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Biomedical subjects

R James

Publications and source records attributed to R James.

At least 145 records · Page 8Linked to original sources
PubMed1995

Protein-protein interactions in colicin E9 DNase-immunity protein complexes. 2. Cognate and noncognate interactions that span the millimolar to femtomolar affinity range.

The in vivo and in vitro cross-binding of the colicin endonuclease-specific immunity proteins toward the DNase domain of colicin E9 is described. In vivo cross-protection was tested by toxin plate assays in which bacterial cells overexpressing each immunity (Im2, Im7, Im8, and Im9) were challenged with the ColE9 toxin. Im9, the cognate immunity protein, renders cells completely resistant toward very high concentrations of the toxin (> 1 mg/mL), whereas the noncognate immunities display a spectrum of weaker cross-reactivities (< 0.01 mg/mL). The order of biological protection in this assay was Im9 >> Im2 > Im8, with Im7 providing no colicin E9 resistance. In vitro binding between the immunity proteins and the E9 DNase was analyzed by determining the dissociation constants for E9 DNase-Im protein complexes at pH 7.0 in the presence of 200 mM salt and at 25 degrees C. Stopped-flow fluorescence experiments suggest that both Im2 and Im8 associate with the E9 DNase by a two-step mechanism, in which the rate constants for both the bimolecular association (k1 = approximately 6 x 10(7) M-1 s-1) and the subsequent conformational change (k2 + k-2 = 4-5 s-1) are very similar to Im9 binding under the same conditions. Fluorescence chase experiments defined the dissociation rate constants for Im2 and Im8. The estimated values are 10(6)- and 10(8)-fold, respectively, faster than the off-rate for the Im9 protein.(ABSTRACT TRUNCATED AT 250 WORDS)

Bacterial Proteins↗
PubMed1995

Molecular analysis of three cases with hereditary motor and sensory neuropathy with myelin outfolding.

We describe three patients affected by a congenital motor and sensory neuropathy with excessive myelin outfoldings (MOs) [15]. Clinical and electrophysiological features supported the diagnosis of hereditary motor and sensory neuropathy. We previously reported a genetic study on these three patients, which failed to demonstrate either the duplication in chromosome 17p11.2 or the mutations at exons 1 and 2 of the peripheral myelin protein gene (PMP-22) and suggested an autosomal recessive (AR) inheritance. In this study we described the absence of the most common mutations, which characterized other forms of hereditary motor and sensory neuropathy (HMSN). In particular the absence of molecular changes in the PMP-22 gene definitively sets HMSN with MOs apart from the more common CMT1A, hereditary neuropathy with liability to pressure palsies (HNPP) and progressive sensory-motor polyneuropathy with tomaculous changes at sural nerve biopsy.

Charcot-Marie-Tooth Disease↗
PubMed1995

Nucleotide sequence encoding the di-haem cytochrome c551 peroxidase from Pseudomonas aeruginosa.

The nucleotide sequence of the gene encoding cytochrome c551 peroxidase from Pseudomonas aeruginosa is reported. The translated amino acid sequence differs from the sequence reported earlier by peptide mapping most significantly by the presence of a section containing an additional 20 residues. A number of minor differences are also evident. The new sequence translates to a protein containing 346 amino acids, the first 23 being typical of a hydrophobic leader peptide with a characteristic protease cleavage site.

Amino Acid Sequence↗
PubMed1995

Expression of Cdx-2 in the mouse embryo and placenta: possible role in patterning of the extra-embryonic membranes.

Three mouse homologues of the Drosophila homeotic gene Caudal (Cad) have been described. They are currently designated Cdx-1, Cdx-2, and Cdx-4. Cdx-1 and 2 are both strongly expressed in the adult mid- and hindgut, while Cdx-1 and 4 have been shown to be activated in the embryonic primitive streak. Using a polyclonal antibody against a fusion protein containing the amino terminal 109 amino acids of murine Cdx-2, we here describe the topographical location of the gene product from early cleavage to 12.5 days of embryonic development. Cdx-2 expression begins at 3.5 days and is confined to the trophectoderm, being absent from the inner cell mass. Subsequently, staining is located in the extra-embryonic ectoderm adjacent to the epiblast, but sparing the more superficially placed polar, as well as the mural trophoblastic cells. Continuing expression in the fetal membranes involves the chorion, the allantoic bud, and, at even later stages, the spongiotrophoblast. From 8.5 days, Cdx-2 begins to be expressed in embryonic tissues, principally (unlike Cdx-1) in the posterior part of the gut from its earliest formation, as well as in the tail bud and in the caudal part of the neural tube. Cdx-2 is, therefore, transcribed well before any other membrane of the Cad homologue group and of the related Hox-C group; its expression in the extra-embryonic membranes and in the hindgut reflects the phylogenetic relationship between the cloaca and the chorio-allantois and suggests the possibility that homeobox genes may be involved in placental development and/or patterning.

Animals↗
PubMed1995

Molecular diagnosis of hereditary neuropathy with liability to pressure palsies (HNPP) by detection of 17p11.2 deletion in Italian patients.

Hereditary neuropathy with a liability to pressure palsies (HNPP) is an autosomal dominant disorder characterized by recurrent pressure palsies generally precipitated by minor trauma; weakness and paraesthesia usually improve and recover completely in a few months. By Southern blotting and fluorescent in situ hybridization analysis we confirm the presence of a 17p11.2 deletion in familial and in isolated cases of HNPP, suggesting that molecular analysis of the 17p11.2 region could also be a reliable and non-invasive method of diagnosis in sporadic cases, where a correct diagnosis usually requires a nerve biopsy. Although HNPP is a mild disease and not all patients seek medical attention, a presymptomatic diagnosis is useful for assessing the risk during genetic counselling, due to the inheritance of the mutation.

Chromosome Deletion↗
PubMed1995

Progressive sensory-motor polyneuropathy with tomaculous changes is associated to 17p11.2 deletion.

We examined for the presence of 17p11.2 deletion, by Southern blotting and fluorescent in situ hybridization, 3 cases with progressive sensory-motor polyneuropathy and diffuse tomaculous changes at sural nerve biopsy. We demonstrated in all the cases the 17p11.2 deletion, previously reported in hereditary neuropathy with pressure palsy, an inherited disorder of the peripheral nervous system with similar pathologic changes but a different clinical phenotype. The molecular study of the 17p11.2 region should be considered as a non invasive method for differential diagnosis in selected cases of progressive polyneuropathy.

Aged↗
PubMed1995

Alcohol consumption and harm in two Western Australian regional centres.

The application of national or state alcohol harm-prevention programs at a regional level can be inappropriate. The involvement of local communities is critical if harm-prevention responses are to be sensitive to local needs. Unfortunately, individuals and agencies usually have little idea of the impact of alcohol at the local level. Alcohol consumption and harm data have been gathered for Geraldton and Bunbury, two regional centres of comparable size in Western Australia. The indices of harm presented include the nature and cost of hospital morbidity attributable to alcohol, and drink-driving charges. In Geraldton, the impact of alcohol tends to be acute and affects young adults, particularly young males. In Bunbury, the consequences of alcohol use tend to be more chronic in nature and affect older adults. These findings have been used to inform local harm-prevention responses, but more than that, this study is a practical example of how available data can be aggregated at a community level to illustrate local alcohol use and harm. This method can be replicated in any community that wants to understand better the effects of alcohol in its own local context.

Accidents, Traffic↗
PubMed1995

The effect of tendon compliance on in vitro/in vivo estimations of sarcomere length

The errors likely to result from using excised rigor muscles to determine in vivo sarcomere length ranges were calculated for mouse extensor digitorum longus muscle (EDL). This muscle was chosen because its very long tendon makes it particularly susceptible to errors arising from tendon compliance. By placing dissected limbs into different locomotory stances, and allowing them to go into rigor, the range of sarcomere lengths over which muscles operate in vivo can be determined, but it is subject to errors due to tendon compliance. A tendon compliance of 0.24 GPa and a muscle rigor stress of 35 kPa were determined, and these were used to correct the estimates of in vivo sarcomere length, under worst case conditions. The error introduced was very small: a reduction in sarcomere length of less than 0.5 %.

Journal Article↗
PubMed1995

General hospital services for attempted suicide patients: a survey in one region.

A survey of the general hospital services for attempted suicide patients in one Region indicated that most hospitals fell short of many of the standards contained in the Department of Health 1984 guidelines and the recently established Royal College of Psychiatrists guidelines, particularly with regard to active planning and monitoring of the service, involvement of non-medical clinical staff, availability of the service and the training of staff.

England↗
PubMed1995

Neuromuscular dysfunction following eccentric exercise.

This study examined the effects of exercise-induced muscle damage on tremor and proprioception components of neuromuscular function. Six male and six female volunteers (aged 18-30 yr) performed 50 maximal eccentric muscle actions using the forearm flexors of the nondominant arm. Forearm flexor tremor and perception of voluntary force and joint position were monitored to assess changes in neuromuscular function. Data were analyzed using REANOVA. Serum creatine kinase activity increased from a baseline value of 68 +/- 13 IU.l-1 to 2849 +/- 852 IU.l-1 5 d after exercise (P < 0.05). This was accompanied by prolonged impaired joint range of motion (P < 0.01) and reduced maximum strength (P < 0.01). Muscle soreness peaked 3 d postexercise (P < 0.01; Wilcoxon test). Tremor amplitude was increased (P < 0.01) until 48 h after exercise, whereas the power frequency spectrum was unaffected. Perception of joint position at elbow angles of 1.57 rad (P < 0.01) and 2.09 rad (P < 0.05) and perception of force (P < 0.01) were significantly impaired when the control arm acted as the reference. Joint positions were more accurately reproduced when the experimental arm acted as its own reference. The increase in tremor amplitude and loss of proprioceptive function in the days after damage-inducing eccentric exercise suggest significant impairment of neuromuscular function.

Adolescent↗
PubMed1995

Laparoscopic colon surgery: report of a series.

A multicenter retrospective study was performed of laparoscopic colon surgery. Thirty unselected patients underwent a variety of procedures including right hemicolectomy (11), sigmoid and left colectomy (7), takedown of sigmoid colostomies (8), low anterior resection (2), AP resection (1), and colotomy (1). The conversion rate from laparoscopic to open was 10 per cent. Comparisons were made between this group and institutional controls for cost and lymph node harvest. Operating technique is discussed. Lymph node harvest was comparable with open procedures. Postoperative length of stay averaged 8.3 days. Hospital costs were $11,010 compared with an institutional norm of $13,050. Major variations in costs were between institutions rather than surgeons or techniques and correlated as well with postoperative length of stay. An anatomically equivalent oncologic resection was able to be performed with an acceptable morbidity (24%) and mortality (0%).

Carcinoma↗
PubMed1995

Survey and critique of time and medical records.

Although medical records are an example of a temporal database application, they are not satisfactorily supported by existing temporal and non-temporal data models. A new model and corresponding algebra is needed that can support the requirements of medical records. In this paper we identify the requirements medical records impose on a temporal model and highlight the discrepancies in existing models in light of these needs. We conclude the paper with a brief outline of how we approach the development of an extendible, temporal model for supporting medical record-based applications.

Medical Records↗
PubMed1994

Sequential assignments and identification of secondary structure elements of the colicin E9 immunity protein in solution by homonuclear and heteronuclear NMR.

1H-1H, 1H-15N, and 1H-1H-15N multidimensional NMR spectroscopic studies of the 86 amino acid protein that provides immunity against the DNase action of colicin E9 are reported. Through a combination of 2D NOESY and TOCSY and 3D TOCSY-HMQC, NOESY-HMQC, and HMQC-NOESY-HMQC experiments, almost complete 1H NMR and backbone 15N NMR assignments have been obtained, and the secondary structure of the protein has been partially elucidated. Approximately 50% of the protein forms three helices. The specificity determining region of the DNase immunity protein, identified from previously reported biochemical studies to include residues 32-40, is helical, indicating that the protein-protein interaction involves residues from at least one helix.

Amino Acid Sequence↗
PubMed1994

Association of APC gene mutations and histological characteristics of colorectal adenomas.

Fifty-nine colonic adenomas and 6 hyperplastic colonic polyps were analyzed by single-strand conformation polymorphism analysis for mutations in the adenomatous polyposis coli gene (APC). Frameshifts and premature stop codons in at least one copy of APC were detected in 25 of these adenomas. Five adenomas carried 2 APC mutations. No mutations in APC were found in any of the 6 hyperplastic polyps. The detection of APC mutations increased with size and degree of dysplasia and in rectal as compared to colonic adenomas, although the association was not statistically significant. The frequency of detectable APC mutations was higher in tubulovillous and villous adenomas (10 of 13) than in tubular adenomas (15 of 45) (odds ratio, 6.67; 95% confidence limits, 1.39-41.83; P = 0.005). The significance of the association between the detection of APC mutations and a villous architecture was confirmed in multivariate analysis (relative risk, 6.67; 95% confidence limits, 1.54-28.8; P = 0.005). In conclusion, APC mutation plays a role in adenoma progression; its frequency is significantly higher in lesions with a more villous morphology.

Adenoma, Villous↗
PubMed1994

Structure of the murine homeobox gene cdx-2. Expression in embryonic and adult intestinal epithelium.

To gain insight into the mechanisms which govern cellular identity in the intestinal epithelium we have begun a detailed study of the murine cdx-2 homeobox gene. We isolated and sequenced both cDNA and genomic clones in order to define the open reading frame and mature transcript. A detailed analysis of cdx-2 transcript levels late in embryogenesis showed that they increased 6-7-fold at a time when the gut undergoes a major developmental transition. In the adult, cdx-2 was expressed in colon in a region-specific manner with transcripts some 5-fold more abundant in the cecum as compared with the rectum. In situ hybridization and immunohistochemical experiments showed cdx-2 transcripts and protein were present in all epithelial cells in the proximal colon irrespective of their degree of differentiation. In distal colon, however, transcripts were most abundant in undifferentiated cells at the bottom of crypts, whereas the highest protein levels were present in mature cells in the upper half of crypts. We conclude that cdx-2 is expressed specifically in gut epithelium where it is not restricted to a particular cell lineage. Rather, the rostrocaudal expression gradient suggests that it may play a role in specifying positional identity.

Amino Acid Sequence↗