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C J Alexander

Publications and source records attributed to C J Alexander.

At least 19 recordsLinked to original sources
PubMed2002

The dusk flank of Jupiter's magnetosphere.

Limited single-spacecraft observations of Jupiter's magnetopause have been used to infer that the boundary moves inward or outward in response to variations in the dynamic pressure of the solar wind. At Earth, multiple-spacecraft observations have been implemented to understand the physics of how this motion occurs, because they can provide a snapshot of a transient event in progress. Here we present a set of nearly simultaneous two-point measurements of the jovian magnetopause at a time when the jovian magnetopause was in a state of transition from a relatively larger to a relatively smaller size in response to an increase in solar-wind pressure. The response of Jupiter's magnetopause is very similar to that of the Earth, confirming that the understanding built on studies of the Earth's magnetosphere is valid. The data also reveal evidence for a well-developed boundary layer just inside the magnetopause.

Journal Article↗
PubMed2001

Sexual arousal and orgasm in women: effects of spinal cord injury.

Sexual disorders are common in women; however, the neurological basis of female sexual response has not been adequately investigated. This information is necessary to characterize the impact of various neurological disorders on sexual arousal in women and to develop appropriate management strategies for sexual dysfunction. To assess the spinal mediation of sexually stimulated genital vasocongestion in women, we conducted two laboratory-based, controlled analyses: (1) of women's genital, subjective, and autonomic responses to audiovisual erotic and audiovisual erotic combined with manual genital stimulation; and (2) of women's ability to achieve orgasm. Subjects included 68 premenopausal women with spinal cord injuries (SCIs) and 21 able-bodied, age-matched controls. Results indicated that preservation of sensory function in the T11-L2 dermatomes is associated with psychogenically mediated genital vasocongestion. Less than 50% of women with SCIs were able to achieve orgasm, compared with 100% of able-bodied women (p = 0.001). Only 17% of women with complete lower motor neuron dysfunction affecting the S2-S5 spinal segments were able to achieve orgasm, compared with 59% of women with other levels and degrees of SCIs (p = 0.048). Time to orgasm was significantly increased in women with SCIs compared with able-bodied controls (p = 0.049). Independent raters were unable to differentiate between subjective descriptions of orgasm from SCI women compared with controls. This information should be used when counseling women with spinal dysfunction about their sexual potential.

Adult↗
PubMed2000

Sildenafil effects on sexual and cardiovascular responses in women with spinal cord injury.

OBJECTIVES: Sexual dysfunction is common in women with spinal cord injuries (SCIs) and other neurologic conditions. Sildenafil has previously been shown to be safe and effective in the treatment of erectile dysfunction due to SCI. This study is the first to evaluate the sexual and cardiovascular effects of sildenafil in women with SCIs in a controlled, laboratory setting. METHODS: Nineteen premenopausal women with SCIs were randomly assigned to receive either sildenafil (50 mg) or placebo in a double-blind, crossover design study. Physiologic and subjective measures of sexual response, heart rate, and blood pressure were recorded during baseline and sexual stimulation conditions. Adverse events were also recorded. RESULTS: Significant increases in subjective arousal (SA) were observed with both drug (P <0.01) and sexual stimulation conditions (P <0.001), and a borderline significant (P <0.07) effect of drug administration on vaginal pulse amplitude (VPA) was noted. Maximal responses occurred when sildenafil was combined with visual and manual sexual stimulation. Cardiovascular data showed modest increases in heart rate (+/-5 bpm) and mild decreases in blood pressure (+/-4 mm Hg) across all stimulation conditions, consistent with the peripheral vasodilatory mechanism of the drug. Sildenafil was well tolerated with no evidence of significant adverse events. CONCLUSIONS: Findings suggest that sildenafil may partially reverse the sexual dysfunction commonly associated with SCI in women. Consistent with previous findings in men, the sexual effects of the drug were most evident under conditions of optimal stimulation. Mild, clinically insignificant cardiovascular effects were also noted. Further large-scale studies of sildenafil's effects in women with neurogenic sexual dysfunction are strongly indicated.

Adult↗
PubMed1998

Radiology in forensic identification: the Mt Erebus disaster.

Although radiology has exceptional discriminatory power in the identification of individuals, it is not often used for this purpose. This under-utilization stems in part from insufficient appreciation of its potential, and in part from a lack of agreed operational protocols. Descriptions of criteria used for radiological identification are scattered in individual reports and have not been collated. The circumstances in which identification is required are various and pose different problems for which guidelines have not been established. The areas in which radiology has a high capacity for identification of age, sex or identity are reviewed and their strengths and limitations are discussed. A survey of the literature identified three different circumstances in which cadaver identification is needed, and a protocol is suggested to meet the differing requirements of these three situations. The use of these protocols and techniques in the identification of bodies recovered from the Mt Erebus disaster is described. Postmortem radiographs established the identity of 11 bodies not identified by other techniques. There is a need for greater awareness in police and forensic circles of the identifying power of radiology.

Accidents, Aviation↗
PubMed1997

Physiologic parameters associated with sexual arousal in women with incomplete spinal cord injuries.

OBJECTIVE: To compare the physiologic sexual responses of women with incomplete spinal cord injuries (SCIs) with and without preservation of the ability to perceive T11-L2 pinprick sensation. DESIGN: Controlled laboratory-based analysis of responses to varying combinations of audiovisual erotic stimulation, manual genital stimulation, and performance of a distracting task coupled with manual genital stimulation. SETTING: The sexual physiology laboratory at our freestanding rehabilitation hospital. PARTICIPANTS: A volunteer sample of 17 women with incomplete SCIs. INTERVENTIONS: Two 78-minute protocols using 6-minute baselines alternating with 12-minute testing conditions. One protocol was designed to study the effects of psychogenic and psychogenic combined with manual sexual stimulation, while the other was designed to examine the effects of genital sexual stimulation performed in conjunction with a distracting task. DEPENDENT VARIABLES: Vaginal pulse amplitude, subjective arousal, heart rate, respiratory rate, and blood pressure. RESULTS: Subjective arousal increased in both groups of subjects with isolated audiovisual erotic stimulation; however, only those subjects with the ability to perceive T11-L2 pinprick sensation had concomitant increases in vaginal pulse amplitude. In contrast, when manual genital stimulation was added to the audiovisual erotic stimulation, both groups of subjects developed increases in vaginal pulse amplitude, whereas only those subjects with the ability to perceive T11-L2 demonstrated a further increase in their level of subjective arousal. Performance of manual genital stimulation in conjunction with a distracting task resulted in significantly increased vaginal pulse amplitude and arousal level only in those subjects with preservation of the ability to perceive T11-L2 pinprick sensation. With the changeover to masturbation, neither group of subjects developed significant increases in vaginal pulse amplitude. During masturbation, both groups of subjects had increases in their level of sexual arousal; however, only those subjects with T11-L2 pinprick preservation had a significant increase. CONCLUSIONS: Women with preservation of the ability to perceive T11-L2 pinprick sensation tended to maintain the ability for psychogenic genital vasocongestion. Psychogenic protocol results showed that all subjects appeared to develop reflex genital vasocongestion when manual stimulation was added to audiovisual erotic stimulation. Manual genital stimulation in conjunction with the performance of a distracting task only resulted in increased vaginal pulse amplitudes in those subjects with preservation of T11-L2 pinprick sensation. We believe that this was due to increased subjective sexual arousal and that the reason all subjects did not develop increased genital vasocongestion under these conditions was due to poor hand function. Further research examining women with lower levels of SCI is necessary to understand the neurophysiology of female sexual response after SCI.

Adult↗
PubMed1997

Characterization of saccharolytic Bacteroides and Prevotella isolates from infected dog and cat bite wounds in humans.

Saccharolytic, nonpigmented, anaerobic gram-negative rods isolated from infected dog and cat bite wounds in humans have been poorly characterized, and most are not included in the databases of kits used for anaerobic identification; thus, they are problematic for clinical laboratories to identify. Fifty strains isolated from such wounds were characterized with commercial kits for preformed-enzyme detection, carbohydrate fermentation, and other biochemical tests. PCR fingerprinting was performed on these strains to further characterize subgroups within these species. Bacteroides tectum is a frequent isolate in bite wounds and resembles Prevotella bivia in colony morphology and saccharolytic activity, except that it grows in 20% bile and hydrolyzes esculin. Profile numbers generated by various kits associate B. tectum with P. bivia, Prevotella oralis group, or Prevotella melaninogenica. PCR fingerprinting identified at least four subgroups and confirmed the heterogeneous nature of this species. Prevotella heparinolytica was also frequently isolated from these bite wounds. It produces indole and generates a profile number in preformed-enzyme kits that is usually associated with Bacteroides uniformis. However, it is bile sensitive and quite distinct from the Bacteroides fragilis group of anaerobes. The PCR fingerprint profiles generated by strains of P. heparinolytica were very similar to that of the type strain and to each other. Prevotella zoogleoformans, occasionally isolated from dog and cat bite wounds in humans, resembles P. heparinolytica except for a negative indole test. Clinical laboratories should be aware of the characteristics of these animal species when identifying isolates from animal bite wounds in humans.

Animals↗
PubMed1996

Physiological parameters associated with the performance of a distracting task and genital self-stimulation in women with complete spinal cord injuries.

OBJECTIVE: To compare the physiological sexual responses of women with complete spinal cord injuries (SCI) with those of able-bodied women. DESIGN: Controlled laboratory-based analysis of responses to a distracting task coupled with manual genital stimulation versus masturbation. SETTING: The sexual physiology laboratory at our free-standing rehabilitation hospital. PARTICIPANTS: A volunteer sample of 10 women with complete SCI along with 10 able-bodied women, matched for age and educational status. INTERVENTIONS: A 78-minute protocol using 6-minute baselines alternating with 12-minute testing conditions. DEPENDENT-VARIABLES: Vaginal pulse amplitude, subjective arousal, heart rate, respiratory rate, and blood pressure. RESULTS: Subjective sexual arousal increased in able-bodied women with manual genital stimulation in conjunction with performance of a distracting task and was further augmented by removal of the distracting task and continuing with masturbation. In contrast, complete SCI subjects did not demonstrate increased subjective arousal with performance of the distracting task in conjunction with manual genital stimulation; however, they did evidence significant increases in arousal when the distracting task was eliminated. CONCLUSIONS: Genital responses tended to parallel subjective responses in able-bodied women; however, women with SCI revealed nonsignificant changes in genital responses throughout the treatment protocol. It is hypothesized that the genital and subjective responses of able-bodied subjects reflect the additive components of reflex and then psychogenic sexual arousal. Furthermore, the lack of responsivity in the SCI subjects was thought to be related to compromised upper extremity function in the majority of our subjects. Further work is necessary to validate these hypotheses.

Adult↗
PubMed1995

Orgasm in women with spinal cord injuries: a laboratory-based assessment.

OBJECTIVE: To understand the characteristics and physiological sexual responses of women with spinal cord injuries (SCI) during orgasm. DESIGN: Controlled laboratory-based analysis of women's physiological and subjective responses during a single session in which they attempted to perform stimulation to orgasm. SETTING: The sexual physiology laboratory at our free-standing rehabilitation hospital. PARTICIPANTS: A volunteer sample of 25 women with SCI and 10 able-bodied control subjects, matched for age. INTERVENTION: A 75-minute protocol designed to obtain information on the physiological events accompanying orgasm. DEPENDENT VARIABLES: Included vaginal pulse amplitude, heart rate, respiration rate, blood pressure, subjective arousal and subscores on the Derogatis Sexual Functioning Inventory (DSFI). RESULTS: Data were analyzed both within and across neurological groups: complete SCI, incomplete SCI, and able-bodied controls. All able-bodied subjects achieved orgasm whereas 52% of SCI subjects achieved orgasm. Degree and type of SCI did not significantly relate to subjects' ability to achieve orgasm. Subjects with no lower extremity function took significantly longer than able-bodied subjects to achieve orgasm. Differences between baseline and orgasm readings are described for each of the major physiological measures. Results of DSFI revealed that able-bodied subjects acknowledged greater sexual satisfaction than SCI subjects. Subjects who achieved orgasm scored higher on sexual information and sex drive. CONCLUSION: Results support previous self-report studies, in that a large percentage of SCI women achieved orgasm regardless of pattern or degree of neurological injury. No consistent characteristics were identified that would allow prediction of which women with SCI would be able to experience orgasm. However, subjects who achieved orgasms had a higher sex drive and greater sexual knowledge. Implications for sex therapy treatment programs with spinal cord injured women are discussed.

Adult↗
PubMed1995

Physiological parameters associated with psychogenic sexual arousal in women with complete spinal cord injuries.

OBJECTIVE: To compare the physiological sexual responses of women with complete spinal cord injuries (SCIs) with those of able-bodies women. DESIGN: Controlled laboratory-based analysis of responses to audiovisual erotic and audiovisual erotic combined with manual stimulation. SETTING: The sexual physiology laboratory at our free-standing rehabilitation hospital. PARTICIPANTS: A volunteer sample of 13 women with complete SCIs above T6 along with eight able-bodies women, matched for age and educational status. INTERVENTIONS: A 78-minute protocol using 6-minute baseline alternating with 12-minute testing conditions was conducted. DEPENDENT VARIABLES: Included vaginal pulse amplitude, subjective arousal, heart rate, blood pressure, and respiratory rate. RESULTS: Showed comparable increases in subjective arousal in both groups with audiovisual but not audiovisual combined with manual stimulation. Vaginal pulse amplitude increased in able-bodied subjects but no SCI subjects with isolated audiovisual stimulation; however, with the addition of manual stimulation all subjects responded similarly. Other nongenital correlates of sexual arousal were similar between SCI and able-bodies subjects. CONCLUSION: These results provide physiological validation of the hypothesis that women with complete SCI can respond with audiovisual stimulation similarly to able-bodies women in those functions that are controlled neurologically above the level of their injuries, whereas, genital vasocongestion will not occur because the neurological pathway is interrupted. In contrast, reflex genital vasocongestion can occur in women with complete SCI despite a lack of subjective arousal. These findings can be used to educate women with complete SCIs about their sexual responses.

Adult↗
PubMed1995

Identification and antimicrobial resistance patterns of clinical isolates of Clostridium clostridioforme, Clostridium innocuum, and Clostridium ramosum compared with those of clinical isolates of Clostridium perfringens.

Clostridium ramosum, C. innocuum, and C. clostridioforme are frequently isolated from clinical specimens including blood. Because of Gram stain variability, a lack of spores, and atypical colonial morphology, identification of these species is often difficult. Three anaerobe identification kits were evaluated for their abilities to identify these species. For comparison, 11 strains of C. perfringens were evaluated in parallel. By using profile numbers and codebooks, the correct genus and species were identified, as follows: with the RapID ANA II kit, 100% (20 of 20) of C. ramosum isolates, 24% (5 of 21) of C. innocuum isolates, and 50% (10 of 20) of C. clostridioforme isolates; with the AnIDent kit, 60% (12 of 20) of C. ramosum isolates, 28% (6 of 21) of C. innocuum isolates, and 90% (18 of 20) of C. clostridioforme isolates; with the ATB32A kit, 70% (14 of 20) of C. ramosum isolates, 0% (0 of 21) of C. innocuum isolates, and 40% (8 of 20) of C. clostridioforme isolates. Profile numbers that overlapped several species were obtained as follows: with the RapID ANA II kit, 0% of C. ramosum isolates, 76% of C. innocuum isolates, and 40% of C. clostridioforme isolates; with the AnIDent kit 40% of C. ramosum isolates, 62% of C. innocuum isolates, and 5% of C. clostridioforme isolates; with the ATB32A kit, 15% of C. ramosum isolates, 52% of C. innocuum isolates, and 25% of C. clostridioforme isolates. One strain of C. innocuum was misidentified by the AnIDent kit, and the remainder yielded profile numbers that were not listed in the codebooks. The MICs of 11 antimicrobial agents including penicillin G, metronidazole, clindamycin, cefoxitin, cefotetan, imipenem, meropenem, amoxicillin-clavulanate, ampicillin-sulbactam, piperacillin-tazobactam, and vancomycin were determined by the agar dilution method. All C. perfringens strains were susceptible to all antimicrobial agents tested. Various levels of resistance to cefoxitin, cefotetan, and penicillin G were noted with C. ramosum, C. clostridioforme, and C. innocuum. In addition, resistance to clindamycin was noted with C. ramosum (5%) and C. innocuum (10%). Most strains of C. innocuum were only moderately susceptible to vancomycin (MIC at which 90% of strains are inhibited, 4 micrograms/ml).

Bacteriological Techniques↗
PubMed1995

Lewis X antigen immunostaining in the diagnosis of transitional cell carcinoma.

Immunodetection of the Lewis X antigen has been suggested as a useful adjunct in the diagnosis of transitional cell carcinoma. To determine the specificity of Lewis X antigen immunostaining in this setting, we studied routinely processed, formalin-fixed tissue from 38 transitional cell carcinomas and 42 nonneoplastic urothelial lesions using the P12 monoclonal antibody to Lewis X antigen and an avidin-biotin immunohistochemical technique. Because Lewis X immunostaining of occasional umbrella cells has previously been noted in normal urothelium, staining of umbrella cells was not considered sufficient for a positive reaction in our study. Immunoreactivity for Lewis X antigen was seen in 34 of 38 (89%) cases of transitional cell carcinoma, in three of three cases of urothelial dysplasia, and in 20 of 39 (51%) of the reactive urothelial lesions. We conclude that immunostaining for the Lewis X antigen is not specific in the diagnosis of transitional cell carcinoma.

Antibodies, Monoclonal↗
PubMed1994

Relation between the finger positions used in the precision and partial power grips and the regional prevalence of osteoarthritis.

The correlation between digital flexion angles used in the precision and partial power grips and the reported regional prevalence of osteoarthritis was studied by goniometric measurement of six female subjects using the grips in 40 preselected activities. Normal interphalangeal ranges were determined by goniometric measurement in 20 normal female subjects. Both grips show a highly significant inverse correlation between mean flexion at each joint and the local prevalence of osteoarthritis. The conflict between these data implicating underuse and those supporting the theory of overload can be reconciled by postulating that primary and secondary osteoarthritis arise from different mechanisms. The former may be bifactorial, with incomplete use initiating the process and cartilage loading determining the rate of progress.

Adult↗
PubMed1994

Utilisation of joint movement range in arboreal primates compared with human subjects: an evolutionary frame for primary osteoarthritis.

OBJECTIVE: To determine whether an arboreal lifestyle required full use of movement ranges underutilised in nine joint groups in humans, because under-utilisation of available movement range may be associated with susceptibility to primary osteoarthritis. METHODS: Utilisation of the nine joint groups was studied in two species of primate exercising in a simulated arboreal environment, using 'focal animal' observation techniques supplemented by telephoto photography and by review of archival material from other sources. Fifteen apes were observed over a total observation period of 20.2 man-hours and 152 films were analysed for utilisation of movement range. RESULTS: With one exception, all the movement ranges reported to be under-utilised in humans were fully utilised by the apes in climbing activities. The exception, metacarpophalangeal extension, was an essential component of the chimpanzee ground progression mode of knuckle walking. CONCLUSIONS: The underused movement range in several human joints is explicable as residual capacity from a semiarboreal lifestyle. If the correlation with primary osteoarthritis is confirmed, it suggests that the disease may reflect a disparity between inherited capacity and current need. The significance of the result lies in its implication that primary osteoarthritis may be preventable.

Animals↗
PubMed1993

Osteoarthritis of the metacarpophalangeal joints: the relation between ray prevalence, trauma, and utilisation.

The gradient in prevalence of idiopathic osteoarthritis of the metacarpophalangeal (MCP) joints from the index to the little finger was used to test three theories. Trauma was correlated by analysis of fracture incidence in the four rays in 142 patients. Correlation with utilisation of arc was assessed by goniometric measurement of mean MCP flexion in five hand positions in a sample of 200 activities, and recording utilisation of these positions by behavioural observation techniques in the course of 2831 actions, 2746 domestic and 85 nondomestic. Both correlations were negative. The hypotheses of excessive loading and incomplete use were compared and tested against external evidence. It is suggested that the gradient in MCP prevalence of osteoarthritis is consistent with a bifactorial aetiology, with site and incidence determined by incomplete use, and with the rate of progress by cartilage loading.

Female↗
PubMed1993

Sexual activities, desire, and satisfaction in males pre- and post-spinal cord injury.

Thirty-eight spinal cord injured (SCI) males (median age = 26) completed an 80-item multiple choice questionnaire (median 37 months postinjury) which assessed sexual functioning pre- and post-spinal cord injury in four areas: (i) sexual activities and preferences, (ii) sexual abilities, (iii) sexual desire, arousal, and satisfaction, and, (iv) sexual adjustment. Frequency of sexual activity decreased following SCI with a reduction in intercourse and increased interest in alternative sexual activities. Of complete quadriplegic subjects 38% reported the ability to have an orgasm accompanied by ejaculation underscoring the need for physiological studies. Partner's desire for sex as perceived by the SCI individual was correlated with frequency of sex and numbers of sexual partners postinjury. Subject's perceptions of their own and partner's sexual desire decreased following SCI. Sexual satisfaction decreased postinjury and was positively correlated with both the patients' and their partners' interest in penile-vaginal intercourse. Of the subjects, 27% reported sexual adjustment difficulties and 74% relationship difficulties but only 22% received counseling. Results indicate the importance of the availability and desire of a sexual partner in the sexual activities and satisfaction of the SCI individual. SCI patient and staff sexual education and counseling continue to be strong needs.

Adolescent↗
PubMed1993

Sexual activities, response and satisfaction in women pre- and post-spinal cord injury.

Twenty-five spinal cord injured (SCI) women (median age = 34) completed an 80-item multiple choice questionnaire (median 50 months postinjury) that assessed sexual functioning pre-spinal cord injury and post-spinal cord injury in four areas: (1) sexual adjustment; (2) sexual activities and preferences; (3) sexual desire, arousal and satisfaction; and (4) sexual abilities. Frequency of sexual activity decreased following SCI. Intercourse was the favorite activity preinjury; whereas, kissing, hugging and touching were favored postinjury. Sexual desire and satisfaction decreased postinjury. Ability to achieve lubrication and orgasm with various types of spinal injuries is reported. Although most women did not receive sexual information or counseling, 76% of the sample believed they had been adjusting well sexually. Results are discussed accounting for the limitations of self-report methodology in sexuality research. The need for laboratory based, physiologic studies is underscored.

Adolescent↗