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Biomedical subjects

R G Roberts

Publications and source records attributed to R G Roberts.

At least 73 records · Page 4Linked to original sources
PubMed1994

Chlorine Dioxide for Reduction of Postharvest Pathogen Inoculum during Handling of Tree Fruits.

Alternatives to hypochlorous acid and fungicides are needed for treatment of fruit and fruit-handling facilities. Chlorine dioxide was evaluated and found effective against common postharvest decay fungi and against filamentous fungi occurring on fruit packinghouse surfaces. In vitro tests with conidial or sporangiospore suspensions of Botrytis cinerea, Penicillium expansum, Mucor piriformis, and Cryptosporiopsis perennans demonstrated >99% spore mortality within 1 min when the fungi were exposed to aqueous chlorine dioxide at 3 or 5 mug . ml. Longer exposure times were necessary to achieve similar spore mortalities with 1 mug . ml. Of the fungi tested, B. cinerea and P. expansum were the least sensitive to ClO(2). In comparison with the number recovered from untreated control areas, the number of filamentous fungi recovered was significantly lower in swipe tests from hard surfaces such as belts and pads in a commercial apple and pear packinghouse after treatment of surfaces with a 14.0- to 18.0-mug . ml ClO(2) foam formulation. Chlorine dioxide has desirable properties as a sanitizing agent for postharvest decay management when residues of postharvest fungicides are not desired or allowed.

Journal Article↗
PubMed1994

BPH: new guidelines based on symptoms and patient preference. The Agency for Health Care Policy and Research.

Benign prostatic hyperplasia (BPH) is the most common tumor in the aging human male. BPH is rarely a life-threatening condition, but it can affect the quality of an older man's life when it causes urinary symptoms. Several interventions are available for BPH: surgery, most often transurethral resection of the prostate (TURP); medication, including alpha blockers and 5-alpha reductase inhibitors; and balloon dilation. An appropriate option for many men is no active treatment but "watchful waiting." The common nature and cost of BPH and the range of available therapies stimulated the development of a guideline by a multidisciplinary panel sponsored by the federal Agency for Health Care Policy and Research (AHCPR).

Aged↗
PubMed1993

Direct diagnosis of carriers of point mutations in Duchenne muscular dystrophy.

In about one-third of patients with Duchenne/Becker muscular dystrophy, the causative mutation does not involve gross alterations in the structure of the dystrophin gene. Prenatal diagnosis and carrier detection for such families is therefore dependent on the indirect method of linkage analysis with polymorphic DNA markers, a method that is subject to error. The identification of point mutations in the dystrophin gene in six affected males enabled us to develop direct assays, based on the polymerase chain reaction, that are specific for each of the mutations. In all six cases, the assays allowed us to offer families accurate carrier testing and prenatal diagnosis.

Base Sequence↗
PubMed1993

Infidelity in the structure of ectopic transcripts: a novel exon in lymphocyte dystrophin transcripts.

Ectopic (or "illegitimate") transcripts have recently become popular as a means of facilitating the study of transcripts normally considered to have a pattern of expression restricted to one or a few tissues. It has been generally assumed that the structure of an ectopic transcript faithfully represents that of its tissue-specific counterpart. We describe here the inclusion of a novel exon in 50% of ectopic dystrophin transcripts from human peripheral blood lymphocytes. The novel sequence resembles a conserved region in the 3' untranslated region of members of the carcinoembryonic antigen gene family and lies within the first intron of the human dystrophin gene. This constitutes a significant departure from the expected in vivo splicing behaviour in an ectopic transcript and suggests that there may be exceptions to the assumption that ectopic transcripts are processed in a similar way to their tissue-specific counterparts.

Amino Acid Sequence↗
PubMed1993

Exon structure of the human dystrophin gene.

Application of a novel vectorette PCR approach to defining intron-exon boundaries has permitted completion of analysis of the exon structure of the largest and most complex known human gene. We present here a summary of the exon structure of the entire human dystrophin gene, together with the sizes of genomic HindIII fragments recognized by each exon, and (where available) GenBank accession numbers for adjacent intron sequences.

Chromosomes, Fungal↗
PubMed1993

Characterisation of the exon structure of the Fanconi anaemia group C gene by vectorette PCR.

A cDNA for Fanconi anaemia complementation group C (FACC) has recently been cloned. We have now isolated a yeast artificial chromosome clone containing the FACC gene, and used vectorette PCR to determine its exon structure. The 1674-nucleotide coding sequence of the gene is highly interrupted, and contains 14 exons ranging in size from 53-204 bp. All exon donor and acceptor splice sites fit well with consensus sequences. Knowledge of the FACC exon boundaries and adjacent intron sequences was used to design polymerase chain reactions for amplification of all 14 exons from genomic DNA. Characterisation of splice site mutations in Fanconi anaemia patients with abnormal FACC transcripts and screening of large numbers of patients for mutations by amplification of the coding sequence from genomic DNA will now be possible.

Base Sequence↗
PubMed1993

Protein truncation test (PTT) for rapid detection of translation-terminating mutations.

Currently available techniques used to recognize point mutations in genetic disease are time consuming and are capable of screening only small pieces of DNA. Moreover, they detect all sequence differences including phenotypically silent changes. Consequently, they are not convenient to analyse mutations in large, multi-exonic genes, where a large fraction of pathological point mutations arises from early termination, as is the case for the one third non-deletion/duplication cases of Duchenne Muscular Dystrophy. We have developed a rapid and sensitive method, the Protein Truncation Test (PTT). PTT is based on a combination of RT-PCR, transcription and translation and selectively detects translation-terminating mutations. We demonstrate its effectiveness to detect point mutations in DMD-patients and carrier females. PTT should be widely applicable diagnostically in any disease where early terminations contribute substantially to the disease cause.

Base Sequence↗
PubMed1993

Denervation impairs cutaneous microvascular function and blister healing in the rat hindlimb.

Skin sensory nerve nocifensor functions were investigated non-invasively in rats by measuring neurogenic inflammation and blister healing-rate after unilateral hindlimb denervation. Axon reflexes were evoked by transdermal iontophoresis of acetylcholine (ACh) or noxious electrical stimulation (TNS). Sodium nitroprusside (SNP) evoked direct dilator responses. Resultant changes in skin microvascular blood flux were measured by laser Doppler flowmetry. Compared with their sham-operated control limbs, denervation reduced inflammatory responses (ACh or TNS) by more than 85% and SNP responses by 28% (p < 0.05). Healing of dry-ice blisters raised on the hindpaw 14d post-denervation was significantly slower to complete healing (42d) than controls (26d) and initial inflammation was attenuated, confirming that innervation is important for inflammation and blister-healing.

Acetylcholine↗
PubMed1993

The role of skin nociceptive afferent nerves in blister healing.

Because sensory neuropeptides improve survival of critical skin and muscle flaps in rats, skin nociceptive sensory nerve function in blister healing was examined. Sensory nerve ablation by unilateral hindlimb denervation or cutaneous axon reflex enhancement by 14 days systemic nicotine treatment (5 mg kg-1 day-1) decreased and increased, respectively, peripheral motor functions of nociceptive (peptidergic) skin nerves. Effects on nociception were measured by a radiant heat tail-flick test. Axon reflex flares were evoked by transdermal iontophoresis of acetylcholine or noxious electrical stimulation under pentobarbitone 40 mg kg-1 anaesthesia. Resultant changes in cutaneous microvascular blood flux were measured non-invasively by laser Doppler flowmetry. In nicotine-treated rats compared with placebo-treated controls, acetylcholine-evoked axon reflex flare was enhanced by 240% (p < 0.01) without enhancement of electrically evoked flare. Thus, nicotine-sensitized nociceptors show stimulus specificity in their enhancement of neurogenic flare responses. No significant changes were seen in other endothelial-dependent or smooth muscle-dependent microvascular dilator responses. Nicotine-treated rats had prolonged tail-flick withdrawal latencies to noxious radiant heat stimuli compared with placebo-treated controls (p < 0.05), suggesting an antinociceptive or analgesic effect of nicotine-treatment. Neurogenic effects on wound healing rate were assessed by measuring the dimensions of standardized blisters twice daily. The blisters were raised on hindpaw glabrous skin using a constant weight and diameter of compressed dry ice pellet applied for 30 secs at constant force. Dry-ice blisters raised on the hindpaw 14 days post-denervation were significantly slower to heal completely (42 days) than controls (30 days: P < 0.05) and the surrounding inflammation was reduced. By contrast, nicotine-treated rats showed more rapid blister healing (25 days) than controls (30 days), seen only in the later phase after day 15. Finally, resting substance P release from blisters, after direct cutaneous nerve stimulation, appears to be enhanced in nicotine-treated rats. Thus nociceptive innervation appears critical for inflammation and rapid healing of blisters in rat skin. The data signal a possible important role for neuropeptides in these processes and question the function of nicotinic receptors on sensory nerves.

Animals↗
PubMed1993

Evidence for skin microvascular compartmentalization by laser-Doppler and photoplethysmographic techniques.

Indices of perfusion were obtained using commercial laser-Doppler instruments with differing wavelengths on metatarsal skin of sheep (which is abundant with AVAs) and compared with quantitative measurements of AVA and capillary blood flow using microspheres; an infra-red photoplethysmograph was also compared. The data provide physiological evidence that laser-Doppler instruments of longer wavelength sense to a greater depth, and our photoplethysmograph behaves similarly to a "near-infra-red" laser. Thus, we suggest that near-infra-red light, either laser-Doppler or photoplethysmograph, should be used to measure a parameter most representative of total local blood flow, and light of a very much shorter wavelength, probably green light, would allow more confidence in estimates of true capillary perfusion. Because the commonly used visible red light can, but does not necessarily detect deep AVA perfusion, the influence depending upon the magnitude of the AVA perfusion, measurements by an instrument based on such red light is difficult to define.

Animals↗