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Biomedical subjects

A Mills

Publications and source records attributed to A Mills.

At least 73 records · Page 4Linked to original sources
PubMed1995

Tris-dependent oxidative DNA strand scission during electrophoresis.

The DNA of two Streptomyces species contains site-specific labile modifications. During gel electrophoresis the DNA can undergo Tris-dependent strand scission at the positions of these modifications. Our investigations into the nucleolytic activity which reacts with the modifications implicate a peracid derivative of Tris formed at the anode; the kinetics of production and decay of this activity were followed using both a DNA cleavage assay and a reduced methyl viologen assay to measure oxidant. Anode activation could be chemically mimicked by addition of peracetic acid to Tris buffers. We tested the DNA cleavage activity of several other compounds after anode or chemical activation; we used an analogue of Tris lacking a primary amine group and also several reagents known to promote DNA strand cleavage by amine-catalysis at abasic sites. Anode generation of oxidant could be detected for compounds containing either hydroxyl or carboxyl groups. However, DNA cleavage activity correlated with oxidant formation only for those compounds also containing primary amine groups. These results support a mechanism of DNA strand scission at modification sites via concerted peracid-mediated oxidative and amine-catalysed reactions. The novel finding of Tris-dependent formation of a long-lived reactive oxidant at the anode suggests that this compound is unsuited as an electrophoresis buffer for certain biological macromolecules.

Amines↗
PubMed1995

What is the relationship between perineal descent and anal mucosal electrosensitivity?

PURPOSE: Perineal descent is found in many patients with anorectal disorders. There is now substantial evidence against perineal descent causing damage to the motor axons in the pudendal nerves, but the sensory sequelae of perineal descent have been neglected. The purpose of this study was to establish the relationship between perineal descent and anal sensation. METHODS: Perineal position was determined in relation to the bony pelvis by means of defecating proctography. Anal mucosal electrosensitivity was determined by using a constant current generator. RESULTS: This study demonstrated significant correlations between perineal position at rest and sensitivity in each third of the anal canal in the study group overall. In women studied alone, there were significant correlations between perineal position at rest and at squeeze and anal mucosal electrosensitivity in each third of the anal canal. CONCLUSIONS: We propose that perineal descent traumatizes the pudendal nerves, damaging the large diameter sensory axons. This may be a precursor of motor axon damage or may correlate with the global pelvic sensory loss found in patients with perineal descent and fecal incontinence.

Adolescent↗
PubMed1995

Reporting simplified colonic transit studies using radionuclides: clinician friendly reports.

This study describes a graphic presentation of the results of a simplified segmental colonic transit model. This study requires three sets of images on three consecutive days after intake of indium-111 resin capsule at each time point. The per cent of ingested activity is calculated in each region of the colon and in the faeces. The program uses standard PC compatible graphic package, CorelDRAW (Corel Corporation). The report for the patients' notes consists of three schematic diagrams of colon with regions identified and a pot representing the faecal activity. The per cent of administered activity in each region and pot is both printed and represented by shades of grey (white representing 0% and black 100% activity), for each region and the pot. The distribution of activity is clearly seen at each time point and the report is presented on single A4 size sheet of paper. Using a simplified colonic study protocol it is possible to produce clinician friendly reports on a single sheet of paper.

Colon↗
PubMed1995

Precipitating causes of acid reflux episodes in ambulant patients with gastro-oesophageal reflux disease.

Previous studies of the mechanisms that precipitate acid reflux episodes have used short term hospital based measurements. A 24 hour pH and motility recording system, incorporating a sphincter monitoring device, has been developed to study naturally occurring acid reflux episodes in control subjects and patient groups with different grades of oesophagitis. Lower oesophageal sphincter relaxations related to episodes of acid reflux were common in control subjects (67% of episodes) but became more difficult to detect as the grade of oesophagitis increased (grade 0/1 - 67%, grade 2/3 - 35%, grade 4 - 13%). A variety of events that produced recognisable transdiaphragmatic pressure patterns were associated with acid reflux episodes. In control subjects 74% of acid reflux episodes were precipitated by belching but this mechanism became less evident as the grade of oesophagitis increased (grade 0/1 - 43%, grade 2/3 - 40%, grade 4 - 29%). Activities that produced a pressure gradient across the diaphragm became increasingly important as events precipitating acid reflux as oesophagitis became more severe (controls--2%, grade 0/1 - 15%, grade 2/3 - 11%, grade 4 - 22%). This study has shown the pressure events surrounding acid reflux in fully ambulant patients with gastro-oesophageal reflux disease.

Adult↗
PubMed1994

High-level expression of the human neurokinin-1 receptor in mammalian cell lines using the Semliki Forest virus expression system.

Human neurokinin-1 receptor cDNA was introduced into the pSFV1 Semliki Forest virus (SFV) vector and the in vitro transcribed RNA was electroporated into BHK cells with pSFV-Helper RNA. This procedure resulted in the packaging of a high-titer SFV-NK-1 virus stock containing approximately 5 x 10(9) infective units/ml. Infection of baby hamster kidney, COS-7, Chinese hamster ovary and human osteosarcoma cells yielded high levels of human neurokinin-1 receptor expression as assessed by [3H]substance P binding. The maximal receptor expression level obtained was 4 x 10(6) receptors/cell and studies of the post-infection time indicated that a high level of receptor expression was observed 10-24 h post-infection. The human neurokinin-1 receptor expressed in infected baby hamster kidney, COS-7 and Chinese hamster ovary cells was able to stimulate Ca2+ mobilization indicating functional coupling to guanine-nucleotide-binding proteins. The application of the Semliki Forest virus expression system will permit the rapid and efficient production of large quantities of receptor protein for both pharmacological and structural studies.

Animals↗
PubMed1994

Actin filament bundles are associated with fiber gap junctions in the primate lens.

A unique association between actin filament bundles and gap junctions in cortical fiber cells of human and monkey lenses was studied with thin-section electron microscopy and immunocytochemistry. Thin-section electron microscopy showed that distinct layers of filament bundles (approximately 55 nm thick) were consistently associated with fiber gap junctions (approximately 16 nm thick) from intermediate to deep cortical regions in both species studied. The filament bundle was composed of 6-8 nm microfilaments which lay along both cytoplasmic surfaces of the junction. Fluorescence microscopy revealed a patchy pattern of F-actin labeling along the fiber cell membranes in the intermediate and deep cortical regions of the lens. The size and distribution pattern of F-actin labeling appear to correlate well with those of filament bundles/gap junctions seen in thin-section electron microscopy. By immunoelectron microscopy, the anti-actin antibody was shown to be localized to filament bundles/gap junctions in the intermediate cortical fibers of human lens, indicating that filament bundles are F-actin in nature. The identical filament bundle/gap junction association was not found in other species examined, including rodent, bird and fish, by the same procedure, suggesting that an association between actin bundles and gap junctions has a special functional role in the primate lens. It is proposed that gap junction-associated actin bundles may provide added structural stability for the primate lens.

Actins↗
PubMed1994

Recombinant protein expression in a Drosophila cell line: comparison with the baculovirus system.

In this report, we compare two different expression systems: baculovirus/Sf9 and stable recombinant Drosophila Schneider 2 (S2) cell lines. The construction of a recombinant S2 cell line is simple and quick, and in batch fermentations the cells have a doubling time of 20 hours until reaching a plateau density of 20 million cells/ml. Protein expression is driven by the Drosophila Metallothionein promoter which is tightly regulated. When expressed in S2 cells, the extracellular domain of human VCAM, an adhesion molecule, is indistinguishable from the same protein produced by baculovirus-infected Sf9 cells. Additionally, we present data on the expression of a seven trans-membrane protein, the dopamine D4 receptor, which has been successfully expressed in both systems. The receptor integrates correctly in the S2 membrane, binds [3H]spiperone with high affinity and exhibits pharmacological characteristics identical to that of the receptor expressed in Sf9 and mammalian cells. The general implications for large scale production of recombinant proteins are discussed.

Animals↗
PubMed1994

Orphan seven transmembrane domain receptors: reversing pharmacology.

The application of molecular genetic approaches to the study of seven transmembrane domain receptors has allowed the cloning of many receptors for which the ligand is initially unknown. These are commonly referred to as 'orphan receptors', and several have subsequently proved to be important pharmacological targets. This article discusses how these receptor sequences were isolated, and presents some of the methods by which the corresponding ligands were identified. These examples are used to propose a rational approach for the study of further orphan receptors.

Amino Acid Sequence↗
PubMed1994

The economic consequences of malaria for households: a case-study in Nepal.

Increased attention has recently been paid to the impact of illness on the well-being of households in developing countries. This has been a particular theme in the case of malaria, but relatively little evidence is available on how households react to malaria and on its impact on expenditure and time allocation patterns. This paper reports the results of a study designed to investigate the economic consequences of malaria for households in Nepal. A household survey of malaria cases in two districts provided information on use of various sources of treatment, their cost to households, time lost by the person with malaria, the extent to which others inside or outside the household provided assistance with the normal work of the malaria patient, the time spent caring for a child with malaria and any financial losses associated with the malaria episode. Out-of-pocket expenditure on treatment differed greatly between the two districts, for reasons associated with the choice of public or private sources of treatment and the number of visits made per episode. The majority of households appeared to cope without great difficulty with the reduction in labour supply caused by a malaria episode, by drawing largely on the time of adult family members. Caution is advised in extrapolating the results to other situations, given the extent to which local factors are likely to influence the impact on households. Moreover, the findings relate to a situation where a malaria control programme is in place: a relatively greater impact per household would occur in the absence of control. However, it is argued that such surveys have value in informing health policy, particularly in relation to setting priorities and treatment policy.

Adolescent↗
PubMed1994

Characterization of the functional activity of dopamine ligands at human recombinant dopamine D4 receptors.

The human D4 dopamine receptor has been expressed in Sf9 insect cells where it appears to couple to endogenous G proteins. Increased guanine nucleotide exchange to G proteins is a reflection of receptor activation and can be followed using a [35S]GTP gamma S binding assay. By measuring D4 receptor stimulation of [35S]-GTP gamma S binding we have been able to characterize several dopaminergic compounds for their functional activity at this receptor. In Sf9 cells expressing the D4 receptor, dopamine, quinpirole, and dp-2-aminodihydroxy-1,2,3,4-tetrahydronaphthalene were all full agonists, whereas (-)-apomorphine appeared to be a partial agonist. No increase in [35S]GTP gamma S binding was observed for noninfected cells or cells infected with an unrelated sequence. The quinpirole-stimulated [35S]GTP gamma S binding could be inhibited by the antagonists clozapine, eticlopride, and haloperidol, and a Schild analysis of these data showed that all three compounds were acting as competitive antagonists of D4 receptors. The rank order of affinities derived from the Schild analysis correlated with that obtained from [3H]spiperone competition binding assays. In conclusion, we have shown that, using this assay system, it is possible to investigate functionally the pharmacology of a recombinant G protein-coupled receptor in the absence of any information regarding the eventual second messenger pathways involved.

Animals↗
PubMed1994

Total energy expenditure and energy intake in the pre-school child: a comparison.

In a cohort (n 81) of healthy children aged 1.5-4.5 years, measurements of energy intake and energy expenditure were compared. Energy intake was calculated following a 4 d weighed record completed by the mother or guardian of the child. Total energy expenditure was measured using the doubly-labelled water technique. Mean energy intake and expenditure in the cohort were 4773 kJ/d and 4928 kJ/d respectively. The mean relative bias between the techniques was 154 kJ/d. In the older children (3.5-4.5 years) the mean relative bias was only 37 kJ/d. At the population level the measurements of energy intake and energy expenditure were extremely close, and the study has provided sufficient confidence in weighed intake methodology for it to be used in a major nationwide study of dietary intake and nutritional status of children aged 1.5-4.5 years.

Age Factors↗
PubMed1994

The economics of vector control strategies for controlling tropical diseases.

This paper describes the techniques of economic evaluation and how they can help improve the efficiency of vector control strategies for controlling tropical diseases. The differences among the techniques are clarified, and the main components of each analytical approach are presented, as well as some of the major problems in their application. The historic evolution of the application of economics to vector control in developing countries is summarized, before analyzing some more recent studies that have explored some of the choices concerning vector control. The paper concludes with some recommendations for improving the quality and, therefore, the usefulness of studies.

Animals↗
PubMed1994

Financing mechanisms for village activities in The Gambia and their implications for financing insecticide for bednet impregnation.

The recent enthusiasm for impregnated bednets as a malaria control measure leaves unresolved the question of how to finance them. The National Impregnated Bednet Programme in The Gambia faced the question of how to obtain funds from villages to finance the cost of insecticide, but knew very little about current village fundraising for development purposes. A survey was conducted of such fundraising, and questions also asked about willingness to pay for insecticide and preferred means of paying. All 53 villages surveyed paid taxes/rates, but 34% of villages reported no voluntary fundraising. The most common reason for collecting money was for the maintenance of wells (40% of villages). Collective farming was used as a means of raising money in 32% of villages. There was some variation in the type and extent of fundraising by region and also by the predominant ethnic groups of the village. Villages with voluntary fundraising activities seemed to have well established collective mechanisms for agreeing on sums to be collected and their use, and for collecting and recording income and expenditure. Non-payment was rare, and misuse of funds was not reported. Respondents were asked how much compounds might be willing to pay for insecticide impregnantion: the most frequently cited maximum amounts were D5 and 10, and minimum D1 and 5 (D15 = 1 pound). The paper discusses payment options for insecticide, such as whether the village should be allowed to decide itself how to raise funds, and whether the payment should be made only by households with nets or by a village-wide mechanism such as collective farming.(ABSTRACT TRUNCATED AT 250 WORDS)

Agriculture↗
PubMed1994

Persistent right umbilical vein: sonographic detection and subsequent neonatal outcome.

OBJECTIVE: To review our experience with antenatal detection and subsequent neonatal outcome of fetuses with a persistent right umbilical vein. METHODS: In a prospective observational study, 33 cases of persistent right umbilical vein were detected during 15,237 obstetric ultrasound examinations performed after 15 weeks' gestation. RESULTS: Persistent right umbilical vein was detected at a rate of one per 476 obstetric ultrasound examinations. Six of 33 (18.2%) fetuses with a persistent right umbilical vein had additional important congenital malformations. CONCLUSIONS: Careful second- and third-trimester ultrasound examinations can detect a persistent right umbilical vein. When this particular anomaly is detected, a thorough fetal anatomic survey, including echocardiography, should be performed to rule out more serious congenital malformations.

Abortion, Eugenic↗
PubMed1994

Antenatal diagnosis of fetal pelvic kidneys.

OBJECTIVE: To review our experience with the antenatal detection and subsequent neonatal outcome of fetuses with a pelvic kidney. METHODS: A retrospective review of 25,551 obstetric ultrasound examinations performed after 16 weeks' gestation identified 13 cases of fetal pelvic kidneys (one per 1965 examinations). RESULTS: Three pelvic kidneys were dysplastic; the remainder appeared sonographically normal. Seven pelvic kidneys were measured; five were smaller than expected for gestational age. Associated anomalies were detected in three cases. CONCLUSIONS: Careful second- and third-trimester ultrasound examinations can detect an absence of the kidney in the renal fossa. Evaluating the migratory path of the kidney from the pelvis to the renal fossa will frequently result in detection of an ectopic kidney.

Female↗