Using city gates as a means of estimating ancient traffic flows.

Despite the recent flurry of interest in various aspects of ancient urbanism, we still know little about how much traffic flowed in and out of ancient cities, in part because of problems with using commodities as proxies for trade. This article investigates another approach, which is to estimate these flows from the built environment, concentrating on transport infrastructure such as city gates. To do this, I begin by discussing a new model for how we would expect this kind of infrastructure to expand with population, before investigating the relationship between the populations of sites and the total numbers and widths of city gates, focusing on the Greek and Roman world. The results suggest that there is indeed a systematic relationship between the estimated populations of cities and transport infrastructure, which is entirely consistent with broader theoretical and empirical expectations. This gives us a new way of exploring the connectivity and integration of ancient cities, contributing to a growing body of general theory about how settlements operate across space and time.

Urbanism and the division of labour in the Roman Empire.

One of the hallmarks of human agglomeration is an increase in the division of labour, but the exact nature of this relationship has been debated among anthropologists, sociologists, economists, and historians and archaeologists. Over the last decade, researchers investigating contemporary urban systems have suggested a novel explanation for the links between the numbers of inhabitants in settlements and many of their most important characteristics, which is grounded in a view of settlements as social networks embedded in built environments. One of the remarkable aspects of this approach is that it is not based on the specific conditions of the modern world (such as capitalism or industrialization), which raises the issue of whether the relationships observed in contemporary urban systems can also be detected in pre-modern urban or even non-urban systems. Here, we present a general model for the relationship between the population and functional diversity of settlements, where the latter is viewed as an indicator of the division of labour. We then explore the applicability of this model to pre-modern contexts, focusing on cities in the Roman Empire, using estimates of their numbers of inhabitants, numbers of documented professional associations, and numbers of recorded inscriptions to develop an index of functional diversity. Our results are consistent with theoretical expectations, adding further support to the view that urban systems in both contemporary and pre-modern contexts reflect a common set of generative processes.

The effect of follow-up on limiting non-participation bias in genetic epidemiologic investigations.

The use of a comprehensive follow-up strategy to limit non-participation bias was evaluated in a population-based case-control study of orofacial clefts. Birth parents were requested to provide exposure data, and index children and parents were asked to provide blood specimens. Follow-up included telephone or postal reminders every two weeks for up to three months. Consent to participate was received from 281 (76.6%) case mothers and 246 (72.4%) case fathers. The corresponding totals for controls were 279 (54.7%) and 245 (49.8%). Evaluation of participation rates by intensity of follow-up showed that 23% of case and 18% of control families consented without reminders (first stage); 81% of cases and 83% of controls agreed following one or two reminders (second stage); and the remainder of participants consented following three or more reminders (final stage). Cumulative distributions of sociodemographic characteristics differed little between second and final stage participants. Odds ratios for maternal multivitamin use were similar between second and final stage participants, whereas those for maternal and paternal smoking tended to decline. Although follow-up measures were necessary to enroll most families, use of more than two reminders did not appear to increase the representativeness of the sample; however, termination of recruitment after only two reminders would have led to different conclusions. Future studies require data collection protocols that encourage participation from all population subgroups, and one alternative is presented.

Shprintzen-Goldberg syndrome: a clinical analysis.

Shprintzen-Goldberg syndrome is one of a group of disorders characterized by craniosynostosis and marfanoid habitus. Eleven cases were reported previously. We present 4 new patients and review one of the patients of the original report of Shprintzen and Goldberg [1982: J Craniofac Genet Dev Biol 2:65-74], 15 years later. The clinical and radiologic findings on our patients are compared with those of the previously reported patients and also with those of Furlong et al. [1987: Am J Med Genet 26:599-604] and Lacombe and Battin [1993: Clin Dysmorphol 2: 220-224], who share many of the characteristics of Shprintzen-Goldberg syndrome. Some of the clinical data are helpful in determining if the patients of Furlong et al. [1987: Am J Med Genet 26:599-604] and Lacombe and Battin [1993: Clin Dysmorphol 2: 220-224] have a separate syndrome or represent a variant of Shprintzen-Goldberg syndrome. However, radiologic investigations appear to be more specific, since an abnormality of the first and second cervical vertebrae, hydrocephalus, dilatation of the lateral ventricles, and a Chiari-I malformation of the brain were found only in the patients with Shprintzen-Goldberg syndrome. The apparently diagnostic findings of the 15 patients with this syndrome may be helpful in differentiating between Shprintzen-Goldberg syndrome and other syndromes with craniosynostosis and marfanoid habitus.

Assessment of reproductive disorders and birth defects in communities near hazardous chemical sites. I. Birth defects and developmental disorders.

Members of the workgroup on birth defects and developmental disorders discussed methods to assess structural anomalies, genetic changes and mutations, fetal and infant mortality, functional deficits, and impaired fetal and neonatal growth. Tier 1 assessments for all five adverse reproductive outcomes consist of questionnaires and reviews of medical records rather than laboratory testing of biologic specimens. The work-group members noted a role for neurodevelopmental testing and for limited genetic studies, such as karyotyping in Tier 2 assessments. Emerging methodologies to identify chromosomal aberrations, DNA adducts, and repair inhibition were reserved for Tier 3.

Magnetic resonance imaging of brain anomalies in fetal alcohol syndrome.

OBJECTIVE: Postmortem studies of fetuses, infants, and young children with fetal alcohol syndrome (FAS) have demonstrated a variety of severe central nervous system (CNS) anomalies. We undertook this magnetic resonance study (1) to assess the spectrum of CNS anomalies that occur in a clinical sample of typical patients with FAS who are medically stable; and (2) to examine the relationship between CNS and facial anomalies. METHODOLOGY: Magnetic resonance imaging was performed on a series of 10 patients (4 children, 3 adolescents, and 3 adults) who met criteria for FAS. We systematically evaluated each scan for brain anomalies and compared total brain tissue volume with that of healthy child, adolescent, and adult control subjects. RESULTS: Six patients had some type of midline anomaly, ranging from partial to complete callosal agenesis (three patients) to hypoplastic corpus callosum (one patient), cavum septi pellucidi (three patients), and cavum vergae (two patients). These midline anomalies were associated with a greater number of facial anomalies. Other brain anomalies identified included micrencephaly, ventriculomegaly, and hypoplasia of the inferior olivary eminences. CONCLUSION: Patients with classic FAS have a high incidence of midline brain anomalies. This finding is consistent with the concept that the midline CNS is a developmental field that is particularly susceptible to the teratogenic effects of alcohol. Furthermore, patients with more severe facial dysmorphologic characteristics are more likely to have midline brain anomalies. In addition, we observed a high incidence of micrencephaly with a wide range of severity.

Incidence of fetal alcohol syndrome and prevalence of alcohol-related neurodevelopmental disorder.

We critique published incidences for fetal alcohol syndrome (FAS) and present new estimates of the incidence of FAS and the prevalence of alcohol-related neurodevelopmental disorder (ARND). We first review criteria necessary for valid estimation of FAS incidence. Estimates for three population-based studies that best meet these criteria are reported with adjustment for underascertainment of highly exposed cases. As a result, in 1975 in Seattle, the incidence of FAS can be estimated as at least 2.8/1000 live births, and for 1979-81 in Cleveland, approximately 4.6/1,000. In Roubaix, France (for data covering periods from 1977-1990), the rate is between 1.3 and 4.8/1,000, depending on the severity of effects used as diagnostic criteria. Utilizing the longitudinal neurobehavioral database of the Seattle study, we propose an operationalization of the Institute of Medicine's recent definition of ARND and estimate its prevalence in Seattle for the period 1975-1981. The combined rate of FAS and ARND is thus estimated to be at least 9.1/1,000. This conservative rate--nearly one in every 100 live births--confirms the perception of many health professionals that fetal alcohol exposure is a serious problem.

Web neck anomaly and its association with congenital heart disease.

To investigate the relationship between congenital heart disease and jugular lymphatic obstruction as manifested in web neck anomaly, we used the Iowa Birth Defects Registry to determine the incidence of congenital heart defects (CHD) in infants with and without web neck. Sixty percent of infants with web neck had CHD, with a high incidence of flow-related defects such as hypoplastic left heart, coarctation, and secundum atrial septal defect. Sixty-eight percent of infants with web neck had a genetic syndrome (37% Down syndrome, 13% Ullrich-Turner syndrome, and 5% Noonan syndrome), and 24% had dysmorphic features consistent with lymphatic obstruction sequence. When infants with Down, Ullrich-Turner, and Noonan syndrome and web neck were compared to infants with the same syndrome but without web neck, those with web neck were significantly more likely to have flow-related heart defects. Infants with Ullrich-Turner syndrome and web neck had an 11-fold higher incidence of coarctation, compared to those with a normal neck. Our data suggests web neck is associated with both flow and nonflow-related heart defects. This association implies a pathogenetic relationship and appears to be independent of causal factors. The finding of web neck or nuchal cystic hygroma on a prenatal ultrasound or newborn examination should prompt a search for CHD.

Postintubation tracheal stenosis: diagnosis and management.

Postintubation damage is a potential hazard in any patient intubated with an oral or nasal endotracheal tube or with a tracheostomy tube for ventilatory support. Postintubation tracheal stenosis may be fatal unless it is recognized and treated promptly. This paper reviews the important features of diagnosis and treatment of postintubation tracheal stenosis.

Craniofacial development in myotonic dystrophy.

Anthropometric, cephalometric, and dental data from 23 subjects (12 males and 11 females) afflicted with myotonic dystrophy were compared to similar data from normal subjects who participated in the Iowa Facial Growth Study. A two by two analysis of variance showed that myotonic subjects differed from normal subjects in headlength, head breadth, cephalic index, bizygomatic face width, nosebreadth, maxillary arch widths, palatal depth, anterior and posterior face heights, cranial base lengths, cranial base angles, and other cephalometric measures. Sex differences were observed for many of the variables. It is hoped that these findings will assist clinicians who treat patients having this disorder.

The association of waterborne chloroform with intrauterine growth retardation.

The potential reproductive effects of long-term, low-dose exposure to chloroform have received little attention despite the known, acute toxicity of high exposures and the wide-spread occurrence of low concentrations in drinking water. We studied the association of waterborne chloroform with low birthweight (less than 2,500 gm), prematurity (less than 37 weeks gestation), and intrauterine growth retardation (less than 5th percentile of weight for gestational age). Cases were not mutually exclusive, but each outcome was analyzed independently. Birth certificates from January 1, 1989, to June 30, 1990, were used to identify cases and randomly selected controls. All were live, singleton infants born to non-Hispanic, white women from Iowa towns with 1,000-5,000 inhabitants. Exposures to chloroform and other trihalomethanes were ecologic variables based on maternal residence and a 1987 municipal water survey. After adjustment for maternal age, parity, adequacy of prenatal care, marital status, education, and maternal smoking by multiple logistic regression, residence in municipalities where chloroform concentrations were greater than or equal to 10 micrograms/liter was associated with an increased risk for intrauterine growth retardation (odds ratio = 1.8, 95% confidence interval = 1.1-2.9). The major limitations of this study involve the ascertainment and classification of exposures to trihalomethanes, including such issues as the imprecision of using aggregate municipal measures for classifying exposure at the level of the individual, the potential misclassification due to residential mobility, and the fluctuation of trihalomethane levels.

A five-year statewide experience with congenital diaphragmatic hernia.

Antenatal in utero surgery for congenital diaphragmatic hernia has been justified by reported perinatal mortality rates of 77% to 80%. Such rates may have been subject to bias of ascertainment and may include fetuses with additional severe malformations who would not be surgical candidates. We used the Iowa Birth Defects Registry to conduct a complete population survey to determine the incidence of congenital diaphragmatic hernia, the frequency of associated severe malformations, and the morbidity and mortality of infants with isolated congenital diaphragmatic hernia who were not subjected to antenatal surgery. The incidence of congenital diaphragmatic hernia was 1 in 3715. Twenty-eight percent of affected fetuses had associated severe malformations that were potentially identifiable prenatally and that would have precluded antenatal surgery. Of those with isolated congenital diaphragmatic hernia, 55% survived in spite of delivery (88.5%) and/or surgical repair (44%) in a level I or II hospital. Any decision for in utero surgery to repair congenital diaphragmatic hernia must be based on this or similarly obtained information.

Unique phenotype associated with a pericentric inversion of chromosome 6 in three generations.

We observed a pericentric inversion of chromosome 6 in three generations of one family. Carriers had several phenotypic alterations including congenital cataracts, hearing loss, dental anomalies, ear anomalies, premature graying, unilateral strabismus, coloboma, and mild mental retardation. These manifestations may all be explained by a failure or delay in development of tissues derived from neural crest cells and are similar to these seen in the Rieger syndrome. The description of this family extends the known phenotypic abnormalities associated with alterations of chromosome 6.

Clinical management issues in males with sex chromosomal mosaicism and discordant phenotype/sex chromosomal patterns.

The recent availability of Y DNA probes has made it possible to identify two forms of 46,XX male syndrome: Y DNA positive and Y DNA negative. The Y DNA positive male results from a X;Y translocation with a low recurrence risk; the Y DNA negative males are due to a mutation with a high recurrence risk. 46,XX males and mosaic forms are phenotypically indistinguishable. A review of the case histories for 11 individuals indicates that affected males have highly variable genital and nongenital phenotypes. Physical findings may be clearly apparent or nonexistent. With the exception of external genitalia, the basis for this variability is unknown. It may be related to differences in Y chromatin expression as the result of variable inactivation of the X chromosomes, or to the existence of minor deletions or point mutations secondary to an exchange of genetic material. Common and uncommon clinical problems in these individuals require evaluation and follow-up care that is provided through a cooperative, interdisciplinary approach.

Genetic counseling.

Achieving the clinical goal of genetic counseling continues to be the proper role of all professionals who deal with disorders and conditions that have a genetic component. That group includes the SLP. One major problem is determining when information can be given generally and when referral to a genetic counselor is needed. Another problem is helping the public accept the idea of genetic counseling as one useful part of the health care system. Of special importance now is the development of new methods for identifying the genetic contribution to diseases and disorders. Careful attention is needed for the effective integration of this new technology into our patterns of health care delivery and public health policy in general.

Prenatal cocaine exposure and fetal vascular disruption.

The question of the potential teratogenicity of cocaine has been raised by the increasing frequency of its abuse in the United States. In previous studies, an increased incidence has been documented of spontaneous abortion, placental abruption, prematurity, intrauterine growth retardation, and neurologic deficits in the infants of women who abused cocaine. More recently, it has been suggested in studies that fetal vascular disruption accompanying maternal cocaine abuse may lead to cavitary central nervous system lesions and genitourinary anomalies. In this article, 10 children born of women who abused cocaine are described, 9 of whom have congenital limb reduction defects and/or intestinal atresia or infarction. The spectrum of anomalies associated with embryonic and fetal vascular disruption accompanying maternal cocaine abuse is thus enlarged. The specific risk for congenital anomalies accompanying maternal cocaine abuse during an individual pregnancy is unknown. However, data from these patients and the available literature suggest that counseling pregnant women concerning cocaine use should incorporate warnings about the possibility of associated embryonic or fetal vascular disruption.