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Biomedical subjects

N J Smith

Publications and source records attributed to N J Smith.

At least 55 records · Page 3Linked to original sources
PubMed1990

Use of plasmid analysis to determine the source of bacterial invasion of the urinary tract.

Gram negative colonisation and infection of the urinary tract is a well recognised complication of the neuropathic bladder caused by spinal cord injury (SCI). K. pneumoniae accounts for one third of all urinary tract infections in hospitalised SCI patients. Plasmid analysis has been shown to reliably fingerprint bacterial strains, particularly K. pneumoniae, so that growth from two separate locations in or on the body can be accurately analysed as to migration from a reservoir to a target location. Eighty seven hospitalised SCI patients on intermittent catheterisation for a total of 586 patient-weeks were studied. Twice weekly catheterised urine specimens and once weekly rectal swab cultures were taken from each patient. Thirty seven patients experienced at least one clinically significant (colony count greater than 10,000/mL) urinary tract colonisation caused by K. pneumoniae, representing 66 total colonisations. Further analysis of 31 of these 37 patients revealed: K. pneumoniae in all of their stool cultures (p less than 0.05) and the identical strain of K. pneumoniae in the urine as well as the stool in 72% of the 66 colonisations (p less than 0.05). Analysis of 14 patients without K. pneumoniae urinary colonisations showed absence of faecal K. pneumoniae in 3, and predominant growth in only 4. In 22 of the 37 patients, multiple K. pneumoniae urinary colonisations were noted, representing 27 pairs of colonisation. Fifteen of the pairs were found to be relapsing (caused by two identical bacterial strains), and 12 were recurrent (caused by two different bacterial strains). Thirteen of the 15 relapsing pairs also had identical urine and stool K. pneumonia strains (p less than 0.05). All colonisations were treated with appropriate antibiotics based on culture and sensitivity reports. Fourteen of the 15 relapsing colonisation pairs have identical antibiograms (p less than 0.05), while all 12 of the recurrent colonisation pairs had different antibiograms (p less than 0.05). The differences noted on sensitivity patterns (antibiograms) correlated with differences among strains of K. pneumoniae based upon plasmid analysis. Treatment of bacteriuria did not affect the nature of repeated colonisations regardless of the antibiotic chosen, the route of administration or the duration of treatment.

Adolescent↗
PubMed1989

Do lung volumes change with sleep state in the neonate?

We have studied 12 healthy full-term babies, mean age 3.2 days, using physiological criteria--EEG, electrooculogram, electromyogram, respiratory regularity and visible movement--to assess sleep state, and a respiratory jacket to record changes in functional residual capacity (FRC). A total of 593 min of sleep data were analysed. Of the recordings, 39% were scored as quiet sleep, 40% as active and 21% as indeterminate sleep. The mean maximum variation in FRC overall was 29 ml (SD +/- 15.4 ml). Examination of these figures showed that FRC variations during sleep state changes were smaller than those seen within a defined sleep state. We conclude that changes in sleep state are not associated with variations in FRC.

Functional Residual Capacity↗
PubMed1989

Research databases: a new direction in collection development.

A need for centralized access to biomedical databanks was identified at the Medical University of South Carolina. The library has taken a leadership role in administering selection, acquisition, storage, and dissemination of access to these databases. A discussion of established policies and procedures is included. The appendix describes the biomedical databanks and search software selected.

Humans↗
PubMed1988

Biological monitoring of occupational exposure in the chromate pigment production industry.

A survey of occupational exposure to hexavalent chromium in chromate pigment production was undertaken in factories producing lead chromate (PbCrO4) and strontium chromate (SrCrO4). Sampling pre and post-shift in a factory where SrCrO4 production had just started showed the optimum strategy for biological monitoring is the measurement of urinary chromium, in urine samples taken at the end of Friday shift and pre-shift the following Monday. However, short-term uptake may be assessed under these circumstances by the increase in urinary chromium over a shift. Body burden, representing long-term chromate exposure is best assessed by measuring chromium in whole blood or pre-shift urinary chromium at the beginning of the working week. Exceptionally high levels of chromium in blood (387-4160 nmol l-1) and urine (41-1250 nmol nmol-1 creatinine) as well as skin and nasal lesions, were discovered amongst the workforce at the strontium chromate plant. These contrasted with occupationally unexposed levels of less than 20 nmol l-1 and less than 1 nmol nmol-1 creatinine, respectively, and led to the continuation of the biological monitoring programme. At the same time, improved working practices and respiratory protection equipment were introduced. A steady elimination of chromium from whole blood with a half-life of approximately 24 days was found. This elimination rate was confirmed over a 14 day period when the workforce were completely removed from exposure. The study confirms the usefulness of biological monitoring in assessing the uptake of hexavalent chromium and control of exposure.

Chromates↗
PubMed1988

Soccer injuries and their relation to physical maturity.

A prospective study of injuries encountered during participation in a summer soccer camp for youths aged 6 through 17 years revealed an injury incidence of 10.6 per 1000 hours for girls (107 injuries in 458 girls) and 7.3 per 1000 hours for boys (109 injuries in 681 boys). For both sexes, the incidence of injury increased at age 14 years. One certified athletic trainer (W.D.C.) assessed and documented all injuries during the course of the study. Seventy percent of injuries involved the lower extremities. Contusions represented 35.2%, strains 27.8%, sprains 19.4%, and fractures and dislocations 2% of all reported injuries. The ankle was the most frequent site of injury in both sexes. Quadriceps strain was a common injury in boys. The boys with the highest incidence of injury were tall (greater than 165 cm) and had a weak grip (less than 25 kg), suggesting that skeletally mature but muscularly weak boys may be more susceptible to injury while playing soccer with peers of the same chronological age.

Adolescent↗
PubMed1988

Vibration white finger.

Nineteen consecutive patients claiming compensation for vibration white finger were reviewed. The cold provocation test was found to be of no value in confirming a diagnosis of vibration white finger. Small cysts were apparent on the radiographs in 61% of patients' wrists but none had developed significant degenerative changes of the wrist or digits. In this group of claimants, 63% had carpal tunnel syndrome on nerve conduction studies.

Adult↗
PubMed1988

Atypical simple bone cysts of the jaws. I: Recurrent lesions.

The aetiology, clinical and radiographic features and the treatment of simple bone cysts of the jaws are discussed. Recurrence of jaw lesions is unusual. Two cases are presented of simple bone cyst in the mandible which recurred following conventional treatment. The importance of clinical and radiographic follow-up is emphasised.

Adolescent↗
PubMed1988

Relations between liver cadmium, cumulative exposure, and renal function in cadmium alloy workers.

Detailed biochemical investigations of renal function were made on 75 male workers exposed to cadmium and an equal number of referents matched for age, sex, and employment status. The exposed group consisted of current and retired workers who had been employed in the manufacture of copper-cadmium alloy at a single factory in the United Kingdom for periods of up to 39 years and for whom cumulative cadmium exposure indices could be calculated. In vivo measurements of liver and kidney cadmium burden were made on exposed and referent workers using a transportable neutron activation analysis facility. Significant increases in the urinary excretion of albumin, retinol binding protein, beta 2 microglobulin, N-acetylglucosaminidase (NAG), alkaline phosphatase, gamma-glutamyl transferase and significant decreases in the renal reabsorption of calcium, urate, and phosphate were found in the exposed group compared with the referent group. Measures of glomerular filtration rate (GFR) (creatinine clearance, serum creatinine, and beta 2 microglobulin) indicated a reduction in GFR in the exposed population. Many of these tubular and glomerular function indicators were significantly correlated with both cumulative exposure index and liver cadmium burden. Using cumulative exposure index and liver cadmium as estimates of dose, a two phase linear regression model was applied to identify an inflection point signifying a threshold level above which changes in renal function occur. Many biochemical variables fitted this model; urinary total protein, retinol binding protein, albumin, and beta 2 microglobulin gave similar inflection points at cumulative exposure levels of about 1100 y.micrograms/m3 whereas changes in the tubular reabsorption of urate and phosphate occurred at higher cumulative exposure indices. Measures of GFR, although fitting the threshold model did not give well defined inflection points. Fewer variables fitted the two phase model using liver cadmium; those that did gave threshold levels in the range 20.3-55.1 ppm. When cadmium workers with cumulative exposure indices of less than 1100 y.micrograms/m3 were compared with their respective referents only serum beta 2 microglobulin and urinary NAG were significantly increased in the exposed group and these differences were not related to the degree of cadmium exposure.(ABSTRACT TRUNCATED AT 400 WORDS)

Alloys↗
PubMed1988

Erbium filtration for dose reduction in dental radiography.

Previous work has suggested that rare-earth filtration of diagnostic X rays is an effective means of dose reduction in radiology. Erbium (atomic number 68) is particularly promising in this respect. The effects on the X-ray beam and surface dose of the addition of 0.1 mm of erbium foil to the conventional filtration of a GE1000 dental X-ray set were investigated. Filtration by 0.1 mm of erbium produced a beam of narrower spectrum, greater penetration but lower intensity than that filtered conventionally by aluminium alone. The overall dose reduction achieved in dental radiography was greater than 30% between 65 and 85 kVp with a maximum dose reduction of 42% at 65 kVp. The question of the cost-effectiveness of erbium filtration as a radiation protection measure is also addressed.

Erbium↗
PubMed1988

Dental radiology.

Explore the source record for details and available documents.

Radiography, Dental↗
PubMed1987

Orthodontic radiology: a review.

Before starting orthodontic treatment it is important to have status radiographs to ascertain the state of the patient's general dental health. A dental panoramic tomogram is very suitable in this respect, but right and left bimolar projections together with upper and lower occlusal films provide an appropriate alternative. Unerupted upper cuspids can be localized by means of parallax shift or by using the vertex occlusal projection. The cephalometric radiograph is an invaluable adjunct to the clinical examination and models of the dentition, which together form the basis for orthodontic diagnosis and treatment planning. However, the user should be aware of the various errors which can detract from the reliability of this technique. Cephalometric landmarks are identified and tracings of the radiograph are made. Angular measurements taken from the tracing enable the maxillary and mandibular bases to be related to each other and to the cranial base. Recent developments in computer science and information transfer offer the possibility that in the future cephalometric radiographs will be analysed with the aid of a computer at sites which may be remote from the dental office.

Cephalometry↗
PubMed1987

Risk assessment: the philosophy underlying radiation protection.

Our present understanding of the role of ionizing radiation in the induction of malignant disease and genetic disorders has taken many years to develop. Over this period there has been a considerable degree of international collaboration in producing recommendations for good practice, and today many countries have legislation which aims to protect both the user of a dental x-ray set and the patient from receiving unnecessary doses of radiation. It is, however, not possible to eliminate completely the stochastic risks and considerable effort is being expended to see that these risks are minimized. In the case of the dentist using the set, it is important to ensure that these risks are small compared to other risks of everyday life. In the case of the patient it is vital to ensure that the benefits of a radiographic examination outweight the risks. A number of fatal malignancies are likely to be induced each year as a result of the use of dental radiology, and it is very necessary that there is proper clinical justification for every radiograph. The dental profession must ensure that the collective dose to the population is kept as low as reasonably achievable.

Humans↗
PubMed1986

Occupational cadmium exposure in jig solderers.

The cadmium body burden, blood and urine cadmium concentrations, and renal function were studied in a group of 53 cadmium solderers. The results showed raised blood and urine cadmium concentrations and raised cadmium body burden in all workers (31) with more than five years exposure, with 27 having urine cadmium concentrations in excess of the proposed biological threshold of 10 nmol/mmol creatinine. Renal tubular dysfunction was found in 17 of the subjects with more than five years exposure and in one this was associated with glomerular dysfunction. These data indicate that cadmium body burden and frequency of tubular dysfunction in end users of cadmium may be as high as those found in smelters or production workers. Subjects with tubular dysfunction did not show greatly increased urine cadmium concentrations compared with those without dysfunction, supporting a previous suggestion that tubular dysfunction occurs before the wash out of cadmium from the kidney. At the time of our study, cadmium exposure stopped as cadmium free soldering rods were introduced. Repeat urine samples from 19 subjects, one to two years after exposure ended indicated that there was no further increase in the level of excretion of low molecular weight proteins, perhaps indicating that the tubular proteinuria does not increase or more severe renal dysfunction develop without continuous exposure.

Adult↗
PubMed1986

External quality assessment of assays of lead in blood.

The operation and results of the United Kingdom External Quality Assessment Scheme for Lead in Blood, which currently has about 140 participants within and outside the U.K. are described. The choice of specimens, scheme design, and scoring of performance are discussed, as is the validity of the consensus values used as a basis for the scoring. There has been a continued improvement in performance as assessed by this program, some of which appears to have been stimulated by the introduction of Variance Index scoring. The relative performance of the methods for assaying lead in blood is also examined.

Evaluation Studies as Topic↗