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Biomedical subjects

R G Roberts

Publications and source records attributed to R G Roberts.

102 records · Page 6Linked to original sources
PubMed1988

Effects of topical capsaicin on normal skin and affected dermatomes in herpes zoster.

Hyperalgesia and allodynia, lasting for months or even years, occurs in the form of post-herpetic neuralgia in approximately 70% of adults previously infected with the varicella herpes zoster virus. The present study aimed at testing the analgesic desensitising actions and reversibility of repeated application of topical capsaicin on disordered polymodal nociceptors and peptidergic sensory fibres mediating warm and pain sensation. Cutaneous nociceptor desensitisation was measured using the Glasgow automated thermal threshold test (Medelec TTT). For normal subjects (n = 69) the mean forearm warm threshold was 0.15 +/- 0.07 degrees C and the cold threshold was 0.14 +/- 0.10 degrees C. A variable degree of partial desensitisation of herpes-affected skin was found in 15 patients with post-herpetic neuralgia before capsaicin treatment where the mean threshold elevation for warm detection was 1.19 degrees C and 0.7 degrees C for cold detection, compared with the corresponding normal skin. In preliminary studies of 15 patients with post-herpetic neuralgia, good pain relief averaging 30% or 77% occurred in the affected dermatome(s) after 3 to 4 weeks of 0.01% or 0.05% capsaicin cream respectively, applied 3-4 times daily. The warm thresholds, after chronic capsaicin treatment, increased between 0.1 and 7.60 degrees C, the average elevation being 3.69 degrees C. By contrast cold thresholds after capsaicin altered inconsistently and by only an average of 0.08 degrees C. The results suggest that elevation of the warm threshold may indicate the desensitisation achieved by capsaicin treatment of skin polymodal nociceptors. Cold detection, being dependent upon A-delta cold fibre function, is unaffected by capsaicin treatment. There was a poor correlation between pain relief and elevation of warm detection in response to capsaicin treatment. Generally, it was found that those patients with less initial desensitisation to warm detection as a consequence of post-herpetic neuralgia experienced better pain relief after capsaicin was applied. The method used permits determination of the minimum effective desensitising dose of capsaicin, enables patient compliance and progress to be monitored and should allow the prediction of patients likely to achieve the best response to treatment.

Administration, Topical↗
PubMed1987

HPLC determination of ferrochelatase activity in human liver.

A method utilizing HPLC to estimate ferrochelatase activity in human liver cells is presented. A partially purified homogenate of liver cells is incubated with mesoporphyrin IX and cobalt(II)ion. The ferrochelatase in the homogenate incorporates the cobalt(II)ion into the mesoporphyrin. After a fixed time (90 min) the porphyrins are extracted into an ethyl acetate-acetic acid mixture. The porphyrins are then separated using reversed phase HPLC with a mobile phase of methanol-acetonitrile-phosphate buffer pH 3.0 (200:60:30 v/v). The enzyme activity is estimated by measuring the rate of utilization of mesoporphyrin. The optimum pH and substrate concentration for the reaction have been determined.

Chromatography, High Pressure Liquid↗
PubMed1978

Serum deoxycytidylate deaminase activity after myocardial infarction.

The activity of serum deoxycytidylate deaminase, not hitherto reported to increase after myocardial infarction, has been investigated and the results have been related to other cardiac enzymes, including the MB fraction of creatine phosphokinase. Deoxycytidylate deaminase was found to increase to maximum activity on the third day after infarction. It may therefore be added to the list of 'cardiac enzymes.

Aspartate Aminotransferases↗
PubMedDate not supplied

Trial of labor or repeated cesarean section. The woman's choice.

OBJECTIVE: To develop recommendations for the preferred delivery method for a pregnant woman who underwent a previous low transverse cesarean section and who has no contraindications to labor. DATA SOURCES: MEDLINE searches and the references from retrieved articles yielded 759 citations. Search terms included trial of labor (TOL), trial of scar, vaginal birth after cesarean section (VBAC), and uterine rupture. STUDY SELECTION: Articles with primary outcomes data contrasting TOL and elective repeat cesarean section (ERCS) were analyzed. Studies from developing countries or before 1980 were excluded. DATA EXTRACTION: Data from 292 articles were extracted independently by at least 2 team members using a structured form. DATA SYNTHESIS: Outcome data were combined using commercially available software and are presented as absolute differences per 10,000, with 95% Bayesian confidence intervals. Maternal outcomes showed that TOL increased the risk for uterine rupture (23.9 [0.24%]); ERCS increased the risk for infection (522 [5.22%]) and bleeding (58.6 [0.59%]). Infant outcomes differed only for 5-minute Apgar scores of less than 7, which were more likely for infants whose mothers underwent TOL (85 [0.85%]). Other outcomes (eg, disability), patient preferences, and cost data did not lend themselves to meta-analysis and were examined separately. While two thirds of women desired TOL, one third preferred ERCS. Costs were 1.7 to 2.4 times greater for ERCS. CONCLUSIONS: A woman should be given information on both delivery methods and encouraged to undergo TOL, but her preference for ERCS should be respected.

Decision Making↗
PubMedDate not supplied

Direct diagnosis of carriers of Duchenne and Becker muscular dystrophy by amplification of lymphocyte RNA.

Rapid detection of deletion and duplication mutations that cause Duchenne and Becker muscular dystrophy was achieved in patients and carriers after amplification of small amounts of mRNA from peripheral blood lymphocytes. The entire coding region of the dystrophin mRNA was amplified in 10 sections by reverse transcription and nested polymerase chain reaction, and the products were directly visualised on acrylamide minigels with ethidium staining. Major structural gene mutations were identified by the appearance of a band of different size to that of the wild type. The altered band was readily detected in all patients and heterozygous relatives. This non-radioactive test of venous blood samples can be used for unambiguous and rapid identification of virtually all carriers of deletions or insertions within the dystrophin gene.

Base Sequence↗
PubMedDate not supplied

Protein truncation test (PTT) to rapidly screen the DMD gene for translation terminating mutations.

We have developed a rapid and sensitive method to screen the Duchenne muscular dystrophy (DMD) mRNA for translation terminating mutations by a combination of RT-PCR (Reverse Transcription and Polymerase Chain Reaction) and in vitro transcription/translation applied to white blood cell mRNA. This technique was termed the protein truncation test (PTT). Here we demonstrate the detection of a point mutation in a DMD patient and his mother, a carrier. The PTT can also be used for carrier detection when no patient material is available, or in the case of spontaneous mutations. We developed a protocol to screen the total coding region of the DMD gene in 5-10 PTT reactions. Furthermore, PTT could be of diagnostic value in any disease where premature terminations form a substantial part of the total mutation spectrum.

Base Sequence↗
PubMedDate not supplied

What have isotope studies in humans told us about the nutritional effects of acidosis in dialysis?

In order to understand how acidosis might predispose to loss of lean body mass it is important to recognise that body protein is in a dynamic state with a daily turnover of approximately 300 g of protein in a 60 kg man. This is significantly greater than the daily protein intake at a level of 1 g.kg-1.day-1. Loss of lean body mass occurs when the balance between whole body protein synthesis and breakdown is negative. Measurement of whole body protein turnover is possible using either boluses or primed constant infusions of isotopically labelled amino acids. Previously, a variety of in vitro and in vivo animal studies have shown that acidosis increases protein degradation and amino acid oxidation. Several research groups including our own have used amino acid tracer techniques to examine whether protein degradation is increased in vivo in human subjects with acidosis and chronic renal failure. The results from these studies have shown a remarkable concordance with increased protein degradation in all groups of patients studied. However, the results for protein synthesis have been more difficult to interpret, with only a few studies directly measuring the effects of acidosis on amino acid incorporation into protein.

Acidosis↗