less than one per 10,000 for blacks in the Rocky Mountain states and the Pacific Northwest. Until more exact data are available, these maps represent the best current available data on racial and geographic birth prevalence rates in the United States. They are useful for program planning and as an aid in interpreting maternal serum alpha-fetoprotein levels to detect neural tube defects.

Black or African American↗
PubMed1983

Maternal factors in cleft lip with or without palate: evidence from interracial crosses in the United States.

Maternal determinants of oral clefts have been documented in studies of experimental animals but not of humans. We studied maternal and paternal influences on the well-known differences in the incidence of oral clefts between Whites and Blacks in the United States. Using United States birth certificate data for 1973-1978, we compared the incidence of oral clefts in offspring of White-White, Black-Black, and White-Black couples. Because oral clefts are underreported on birth certificates, we also compared oral clefts as a proportion of all defects reported for offspring of various combinations of parental races. After adjusting for fathers race, offspring of White mothers had a higher rate of cleft lip with or without palate (CLP) than those of Black mothers (odds ratio [OR] = 2.33, P less than 10(-4] and a higher proportion of CLP in their reported defects (OR = 2.41, P less than 10(-4]. This maternal race effect did not apply to cleft palate (CP), and it persisted after adjusting for mother's age, parity, and education. However, after adjusting for mother's race, offspring of White fathers did not have a higher rate or proportion of CLP or CP than those of Black fathers. The study shows that the difference in the reported rates of CLP between Whites and Blacks is due to the effect of mother's race, whereas the difference in the reported rates of CP cannot be attributed to the independent effect of mother's or father's race. The study documents the existence of maternal determinants of CLP in humans.

Black People↗
PubMed1983

Paraquat and marijuana: epidemiologic risk assessment.

In March 1978, 13 (21 per cent) of 61 marijuana samples from the southwestern United States were found to be contaminated with the herbicide paraquat, a pulmonary toxin, in concentrations from 3 to 2,264 parts per million. The source of the contamination was an aerial spraying program in Mexico, supported indirectly by United States funds. To evaluate US exposure, a nationwide survey of the paraquat content of confiscated marijuana was conducted. The survey found 33 (3.6 per cent) of 910 marijuana specimens to contain detectable paraquat. In states adjacent to Mexico (Census Region VI), 23 (12.8 per cent) of 180 specimens were contaminated. Combustion testing indicated that approximately 0.2 per cent of paraquat on marijuana passes into smoke. From these data, we projected that 100-200 marijuana smokers in Census Region VI would be exposed by inhalation to 500 micrograms or more of paraquat per year, a dose judged to represent a health hazard; nationally, between 150 and 300 smokers were projected to have such exposure. Another 6,000 persons in Region VI and 9,000 nationally were projected to be at risk of exposure to between 100 and 499 micrograms of paraquat annually. The risk of paraquat exposure was greatest among those smokers who make one large purchase of marijuana per year. No clinical cases of paraquat poisoning were recognized among marijuana smokers during these studies, but no systematic national search for such cases was undertaken.

Cannabis↗
PubMed1983

A population study of the VACTERL association: evidence for its etiologic heterogeneity.

Using the population-based data from the Metropolitan Atlanta Congenital Defects Program, the interrelation of the six defects that are components of the VACTERL association were investigated. There were 400 cases with two or more of these defects, whereas only 29 cases would be expected if the defects had occurred together randomly. There were 76 cases with three or more defects, whereas less than one case was expected. Of these 76 cases, seven had recognized causes (five chromosomal anomalies, two single-gene disorders); another 19 had recognized clinical phenotypes or syndromes of unknown etiology. In the remaining 50 cases, ventricular septal defect was the most common cardiovascular defect (30.0%), and renal agenesis was the most common renal anomaly (30%). Their most common limb defects were reduction deformities (34%) and polydactyly (20%). This study confirms the clinically recognized nonrandom occurrence of the VACTERL association. It also shows that the association is a spectrum of various combinations of its components, which can be a manifestation of several recognized disorders, rather than a distinct anatomic or etiologic entity. A common denominator of the VACTERL association is suggested to be a defective mesodermal development during embryogenesis, due to a variety of causes and leading to overlapping manifestations.

Abnormalities, Multiple↗
PubMed1982

Etiologic heterogeneity of neural tube defects: clues from epidemiology.

The epidemiology of neural tube defects was reviewed, using data from two birth defects surveillance systems: the nationwide Birth Defects Monitoring Program and the Metropolitan Atlanta Congenital Defects Program, for 1970-1978 and 1968-1979, respectively. After excluding cases with recognized causes, neural tube defects were divided into two major groups: "singles" and "multiples," depending on the presence of associated major defects. Only singles, which accounted for the majority of cases, were shown to have the well-known epidemiologic characteristics of neural tube defects: marked predominance of females and whites, geographic variation with an east-to-west gradient, and decreasing rates over time. On the other hand, multiples had no excess of females and occurred less predominantly in whites; moreover, their rates showed no geographic variation and little or no downward trends over time. The presence of associated defects indicates that neural tube defects are epidemiologically and probably etiologically heterogeneous. It is suggested that analytic studies of neural tube defects may be more rewarding if they try to identify different risk factors associated with various subgroups. This approach to the study of birth defects may provide better clues to their etiology and pathogenesis.

Chromosome Aberrations↗
PubMed1982

Etiologic heterogeneity of neural tube defects. II. Clues from family studies.

We previously reported that among neural tube defects (NTDs) with no known causes the ones that occur alone (singles) have different epidemiologic characteristics from those that occur in combination with other defects (multiples), suggesting an underlying causal heterogeneity. In this study, we compared family histories of 223 single NTD cases and 66 multiple cases ascertained through the Metropolitan Atlanta Congenital Defects Program (MACDP) between 1970 and 1979. Compared with siblings of multiples, siblings of singles had a higher precurrence rate for NTDs (2.0% vs. 0.0%) and for birth defects in general (10.9% vs. 3.0%). Furthermore, siblings of singles that were born within 2 years before the birth of the index case had a higher precurrence rate for NTDs (8.0% vs. 1.1%) and for major birth defects (20.0% vs. 2.9%) than had those born earlier. These results further suggest that NTDs are etiologically heterogeneous, depending on the presence of associated defects, and point to important environmental influences in the increased risk for birth defects among siblings of singles. Larger studies are needed to confirm these data and show that single and multiple NTDs have different recurrence rates, not only for NTDs but also for other birth defects.

Adult↗
PubMed1981

Is Bendectin a teratogen?

We studied the first-trimester exposure to Bendectin for several major categories of birth defects among infants ascertained through the Metropolitan Atlanta Congenital Defects Program from 1968 to 1978. No associations were found between any of these defect categories and Bendectin exposure. An association, however, was found for the amniotic bands cases--a subgroup of limb reductions. We stratified our data to reflect the 1976 change in formulation when one of the three ingredients was removed. An association was found between esophageal atresia and the three-ingredient product and another between encephalocele and the two ingredient product. These statistical associations do not establish a causal relationship between Bendectin and the birth defects we studied. Furthermore, even if the associations are causal, the implied risk is extremely low, approximately one in 1,000 births.

Abnormalities, Drug-Induced↗
PubMed1981

Congenital malformations surveillance: two American systems.

As part of its epidemiologic studies of congenital malformations, the Centers for Disease Control (CDC) conducts two birth defects surveillance systems in the United States. The Metropolitan Atlanta Congenital Defects Programme (MACDP) is an intensive surveillance system using several methods to identify infants born with birth defects in the Atlanta area. The Birth Defects Monitoring Programme (BDMP) is a nationwide surveillance system that monitors 1 million births per year, about a third of all births in the U.S. It relies on diagnoses from newborn discharge summaries to ascertain affected infants. The systems were originally designed to detect potential 'epidemics' of birth defects that could occur following the widespread dissemination of new teratogens similar to thalidomide. In addition to monitoring, they have also proved to be useful resources for a variety of studies of the epidemiology of birth defects.

Abnormalities, Drug-Induced↗
PubMed1978

Congenital central nervous system malformations and vinyl chloride monomer exposure: a community study.

Incidence rates for central nervous system (CNS) malformations in infants born to residents of Kanawha County, West Virginia, 1970-1974, were significantly higher than comparable United States rates during those years. Since Kanawha County contains a polyvinyl chloride (PVC) polymerization plant, a case-control study was conducted on the possible relationship between the occurrence of CNS defects and parental occupational or residential exposure to vinyl chloride monomer emissions from this plant. No relationship with parental occupation was found. While a tendency was noted for residences of case families to be located in an area northeast of the plant, this observation did not entirely correlate with existing data on local patterns of wind direction and air pollution.

Abnormalities, Drug-Induced↗