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Biomedical subjects

N Joseph

Publications and source records attributed to N Joseph.

At least 19 recordsLinked to original sources
PubMed2007

PET CT imaging in patients undergoing sentinel node biopsy for melanoma.

AIMS: Sentinel lymph node biopsy (SLNB) has been adopted in the surgical treatment of melanoma to reduce morbidity and enhance staging. Positron emission tomography with computerised tomography (PET/CT) has been utilised in the staging of patients with malignancy though the role of this imaging modality in early stage melanoma is unclear. This study examined the preoperative value of PET/CT in patients undergoing SLNB for malignant melanoma. METHODS: Patients presenting with primary melanoma without evidence of either locoregional or systemic metastasis were considered candidates for SLNB. Selected patients underwent preoperative PET/CT followed by definitive surgical therapy including SLNB with regional lymphadenectomy, where indicated. RESULTS: During a 12-month period 83 patients were identified as having undergone SLNB for melanoma, of which 37 (45%) had preoperative PET/CT. Mean melanoma thickness 1.9 mm and 2.4 mm (PET/CT vs. no PET/CT, p>0.05). 13 (15.6%) patients were found to have lymphatic metastasis at SLNB; nine of these patients underwent PET/CT, only two of these scans were suggestive of lymphatic metastasis (positive predictive value 24%, negative predictive value 76%). PET/CT revealed no unheralded metastatic disease but did identify a second occult malignancy in 4 (10.8%) patients undergoing therapy for melanoma. CONCLUSIONS: The results of this study do not support the use of PET/CT in patients undergoing SLNB for melanoma. SLNB appears to be a more sensitive staging modality in the detection of lymphatic metastasis; however PET/CT may have a future role as a screening tool for malignancy.

Diagnosis, Differential↗
PubMed2006

Salinity-induced survival strategy of Vibrio cholerae associated with copepods in Cochin backwaters.

The occurrence of Vibrio cholerae in water, sediment and copepods was studied over a wide range of salinity using conventional and polymerase chain reaction (PCR) techniques in the Cochin backwaters. V. cholerae occurred either as culturable or non-culturable form in this tropical estuary. During the pre monsoon period when high salinity prevailed (35.5psu) V. cholerae was associated with copepods only in non-culturable form, but with the onset of monsoon when lower salinity prevailed, copepod-associated-V. cholerae reverted back to culturable form. The optimum salinity range for culturability was found to be 15-20psu. This points to the fact that salinity is a major factor that which influences V. cholerae's culturability and its association with copepods in Cochin backwaters.

Adaptation, Physiological↗
PubMed2006

Probability of an egg cracking during packing can be predicted using a simple non-destructive acoustic test.

1. The aim of this investigation was to test the predictive power of the dynamic stiffness measurement to identify eggs which are most likely to crack under field conditions. 2. A representative sample of eggs (n = 1660) was collected from the front of the cages in a commercial battery unit. Egg weight, % damping and dynamic stiffness (Kdyn) were recorded using an acoustic crack detection device. Intact eggs were marked and replaced in the front of the cages. These eggs were subsequently passed through online collection, grading and packing machinery, along with a volume of unmarked eggs. At the end of packing the acoustic test was repeated on the marked eggs, and these were subsequently categorised as being either intact (0) or cracked (1). 3. A logistic regression of the probability of cracking vs Kdyn revealed that as the Kdyn measurement decreases below 15,000 N/m there is a rapid increase in the probability that an egg will crack during routine handling. 4. Additional variables (visit, egg weight,% damping and position in the house (battery [1 to 7], side [1, 2] and tier [1 to 8]) were also fitted to the model but only egg weight, visit and tier effects significantly improved the model fit. 5. This study confirms that the dynamic stiffness measurement can predict the probability of an egg cracking in the field and with high precision. As this measurement also has a high heritability, it could be incorporated into breeding programmes, where it would offer an excellent method to improve eggshell quality and reduce the incidence of cracked eggs.

Acoustics↗
PubMed2005

Heritability and genetic correlation of measurements derived from acoustic resonance frequency analysis; a novel method of determining eggshell quality in domestic hens.

Cracked eggshells result in economic loss and provide a route for pathogenic organisms to enter the egg. Genetic factors that contribute to shell strength are likely to decrease the risk that an egg will crack when subject to insult. A novel measurement, the dynamic stiffness of the eggshell (Kdyn) was examined to determine if it might be used in the genetic selection of hens with improved eggshell characteristics. The measurement is determined from acoustic resonance frequency analysis. The estimates of heritability for the novel measurement of Kdyn were moderately high and ranged from 0.33 to 0.53 depending on the model used for the estimation. The estimates of genetic correlation of Kdyn with eggshell breaking strength (0.49) and static stiffness (0.57) were positive and relatively large as expected. There was a small negative genetic correlation between Kdyn and egg production from 26 to 50 weeks of age (-0.19) and a moderate one from 58 to 74 weeks of age (-0.36). The moderate heritability and relative independence of Kdyn indicates that this measurement could be used successfully in a breeding programme to improve shell quality and to reduce the incidence of cracks.

Animals↗
PubMed1999

Ribosomal internal transcribed spacer 2 (ITS2) exhibits a common core of secondary structure in vertebrates and yeast.

Molecular mechanisms of ITS2 processing, a eukaryotic insertion between the 5.8S and LSU rRNA, remain largely elusive even in yeast. To delineate ITS2 structural and functional features which could be common to eukaryotes, we first produced phylo-genetically supported folding models in the vertebrate lineage, then tested them in deeper branchings and, more particularly, among yeasts. ITS2 comparisons between four Teleostei, a Chondrichthyes specimen and two jawless organisms have revealed a common folding architecture in four to five domains of secondary structure emerging from a preserved structural core. This folding, largely reminiscent of ITS2 architecture in mammals, is also preserved in amphibia and in chicken, despite dramatic sequence variations. Preferential conservation is located around a central loop and at the apex of a long stem in the ITS2 3'-half. Interestingly, these two independent structural features contain, respectively, the 3'-ends of the two transient rRNA precursors 8S and 12S RNA identified in mammals, suggesting a preservation of these intermediates of processing over the entire vertebrate group. Surprising similarities between the vertebrate ITS2 folding shape and that of invertebrates as well as protista have made intriguing the significant differences from the yeast model. A detailed comparative analysis including four relatively close species and Schizosaccharomyces pombe, a deep yeast branching, has revealed an alternative phylogenetically supported four-domain folding presenting strong similarities to the vertebrate model. Remarkably, the two best conserved regions of vertebrates have unambiguously preserved counterparts which are also sites for internal processing in yeast. Therefore, molecular mechanisms involved in ITS2 excision in vertebrates and yeast might be more closely related than currently believed and might require a very similar trans -acting machinery.

Animals↗
PubMed1999

Evolutionarily conserved structural features in the ITS2 of mammalian pre-rRNAs and potential interactions with the snoRNA U8 detected by comparative analysis of new mouse sequences.

Mechanisms of ITS2 excision from pre-rRNA remain largely elusive. In mammals, at least two endonucleolytic cleavages are involved, which result in the transient accumulation of precursors to 5.8S rRNA termed 8S and 12S RNAs. We have sequenced ITS2 in four new species of the Mus genus and investigated its secondary structure using thermodynamic prediction and comparative approach. Phylogenetic evidence supports an ITS2 folding organized in four domains of secondary structure extending from a preserved structural core. This folding is also largely conserved for the previously available mammalian ITS2 sequences, rat and human, despite their extensive sequence divergence relative to the Mus species. Conserved structural features include the structural core, containing the 3' end of 8S pre-rRNA within a single-stranded sequence, and a stem containing the 3' end of the 12S pre-rRNA species. A putative, phylogenetically preserved pseudoknot has been detected 1 nt downstream from the 12S 3' end. Two long complementarities have also been identified, in sequences conserved among vertebrates, between the pre-rRNA 32S and the snoRNA (small nucleolar RNA) U8 which is required for the excision of Xenopus ITS2. The first complementarity involves the 5.8S-ITS2 junction and 13 nt at the 5' end of U8, whereas the other one occurs between a mature 28S rRNA segment known to be required for ITS2 excision and positions 15-25 of snoRNA U8. These two potential interactions, in combination with ITS2 folding, could organize a functional pocket containing three cleavage sites and key elements for pre-rRNA processing, suggesting a chaperone role for the snoRNA U8.

Animals↗
PubMed1997

Comparison and application of ribosome spacer DNA amplicon polymorphisms and pulsed-field gel electrophoresis for differentiation of methicillin-resistant Staphylococcus aureus strains.

Analysis of sequences in the fragments of the 16S-23S rRNA intergenic spacer region by the ribosome spacer PCR (RS-PCR) can differentiate strains of methicillin-resistant Staphylococcus aureus (MRSA). We compared this technique with pulsed-field gel electrophoresis (PFGE) for typing MRSA strains and its application during an investigation of an outbreak. A total of 180 isolates of MRSA collected from various hospital laboratories within the United Kingdom and elsewhere were typed by PFGE and RS-PCR. PFGE identified 17 different types among the 180 strains examined, and RS-PCR generated 13 different types. PFGE could detect minor genetic variations among the isolates and could identify the variants which were not discriminated by RS-PCR. Four unique strain types detected by PFGE were not detected by RS-PCR. When applied to typing the outbreak-related strains from the vascular surgery unit at the General Infirmary at Leeds, the results of RS-PCR were identical to those of PFGE. Our results have shown that RS-PCR is a rapid, inexpensive technique that is highly reproducible and almost as discriminatory as PFGE for typing MRSA isolates and should be useful in the local investigation of MRSA outbreaks.

DNA, Bacterial↗
PubMed1992

Structure of the differentially expressed mouse U3A gene.

Two markedly different forms of U3 RNA are present in mouse, the relative abundance of which largely depends upon the tissues. In all cases studied so far, the more abundant form is U3B, encoded by four previously characterized genes. We report here the isolation and analysis of the unique gene encoding the U3A variant, which completes the characterization of the mouse U3 multigene family. Comparisons with rat U3 genes indicate that the diversification of the A and B forms has predated the mouse/rat separation. The two forms of U3 RNA are submitted to similar, but not identical, primary and secondary structure constraints. As for the sequences flanking the RNA coding region, similar observations emerge for both types of genes: for each type, the 5' flanks are strongly conserved between mouse and rat, over at least the proximal 500 bp, whereas only about 30 bp of proximal 3' flanks are preserved, which include a signal for the formation of vertebrate U small nRNA 3' end. By contrast the 5' flanks of the two types of genes diverge extensively from each other, either in mouse or in rat, and could be involved in the differential expression of the two forms. Even over the few conserved motifs thought to be involved in the basic transcriptional control of vertebrate U small nRNA genes, the A and B forms of U3 genes exhibit specific differences maintained in the two rodent species.

Animals↗
PubMed1989

A very risky business. Medical professionals are demanding more effective AIDS protection for themselves.

Physicians, nurses and other health-care workers have always been willing to risk exposure to infectious diseases; it goes with the territory. But AIDS is in a grim category all by itself--a contagious illness that, so far, is almost always fatal. Today many health professionals no longer feel safe on the job--and they're demanding better protection for themselves.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Structure of the 5'-external transcribed spacer of the human ribosomal RNA gene.

We report the complete nucleotide sequence of the 3627 bp long 5'-external transcribed spacer (ETS) of a human ribosomal RNA gene. This sequence exhibits only very limited homologies with its mouse counterpart, the only other mammalian specimen analyzed so far. It has very peculiar compositional characteristics, with a highly biased base content (very rich in G + C, very poor in A) and also some very strong dinucleotide preferences. Interestingly, these specific features are shared by the mouse sequence, despite the extensive sequence divergence, and also apply to the other transcribed spacers of mammals indicating that a common and strong structural constraint is exerted on all these regions of the ribosomal gene. An outstanding secondary structure can be formed within the human ETS RNA, which could have a significant role in preribosome assembly.

Animals↗
PubMed1989

Clones containing variant forms of complete human rRNA genes. Characterization and sequence of their transcription initiation region.

In order to assess the extent of structural heterogeneity among ribosomal genes in the human genome, several cosmid clones, each containing an entire transcription unit, have been isolated and analyzed. Five cloned genes were recognized as structurally different from each other to some extent, either within the transcription unit or in its immediate vicinity. The sequence of a 1.2 kb region encompassing the transcription start site has been determined for the five cloned genes. Point differences among the genes are observed at five nucleotide positions within the analyzed portion of the 5' external transcribed spacer of the ribosomal gene. Moreover, upstream from the transcription start site, a unique difference is observed with the absence from the three genes of a 19-nucleotide long stretch which is present in the two other variant gene forms.

Base Sequence↗
PubMed1988

Gynecologic imaging: comparison of transabdominal and transvaginal sonography.

The sonographic findings in 200 patients who underwent concurrent transabdominal and transvaginal pelvic ultrasound were reviewed. The sonographic techniques were compared for image quality, completeness of anatomic detail depicted, and unique diagnostic information. Transvaginal image quality was better in 79%-87% of scans; transabdominal image quality was better in 3%-5% of scans; images of both techniques were equally good in 10%-18% of scans. The techniques provided equivalent diagnostic information in 60%-84% of cases. Transvaginal sonography was particularly helpful when exclusion of ectopic pregnancy was the clinical concern. Individual organs and fine structures were better seen transvaginally, but the regional survey offered by the transabdominal full-bladder approach remains necessary to provide anatomic orientation, particularly when the patient has not been studied previously.

Adolescent↗
PubMed1988

Endometrial abnormalities: evaluation with transvaginal sonography.

The value of transvaginal sonography in detecting gynecologic disease currently is being defined. To evaluate transvaginal depiction of the endometrium, transvaginal sonograms were compared with conventional transabdominal scans in 29 patients whose sonograms revealed endometrial abnormalities. The two techniques were compared for image quality and ability to provide unique diagnostic information. Sonographic findings included fluid collections (16), thickened and/or echogenic endometria (10), endometrial irregularities (two), and echogenic foci (two). Clinical diagnoses included early intrauterine pregnancies (five), pseudogestational sacs of ectopic pregnancy (one), intrauterine contraceptive devices (two), endometrial carcinoma (one), and intrauterine synechiae with amenorrhea (Asherman syndrome) (two). In most cases (77%), diagnostic information was obtainable by either transabdominal or transvaginal sonograms, although in 23% transvaginal scanning provided unique diagnostic information not available with the transabdominal technique. In no case did transabdominal sonography contribute diagnostic information not provided transvaginally. The quality of the transvaginal image was judged to be better than that of the transabdominal image in 63% of cases; image quality was the same in 33% of cases and worse in 3% of cases. The results show that transvaginal sonography is often superior to transabdominal scanning in the evaluation of endometrial abnormalities. Transvaginal sonography may be the preferred technique in these cases.

Adolescent↗