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Biomedical subjects

S Roberts

Publications and source records attributed to S Roberts.

At least 253 records · Page 14Linked to original sources
PubMed1992

The fluid content of the human intervertebral disc. Comparison between fluid content and swelling pressure profiles of discs removed at surgery and those taken postmortem.

The fluid content of the disc, which governs its mechanical response and biological behavior, varies with external load. Because load on the disc changes after death, the fluid content and swelling pressure profiles of human discs taken at autopsy were measured, and compared with discs removed during surgical procedures. In general, discs taken at surgery had a lower fluid content in the nucleus and a higher fluid content in the outer anulus than discs removed at autopsy. In discs removed at surgery, the swelling pressure of the nucleus was higher than that of the anulus, whereas in autopsy discs the swelling pressure profile was flat. These changes are though to result from changes in load after death, and could influence the results of in vitro mechanical tests on the disc.

Biomechanical Phenomena↗
PubMed1992

A protein-binding site in the c-myc promoter functions as a terminator of RNA polymerase II transcription.

Termination of transcription not only allows polymerases that have completed RNA synthesis to recycle, but it also has important functions in transcriptional regulation and in preventing promoter interference. The molecular basis for termination by RNA polymerase II (pol II) is unclear, however. We have identified a termination site in the promoter region of the c-myc gene, whose function correlates with DNA binding by a nuclear factor. When the c-myc gene was transcribed in injected Xenopus oocytes or a HeLa nuclear extract, a fraction of RNA initiated at the first promoter, P1, terminated at two positions, T1A and T1B, which flank the TATA box of the second promoter, P2. T1B is a T-rich sequence that resembles previously identified attenuation sites, but T1A appears to represent a different class of termination site. T1A is situated approximately 10 bases upstream of an element that overlaps the P2 TATA box. Mutagenesis of this element affected both the efficiency and the position at which termination occurred. A 28-base sequence including this element caused a low level of termination when inserted into the alpha-globin gene in either orientation. This sequence bound a factor called TBF I (terminator-binding factor), whose binding specificity correlated with T1A terminator function. We suggest that TBF I may function as a pol II termination factor.

Animals↗
PubMed1992

Genetic analysis of atopy in three large kindreds: no evidence of linkage to D11S97.

Both genetic and environmental influences have been implicated in the pathogenesis of atopic disease. A recent report suggested that a major gene providing susceptibility to atopy was transmitted in a pattern consistent with autosomal dominant inheritance and evidence was presented that places the disease locus near the D11S97 marker on human chromosome 11q. In this report, we present three large, highly characterized pedigrees in which atopy is transmitted in a pattern consistent with autosomal dominant inheritance. Genotypes at the D11S97 and HLA loci were evaluated using both lod score and sib pair methods of analysis. In these pedigrees, we reject close moderate linkage (up to 10 cM) of atopy with both D11S97 and HLA.

Genetic Linkage↗
PubMed1992

Coliform bacteria from aquatic sources in Fiji.

Coliform bacteria were abundant in water and bivalve molluscs in the rivers and present to a lesser extent in the coastal areas of Fiji. The rivers fed by treated sewage were highly polluted. There was a noticeable increase in concentration of coliforms in bivalve molluscs. It was also found that these bacteria could survive and grow in river water and seawater over a 5-d period, and had a rapid growth rate in nutrient broth under ideal laboratory conditions. They were characterized by the API 20E identification system.

Animals↗
PubMed1992

A comparison of natural product, triclosan and chlorhexidine mouthrinses on 4-day plaque regrowth.

There is a continuing search for ingredients to enhance the chemical plaque inhibitory action of oral hygiene products. Sanguinarine, other natural extracts and triclosan have already been used in products. The aim of this study was to evaluate a number of triclosan and natural product rinses for effects on plaque regrowth. In particular, the influence of other rinse components were assessed, notably sodium lauryl sulphate (SLS) and zinc. The study was a randomised, blind, 9-cell cross-over design to measure the effects of each rinse on 4-day plaque regrowth from a zero baseline. 15 volunteers rinsed 2x daily with each product and plaque was recorded by area and score. The 0.2% chlorhexidine rinse (positive control) was significantly more effective, and the saline rinse (negative control) significantly less effective, than other rinses. Sanguinarine alone was little different from saline and the addition of zinc made a modest improvement in activity. The 3 triclosan/SLS rinses were more effective than the sanguinarine rinses but similar to their minus triclosan control rinse. A natural product/SLS experimental rinse was second to chlorhexidine and, in many analyses, significantly better than all other rinses, but caused some oral erosions. The results indicate that the plaque inhibitory properties of basic ingredients such as SLS may be difficult to enhance or surpass. However, the possible range of recipes, particularly using natural ingredients, provides scope for research and development in the field of oral hygiene products.

Adult↗
PubMed1991

Effectiveness of ofloxacin in the treatment of Chlamydia trachomatis and Neisseria gonorrhoeae cervical infection.

Forty patients with cervical infection caused by Chlamydia trachomatis were treated with ofloxacin (20) or doxycycline (20). Ofloxacin was successful in eradicating C. trachomatis from all 20 (100%) patients. Doxycycline was effective in 18 of 20 (90%) patients. Three patients had a concomitant cervical gonococcal infection. All three were successfully treated: one with ofloxacin and two with doxycycline. Ofloxacin, 300 mg, taken twice daily for 7 days, is effective in eradicating endocervical C. trachomatis infection.

Adolescent↗
PubMed1991

Cancer of the cervix--old and young, now and then.

A study of two 5-year periods, 1960-1964 and 1982-1986, in Queensland is made. Changing patterns of preinvasive and invasive cervical carcinoma in the world literature are discussed. The age of presentation, stage, histology, and results in Queensland for cervical carcinoma are analyzed. There are over 500 patients in each quinquennium. While the total female population has increased 86%, the maximum increase is in patients under 35 years and over 65. There has been a 50% decrease in the incidence of cervical carcinoma, but a doubling under the age of 30. The stage at diagnosis has markedly improved with 88% stage Ib in the young as opposed to 50% formerly. Late-stage disease remains a problem of the aged. The mortality in both time spans increases with age. Histologic patterns show an increase in nonsquamous patterns and increased mortality in the rare patterns. We have no evidence of the emergence of a rapidly progressive carcinoma in the young. Papanicolaou smear and education programs appear to be preventing cervical carcinoma and allowing diagnosis of the disease at an earlier stage and age. This is reflected in a decrease in mortality from 9.6 per 100,000 (1960-1964) to 4 per 100,000 (1982-1986).

Adult↗
PubMed1991

Early life precursors of psychiatric outcomes in adulthood in subjects at risk for schizophrenia or affective disorders.

In the New York High-Risk Project (NYHRP), 186 offspring of schizophrenic, affectively ill, and psychiatrically normal parents have been followed prospectively from 1971-72 to the average age of 27 years in 1990 with the goal of identifying early precursors of later psychopathology. In this report, we use path analyses to examine the relationship of several life-history variables to three pathological outcomes in the offspring: namely, psychosis, psychiatric hospitalization, and psychological dysfunction. The chief direct relationship with these outcomes is the effect of having a schizophrenic parent. The latter effect is also mediated indirectly by IQ.

Adolescent↗
PubMed1991

Cost efficiency of neonatal nurseries: the significance of unit size.

The cost of neonatal intensive care is high, and human and financial resources are finite. It is therefore essential to provide such care efficiently in terms of costs while still maintaining standards of care. We looked at the relationship of unit size to cost and determined the optimum and minimum size of the unit in terms of cost efficiency. Our data suggest that units with fewer than 6 ventilator cots were less cost-efficient than those with more cots while those with 12 ventilator cots were the most efficient. The calculations were done only up to 16 ventilator cots. Similarly, level II units were most cost-efficient when attached to an intensive care unit and had over 16 cots.

Australia↗
PubMed1991

Immunolocalisation of type VI collagen in the intervertebral disc.

Type VI collagen has been isolated from many connective tissues, including the intervertebral disc. Distribution of this collagen, however, varies considerably within different tissues. In adult mammalian nasal and articular cartilage it is localised preferentially in the matrix immediately surrounding the cell. Intervertebral discs from various species and of various ages were studied and a similar pericellular localisation was found. When antisera to type VI collagen were used staining was seen around the cells of all sections of intervertebral disc, being particularly prominent in the nucleus pulposus. Staining on or around the cells was also seen in the adjacent cartilaginous end plate and bone.

Adult↗
PubMed1991

Prevalence of paediatric cardiac disease in rural Kenya.

A series of 31 patients referred for evaluation of paediatric cardiac disease in rural Kenya is reported. The prevalence of symptomatic rheumatic heart disease is unchanged from previous data in the literature which is well over a decade old. We can conclude that recent improvements in medical care in Kenya have not yet reached certain rural areas as far as rheumatic fever is concerned. In addition, a significant number of children presumed to have had no discernible heart disease at this evaluation, suggesting the need for critical re-evaluation of this population at intervals. Finally, cyanotic disease seems under-represented in the series, suggesting that infants with certain cyanotic lesions may have been selected out and hence not referred to us.

Child↗
PubMed1991

1991 Volvo Award in basic sciences. Collagen types around the cells of the intervertebral disc and cartilage end plate: an immunolocalization study.

Several types of collagen are known to exist in the intervertebral disc in addition to the fibrillar collagens, Types I and II. Although they constitute only a small percentage of the total collagen content, these minor collagens may have important functions. This study was designed to investigate the presence of Types I, II, III, IV, VI, and IX collagens in the intervertebral disc and cartilage end plate by immunohistochemistry, thereby establishing their location within the tissues. Types III and VI collagen have a pericellular distribution in animal and human tissue. No staining for Type IX collagen was present in normal human disc, but in rat and bovine intervertebral disc, it was also located pericellularly. These results show that cells of the intervertebral disc and cartilage end plate sit in fibrous capsules, forming chondrons similar to those described in articular cartilage. In pathologic tissue the amount and distribution of the collagen types, and the organization of the pericellular capsule, differ from that seen in control material.

Adult↗
PubMed1990

Computer detection and analysis of periodic movements in sleep.

Standard polysomnography (PSG) and electromyographic (EMG) recording of the right and left anterior tibial muscles by Medilog 9000 recorder was carried out in 10 patients with periodic movements in sleep (PMS). The analog EMG signals and the sleep data from the Oxford ss90III sleep stager were fed into an IBM compatible personal computer for automatic detection and analysis using specific criteria to define the leg events, the interevent interval, the number of epochs (greater than 30 jerks), and the number of bursts (4 to 29 jerks). The results of automatic analysis were compared with data obtained from visually scored paper PSG. The total number of leg jerks detected by visual scoring was 2,812 and by automatic scoring was 2,789. The mean duration of the leg jerks 2.77 s [standard deviation (SD), 1.22] and the mean inter-interval event duration was 27.3 s (SD, 14.7). The total numbers of epochs scored visually was 35 and scored automatically was 33. The correlation co-efficient to the line of identity was 0.8 (p less than 0.005). The sensitivity of automatic scoring was 94% and the specificity was 85%. Automatic detection and analysis of PMS can provide an objective method for the study of several aspects of this disease that are still not yet fully understood.

Adult↗
PubMed1990

Heterogeneity of adverse hepatic reactions to tetrahydroaminoacridine.

Of 14 patients taking tetrahydroaminoacridine (THA) for the trial treatment of Alzheimer's disease, five developed mildly abnormal liver function tests. Four asymptomatic patients with persistently abnormal serum transaminase levels underwent liver biopsy, in order to determine the nature of the hepatic lesions. One subject had granulomatous hepatitis while three showed focal, predominantly centrilobular, liver cell necrosis and mild fatty change. One of the latter showed both tissue and peripheral blood eosinophilia. The liver function tests of the fifth patient, who was symptomatic, became normal after reduction of the dose of THA so he did not undergo biopsy. These findings suggest that the pathogenic mechanisms for THA-induced liver injury are heterogeneous ranging from hypersensitivity reactions to direct injury, and including combinations of the two. Patients receiving THA for treatment of Alzheimer's disease need regular monitoring of liver function.

Aged↗