Expression of the familial cardiac valvular dystrophy gene, filamin-A, during heart morphogenesis.

Myxoid degeneration of the cardiac valves is a common feature in a heterogeneous group of disorders that includes Marfan syndrome and isolated valvular diseases. Mitral valve prolapse is the most common outcome of these and remains one of the most common indications for valvular surgery. While the etiology of the disease is unknown, recent genetic studies have demonstrated that an X-linked form of familial cardiac valvular dystrophy can be attributed to mutations in the Filamin-A gene. Since these inheritable mutations are present from conception, we hypothesize that filamin-A mutations present at the time of valve morphogenesis lead to dysfunction that progresses postnatally to clinically relevant disease. Therefore, by carefully evaluating genetic factors (such as filamin-A) that play a substantial role in MVP, we can elucidate relevant developmental pathways that contribute to its pathogenesis. In order to understand how developmental expression of a mutant protein can lead to valve disease, the spatio-temporal distribution of filamin-A during cardiac morphogenesis must first be characterized. Although previously thought of as a ubiquitously expressed gene, we demonstrate that filamin-A is robustly expressed in non-myocyte cells throughout cardiac morphogenesis including epicardial and endocardial cells, and mesenchymal cells derived by EMT from these two epithelia, as well as mesenchyme of neural crest origin. In postnatal hearts, expression of filamin-A is significantly decreased in the atrioventricular and outflow tract valve leaflets and their suspensory apparatus. Characterization of the temporal and spatial expression pattern of filamin-A during cardiac morphogenesis is a crucial first step in our understanding of how mutations in filamin-A result in clinically relevant valve disease.

Segmentation of whole cells and cell nuclei from 3-D optical microscope images using dynamic programming.

Communications between cells in large part drive tissue development and function, as well as disease-related processes such as tumorigenesis. Understanding the mechanistic bases of these processes necessitates quantifying specific molecules in adjacent cells or cell nuclei of intact tissue. However, a major restriction on such analyses is the lack of an efficient method that correctly segments each object (cell or nucleus) from 3-D images of an intact tissue specimen. We report a highly reliable and accurate semi-automatic algorithmic method for segmenting fluorescence-labeled cells or nuclei from 3-D tissue images. Segmentation begins with semi-automatic, 2-D object delineation in a user-selected plane, using dynamic programming (DP) to locate the border with an accumulated intensity per unit length greater that any other possible border around the same object. Then the two surfaces of the object in planes above and below the selected plane are found using an algorithm that combines DP and combinatorial searching. Following segmentation, any perceived errors can be interactively corrected. Segmentation accuracy is not significantly affected by intermittent labeling of object surfaces, diffuse surfaces, or spurious signals away from surfaces. The unique strength of the segmentation method was demonstrated on a variety of biological tissue samples where all cells, including irregularly shaped cells, were accurately segmented based on visual inspection.

The noradrenergic system influences the fate of Cajal-Retzius cells in the developing cerebral cortex.

Cajal-Retzius cells are neurons prominently located in layer I of the developing cerebral cortex. They are the first neurons to be born in the cortex reaching maturity long before any other cortical neuronal cell type; later in development they degenerate and/or change phenotype. The noradrenergic system, which originates in the locus coeruleus in the brain stem, is one of the earliest axonal systems to enter the cortex forming contacts with Cajal-Retzius cells in layer I. Here we followed the course of development of the Cajal-Retzius cells in postnatal life in animals depleted of noradrenaline in the cortex. We found that removal of this system after birth resulted in significantly more Cajal-Retzius cells during the first 2 weeks of life. This may be due to the observed decline in the number of dying cells in layer I of these animals during the same period. We speculate that the noradrenergic system regulates the development of Cajal-Retzius cells which have been implicated in neuronal migration and laminar formation in the cerebral cortex.

Lens epithelial proliferation cataract in segmental trisomy involving mouse Chromosomes 4 and 17.

A dominant induced mutation in the mouse, tightly associated with a reciprocal chromosomal translocation between Chrs 4 and 17, causes abnormal head tossing and circling behavior (the translocation induced circling mutation, Tim). Affected mice develop an unusual anterior subcapsular cataract that appears after birth and is progressive. The most likely explanation for the phenotypic observations is that the translocation breakpoint disrupted a gene or its regulation. Although the Mos protooncogene is located close to the translocation breakpoint and transgenic mice that overexpress Mos demonstrate cataracts and circling behavior, there were no gross changes in the Mos gene or in its level of expression. The morphological changes observed in the lens resemble those seen in some human congenital cataract syndromes.

Cancer mortality following treatment for adult hyperthyroidism. Cooperative Thyrotoxicosis Therapy Follow-up Study Group.

CONTEXT: High-dose iodine 131 is the treatment of choice in the United States for most adults with hyperthyroid disease. Although there is little evidence to link therapeutic (131)I to the development of cancer, its extensive medical use indicates the need for additional evaluation. OBJECTIVE: To evaluate cancer mortality among hyperthyroid patients, particularly after (131)I treatment. DESIGN: A retrospective cohort study. SETTING: Twenty-five clinics in the United States and 1 clinic in England. PATIENTS: A total of 35 593 hyperthyroid patients treated between 1946 and 1964 in the original Cooperative Thyrotoxicosis Therapy Follow-up Study; 91 % had Graves disease, 79% were female, and 65% were treated with (131)I. MAIN OUTCOME MEASURE: Standardized cancer mortality ratios (SMRs) after 3 treatment modalities for hyperthyroidism. RESULTS: Of the study cohort, 50.5% had died by the end of follow-up in December 1990. The total number of cancer deaths was close to that expected based on mortality rates in the general population (2950 vs 2857.6), but there was a small excess of mortality from cancers of the lung, breast, kidney, and thyroid, and a deficit of deaths from cancers of the uterus and the prostate gland. Patients with toxic nodular goiter had an SMR of 1.16 (95% confidence interval [CI], 1.03-1.30). More than 1 year after treatment, an increased risk of cancer mortality was seen among patients treated exclusively with antithyroid drugs (SMR, 1.31; 95% CI, 1.06-1.60). Radioactive iodine was not linked to total cancer deaths (SMR, 1.02; 95% CI, 0.98-1.07) or to any specific cancer with the exception of thyroid cancer (SMR, 3.94; 95% CI, 2.52-5.86). CONCLUSIONS: Neither hyperthyroidism nor (131)I treatment resulted in a significantly increased risk of total cancer mortality. While there was an elevated risk of thyroid cancer mortality following (131)I treatment, in absolute terms the excess number of deaths was small, and the underlying thyroid disease appeared to play a role. Overall, (131)I appears to be a safe therapy for hyperthyroidism.

Decreased retinal ganglion cell number and misdirected axon growth associated with fissure defects in Bst/+ mutant mice.

PURPOSE: The autosomal semidominant mutation Bst (belly spot and tail) is often associated with small and atrophic optic nerves in adult mice and shares several important attributes with heritable optic nerve atrophy in humans. In this article, the authors present adult and developmental studies on the retinal phenotype in Bst/+ mice. METHODS: Retinal ganglion cells in adult Bst/+ mice were labeled retrogradely with horseradish peroxidase injected into the right optic tract. Labeled ganglion cells were mapped in whole-mounted retinas ipsilateral and contralateral to the injection site. The number of axons in optic nerves of these and other cases were quantified using an electron microscopic method. Eyes of neonatal, embryonic day 15 (E15), and embryonic day 12 (E12) Bst/+ mutants were examined histologically to understand the etiology of the retinal phenotype. RESULTS: Approximately 60% of adult Bst/+ mice have deficient direct pupillary light responses. This neurologic phenotype is associated with a reduction in the number of retinal ganglion cells from the wild-type average of 67,000 to less than 20,000 in Bst/+ mutants. Ganglion cells with crossed projections are more severely affected than those with uncrossed projections. Histologic analysis of eyes from E12 mice reveals a delayed closure of the optic fissure. Despite this abnormality, other ocular structures appear relatively normal. However, some E15 mutants exhibit marked disorganization of the retinal neuroepithelium, and ganglion cell axons are found between pigmented and neural retina. At birth, optic nerves of affected mice are smaller than those of wild-type mice, ectopic axons are found within the eyes, and the ganglion cell layer contains many dying cells. CONCLUSIONS: The expression of the retinal phenotype in Bst/+ mutants is highly variable-ranging from a complete absence of ganglion cells to numbers comparable to that in wild-type mice. The reduction in ganglion cell number in affected adult Bst/+ mice is attributable to the failure of ganglion cell axons to reach the optic nerve head early in development. Delayed fusion of the fissure is consistently associated with the Bst/+ genotype and probably contributes to the failure of ganglion cell axons to grow out of the eye.

Forebrain overgrowth (fog): a new mutation in the mouse affecting neural tube development.

Forebrain overgrowth, fog, is a spontaneous autosomal recessive mutation in the mouse producing forebrain, lumbo-sacral, and facial defects. The defects appear to result from excessive growth or cellular proliferation leading to abnormalities in neural tube closure. Three unique features of the mutant are: (1) the growth of telencephalon cells into the surrounding mesenchyme, (2) presence of an encephalocele through the midline cleft in some mutants, and (3) dissociation of the tail defect from the caudal neural tube defect. We used an intersubspecific intercross between mice carrying the fog mutation and mice from an inbred Mus musculus castaneus strain (CAST/Ei) to map the fog mutation to mouse Chromosome 10 near D10Mit262 and D10Mit230 in a region with several potential candidate genes.

A new mouse mutation causing male sterility and histoincompatibility.

Male sterility and histoincompatibility, mshi, is an autosomal recessive mutation in BALB/cBy mice that causes reduced testis size and sterility in homozygous males. The testes of homozygous mutants are highly disorganized and appear to have a block in the regulation of male germ cell proliferation. No heterozygous effect is detectable. Reproduction is unaffected in females carrying the mutation. The mutation also affects histocompatibility; most homozygous males and females reject sex-matched skin grafts from BALB/cBy mice. We used an intercross between BALB/cBy and CAST/Ei to map the mshi mutation to the proximal end of Chromosome (Chr) 10. The most likely gene order places the mutation between D10Mit80 and D10Mit16, near the interferon gamma receptor locus, Ifgr, which may be a candidate gene for this mutation.

Segmental trisomy as a mouse model for Down syndrome.

Mice trisomic for Chromosome (Chr) 16 have been used extensively as an animal model for human Down Syndrome (Trisomy 21). This system has drawbacks, however: trisomy for all of Chr 16 is incompatible with postnatal survival and produces trisomy for many more genes than those conserved in human Chr 21. We report here the development and preliminary characterization of mice that are trisomic for only the segment of mouse Chr 16 that is conserved in human Chr 21. While these segmentally trisomic mice, Ts(17(16)) 65Dn, do not appear to have all the features characteristic of Down Syndrome, they represent a mouse model that survives to adulthood and may be useful to study features of Down Syndrome that develop later in life, such as susceptibility to infection, increased incidence of leukemia, and Alzheimer-like neuropathology.

Genetic localization of Hao-1, blind-sterile (bs), and Emv-13 on mouse chromosome 2.

The blind-sterile (bs) mutation in the mouse was localized on Chromosome 2 between Hao-1 and Emv-13. N2 progeny from a backcross between congenic female 129.AKR-bs Emv-13 mice and (129.AKR-bs/bs x Mus musculus molossinus) F1 male mice were typed by analysis of isozyme variants for Hao-1, visible inspection for bs, and restriction fragment length polymorphism for Emv-13 and Emv-15. Comparison between markers on mouse Chromosome 2 and corresponding markers on human chromosomes suggest that the human homolog of bs will be located on 20q11-q13.

Breast cancer in women with scoliosis exposed to multiple diagnostic x rays.

Although exposure to ionizing radiation is a recognized risk factor for breast cancer, the potential hazard from low-dose, fractionated exposures during early breast development has not been thoroughly evaluated. Women with scoliosis represent a valuable population for studying this issue because they are exposed to multiple diagnostic x rays during childhood and adolescence, times when the breast may be highly sensitive to the carcinogenic effects of radiation. A study was conducted of 1,030 women with scoliosis who were seen at four Minneapolis area medical facilities between 1935 and 1965. The average age at diagnosis was 12.3 years; 60% of the women had idiopathic scoliosis. Individual x-ray films were counted and the number per patient ranged from 0 to 618 films (mean, 41.5). On average, the x-ray exposures were given over an 8.7-year period. Ninety percent of the women were located, of whom over 92% responded to a mail questionnaire or telephone interview. The average period of observation was 26 years. Overall, 11 cases of breast cancer were reported, compared with six expected (standardized incidence ratio = 1.82, 90% confidence interval = 1.0-3.0). Excess risk increased with time since exposure and was highest among those followed for more than 30 years (standardized incidence ratio = 2.4). Risk also increased with the number of x rays and with the estimated radiation dose to the breast (mean, 13 rad). These data suggest that frequent exposure to low-level diagnostic radiation during childhood or adolescence may increase the risk of breast cancer.

Reproductive outcomes in scoliosis patients.

In a retrospective cohort study of 1,409 persons diagnosed with scoliosis between 1927 and 1965 in Minneapolis and St. Paul, Minnesota, mailed questionnaires were obtained for 846 white women. Six hundred and eight (72%) of these women had ever been pregnant, and they reported a total of 1,733 pregnancies and 1,413 livebirths. Adverse outcomes among the pregnancies and livebirths of the 608 women were reported, including spontaneous abortion, stillbirth, low birth weight, prematurity, congenital anomalies, and complications of pregnancy or delivery. Rates of these events for the scoliosis patients were compared with corresponding expected rates. Comparison of the overall rates suggested that the scoliosis patients had more premature births than expected, but their rates of other adverse reproductive events did not differ from expected.

Percutaneous placement of ventriculoatrial shunts: four-year case experience.

During the past 4 years, we have used percutaneous placement of the atrial catheter in 39 patients who have undergone ventriculoatrial shunting. The age range of our patients has been from 9 to 74 years of age, with routine indications existing. Both subclavian and internal jugular venous access have been utilized, with the latter being our preferred route of access for reasons of safety. Average operative time has been approximately 35 to 40 minutes. Both traditional and split-sheath introducer catheters have been used. Patient follow-up has been up to 4 years. Intraoperative complications have been limited to puncture of the carotid artery on two occasions; neither affected the ultimate performance of the procedure. Postoperative complications have been limited to those peculiar to shunt procedures in general and have required revision in four instances. One patient suffered an infection secondary to shunting. The benefits of this procedure seem to include safety, decreased operative site exposure, and decreased operative time, all factors that may contribute to a lower than normal infection rate and may warrant consideration of this procedure in adolescents and adults for whom ventriculoatrial shunting is indicated.

A survey approach for finding cases of epilepsy.

Identify persons with epilepsy by first looking for prescriptions for particular antiseizure drugs. Follow these prescriptions from the pharmacies to the physicians who wrote them for patients. Ask the physicians whether the patients have epilepsy. Finally, contact the patients who do have epilepsy to elicit information about the impact of that condition on their lives. With these steps, it may be possible to carry out successfully a probability survey of epilepsy in the United States population. To learn more about this approach, a field test was funded by the National Institute of Neurological and Communicative Disorders and Stroke (NINCDS) of the Public Health Service. From 1978 through 1982, the work was planned, carried out, and evaluated by Research Triangle Institute, Research Triangle Park, NC. Epilepsy is a sensitive topic to ask about in a survey. Also, the condition is sufficiently rare to render ordinary survey approaches inefficient. Even if rarity were not an issue, there would be the problem of response error because a person with epilepsy does not, as a rule, have much clinical information on his or her condition. Better information lies with the physician who provides the care, but many physicians are busy with their practices. Furthermore, their record systems are usually not designed for easy retrieval of information, unless the names of patients are available. In the survey approach considered here, the names of patients are obtained through a random sampling of prescriptions for antiseizure drugs. The field test was divided into three phases with special activities reserved for each. The most important problem confronted was how to safeguard the confidentiality of relationships between pharmacist and patient and between physician and patient.Special guidelines on confidentiality were put into effect for the data collection. These guidelines,however, contributed to serious problems of nonresponse-especially for physicians. This article provides a brief account of the field test, including a rationale for the survey strategy of finding cases of epilepsy through prescriptions for antiseizuredrugs.