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D J Robinson

Publications and source records attributed to D J Robinson.

At least 73 records · Page 4Linked to original sources
PubMed1984

Effects of gonadotrophin-releasing hormone on testosterone secretion by fetal and neonatal rat testes in vitro.

Testosterone production by fetal (20.5 days) and neonatal (1-day-old) rat testes was measured to study the possible direct effect of gonadotrophin-releasing hormone (GnRH) on steroidogenesis in early development. Single gonads were incubated in the presence and absence of GnRH (10(-10) to 10(-6) M) or agonistic analogues (10(-11) to 10(-7) M). For comparison, some testes were incubated with ovine luteinizing hormone (0.001-0.01 microgram oLH1 NIH-LH-S20/ml of medium TC199. No clear evidence of stimulation by an agonist (10(-7) M) was seen with fetal testes, but the lowest concentration (10(-11) M) gave results suggestive of an inhibitory action. Similar experiments with neonatal testes showed stimulation. With the highest concentration of GnRH or agonist the amounts of testosterone produced were about 2-3-fold greater than from control testes. Greater quantities of testosterone were found with testes exposed to LH. Hourly sampling in one experiment showed that significant stimulation of testosterone secretion had occurred within the first hour with GnRH (10(-6) M). It was concluded that fetal-neonatal rat Leydig cells are responsive to GnRH.

Animals↗
PubMed1982

Genome reconstitution and nucleic acid hybridization as methods of identifying particle-deficient isolates of tobacco rattle virus in potato plants with stem-mottle disease.

NM isolates of tobacco rattle virus (TRV) are perpetuated by the larger genome nucleic acid (RNA-1) but do not produce nucleoprotein particles; their identification therefore presents special problems. Assays of the infectivity of nucleic acid extracts, and of previously frozen sap, suggested that such isolates occur in potato plants with stem-mottle disease. These isolates were identified by two tests. In the first, TRV nucleoprotein particles were produced in plants inoculated with a mixture of nucleic acid from diseased potato leaves and non-infective RNA-2 of an authentic culture of TRV, showing that the TRV genome had been reconstituted. In the second test, TRV RNA was identified in nucleic acid from diseased potato leaves by hybridization to 3H-labelled DNA complementary in nucleotide sequence to RNA-1 of the PRN strain of TRV. This cDNA test consistently identified TRV in stem-mottle affected potato plants grown in the glasshouse or in field crops. Although particle-producing isolates of TRV have been reported in potato, stem-mottle disease is apparently usually caused by infection with NM isolates.

DNA↗
PubMed1975

Revision of estimates of the molecular weights of tobravirus coat proteins.

The molecular weights of proteins from several tobacco rattle viruses (or tobraviruses) have been determined by electrophoresis with 'marker' proteins in acrylamide gels of different strengths. Plotting KR, a measure of the effect of varying the gel strength, against molecular weight gave a value of 23,000 +/- 2,800 for tobacco rattle virus (TRV) strain CAM and similar values for other strains of TRV and pea early-browning virus. A value of 21,700 +/- 700 was obtained for TRV strain PRN by sedimentation to equilibrium in 6 M guanidine hydrochloride. These estimates are similar to those made by a statistical reappraisal of published data on amino acid composition, and a value of about 22,000 is proposed for TRV coat proteins.

Molecular Weight↗
PubMedDate not supplied

Sensitivity and specificity of nucleic acid probes for potato leafroll luteovirus detection.

Complementary DNA (cDNA) probes, prepared by nick-translation or by oligolabelling of a 520 bp fragment representing residues 4741 to 5261 in the potato leafroll luteovirus (PLRV) sequence, were equally sensitive, with a detection limit equivalent to sap from about 600 micrograms of infected potato or Nicotiana clevelandii leaf tissue and to RNA from about 120 micrograms tissue. Increasing the concentration of oligolabelled probe gave similar results with shorter autoradiographic exposures, but also resulted in positive signals with sap extracts from healthy plants. In contrast, a complementary RNA (cRNA) probe made by in vitro transcription of the cDNA insert could be used at higher concentration without giving rise to reactions with healthy plant extracts, and had a detection limit equivalent to 5 micrograms tissue/spot. Five oligolabelled probes representing different regions of the PLRV genome detected PLRV equally well. A probe that represented a portion of the particle protein gene also detected beet western yellows luteovirus (BWYV), with which it has 69% nucleotide sequence homology, and an English strain of the RPV form of barley yellow dwarf luteovirus, and reacted weakly with extracts from plants infected with groundnut rosette assistor luteovirus or carrot red leaf luteovirus. Probes for regions on either side of the particle protein gene also detected RPV, but not any of the other luteoviruses tested, in agreement with earlier suggestions that RPV is more closely related to PLRV than are BWYV or the other luteoviruses tested. An attempt to improve the detection of weak heterologous reactions by using a cRNA probe was unsuccessful, perhaps because tests using cRNA are more affected by mismatching than tests using cDNA probes.

Chromosome Mapping↗
PubMedDate not supplied

Creatine kinase and its CK-MB isoenzyme: the conventional marker for the diagnosis of acute myocardial infarction.

Biochemical markers are commonly used for detection, diagnosis, and management of various diseases. Creatine kinase (CK) is an enzyme found in most tissues, and is the best known marker for the identification of acute myocardial infarction (AMI). We review the most common techniques used to quantify creatine kinase and its cardiac specific fraction, CK-MB. Electrophoresis, immunoinhibition, monoclonal immunoassay, and CK-MB isoform assays are considered for efficacy, sensitivity and specificity, and timeliness in the setting of acute non-traumatic chest pain. Limitations of the various techniques for identifying AMI are identified. Current recommendations for CK-MB panels, including combinations with other cardiac markers, are included.

Algorithms↗
PubMedDate not supplied

A new system for sternal intraosseous infusion in adults.

BACKGROUND: Intraosseous (IO) infusion provides an alternative route for the administration of fluids and medications when difficulty with peripheral or central lines is encountered during resuscitation of critically ill and injured patients. OBJECTIVE: To report the first 50 uses of a new system for emergency IO infusion into the sternum in adults, the Pyng F.A.S.T.1 IO infusion system. METHODS: Six emergency departments and five prehospital emergency medical services (EMS) sites in Canada and the United States provided clinical and/or research data on their use of the IO system in a pilot study of success rates, insertion times, and complications. Indications for use included adult patient, urgent need for fluids or medications, and unacceptable delay or inability to achieve standard vascular access. A basic data set was standardized for all sites, and some sites collected additional data. RESULTS: The overall success rate for achieving vascular access with the system was 84%. Success rates were 74% for first-time users, and 95% for experienced users. Failure to achieve vascular access occurred most frequently in patients (5 of 9) described subjectively by the user as "very obese," in whom there was a thick layer of tissue overlying the sternum. Mean time to achieve vascular access was 77 seconds. Flow rates of up to 80 mL/min were reported for gravity drip, and more than 150 mL/min by syringe bolus. Pressure cuffs were also used successfully, although fluid rate was controlled by clamping the line. Further research on flow rates is needed. No complications or complaints were reported at two-month follow-up. CONCLUSION: These early data indicate that sternal IO infusion using the new F.A.S.T.1 IO system may provide rapid, safe vascular access and may be a useful technique for reducing unacceptable delays in the provision of emergency treatment.

Adolescent↗
PubMedDate not supplied

In vivo fluence rate measurements during Foscan-mediated photodynamic therapy of persistent and recurrent nasopharyngeal carcinomas using a dedicated light applicator.

The objective of this study was to evaluate the performance of a dedicated light applicator for light delivery and fluence rate monitoring during Foscan-mediated photodynamic therapy of nasopharyngeal carcinoma in a clinical phase I/II study. We have developed a flexible silicone applicator that can be inserted through the mouth and fixed in the nasopharyngeal cavity. Three isotropic fibers, for measuring of the fluence (rate) during therapy, were located within the nasopharyngeal tumor target area and one was manually positioned to monitor structures at risk in the shielded area. A flexible black silicon patch tailored to the patient's anatomy is attached to the applicator to shield the soft palate and oral cavity from the 652-nm laser light. Fourteen patients were included in the study, resulting in 26 fluence rate measurements in the risk volume (two failures). We observed a systematic reduction in fluence rate during therapy in 20 out of 26 illuminations, which may be related to photodynamic therapy-induced increased blood content, decreased oxygenation, or reduced scattering. Our findings demonstrate that the applicator was easily inserted into the nasopharynx. The average light distribution in the target area was reasonably uniform over the length of the applicator, thus giving an acceptably homogeneous illumination throughout the cavity. Shielding of the risk area was adequate. Large interpatient variations in fluence rate stress the need for in vivo dosimetry. This enables corrections to be made for differences in optical properties and geometry resulting in comparable amounts of light available for Foscan absorption.

Adolescent↗