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Biomedical subjects

S M Keating

Publications and source records attributed to S M Keating.

9 recordsLinked to original sources
PubMed1991

Nanosecond fluorescence microscopy. Emission kinetics of fura-2 in single cells.

A microscope based time-correlated single photon counting instrument has been constructed to measure fluorescence intensity and emission anisotropy decays from fluorophores in single cells on a nanosecond time scale. The sample is excited and the emission collected using epi-illumination optics with frequency-doubled pulses from the cavity-dumped output of a synchronously pumped dye laser serving as an excitation source. Collection of decays from a single cell is possible due to the presence of an iris in the emission path that can be reduced to less than the diameter of a single cell. Using the instrument the decay of 60 nM 1,6-diphenyl-1,3,5-hexatriene was measured, demonstrating that adequate data for lifetime analysis can be recorded from fewer 10(3) molecules of the fluorophore in an illuminated volume of 23 fl. In addition, the intensity and anisotropy decays of fura-2 in single adherent cells and in suspensions of fura-2 loaded cells in suspension, although the relative amplitudes and decay constants vary somewhat from cell to cell. The results indicate that a significant but variable fraction of fura-2 is bound to relatively immobile macromolecular components in these cells.

Animals↗
PubMed1989

Information from penile swabs in sexual assault cases.

A survey has been made to assess the evidential value of tests carried out on 660 casework penile swabs. Most were from suspects in sexual assaults and were examined to see if the donor had had recent anal, oral or vaginal intercourse. The swabs were tested for one or more of the following: blood, faeces, saliva, vaginal secretions, semen. Blood was seldom found, it was usually weak and insufficient for grouping. Faeces were only identified on a pair of swabs from a dead homosexual showing that proof of buggery by this means is rare. Amylase, suggestive of saliva and oral intercourse, was occasionally detected. Glycogen-rich epithelial cells were sometimes present indicating vaginal intercourse. Semen was frequently found but its presence may not result from a recent sexual act. An ABO group different from the donor was obtained from a fifth of the swabs typed. Grouping in other blood group systems was rarely attempted or successful. Penile swabs provided a means of detecting a victim's ABO blood group on a suspect when it would not have been possible to demonstrate the suspect's group on samples from the victim. They also had value in assaults involving more than one offender. The main limitation of penile swabs was the paucity of material on them and the sampling site affected the interpretation of the results.

ABO Blood-Group System↗
PubMedDate not supplied

The isolation of spermatozoa from sexual assault swabs using proteinase K.

The most common examination in sexual offences is the identification of spermatozoa in aqueous extracts from swabs. Using Proteinase K with sodium dodecyl sulphate, it is possible to digest all the cellular material apart from the spermatozoa, resulting in a quick and effective method of their isolation. Spermatozoa were detected in 18 extracts using this treatment when the normal method had failed to reveal all but one of them.

Endopeptidase K↗
PubMedDate not supplied

Sexual assault patterns.

The numbers and types of all sexual offences examined at the Metropolitan Police Forensic Science Laboratory during the years 1978-1986 are presented. The largest number of sexual assaults took place during the month of August; they were mainly intra-racial and between adults of 18 to 30 years of age. A detailed breakdown is given of the offences against females recorded on the Sexual Assault Index. All these assaults were carried out by adult males, mainly strangers. Nearly half the assaults took place indoors, where victims were more likely to be bound and blindfolded, compared with one-third outdoors and one-sixth in vehicles. About one-fifth of the crimes were carried out by two men or more, and in one-third of cases, weapons were carried. Oral intercourse occurred in one-sixth and anal intercourse in one-twelfth of the offences, both performed more by white males and those of Mediterranean origin.

Adolescent↗
PubMedDate not supplied

Oral sex--further information from sexual assault cases.

A survey was carried out of sexual assault cases submitted to the Metropolitan Police Forensic Science Laboratory during 1988 and 1989. There were 104 cases with male victims, and 1403 with females. In the all-male offences, fellatio was reported in 34%; nearly two-thirds of the acts were by the offender, one-third by the victim. In the offences on females, oral-genital acts were alleged in 22%, 78% of which were fellatio, and 22% cunnilingus. The majority of offenders were white. The few Afro-Caribbeans studied rarely performed oral sex on males or very young females.

Adolescent↗
PubMedDate not supplied

The detection of amylase on swabs from sexual assault cases.

Results are presented of amylase tests performed on more than 400 casework swabs using Phadebas tablets. Amylase levels indicative of saliva were obtained from 25% of the penile swabs tested, 32% of the vaginal swabs and 50% of the breast swabs. The longest time interval between the offence and sampling when such levels were detected was 16 hours for penile swabs, 55 hours for vaginal swabs and 30 hours for breast swabs.

Amylases↗