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Biomedical subjects

M Riley

Publications and source records attributed to M Riley.

At least 145 records · Page 8Linked to original sources
PubMed1973

The reaction of protein amino groups with methyl 5-iodopyridine-2-carboximidate. A possible general method of preparing isomorphous heavy-atom derivatives of proteins.

1. The synthesis of methyl 5-iodopyridine-2-carboximidate and its reaction with amino groups of model compounds and performic acid-oxidized insulin are described. The reagent was designed to introduce heavy atoms into specific sites in proteins. 2. Specific reaction with the amino groups of oxidized insulin can be achieved under reasonably mild conditions giving rise to the corresponding N-monosubstituted amidines. 3. The extent of reaction of this reagent with protein amino groups can be readily determined by difference spectroscopy. Modification of lysine residues inhibits tryptic cleavage at such residues, and this can be of assistance in establishing the site of modification in the primary structure. 4. Evidence is presented to show that methyl 5-iodopyridine-2-carboximidate can react specifically, at pH5.0, with the aromatic amino group of 3-amino-l-tyrosine; the final product of this reaction is a 2-arylbenzoxazole. 5. The use of this reagent as a general method for preparing heavy-atom isomorphous derivatives of proteins is discussed.

Amidines↗
PubMed1970

The reversible reaction of protein amino groups with exo-cis-3,6-endoxo-delta-tetrahydrophthalic anhydride.

1. The reaction of exo-cis-3,6-endoxo-Delta(4)-tetrahydrophthalic anhydride with amino groups of model compounds and lysozyme is described. 2. Reaction with the in-amino group of N(alpha)-acetyl-l-lysine amide gives rise to two diastereoisomeric products; at acid pH the free amino group is liberated with anchimeric assistance by the neighbouring protonated carboxyl group with a half-time of 4-5h at pH3.0 and 25 degrees C. 3. The amino groups of lysozyme can be completely blocked, with total loss of enzymic activity. Dialysis at pH3.0 results in complete recovery of the native primary and tertiary structure of lysozyme and complete return of catalytic activity. 4. The specificity of reaction of this and other anhydrides with amino groups in proteins is discussed.

Amino Acids↗
PubMedDate not supplied

Cardiopulmonary exercise testing in the pre-operative assessment of patients for repair of abdominal aortic aneurysm.

We have investigated the value of cardiopulmonary exercise testing in the pre-operative assessment to patients for abdominal aortic aneurysm repair. Thirty-six patients were entered into the study. All had a pre-operative clinical assessment and investigations including chest radiograph, electrocardiograph, spirometry and echocardiogram with measurement of left ventricular ejection fraction. Each patient performed a symptom limited treadmill exercise test using a STEEP protocol with on-line measurement of respiratory gas exchange. Patients were followed up for 12 months post-operatively by review of casenotes. Thirty out of 36 patients had surgical repair of abdominal aortic aneurysm. There was 1 death in the perioperative period and 2 deaths in the following 12 months. Seven other patients suffered post-operative complications. There were no significant differences in left ventricular ejection fraction, spirometry and peak achieved oxygen consumption (PVO2) between those patients who died or who had post-operative complications and those who had not. However, PVO2 < 20 ml/min/kg was found in 70 per cent of patients who had complications compared with 50 per cent of those who had not. Also 4 patients considered medically unfit for surgery all had PVO2 < 20 ml/min/kg. Cardiopulmonary exercise testing with measurement of PVO2 may be helpful in identifying patients more at risk of post-operative complications but should not be used in isolation without through clinical assessment.

Aged↗
PubMedDate not supplied

Validation study of the Victorian Birth Defects Register.

OBJECTIVE: To determine whether there has been an improvement in ascertainment of birth defects cases ('case validity') by the Victorian Birth Defects Register (BDR) since an earlier study (conducted in 1993), to ascertain the accuracy of registered data ('item validity') and to investigate another possible source of notification. METHODS: The medical records were reviewed of 500 children born after 1 January 1993 who were consecutively admitted after 1 January 1999 to two paediatric teaching hospitals in Victoria. In addition, records of 200 children referred to a clinical genetics service were reviewed for children born after 1 January 1993 and who were seen in two periods: 2 months after 1 January 2001 and 2 months after 1 January 2002. The records from the hospitals and clinical genetics service were reviewed separately to determine whether children recorded as having a birth defect had previously been notified to the BDR. RESULTS: Twenty percent of the hospital records related to a child with a birth defect, as did 70% of the clinical genetics service records. Overall case validity for birth defect cases from the hospitals was 88%. There was 100% ascertainment for three of five categories. Sixty per cent of birth defects cases from the clinical genetics service had been notified to the BDR. When all diagnoses in matched cases were considered, item validity was 54%, however, if only primary diagnoses were included then 92% of cases had the same diagnosis. CONCLUSIONS: Overall case validity from the two paediatric teaching hospitals has significantly improved since our previous study. The addition of an extra data source from a clinical genetics service would identify new cases, particularly genetic disorders and developmental delay, as well as adding new diagnoses to existing ones. This study has highlighted the need to improve item validity, perhaps through routine education for all coders and notifiers on the inclusion and exclusion of specific associated conditions when notifying major birth defects.

Age Factors↗
PubMedDate not supplied

Expression of scaffolding, signalling and contractile-filament proteins in human myometria: effects of pregnancy and labour.

Successful parturition requires the co-ordination of numerous myometrial signalling events to allow for timely and efficient uterine contractions. Late pregnancy and labour onset in humans may be associated with changes in the expression of myometrial proteins implicated in such uterine contractile signal integration. Accordingly, in myometria from non-pregnant women and pregnant women, not in labour or in labour, we examined the content of putative plasmalemmal scaffolding proteins (caveolin-1 and -2) and compared these to the proportions of signal transducing rho-associated kinases (ROKalpha and beta) and contractile filament-associated proteins alpha-actin, myosin regulatory light chain (MLC(20)) and h-caldesmon. There was no effect of pregnancy or labour on the proportion of caveolin, ROK betaor alpha-actin. However, pregnancy was associated with a decrease in ROKalpha and MLC(20) such that ROK alpha: alpha-actin and MLC(20): alpha-actin ratios were reduced compared to myometria of non-pregnant women. In contrast, h-caldesmon was up-regulated in pregnancy resulting in an elevated h-caldesmon: alpha-actin ratio. There were, however, no further significant changes in ROK alpha, MLC(20) or h-caldesmon expression with spontaneous or oxytocin-induced labour. These data suggest that the mechanism(s) integrating myometrial signalling events with the onset of human labour does not involve differential alterations of the cellular expressions of caveolins, ROK, alpha-actin, MLC(20) or h-caldesmon.

Calmodulin-Binding Proteins↗