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Biomedical subjects

S Kemp

Publications and source records attributed to S Kemp.

72 records · Page 4Linked to original sources
PubMed1988

Structural studies of the acquired immunodeficiency syndrome virus reverse transcriptase.

The clinical success of zidovudine has established the human immunodeficiency virus (HIV) reverse transcriptase (RT) as a valid target for the design of drugs to treat acquired immunodeficiency syndrome. In order to facilitate structural studies of this enzyme, expression systems in Escherichia coli, which allow the production of large amounts of RT, have been established. Using this recombinant material the RT has been purified and crystallized. Crystallographic studies currently underway are aimed at elucidating the three-dimensional structure of HIV RT. The availability of a bacterial expression system has enabled structural/functional studies of the RT by site-directed mutagenesis. These studies have identified amino acid residues that are essential for activity of the enzyme and might be involved in substrate binding. It is hoped that structural information of this nature will allow the rational design of HIV RT inhibitors.

Antiviral Agents↗
PubMed1987

Doppler and echocardiographic features of normal and dysfunctioning bioprosthetic valves.

Echocardiographic and Doppler studies were performed on 183 clinically normal and 58 severely dysfunctioning bioprosthetic mitral, aortic and tricuspid valves. The valve dysfunction resulted from spontaneous cusp degeneration in 49 instances and from paravalvular regurgitation in 9. The pulsed Doppler study demonstrated regurgitant flow in 36 (92%) of 39 regurgitant valves and 8 (90%) of 9 paravalvular regurgitant valves. Diagnostic echocardiographic features were present in only 51 and 10% of the patients, respectively. Although the Doppler regurgitant jet was peripheral in seven of the nine patients with paravalvular regurgitation, it was not possible to differentiate these patients from those who had valve degeneration and cusp tear at the periphery of the valve ring. Eight patients presented with a musical holosystolic murmur of mitral insufficiency. In all eight there was a characteristic honking intonation on the audio signal and a striated shuddering appearance on the video Doppler signal. Ten stenotic mitral bioprosthetic valves (less than or equal to 1.1 cm2 valve orifice) were identified by Doppler study. Diagnostic echocardiographic features were present in only two of these patients. The Doppler-derived valve orifice dimension correlated well (r = 0.83) with cardiac catheterization values. Fourteen asymptomatic or minimally symptomatic patients had echocardiographically thickened mitral cusps (greater than or equal to 3 mm). These patients had a significantly (p less than 0.0001) smaller valve area as compared with normal control valves, and during 4 to 24 months of follow-up, five of these patients developed severe valve regurgitation or stenosis. Doppler ultrasound is more sensitive than echocardiography in diagnosing bioprosthetic valve stenosis and regurgitation.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

Demonic possession and mental disorder in medieval and early modern Europe.

Western European belief in demonic possession as a cause of mental disorder has been traced through the medieval and early modern periods. Generally it appears that the range of disorders attributed to demonic possession has gradually narrowed. In any period, however, there seem to have been marked individual and cultural differences in outlook; some of these differences are still evident today in the survival of belief in demonic possession in pentecostal sects.

Christianity↗
PubMed1986

Tinnitus induced by tones.

Noisy sounding tinnitus was induced in 11 normally hearing subjects following monaural presentation of intense pure tones. The sensation level of a comparison noise, matched in loudness to the tinnitus by the subjects, was found to increase first rapidly and then slowly before dying away within about 90 s. The peak level of the tinnitus increased with the level of the inducing tone but was unaffected by its duration or frequency; the duration of the tinnitus was positively related to the frequency but not to the level or duration of the tone. Temporary threshold shift measured with pulsed noise generally occurred after, rather than during, the tinnitus. Substantial individual differences, particularly in the duration of the tinnitus, were apparent.

Acoustic Stimulation↗
PubMed1984

Macular electroretinograms: their accuracy, specificity and implementation for clinical use.

The pattern and the focal electroretinogram (ERG) are both non-invasive, electrophysiological responses recorded from circumscribed retinal areas and are most easily recorded from the macula. This paper describes how our department has incorporated these tests into our clinical protocol, shows how the recording technique and the method of electrode construction may be improved, and describes the normal limits of the macular responses we obtain. The ERG signal-noise ratio we obtained was better than that of the binocular visual evoked potentials (VEPs) recorded simultaneously. Pattern and focal ERGs, using improved methods of recording, show promise of being a valuable addition to the clinical investigation of subtle maculopathies and some forms of optic nerve dysfunction. Three illustrative cases are described. The first demonstrates normal macular ERG responses with abnormal Ganzfeld ERGs due to peripheral retinal damage. The second reveals differential pattern ERG reduction with normal focal ERG in recent optic neuritis. The third case demonstrates reversible simultaneous loss of Ganzfeld ERGs and macular ERGs in vitamin A deficiency.

Adult↗
PubMed1981

Temporal acuity in normal and hearing-impaired listeners.

Temporal acuity, defined as the minimum detectable gap in an otherwise continuous noise, was measured with an adaptive version of the two-alternative forced-choice task. For 6 normal listeners, the minimum duration detectable decreased from an average of 20.3 ms at a noise level of 30 dB SPL to 3.2 ms at 80 dB SPL. By comparison, the temporal acuity of 4 listeners with conductive hearing losses, 2 with otosclerosis, and 7 with sensorineural hearing losses, was poorer than that for normal listeners at equal sound pressure levels. At higher sound pressure levels, the acuity of those with conductive hearing losses or otosclerosis approached normal values, but the acuity for listeners with sensorineural hearing losses did not.

Acoustic Stimulation↗
PubMed1964

Comparative effects of 5-fluorouracil on strains of Bacillus megaterium.

Wachsman, J. T. (University of Illinois, Urbana), S. Kemp, and L. Hogg. Comparative effects of 5-fluorouracil on strains of Bacillus megaterium. J. Bacteriol. 87:1011-1018. 1964.-Growth of Bacillus megaterium strain KM is severely inhibited by 5-fluorouracil (FU). Both thymidine and uridine are required to overcome this inhibition. The addition of uridine alone to a FU-inhibited culture permits good ribonucleic acid (RNA) and protein synthesis for the first 2 hr, but rather poor deoxyribonucleic acid synthesis. Uridine enhances the bactericidal effect of FU, promoting a decrease in the viable count of from 4 to 5 decades in 5 hr. Death begins after a 1-hr lag and is accompanied by hydrolysis of RNA and cell lysis, commencing during the 2- to 5-hr interval. The combination of FU and uridine is not bactericidal, when a methionine auxotroph is deprived of its required amino acid. Substrains of KM, partially resistant to FU, were isolated. Strain T(2) requires only thymidine to overcome the inhibitory effects of FU, whereas strain FU/2 requires only uridine. With a uridine auxotroph of strain KM, FU partially replaces uridine by permitting a small, but reproducible, increase in the amount of protein.

Bacillus megaterium↗
PubMed1964

Thymineless death in Bacillus megaterium.

Wachsman, J. T. (University of Illinois, Urbana), S. Kemp, and L. Hogg. Thymineless death in Bacillus megaterium. J. Bacteriol. 87:1079-1086. 1964.-Strain KM:T(-), a thymine auxotroph of Bacillus megaterium strain KM, rapidly loses the ability to multiply when incubated in the absence of thymine, on an otherwise sufficient medium. At 37 C, there is a lag of approximately 60 min, prior to the onset of exponential death (decrease of 1 decade per 50 min). The extent of the decrease in viable count varies from 4 to 5 decades after 5 hr of starvation. The cells die more slowly at 30 C (decrease of 1 decade per 120 min) after a lag of approximately 90 min. Thymine starvation permits substantial net ribonucleic acid (RNA) and protein synthesis, but only slight deoxyribonucleic acid synthesis. In contrast with the changes occurring at 30 C, thymineless death at 37 C is eventually accompanied by a rapid hydrolysis of RNA and by cell lysis. Chloramphenicol inhibits thymineless death at 37 C. Strain T(-)R(1), a derivative of strain KM:T(-), undergoes a very low rate of thymineless death at 37 C (decrease of 1 decade per 240 min). Neither hydrolysis of RNA nor cell lysis occurs during 8 hr of thymine starvation. Strain KM:T(-)H(-) (doubly auxotrophic for thymidine and histidine) requires histidine for maximal thymineless death at 37 C. Preincubation of this strain on the basal medium supplemented with thymidine alone enables the population to become increasingly immune to subsequent thymineless death.

Bacillus megaterium↗
PubMedDate not supplied

The gene for X-linked myotubular myopathy is located in an 8 Mb region at the border of Xq27.3 and Xq28.

X-linked recessive myotubular myopathy (XLMTM) is a rare and severe neonatal neuromuscular disease characterized by muscle weakness, hypotonia, and respiratory problems. Here we report an extensive linkage analysis in two families with XLMTM. Using 18 markers in the Xq27-Xqter region we found a maximum two-point lod score of Z = 4.00 at theta = 0.00 for the marker II-10 (DXS466). Three recombinations were detected between markers and the disease locus. At the distal side of Xq27.3 a recombination was present in between RNI (DXS369) and VK23b (DXS297), another in between VK23b (DXS297) and II-10 (DXS466), and at the proximal side of Xq28 a recombination in between U6.2 (DXS304) and Cpx67 (DXS134). Combining the results of both families we conclude that XLMTM is located in the 8 Mb(11 cM) region between VK23b (DXS297) and Cpx67 (DXS134).

Adult↗
PubMedDate not supplied

Improving the nutrition of patients using Entera Fibre Plus.

This article examines the role of fibre in the diet with a special focus on Entera Fibre Plus, a new high energy, fibre-containing sip feed. Early enteral feeds were all fibre-free or 'low residue'. In the last 10 years fibre-containing feeds have become available, mostly designed for tube feeding and containing a single fibre source. Entera Fibre Plus contains a mixed fibre source, providing both soluble and insoluble fibre types, including inulin. This helps provide the full range of fibre benefits, which include reduction of constipation and diarrhoea, maintaining the health of the gut and encouraging beneficial gut bacteria to assist the body's defence systems. Inulin has a specific role in the latter. Entera Fibre Plus provides 300 kcal and 5 g of fibre per 200 ml pack and is available in six flavours. It is a convenient and palatable way of improving the nutritional status of patients who are malnourished and may be of particular benefit to elderly people, those on long-term supplements and those who suffer from chronic constipation or diarrhoea. Entera Fibre Plus is approved by the Advisory Committee on Borderline Substances (ACBS) and is available at retall pharmacles or on prescription.

Dietary Fiber↗
PubMedDate not supplied

Solving the problem of weight control for tube-fed patients.

Many patients requiring an enteral tube feed have low energy requirements or are overweight, with some patients gaining weight on as little as 1200 kcal/day. Most standard tube feeds supply 1500-2000 kcal/day. This has previously created a problem for dietitians and clinicians as giving a reduced volume to lower the energy supply has often resulted in the feed being incomplete with respect to vitamins, minerals and trace elements. A new feed, Fresubin1000 Complete, has been specially developed to overcome these difficulties. One litre supplies all nutrient requirements, including fibre, and only 1000 kcal. It is presented in a convenient, easy-to-use, pre-filled bag, the EasyBag. Fresubin1000 Complete is ACBS approved.

Adult↗