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Biomedical subjects

H R Matthews

Publications and source records attributed to H R Matthews.

At least 145 records · Page 8Linked to original sources
PubMed1982

Synchronisation of motor firing by vibration during stretch evoked responses of the human wrist flexors.

The wrist was rapidly dorsiflexed while the flexor muscles were being vibrated at 120 Hz. During both the M1 and the M2 responses the EMG showed a series of waves at the vibration frequency. When the vibration was turned off after overlapping with the stretch for only three to four cycles these EMG waves ceased about 30 ms later. Spinal reflexes are thus shown to continue to influence the discharging motoneurones throughout the human M2 "long-latency" response.

Electromyography↗
PubMed1982

Irradiation-induced motor disorder of the oesophagus.

This case report describes the late development of an achalasia-like disturbance of oesophageal motility following irradiation to the neck for a pharyngeal lymphosarcoma. The radiological, manometric and endoscopic findings are recorded as well as laboratory investigations showing evidence of complete vagal denervation.

Esophageal Diseases↗
PubMed1980

Acetylation of histone H4 and its role in chromatin structure and function.

Histone h4 is a highly conserved structural component of the nucleosome subunit of chromatin. The activation of chromatin is accompanied by changes in structure which may be caused by histone modification or by interactions of specific non-histone proteins, or both. Histone H4 can be modified by acetylation and this modification has been correlated with chromosome assembly and with transcription. We have now tested these correlations by studying H4 acetate content as a function of the cell cycle using the naturally synchronous cell cycle in Physarum polycephalum. The results show two clear correlations: (1) tetra-acetylated H4 correlates with transcription; (2) highly acetylated H4 (2 to 4 acetates per molecule) is inversely correlated with H1 phosphorylation and initiation of chromosome condensation in prophase. The results are consistent with turnover of di-acetylated H4 during chromosome assembly in S phase.

Acetylation↗
PubMed1980

Cat satellite DNA. Isolation using netropsin with CsCl gradients.

The absence of centromeric bands in the karyotype of Felis catus is confirmed. It is also confirmed that no satellite band is visible in CsCl density gradients. However, a satellite is observed both by recentrifuging the fraction of the DNA that bands at high density in CsCl and by using netropsin to enhance the resolution of a CsCl gradient containing total F. catus DNA. The satellite, about 0.5% of total DNA, was isolated by repeated centrifugation in CsCl alone and in CsCl with netropsin. Netropsin was removed and a pure satellite DNA obtained. The reassociation kinetics (C0t1/2 less than 10(-3) M . s) show that the satellite is of the simple sequence type and hence a candidate for centromeric heterochromatin. Its cytological localisation awaits in situ hybridisation experiments.

Animals↗
PubMed1980

Palliation and survival in malignant oesophago-respiratory fistula.

Survival in the presence of malignant oesophago-respiratory fistula is usually limited to a few weeks. In this paper we describe our experience with 3 cases treated by retrosternal oesophagogastric bypass with oesophageal exclusion, and review the experience of previous authors using this and other forms of bypass. The results indicate that both survival and quality of life are considerably better with surgical bypass and exclusion than with any other form of treatment. Indeed, the survival times are frequently better than those achieved after palliative resection of oesophageal carcinoma without fistula. Retrosternal oesophagogastric bypass with oesophageal exclusion is recommended as a simple method of bypass for this condition.

Aged↗
PubMed1980

Hypoxaemia after left thoracotomy for benign oesophageal disease.

Arterial blood gases were measured before and after operation in 14 patients undergoing conservative oesophageal surgery via a left thoracotomy. All the patients had a preoperative partial pressure of oxygen (PO2) of greater than 10 kPa, and none gave a history of chronic respiratory disease. All exhibited a fall in PO2 values after operation, the mean maximum reduction being 31%. The overall pattern of hhypoxaemia was similar to that previously reported after pulmonary resection, and upper abdominal surgery, characterised by the greatest reduction in PO2 on the first two postoperative days, followed by a gradual return towards preoperative values. In addition, there was a marked similarity in the degree of hypoxaemia observed by Parfey et al and by ourselves. These findings are attributed to similar changes occurring in pulmonary function in both series of patients, caused at least in part by different factors associated specifically with the two surgical approaches involved. In our experience, left thoracotomy, even without pulmonary resection, is associated with significant postoperative hypoxaemia. Knowledge of this may assist in the selection of patients for surgery and in their subsequent management.

Adult↗
PubMed1978

Ribosomal genes in Physarum polycephalum: transcribed and non-transcribed sequences have similar base compositions.

The transcribed and non-transcribed sequences in Physarum polycephalum ribosomal DNA (rDNA) were separated by restriction nuclease digestion of pure rDNA and the products fractionated by zone sedimentation in sucrose gradients. The base compositions of the fragments were determined by analytical centrifugation in CsCl or in CsCl with netropsin. All the fragments had dA + dT contents in the range 44-48%. From the known sequence arrangement and transcription pattern of Physarum rDNA it was concluded that coding sequences, transcribed but non-coding sequences, and non-transcribed sequences all possess similar base compositions, contrary to the situation in many other systems. The thermal denaturation profile of Physarum rDNA is reported. It suggests the rDNA sequence is complex and supports the above conclusion of limited heterogeneity of base composition.

DNA↗
PubMed1978

The use of netropsin with CsCl gradients for the analysis of DNA and its application to restriction nuclease fragments of ribosomal DNA from Physarum polycephalum.

Netropsin binds to DNA in caesium chloride density gradients and reduces the density of the DNA. The DNA is saturated at a netropsin/DNA weight ratio of about 6 and the change in density, deltarho, at saturation is given by deltarho = -109 (dA + dT content)1.87 mg/ml for the six DNAs tested covering dA + dT contents from 0.28 to 0.69. At lower netropsin/DNA ratios the observed density shifts are consistent with a two-site model for netropsin binding to DNA. Netropsin approximately doubles the resolution of Physarum polycephalum nucleolar satellite DNA from main-band DNA. The fragments of P. polycephalum nucleolar satellite DNA obtained with the restriction endonuclease HindIII do not separate on CsCl gradients, even in the presence of netropsin, which shows that the transcribed and non-transcribed sequences in this DNA have similar nucleotide compositions.

Centrifugation, Density Gradient↗