Sequences sufficient for programming imprinted germline DNA methylation defined

Epigenetic marks are fundamental to normal development, but little is known about signals that dictate their placement. Insights have been provided by studies of imprinted loci in mammals, where monoallelic expression is epigenetically controlled. Imprinted expression is regulated by DNA methylation programmed during gametogenesis in a sex-specific manner and maintained after fertilization. At Rasgrf1 in mouse, paternal-specific DNA methylation on a differential methylation domain (DMD) requires downstream tandem repeats. The DMD and repeats constitute a binary switch regulating paternal-specific expression. Here, we define sequences sufficient for imprinted methylation using two transgenic mouse lines: One carries the entire Rasgrf1 cluster (RC); the second carries only the DMD and repeats (DR) from Rasgrf1. The RC transgene recapitulated all aspects of imprinting seen at the endogenous locus. DR underwent proper DNA methylation establishment in sperm and erasure in oocytes, indicating the DMD and repeats are sufficient to program imprinted DNA methylation in germlines. Both transgenes produce a DMD-spanning pit-RNA, previously shown to be necessary for imprinted DNA methylation at the endogenous locus. We show that when pit-RNA expression is controlled by the repeats, it regulates DNA methylation in cis only and not in trans. Interestingly, pedigree history dictated whether established DR methylation patterns were maintained after fertilization. When DR was paternally transmitted followed by maternal transmission, the unmethylated state that was properly established in the female germlines could not be maintained. This provides a model for transgenerational epigenetic inheritance in mice.

Nucleolar size polymorphisms in commercial layer chickens; determination of incidence, inheritance, and nucleolar sizes

In the chicken, one chromosome pair encodes the ribosomal (r)RNA genes and two nucleoli are formed in interphase cells. The nucleolus is the site of rRNA synthesis and ribosome biogenesis. Nucleolar size polymorphisms have been detected in research strains of chickens and found to represent heterozygosity for rRNA gene copy number. The objectives of the present study were to determine whether nucleolar size polymorphisms exist in commercial chicken flocks and whether such polymorphisms are under genetic control. The occurrence of nucleolar size polymorphisms was studied in three lines of commercial layer chickens (designated A, B, and C). Nucleolar size polymorphisms were found in all three lines. However, the lines differed in the proportion of individuals exhibiting the polymorphic phenotype of two unequal-sized nucleoli (2P). The 2P phenotype, determined in successive years, was found in 10 to 14% of Line A birds, 18 to 23% of Line B birds, and 41 to 63% of Line C birds. The inheritance pattern of the nucleolar size polymorphism and nucleoli sizes were studied in Line C birds. The 2P phenotype was found to be inherited in Mendelian fashion. The large nucleolus was 1.7x and 1.6x that of the smaller nucleolus in 2P males and females, respectively, and was larger than the nucleoli of 2E birds (2E = nonpolymorphic phenotype of two equal-sized nucleoli). Total nucleolar size was greater in cells of 2P birds than in cells of 2E birds. These data suggest that the genetic basis for the large nucleolus in Line C 2P cells is a "larger than normal" rDNA cluster.

Pressure-volume orbital measurement comparing decompression approaches

Commonly used orbital decompressions are lateral wall, antral-ethmoidal, "three-wall," and "four-wall" decompressions. Bladders filled with saline were placed in intact bony orbits before and after decompression for comparison of compliance curves by these four methods. The lateral wall decompressions produced the least volume change, while the four-wall produced the most. The three-wall decompression provided next best pressure reduction.

Treatment of essential blepharospasm. II. A modification of exposure for the muscle stripping technique

The refinement of a muscle excision technique for the correction of essential blepharospasm has been a major contribution to treatment. In this procedure, incisions are made directly above the eyebrow to excise the brow muscles, often resulting in adherent scars and poor brow position. The bicoronal scalp flap has been used by many other surgical subspecialities for exposure of the frontal bone area, eg, in neurosurgical procedures, sinus surgery, and cosmetic forehead lifts. The use of the coronal flap exposure for excision of the corrugator and procerus muscles has allowed them to be more easily excised and has avoided the problems associated with the direct brow incisions. The Anderson muscle stripping technique, combined with the coronal flap exposure for the brow muscles, provides the best correction for the spasms in patients who have essential blepharospasm. The frequency of complications is low, and patient acceptance is high.

Treatment of essential blepharospasm. I. Comparison of facial nerve avulsion and eyebrow-eyelid muscle stripping procedure

Benign essential blepharospasm is an incurable disease for which many treatment modalities have been suggested. The two surgical procedures that have been used most commonly are avulsion of the facial nerve and stripping of the protractor muscles of the eyelid and brow. We compare two matched series of 22 patients; one group underwent facial nerve avulsion ("Reynold's" procedure), and the other underwent "muscle stripping" ("Anderson's" procedure). We noted the number of procedures required for the patient to obtain a functional visual result and the side effects produced. Additional surgical procedures required by patients undergoing facial nerve avulsion were additional facial nerve avulsion, repair of ectropion, and correction of dermatochalasis and brow droop. Additional procedures required in patients who had muscle stripping were excision of lower lid orbicular fibers or residual brow fibers. The Reynold group required 16 additional procedures (38 separate procedures) to obtain functional results, as opposed to the four additional procedures (26 separate procedures) required in the Anderson group. Two patients in the Reynold group who needed surgery have not yet undergone it at this writing. If they did, that would boost the total number of procedures to 40. Secondary procedures are needed 4.5 times more often with the Reynold procedure than with the Anderson procedure. The patient's subjective response to and acceptance of the procedure are much greater for the Anderson procedure.

Clinical engineering's involvement with a computerized hospital information system

This paper describes a computerized Hospital Information System (HIS) installed in Mount Zion Hospital and Medical Center along with the Clinical Engineering Department's involvement in the minor and major maintenance of the 48 data stations consisting of terminals and printers. This paper also includes a summary of maintenance man-hour distribution, data station repair problems and the type of repair equipment and personnel needed to maintain hospital computer systems.

ECG/respiration monitor calibrator

This paper describes an ECG/Respiration monitor calibrator used by the Biomedical Staff to check such units quickly, inexpensively and accurately. The calibrator can be constructed by the Biomedical Engineering Staff in one day for a parts cost of less than fifty dollars. Once the calibrator is connected to the patient cable of an ECG/Respiration monitor, the calibrator will generate concurrently a calibrated rate and amplitude ECG-pulse and respiration waveform.