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Biomedical subjects

J Spence

Publications and source records attributed to J Spence.

At least 37 records · Page 2Linked to original sources
PubMed1989

Purification and properties of the Escherichia coli heat shock protein, HtpG.

As a preliminary to the understanding of the function of the highly conserved Escherichia coli heat shock protein HtpG, the protein was purified and partially characterized. The htpG gene was subcloned into the inducible expression vector, pT7-6. Upon induction, the HtpG protein accumulated to approximately 30% of the total protein in the cell. A purification scheme was devised which involved column chromatography on DEAE-cellulose, hydroxylapatite, and Sephacryl S-200. The amino acid composition of the purified protein corresponded closely with the predicted amino acid composition derived from the DNA sequence, and the sequence of the 8 amino-terminal residues matched the predicted sequence exactly. The molecular weight of the denatured protein is 65,500 and the native molecular weight is 144,620, as calculated by using both the Stokes radius and the sedimentation coefficient. As the molecular weight predicted from the DNA sequence is 71,429, this indicates the HtpG protein is a dimer. The HtpG protein was found to be a phosphoprotein. Thus, HtpG is structurally similar to its eukaryotic homologue, hsp83, which is also a phosphoprotein and a dimer.

Amino Acids↗
PubMed1989

Site-specific variations in the biochemical composition of healthy sheep periodontium.

A topographical biochemical analysis of the periodontal soft tissues was carried out. The protein distribution in the tooth-supporting structures was determined from site by amino acid analysis and was compared with the collagen distribution in tissue protein, based upon hydroxyproline content. The biochemical composition of the periodontal ligament was heterogeneous but some specific patterns of protein and collagen distribution emerged. Protein concentration was highest at the gingival epithelium and adjacent to the cementum. Collagen concentrations were highest at the alveolar bone and below the junctional epithelium adjacent to the tooth. Such patterns may influence the way in which periodontal disease is propagated through the tissue.

Amino Acids↗
PubMed1989

Prospective study of nosocomial rotavirus infection in a paediatric hospital.

Hospital-acquired enteric infections, particularly those due to rotavirus, were investigated by studying 220 patients under 3 years of age who were admitted without gastroenteritis to two paediatric general medical wards during a 10 month period. Faecal specimens were collected within 48 h of admission and then daily until the patients were discharged. Samples were also collected after discharge if patients developed enteric symptoms within 2 days of discharge. Fourteen per cent (31 of 220) of patients acquired rotavirus infections while in hospital, 23% (seven of 30) excreted rotavirus only after discharge; 29% of patients infected with rotavirus were asymptomatic (nine of 31). Acquisition of rotavirus infection was most prevalent during the months May-August, with a prevalence of 34% (12 of 35) in May. Hospitalization was prolonged in those patients who acquired rotavirus (11.1 days compared with 8.0 days, P less than 0.05). This study highlights the importance of rotavirus as a cause of hospital cross-infection, particularly in the very young patient, and emphasizes the need for further assessment of factors involved in its acquisition. In order to determine correctly the incidence of hospital-acquired illness, it is essential to follow patients after discharge from hospital. This study reinforces the importance of developing preventive measures in order to reduce the frequency of this illness.

Australia↗
PubMed1989

Modulation of stability of the Escherichia coli heat shock regulatory factor sigma.

The heat shock response of Escherichia coli is under the positive control of the sigma 32 protein (the product of the rpoH gene). We found that overproduction of the sigma 32 protein led to concomitant overproduction of the heat shock proteins, suggesting that the intracellular sigma 32 levels limit heat shock gene expression. In support of this idea, the intracellular half-life of the sigma 32 protein synthesized from a multicopy plasmid was found to be extremely short, e.g., less than 1 min at 37 and 42 degrees C. The half-life increased progressively with a decrease in temperature, reaching 15 min at 22 degrees C. Finally, conditions known previously to increase the rate of synthesis of the heat shock proteins, i.e., a mutation in the dnaK gene or expression of phage lambda early proteins, were shown to simultaneously result in a three- to fivefold increase in the half-life of sigma 32.

Escherichia coli↗
PubMed1985

Characterization of the spo0A locus and its deduced product.

The highly pleiotropic stage 0 sporulation locus of Bacillus subtilis, spo0A, has been cloned in bacteriophage lambda, subcloned in plasmids, and sequenced. The locus was found to code for a protein of 29,691 Da. Analysis of the in vivo transcripts from this region by nuclease S1 protection experiments located the start and stop of transcription of the locus. The transcription start site was preceded by a promoter resembling sigma 37-dependent promoters. Two mutations originally assigned to a second locus, spo0C, in this region because of their weakly pleiotropic phenotypes were cloned and sequenced. The mutations were found to be different missense alterations in the same base of the 10th codon preceding the carboxyl end of the Spo0A protein. These results, along with the finding that mutations in the spo0A gene product [Hoch, J. A., Trach, K., Kawamura, F. & Saito, H. (1985) J. Bacteriol. 161, 552-555] suppress the requirement for spo0B, spo0E, and spo0F gene products in transcription from sigma 28-dependent promoters, suggest that the Spo0A protein interacts directly with the transcription machinery to effect the initiation of sporulation. The deduced amino acid sequence of the Spo0A protein was highly related to that of the OmpR regulatory protein of Escherichia coli.

Amino Acid Sequence↗
PubMed1983

Ultrasound diagnosis of situs inversus in utero. A case report.

A case of situs inversus diagnosed prenatally by ultrasonography is presented. The diagnosis was confirmed on ultrasound examination and radiography in the immediate postnatal period. Subsequent investigations and management are reported, and the incidence, aetiology and clinical features of situs inversus are briefly reviewed.

Adult↗
PubMed1983

Particles in small volume injections.

The level of particulate contamination in small volume injections has been examined using the light blockage (HIAC) and electrical sensing zone (Coulter counter) techniques, the HIAC system being found to be the more suitable. Particle counts on the same batch of injection showed a large and variable difference between the HIAC and the Coulter counter results, especially below 5 micron. None of the injections examined complied with the British Pharmacopoeia limits for particulates in large volume parenterals, suggesting the unsuitability of the limits for small volume parenterals.

Chemistry, Pharmaceutical↗
PubMed1981

Needle biopsy of tumors in the region of the third ventricle.

Twenty-six patients underwent needle biopsy of tumors in the area of the third ventricle. Operative mortality was zero, and the diagnosis was established in 23 of the 26 patients. There was no permanent neurological deterioration in any of the patients. Needle biopsy yields diagnostic information with small risk, and is particularly helpful in the posterior portion of the third ventricle where tumors are likely to be quite radiosensitive.

Astrocytoma↗
PubMed1979

Influence of nitroprusside on cerebral pressure autoregulation.

The authors studied 10 cats to assess the question of abolition of cerebral autoregulation attendant on the use of nitroprusside for hypotensive anesthesia. After the establishment of stable base line parameters, a continuous infusion of sodium nitroprusside was begun in a dose sufficient to maintain a mean systemic arterial pressure of 65 mm Hg. Infusion was continued for incremental periods of 30 seconds to 10 minutes, increasing the time of infusion by 30 seconds after each subsequent trial. At 10 seconds after the cessation of nitroprusside administration, intravenous dopamine was infused to raise the systemic arterial pressure to a mean of 100 mm Hg, and the subsequent response in intracranial pressure was recorded in each instance. In no animal was a loss of cerebral autoregulation noted when the nitroprusside infusion was maintained for 3 minute or less. When the infusion was maintained for 4 minutes or longer, cerebral autoregulation was lost in each animal, and the length of time to return of cerebral autoregulation correlated with the duration of nitroprusside infusion. Sodium nitroprusside disturbs the integrity of cerebral pressure autoregulation, and the onset and extent of this disturbance is a dose-dependent phenomenon.

Animals↗
PubMed1972

[Not Available].

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China↗