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Biomedical subjects

S D King

Publications and source records attributed to S D King.

At least 37 records · Page 2Linked to original sources
PubMed1987

Auxotypes, plasmid contents, and serovars of gonococcal strains (PPNG and non-PPNG) from Jamaica.

The analysis of the auxotypes and plasmid profiles of 459 non-PPNG strains from Jamaica suggests that strains have been imported to the island. Unlike in many developing countries where strains are differentiated by only a few auxotypes, 13 different auxotypes were identified in the non-PPNG strains. In Jamaica over 10% of the strains were plasmid free and required proline, citrulline, and uracil (PCU-) for growth. These isolates predominate in Canada and are increasingly reported from areas of the United States of America and Europe. The serological analysis of 168 of the non-PPNG strains indicated that most (76%, 128) were from serogroup WII/III. Serogroup WII/III strains comprised 17 serovar combinations with GS and Ph reagents, whereas serogroup WI strains included only four serovars. Unusually, most WI Aedgkih non-PPNG strains were wild type or proline requiring. Strains of serovar Aedg were especially noted (in 93%, 13/14) for carriage of the transfer plasmid. The first 20 PPNG strains isolated in Jamaica proved to have multiple origins as they had eight variations of auxotype, serovar, and plasmid content. Most (60%, 12/20) of those isolated were typed as serogroup WI, and 10 of these isolates were serovar Aedgkih. Although most (70%, 14/20) PPNG strains harboured African type plasmids with or without transfer plasmids, six also carried Asian type plasmids (with the transfer plasmid).

Electrophoresis, Polyacrylamide Gel↗
PubMed1987

Treatment of gonorrhoea and susceptibility to antimicrobials of PPNG and non-PPNG strains in Jamaica.

Of 1400 patients in Jamaica screened for uncomplicated gonorrhoea, 54% (753 patients) were culture positive. Of the 459 patients who complied with the terms of the study, 97% (211/218) of those treated with aqueous procaine penicillin G were cured compared with 94% (227/241) of those treated with ampicillin. Penicillinase producing Neisseria gonorrhoeae (PPNG) strains were identified for the first time during the study, and 10 patients infected with PPNG strains (two treated with penicillin, eight with ampicillin) contributed to the 21 treatment failures. The in vitro susceptibility of eight antimicrobial agents for 629 non-PPNG and 20 PPNG strains was estimated. Of the non-PPNG isolates, 8% had an MIC of 1 mg/l or more of penicillin, 11% were resistant to this concentration of ampicillin, 32% to tetracycline, and under 1% to the same concentration of cefuroxime and erythromycin. Fewer than 2% of the isolates were resistant to 2 mg/l or more thiamphenicol, and all isolates were susceptible to spectinomycin and trimethoprimsulphamethoxazole (at a ratio of 1:19). Significantly more strains from the 21 treatment failures were resistant to penicillin (52%) or ampicillin (62%) compared with 7% strains resistant to penicillin and 4% to ampicillin from the successfully treated group.

Adolescent↗
PubMed1987

Bimodality electrophysiologic evaluation of brainstem in sleep apnea syndrome.

Previous electrophysiologic studies in the sleep apnea syndrome (SAS) have used only a single modality (brainstem auditory evoked responses [BAERs]) and yielded conflicting, inconsistent, and inconclusive results. We utilized both BAERs and somatosensory evoked responses in 12 patients with SAS and found normal central conduction times in all patients. These data argue against a significant structural alteration in both rostral and caudal brainstem, insofar as the auditory and somatosensory pathways are concerned, in patients with SAS.

Adult↗
PubMed1987

Electrophysiologic validation of two categories of dementias--cortical and subcortical.

Recently, the dementias have been classified into 2 categories-Cortical (CD) and Subcortical (SD). Some studies have questioned this classification. We attempted to validate the classification on electrophysiologic grounds. Fourteen of 15 patients with SD had relatively normal EEGs as compared to only 3 of 15 patients with CD, matched for age, sex and severity of dementia (p greater than 0.01). SER test results were often abnormal in the SD group but always normal in CD patients. These preliminary data appear to validate the classification of dementias into SD and CD categories.

Aged↗
PubMed1985

An assessment of the variability of early scalp-components of the somatosensory evoked response in uncomplicated, unshunted carotid endarterectomy.

Although many publications deal with the usefulness of the SER in CEAs, the criteria of calling a SER abnormal during a CEA are largely arbitrary. One way to define the limits of normalcy for SERs during the CEA will be to analyze the SER tracings obtained during unshunted and uncomplicated (intra- and postoperative) CEAs. In 23 such CEAs (10 right, 13 left; clamptime 10-23 mins.), data analysis at the ipsilateral parietal electrode, on stimulation of the contralateral median nerve (square pulse -5.1/sec, 10-30 V, 200 microseconds; bandpass-30-3000 Hz trials-500 stimuli), revealed that (1) latency fluctuations of the N20 (21.4 msec) were narrowest, being less than 1.5 msec different during and after clamping compared to the preclamp latency in all 23 CEAs, whereas those of P25 (27.4 msec) and N35 (38.5 msec) were greater than 2.0 msec different from the preclamp latency in 3 and 8 CEAs respectively, and (2) the amplitudes of N20, P25 and N35 measured from the preceding peak of opposite polarity, fell to less than 75% of the preclamp value on 3, 4 and 7 CEAs respectively. It is concluded that N20 was the most stable of the first three short-latency components in the SER and should perhaps be most relied upon to predict abnormality of the SER during CEAs.

Brain Ischemia↗
PubMed1985

Photoelectron enhancement of the absorbed dose from X rays to human bone marrow: experimental and theoretical studies.

A technique is described by which lithium fluoride powder is introduced into the marrow cavities in specimens of human trabecular bone to determine the excess photoelectron dose to marrow, when bone is irradiated by X rays of energies between 20 keV and 140 keV. Three specimens of trabecular bone, containing respectively 10, 15 and 25% bone by volume, were investigated and the results compared with those derived on the basis of earlier calculations for mono-energetic electrons by Whitwell. Reasonable agreement was found between the experimental and theoretical results, although there was some indication that scatter influenced the practical measurements at the higher photon energies. Theoretical calculations are then used to derive photoelectron dose enhancements for complete bones from the measured results on the bone specimens, and mean enhancements of the marrow dose for the whole human skeleton are calculated for subjects aged 44, 9 and 1.7 years.

Absorption↗
PubMed1982

Experimental surface or volume deposition of radionuclides in post-mortem specimens of trabecular bone.

Techniques are described that have been developed to contaminate post-mortem specimens of human trabecular bone uniformly and artificially with three different radionuclides, 14C, 45Ca and 32P, so as to produce either a uniform volume deposition of radionuclide through the bone matrix or an 'infinitely' thin layer of radionuclide on the trabecular surfaces. Uniform volume depositions of 45C and 32P were produced by neutron activation and the 14C volume distribution was successfully achieved by rehydrating the bone matrix with 14C-labelled urea solution. Surface depositions of isotope were attempted by introducing a radionuclide into solution. Surface depositions of isotope were attempted by introducing a radionuclide into solution which was in equilibrium with trabecular bone and depositions approximating to an 'infinitely' thin layer of isotope were achieved for 32P and 14C using adenosine triphosphate-labelled molecules. Ionic calcium penetrates the bone matrix very rapidly and the best 45Ca surface deposition that could be produced penetrated the trabecular surface to an average depth of about 10 micrometer. The uniformity of deposition was analysed by autoradiography and the thickness of the 'surface' layer of radionuclide was estimated using microdensitometer scans across selected strands of the autoradiograph and comparing the film density profiles thus produced with calculations.

Bone and Bones↗
PubMed1981

Safety and immunogenicity of a new Haemophilus influenzae type b vaccine in infants under one year of age.

64 healthy infants 2-3 months old, were randomly assigned to one of three vaccination groups which received either diphtheria-pertussis-tetanus (DPT) vaccine, Haemophilus influenzae type b capsular polysaccharide polyribosyl-ribitol phosphate (PRP) vaccine, or PRP + P (with pertussis adjuvant) vaccine in three doses at intervals of 2 months. Local and systemic reactions occurred most frequently after DPT vaccination and least frequently for PRP alone. Data for 60 infants from whom complete sera sets were available indicated that 70% of the infants who received three doses of PRP + P showed 2-fold or greater increases in titres of antibody to PRP with final values above the level assumed to give protection against invasive H. influenzae type b disease (greater than or equal to 0.15 microgram/ml). In contrast, less than 10% of the infants who received PRP vaccine alone showed 2-fold or greater increases.

Age Factors↗
PubMed1980

Epidemiological investigation for arboviruses in Jamaica, West Indies.

Arbovirus investigation in Jamaica was undertaken between 1960 and 1975. Serological studies showed that antibodies to dengue type virus and St. Louis encephalitis virus (SLE) were prevalent throughout the island for several years. In urban communities, the incidence of dengue antibody was higher than for SLE; however, in children under 10 years of age antibody to both viruses was rarely present. In rural areas, SLE was prevalent in adults and children. This virus was isolated fom Culex nigripalpus (mosquitoes) and from a nestling Mockingbird, Mimus polyglottos, in the same rural area. Dengue type 3 and type 4 were isolated from the sera of patients in an urban area, during two epidemic periods, 1963 and 1968. No other group B arbovirus was encountered on the island. Group A arbovirus was virtually absent prior to the eastern equine encephalomyelitis outbreak of 1962. That virus was isolated from brain tissue of humans and equines. Two strains of Cache Valley virus from mosquitoes, Anopheles grabhami, one strain from Aedes taeniorhynchus, and a strain of Wad Medani virus from a tick, Amblyomma cajenense, were also isolated.

Adolescent↗
PubMed1980

Human leptospirosis infective serogroups and serotypes in Jamaica.

Of a total of 5,021 samples of sera tested in Jamaica between 1960-1978, 651 (12.9%) were positive in significant to microscopic agglutination for leptospirosis. There were 50 (5.9%) positive isolates of 845 cultures. Six serogroups and 13 serotypes of pathogenic leptospiral strains were identified. The serogroup icterohaemorrhagiae serovar icterohaemorrhagiae accounted for 57% of infections and the serogroup hebdomadis, serovar jules accounting for 31% of cases. Human leptospirosis is grossly under-reported in Jamaica and only systematic surveys and surveillance can define the true incidence of the public health problem of this disease.

Female↗
PubMed1978

The role of chickens in the epidemiology of eastern equine encephalomyelitis virus in Jamaica.

Since 1962, when Jamaica experienced its first and only outbreak of eastern equine encephalomyelitis (EEE), surveillance for the causative virus has been in progress. Wild birds, rodents, mosquitoes, sandflies and sentinels (domestic chickens, guinea pigs, mice and hamsters) have been constantly examined for EEE virus and serological conversion. In essence, only negative results have been obtained. Since June 1976, domestic chickens have been investigated as a possible reservoir and several have been found to have haemagglutinating antibodies, with titres ranging from 1:10 to 1:160. These titres fell rapidly, eg, from 1:160 to 1:10 within 60 days. These results incriminate the domestic fowl as a major reservoir for the virus, and suggest that the life of immunoglobulins against EEE is short in birds. Thus, the large number of negative serological tests found in previous investigations might be misleading since positive sera might have been missed between intervals of capture and recapture of the birds. The results indicate that investigators could usefully modify their procedure by bleeding wild birds as early as one to two weeks after initial capture. The importance and duration of the dominant avian anti-EEE virus immunoglobulins should be investigated.

Animals↗
PubMed1977

Salmonella serotypes, Salmonella typhi phage types, and anti-microbial resistance at the University Hospital of the West Indies, Jamaica.

Bacteriologically proved cases of salmonellosis presenting at the University Hospital have increased nearly threefold since 1957. The most striking change has been a considerable increase in the incidence of Salmonella heidelberg and Salmonella derby in the last 5 years, probably resulting from hospital acquired infection. About 80 cases of typhoid fever are reported each year in Jamaica. There has been little change in the prevalence of different phage types of Salmonella typhi since 1961. Paratyphoid fever is rare. Standardized antimicrobial disk-sensitivity testing was performed on selected surviving salmonella strains since 1964. S. typhi has remained fully sensitive to all the agents tested except streptomycin. Other salmonellas, however have shown a significant increase in antimicrobial resistance since 1970. Most of this increase was due to multiple resistance in S. heidelberg and S. derby, and the survival and dissemination of these strains in the hospital environment may be related to antibiotic usage.

Bacteriophage Typing↗
PubMed1977

A radiographic technique for measuring the powder packing density in the cavities of trabecular bone.

An X-ray technique has been developed to enable reproducible and quantitative data to be obtained from radiographs taken by a diagnostic X-ray machine. Careful attention has been paid to the alignment of the specimen and the diagnostic tube and to operating conditions. The choice of X-ray spectrum is described together with the experimental geometry used to minimize the scattered radiation incident on the film. The resultant scattered radiation intensity achieved is about 4% of the unattenuated direct radiation. Careful calibration procedures using objects the same size as the unknown specimen are necessary to avoid the need for complicated corrections for the resulting variation in scatter across the film. The LiF powder packing density is determined as 1-32 g cm-2 with a standard error of 0-52%. Values of projected bone thickness as a function of position in the bone are given. The average percentage of bone in the trabecular specimen is determined as 12-7 +/- 0-5, which is in close agreement with measurements of the same parameter determined from an optical scanning technique. The relationship between average packing density or rho y and the percentage of bone at different positions in the specimen packing density increase in percentage of bone, as would be expected.

Absorptiometry, Photon↗
PubMed1977

Measurements of endosteal surface areas in human long bones: relationship to sites of occurrence of osteosarcoma.

Using techniques of bone scanning and ashing, the areas of the endosteal surfaces in cortical and trabecular bone have been determined for the proximal, mid and distal thirds of each of the six long bones of an adult human subject. The relative frequency of occurrence of bone sarcomas, scored as to site, has been analysed in relation to these measured areas. Data on tumour occurrence have been drawn from three sources: radium-case data from Rowland and Keane (33 cases), naturally-occurring cases from series by Sissons (139 cases) and by Dahlin (473 cases). A strong correlation is demonstrated between tumour frequency and trabecular area, but correlation with cortical area is poor. By comparing the tumour frequency in the mid thirds of the bones with the total recorded it has been possible to show that the probability of tumour occurrence per unit area of cortical bone, relative to that of trabecular bone, is 0.16 +/- 0.06. Analysis of the available dose data for the radium cases shows that in this instance dose has not contributed to the observed correlations. The results lend support to the thesis that tumour occurrence depends on surface area, i.e. on the number of cells at risk.

Anthropometry↗