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Biomedical subjects

M Sanderson

Publications and source records attributed to M Sanderson.

53 records · Page 3Linked to original sources
PubMed1991

Methadone concentrations in plasma and their relationship to drug dosage.

We have developed a sensitive HPLC method for measuring methadone in plasma and have used it to establish that there is a linear relationship between plasma concentration and methadone dose over the range of 3-100 mg of methadone per day in a group of 31 addicts. We found a good correlation between dose and plasma concentration (r = 0.89), with the plasma methadone concentration increasing by 0.263 mg/L for every milligram of methadone consumed per kilogram of body weight. Five patients had unexpected high or low concentrations; this finding is discussed.

Chromatography, High Pressure Liquid↗
PubMed1990

Magnesium metabolism in preterm infants: effects of calcium, magnesium, and phosphorus, and of postnatal and gestational age.

This study tests the hypothesis that increasing the calcium and phosphorus content of formulas for very low birth weight (VLBW) infants to the level required to decrease the incidence of rickets has a negative impact on magnesium balance. Using formulas variously supplemented with these minerals, we measured absorption and retention in two groups of preterm infants: (1) VLBW infants, less than 1500 gm and at less than 32 weeks of gestational age, with 3-day mineral balances begun at days 10, 20, 30, and 40; and (2) low birth weight infants appropriately grown and at 32 to 34 weeks of gestational age, with a single 3-day balance begun at day 10. Magnesium did not affect calcium balance in VLBW or low birth weight infants but promoted phosphorus retention in VLBW infants from day 20 onward. Absorption and retention of magnesium increased with postnatal age in VLBW infants, but this effect was obvious only when calcium or phosphorus intakes were low or when magnesium intake was high. Calcium and phosphorus supplementation further reduced magnesium absorption and retention in VLBW infants to the extent that they were in negative balance throughout the study; however, magnesium supplementation improved absorption and retention in VLBW infants. The low birth weight infants absorbed and retained more magnesium than VLBW infants at the same postnatal age whether or not magnesium was supplemented. We conclude that magnesium deficits occur at currently recommended intakes of 10 mg/kg/day for VLBW infants with calcium and phosphorus intakes that allow retentions equivalent to in utero accretions; however, with magnesium intakes approaching 20 mg/kg/day, appropriate retention can be achieved.

Absorption↗
PubMed1989

Ascorbic acid in the human stomach.

Ascorbic acid, the reduced form of vitamin C, may protect against gastric cancer. Accordingly, this study assessed the variability of ascorbic acid and vitamin C in the gastric juice of 77 patients with dyspepsia. There was a vitamin C concentration gradient from gastric juice down to plasma in subjects with normal gastric mucosa, but not in those with chronic gastritis. Patients with chronic gastritis had significantly lower gastric concentrations of vitamin C and ascorbic acid, and ascorbic acid concentrations were especially low in subjects with hypochlorhydria. The presence of the concentration gradient suggests that a mechanism for the secretion of vitamin C into the stomach exists. This is compromised by chronic gastritis. The very low ascorbic acid concentrations in hypochlorhydria may be a consequence of oxidation by bacterial nitrite. Those patients who by the Correa model are at greatest risk for gastric cancer have the lowest gastric levels of ascorbic acid.

Adult↗
PubMed1989

Concentrations of two organic contaminants in precipitation, soils and plants in the Essex region of Southern Ontario.

Recent research has indicated that the atmosphere is an important pathway by which pollutants enter terrestrial and aquatic ecosystems. We report here concentrations of PCBs and octachlorostyrene (OCS) in precipitation, soils and plants in Essex County, Ontario. The average PCB concentration in urban precipitation (23 ng litre(-1)) was lower than that previously reported for urban areas in the Great Lakes basin. Differences between sites and with varying wind directions were not significant. OCS concentrations in precipitation averaged 1.6 ng litre(-1). Concentrations of PCBs in soils were 2-3 orders of magnitude greater than in precipitation. Concentrations of these pollutants in city soils and plant roots were consistently higher than those from suburban and rural sites. Ratios of urban to suburban concentrations in soils and precipitation were approximately 5:1 for PCBs. However, concentrations of OCS were similar in urban and suburban samples of precipitation, soils and plant tissues. These comparisons suggest an urban source for PCBs, but not OCS. Concentrations of all contaminants in plant leaves, unlike those in precipitation, roots and soils, were relatively similar in urban and suburban areas. That similarity suggests that direct foliar uptake is not an important pathway for pollutant uptake in plants.

Journal Article↗
PubMed1989

Nucleotide sequence and characterization of the Marek's disease virus homologue of glycoprotein B of herpes simplex virus.

The Marek's disease virus (MDV) homologue of the herpes simplex virus (HSV) gene encoding glycoprotein B (gB) has been identified within BamHI fragments I3 and K3 of the 'highly oncogenic' strain RB1B of MDV. The entire nucleotide sequence of the gene has been determined and its predicted amino acid sequence shown to share gross overall structural features with the gB genes of HSV, varicella-zoster virus (VZV) and other mammalian herpesviruses. In particular, all 10 cysteine residues were conserved in MDV gB and there was extensive homology throughout the gene with VZV, HSV and pseudorabies virus except for the N and C termini. The overall percentage amino acid identity between MDV gB and gB of the alphaherpesviruses had a mean of 50% which was almost twice that between cytomegalovirus and Epstein-Barr virus. Northern blot analysis showed that the main RNA transcribed from this gene is approx. 2.7 kb in size. Antibodies raised against synthetic peptides (residues 250 to 271 and 304 to 330) allowed the identification of a family of serologically related glycoproteins of Mr 110K, 64K and 48K in extracts of MDV-infected cells using immunoblots. Furthermore, the antisera were able to differentiate between the antigens of MDV and herpesvirus of turkeys in immunoblots. Immunofluorescence tests indicated that MDV gB is associated with granules in the cytoplasm and is present at the surface of MDV-infected cells.

Amino Acid Sequence↗
PubMed1987

The prone position improves arterial oxygenation and reduces shunt in oleic-acid-induced acute lung injury.

The arterial oxygen tension (PaO2) may increase when patients with the adult respiratory distress syndrome are turned from supine to prone. We sought to reproduce this observation in dogs with acute lung injury to study the physiologic mechanism by which the improvement in oxygenation might occur. Twenty anesthetized dogs were ventilated with a constant tidal volume (20 ml/kg) of 100% oxygen. Oleic acid (0.09 ml/kg) was injected into the right atrium while rotating the animals through 360 degrees in 4 stages. Animals in Group I (n = 5) remained supine for 10 to 120 min until the supine PaO2 fell below 200 mm Hg. Those in Group II (n = 4) were kept prone during this period. Dogs in Groups I and II were then turned supine or prone every 30 min 5 times. Cardiac output and pulmonary vascular pressures, functional residual capacity (helium dilution), and regional diaphragmatic motion (determined by dorsal and ventral diaphragmatic markers relative to markers on the chest wall seen on lateral chest radiographs taken at FRC and at end-inspiration) were obtained in each position. Eleven dogs were kept supine (Group III, n = 6) or prone (Group IV, n = 5) for 2 h after oleic acid infusion, after which intrapulmonary shunt (Qs/QT) and ventilation-perfusion heterogeneity were measured in the supine and prone positions using the multiple inert gas elimination technique.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗
PubMed1982

Use of ultrasound echography for early diagnosis of single and twin pregnancy in the mare.

In 1981 a trial was conducted on 6 Newmarket Thoroughbred stud farms into the use of real-time ultrasound echography (scanning) as an aid to the early diagnosis of pregnancy in the mare. The procedure was found to be practicable and interpretation of the findings was relatively straightforward. Pregnancy was positively diagnosed from as early as 14 days after ovulation and a number of twin pregnancies were recognized, some in which the conceptuses were situated in separate horns of the uterus but an almost equal number in which the conceptuses were together in the same horn. It was concluded that the technique of scanning will become an established part of stud-farm practice because it enables early identification of non-pregnancy and also of twin pregnancy before the critical stage of endometrial cup formation.

Animals↗
PubMed1978

A 1:2 crystalline complex of ApA:proflavine: a model for binding to single-stranded regions in RNA.

The structure of a 1"2 complex of adenylyl-(3',5')-adenosine phosphate and proflavine hemisulfate has been determined using the methods of x-ray crystallography. Since the ApA does not form a mini double helix, it may serve as a model for the interaction of planar molecules with single stranded nucleic acids. The dinucleotide adopts an extended conformation with the adenines in adjacent molecules forming base pairs. A most unusual feature of the molecule is that it does not obey the "rigid nucleotide" concept although none of the torsion angles occur in energetically unfavourable regions. This is most probably due to the strong interactions between the proflavine and the oligonucleotide.

Acridines↗
PubMedDate not supplied

Development of multidimensional scales to measure key leaders' perceptions of community capacity and organizational capacity for teen pregnancy prevention.

This study discusses the development of scales to measure key leaders' self-reported involvement in community capacity building, perceptions of organizational capacity for teen pregnancy prevention, and the relationship between capacity and teen pregnancy rates. Data were collected from 1,516 key leaders across a rural southern state. Findings indicate that key leaders' perceptions of organizational capacity are related to their involvement in community capacity building efforts and community capacity is associated with teen pregnancy rates. This research represents progress toward measuring community and organizational capacity and may be used to inform future work focusing on developing quantitative measures of community capacity.

Adolescent↗
PubMedDate not supplied

Survey of candidates taking the MRCP(UK) Part 2 examination.

This paper presents the results of a questionnaire given to candidates taking the MRCP(UK) Part 2 examination through the Royal College of Physicians of London in June 1993. The aim of the study was to survey their pre-examination preparation and experience in the different parts of the clinical examination. Candidates were given a questionnaire at the end of the examination and asked to return it by post. The response rate was 45% (203 out of 456). We collected data covering a number of areas: usual forms of teaching (short case or long case), standard of in-hospital teaching, type of preparation taken for the examination (including number of courses attended), candidates' satisfaction with their performance, and candidates' use and assessment of counselling services.

Adult↗