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Biomedical subjects

J S Noble

Publications and source records attributed to J S Noble.

11 recordsLinked to original sources

Isolation and sequencing of CA/GT repeat microsatellites from chromosomal libraries without subcloning.

A method for the isolation of (CA)n microsatellites from chromosome-specific genomic libraries is described. Clones were first screened using a polynucleotide CA/GT probe. Those shown to contain CA repeats were plaque purified and either subcloned or the insert amplified directly using vector primers. Polymerase chain reaction products were then used to directly sequence the regions flanking CA repeats by using biotinylated primers that amplify cloned inserts outward from CA repeat containing regions of DNA to vector primers. This method provides rapid access to microsatellites from chromosomes or chromosome regions of interest.

Alleles

The effects of graft tensioning on the laxity and kinematics of the anterior cruciate ligament reconstructed knee.

An in vitro study of eight cadaveric knees was conducted to investigate the effect of initial graft tension on the laxity and full three-dimensional kinematics of the anterior cruciate ligament reconstructed knee. A parallel strand, prototype, expanded polytetrafluoroethylene graft (W. L. Gore and Associates, Flagstaff, AZ, U.S.A.) was used. The graft was placed in the over-the-top position with initial tensions of 18, 36, 54, 72, and 90 N applied with the knee in full extension or at 30 degrees of flexion. The motion of the tibia relative to the femur was measured by a 6 degrees-of-freedom spatial linkage, and the applied forces and moments, the quadriceps force, and the graft tension were measured by load cells. Near normal anterior laxity in the Lachman test was restored with all the tested initial graft tensions. However, over constraint, posterior, lateral, and external tibial subluxation, and abnormalities in joint stiffness developed as the initial graft tension increased. Graft tension-related posterior tibial subluxation resulted in an increase in quadriceps force needed to achieve full extension.

Aged

An appreciation of posterior instability of the shoulder.

Fortunately, posterior instability of the shoulder is a relatively uncommon occurrence in the athlete. Acute traumatic posterior dislocations can be readily managed by conservative measures. Recurrent posterior subluxation, however, represents a more challenging problem for the orthopedic surgeon. As has been discussed, most patients with this disorder respond to nonsurgical treatment including physical therapy and modification of the offending activities. Should these modalities fail, operative treatment may be necessary. Careful assessment of the patient to rule out the associated presence of excessive ligamentous laxity or a voluntary component to the instability is mandatory. Pain is clearly the principal indicator for surgical treatment. Painless subluxation, either voluntary or involuntary, should first be treated conservatively. The surgical options discussed in this article range from simple soft-tissue repair to more complex osteotomies with combined capsular plication. It is important that the procedure be appropriate to the pathology. We do not believe that one technique alone can address all variants of posterior instability. Most instances of recurrent posterior subluxation represent unidirectional instability in patients with otherwise normal bony morphology. In these patients, a posterior capsulorrhaphy combined with appropriate immobilization should be effective. In select instances, when either excessive glenoid retroversion or deficiency is encountered, a glenoid osteotomy and posterior capsulorrhaphy have proved successful. This technique, more than any other, carries a number of potential technical pitfalls and should be employed cautiously. Multidirectional posterior instability, now a well-recognized entity, requires a different surgical approach--the capsular shift. Designed to address the inferior redundancy, as well as posterior laxity, this procedure is applicable to the multidirectional posterior subluxator. In conclusion, posterior instability of the athlete's shoulder is an increasingly recognized entity. Most instances are amenable to nonsurgical care. Should surgical treatment be necessary, optimal results may be achieved by careful attention to patient assessment, instability categorization, determination of the presence of ligamentous laxity, and appropriate surgical technique.

Humans

Isolation and translation in vitro of poly(A)+RNA from the free-living nematode Panagrellus silusiae.

Polysomal RNA was isolated from the free-living nematode Panagrellus silusiae. Passage of this RNA through a cellulose column resulted in the fractionation of the input RNA into poly(A)-RNA (ca. 97.5% of the total) and poly(A)+ RNA (ca. 2.5% of the total). RNase digestion, followed by polyacrylamide gel electrophoresis, revealed that the poly(A)+ RNA contained poly(A) tracts that ranged from 75 to 104 nucleotides in length with a mean value of about 90 residues. There was no evidence of poly(A) sequences in the poly(A)- RNA fraction. Poly(A)+ RNA gave a 25- to 50-fold stimulation (over background) of amino acid incorporation in the wheat germ cell-free protein-synthesizing system. At least 26 proteins were evident after electrophoresis in cylindrical sodium dodecyl sulfate-polyacrylamide gels. Poly(A)-RNA was capable of stimulating protein synthesis in vitro with about five discrete proteins being produced. In summary, the properties of mRNA from a simple organism such as P. silusiae are very similar to those of more complex eukaryotes.

Animals

Relative ribosomal RNA cistron multiplicity in oocytes and postembryonic stages of the eutelic nematode Panagrellus silusiae.

The number of ribosomal RNA cistrons has been measured in the total DNA extracted from L2 juvenile and adult stages of the free-living nematode Panagrellus silusiae. Saturation hybridization studies with homologous rRNA indicate that both stages have about 275 ribosomal genes per haploid equivalent. Using homologous 125I-labelled rRNA for in situ hybridization, the mean number of silver grains per DNA content for oocyte, hypodermis and gut nuclei was similar. The mean DNA contents of maturing oocyte, hypodermis and gut nuclei are about 20C, 2C, and 10C respectively. We conclude that rDNA amplication alone is insufficient to account for the variation in DNA content of oocytes and that postembryonic development in this eutelic organism occurs without a significant differential increase in the number of ribosomal cistrons per worm.

Animals

Properties and synthesis of ribosomal RNA in the free-living nematode Panagrellus silusiae.

The normal S values of ribosomes and ribosomal subunits extracted from the free-living nematode. Panagrellus silusiae are similar to those of other eukaryotic organisms. Upon heating (70 degrees C, 15 min) a 5.5-S RNA is released from the larger ribosomal RNA (27 S; 1.40-10(6) daltons). Unlike other protostomes, however, the 27-S rRNA does not dissociate in an orderly manner to yield 18-S components. The electrophoretic mobility of the small ribosomal RNA species (18 S; 0.72-10(6) daltons) is unaltered by heat treatment. The base composition of both Panagrellus rRNA species has a 51% G+C content. Labelling worms with either [Me-3H] methionine or [14C] uridine at various stages of postembryonic development and subsequent analysis of the extracted RNA revealed eight radioactive fractions, two of which were the mature ribosomal RNAs. From both the time sequence of appearance of the eight RNA species and the relative degree of methylation of the various RNA fractions two maturation pathways for ribosomal RNA processing were deduced. A 37-S (3.6-10(6) daltons) RNA is the precursor to both 27-S and 18-S RNA. During processing about two-fifths of the original transcriptional unit is lost. In this organism the "transcribed spacer" regions may be methylated although alternate interpretations have not been precluded.

Cell Fractionation

A rapid PCR-based method to distinguish between fetal and maternal cells in chorionic biopsies using microsatellite polymorphisms.

In some chorionic villus biopsy (CVB) cases the fetal/maternal origin of the tissue obtained is uncertain. An approach which only requires small amounts of CVB tissue to establish its origin is described. Since it is only the samples typed as female that could be either fetal or maternal, a paternal X chromosome contribution is sought by using highly polymorphic X-linked microsatellites.

Alleles