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N Robson

Publications and source records attributed to N Robson.

11 recordsLinked to original sources
PubMed1996

Heme stability in the human embryonic hemoglobins.

The three human embryonic hemoglobins undergo both monomolecular and nucleophile stimulated bimolecular oxidations. Azide acts as an efficient nucleophile for the oxidative process in which the three embryonic hemoglobins exhibit lower oxidation rates than the adult protein. The absolute rates of azide-induced oxidation together with the rates of spontaneous autooxidation correlate with the previously determined oxygen affinities of the embryonic hemoglobins. The pH dependence of the rates of oxidation and their chloride ion concentration dependence are discussed. Heme exchange to human serum albumin has been used to determine the relative binding constants for heme for each of the embryonic proteins. Rate data have also been employed to evaluate the tetramer-dimer equilibrium constant for each hemoglobin. Overall, the data indicate that the high oxygen affinity human embryonic hemoglobins are significantly less susceptible to anion-induced oxidation, and the heme groups in each of the embryonic globin proteins are more tightly bound than in the corresponding adult protein.

Adult↗
PubMed1996

Patterns of supradiaphragmatic metastases in testicular germ cell tumours.

The imaging and clinical findings of 31 patients with supradiaphragmatic nodal metastases from primary testicular germ cell cancers were reviewed. In 11 patients the primary testicular tumor was a seminoma, and in 20 a non-seminomatous germ cell tumour (NSGCT). The patterns of spread of these tumour types were compared. All patients had chest radiographs (CXR): 27 had chest computed tomography (CT). One patient with seminoma and eight with NSGCT (40%) had lung metastases. Mediastinal lymphadenopathy was seen on CT in seven patients with seminoma (64%) and in nine patients with NSGCT (45%). Neck lymphadenopathy was present in 10 of 11 (91%) patients with seminoma, and 13 of 20 (65%) patients with NSGCT. Neck disease co-existed with mediastinal disease in six of 11 (55%) patients with seminoma, but in only two of 20 (10%) patients with NSGCT (P=0.012). This study gives further supporting evidence for the relative importance of haematogenous spread in teratoma, and lymphatic spread in seminoma. The contiguous nature of disease spread from abdomen to chest and neck in seminoma is confirmed. In NSGCT, supradiaphragmatic spread is more random but tends to occur in the paraoesophageal and subcarinal groups.

Abdomen↗
PubMed1996

In vitro and in vivo assessment of urethral warming catheters for the transperineal cryoablation of prostatic carcinoma.

OBJECTIVE: To evaluate the two most common urethral warming catheters currently available for their effectiveness in preventing urethral injury in an animal model and thus during transperineal cryosurgery for the treatment of prostate cancer. PATIENTS, MATERIALS AND METHODS: The warming efficiency of the variable-diameter thin latex-balloon catheter (Cook, Australia) and the fixed-diameter PVC catheter (Candela, USA) were evaluated in a water-bath. A sheep model was then used for subsequent experiments to further evaluate the better catheter. The technique used for the insertion of the Cook catheter in a series of 33 patients treated with prostate cryosurgery is also described. RESULTS: In vitro, the Cook catheter was more effective (P < 0.01) than the Candela catheter in preventing localized cooling. In vivo, results in five animals showed that the urethral epithelium was viable in all sections that had been protected by the catheter and focally denuded or necrotic in those sections not protected, with each animal used as its own control (P < 0.01 Fisher's exact test). The 33 patients treated while using the Cook catheter had no subsequent complications. CONCLUSION: The urethral warming catheter currently in use for prostatic cryosurgery in Australia is more effective in vitro than its competitor and is effective in preventing urethral injury in vivo.

Catheterization↗
PubMed1996

Conformational relaxation and ligand binding to singly reduced human embryonic haemoglobins.

The reaction of the three human embryonic haemoglobins with aquated electrons follows a complex set of steps in which a single haem centre undergoes both reduction and spin state changes coupled to slower protein relaxation events. In the presence of ferrous haem ligands the spin state changes are coupled directly to the ligand binding process. The rate constants for the reaction of the single reduced haem with O2 are similar to those determined by flash photolysis at high pH, whilst CO binding to the beta type haems is more rapid and the alpha haems less rapid than the analogous processes observed using photolysis techniques.

Adult↗
PubMed1995

The chloride effect in the human embryonic haemoglobins.

The interactions of the three human embryonic haemoglobins with chloride ions have been investigated. Each of the three embryonic haemoglobins exhibits a unique pattern of oxygen-affinity-dependence on chloride ion concentration. Human embryonic haemoglobin Portland (zeta 2 gamma 2) is found to be completely insensitive to chloride ion concentration. Haemoglobin Gower I (zeta 2 gamma 2) shows a small concentration dependence, whilst haemoglobin Gower II (alpha 2 epsilon 2) exhibits a dependence approaching that of the adult protein. The degree of co-operativity for each protein is essentially chloride concentration independent. The chloride-dependent and -independent components of the alkaline Bohr effects have been measured for each of the embryonic haemoglobins and compared with that of the adult protein. Both the chloride-binding data and the Bohr effect have been analysed in terms of the recently developed allosteric model proposed by Perutz [Perutz, Fermi, Poyart, Pagnier and Kister (1993) J. Mol. Biol. 233, 536-545].

Chlorides↗
PubMed1989

Effect of diluting propofol on the incidence of pain on injection and venous sequelae.

The effect of diluting propofol in 5% dextrose on the incidence of i.v. injection pain was studied in 100 adult patients. Severe injection pain occurred in 32% (16 patients) who received undiluted propofol, compared with 10% (five patients) who received dilute propofol. We concluded that the dilution of propofol significantly reduced the incidence of severe pain during injection without increasing postoperative venous sequelae.

Adult↗
PubMed1986

Plasma cholinesterase changes during the puerperium.

Changes in plasma cholinesterase activity during the puerperium were studied in 16 women who received epidural analgesia for labour followed by vaginal delivery, and in five women who underwent elective Caesarean section under epidural analgesia. A consistent fall in cholinesterase activity was demonstrated during the first 2 to 3 days post partum, followed by a rise to approximately normal nonpregnant values by the end of the puerperium. An additional patient who manifested prolonged paralysis following an emergency Caesarean section under general anaesthesia, including a suxamethonium infusion, was also studied. Possible mechanisms by which the transient decrease in cholinesterase activity is produced, and its clinical significance, are discussed.

Anesthesia, Epidural↗
PubMed1985

Casualty X-ray reporting: a student survey.

The radiographs of 337 patients attending the casualty department of a large teaching hospital were reviewed by two medical students of different seniority, a radiology registrar and a consultant radiologist. All the films had been examined initially by the casualty officer when the patient attended. The senior medical student reported the films more reliably than the junior student and was only slightly less reliable than the casualty officer. The radiology registrar was more accurate than the casualty officer where both reports could be compared with the consultant's opinion. Only rarely did the consultant radiologist disagree with the radiology registrar but in one patient this led to a change in management. The need for a radiological opinion has been confirmed.

Clinical Competence↗