The substructure of centriole subfibers.
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Biomedical subjects
Publications and source records attributed to A Ross.
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Time exposure photomicrography and interspecific in vitro fertilization techniques have been used to compare the responses to the divalent cation ionophore A23187 of spermatozoa from normal fertile and oligozoospermic men. The fertilizing capacity of spermatozoa from the fertile controls produced a bell-shaped dose response curve when assessed in the presence of ionophore. The optimal responses occurred in the presence of 50 and 100 microM A23187. At this concentration, a mean penetration rate of about 75%, in association with multiple polyspermy, was observed without significant changes in motility patterns. At higher doses of A23187, there was a decline in fertilization rates, an independent reduction in sperm motility, and a significant decrease in the amplitude of lateral sperm head displacement. In contrast to the fertile controls, spermatozoa recovered from patients with oligozoospermia failed to exhibit a significant change in their fertilizing potential following exposure to A23187. Calculations based on the Poisson distribution theory indicated that this lack of responsiveness was not related to any differences in the motility of the spermatozoa from the oligozoospermic patients compared to the controls. These results suggest that calcium ionophores may be of value in providing a rapid and sensitive indicator of the functional competence of human spermatozoa, which circumvents problems concerning the rate and efficiency of sperm capacitation encountered with conventional protocols.
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A procedure was devised to investigate discrimination and control of heart rate (HR) concurrently. Eighteen volunteers were divided into two equal groups instructed either to increase or to decrease HR during four experimental sessions. In addition, subjects were required to indicate whenever they thought they were successful during the HR control task by pressing a switch. Activation of the switch automatically enabled the presentation of a feedback tone provided that the HR level at that moment, met a preset criterion of change. The feedback was not available during pre- and post-training testing periods. Responses to bidirectional HR control instructions alone were also investigated. Respiration volume and general movement were recorded throughout. While the group given HR increase instructions improved both their discrimination and control performances, the group instructed to decrease HR did not improve. It is suggested that the optimal procedures for training HR increases and decreases may differ, but that the relationship between discrimination and control posited by the calibration model can accommodate these differences.
With more than 5 million patient visits annually, certified nurse-midwives (CNMs) substantially contribute to women's health care in the United States. The objective of this study was to describe ambulatory visits and practices of CNMs, and compare them with those of obstetrician-gynecologists (OB/GYNs). Sources of population-based data used to compare characteristics of provider visits were three national surveys of CNMs and two National Ambulatory Medical Care Surveys of physicians. When a subset of 4,305 visits to CNMs in 1991 and 1992 were compared to 5,473 visits to OB/GYNs in similar office-based ambulatory care settings in 1989 and 1990, it was found that a larger proportion of CNM visits were made by women who were publicly insured and below age 25. The majority of visits to CNMs were for maternity care; the majority of visits to OB/GYNs were for gynecologic and/or family planning concerns. Face-to-face visit time was longer for CNMs, and involved more client education or counseling. This population-based comparison suggests that CNMs and OB/GYNs provide ambulatory care for women with diverse demographic characteristics and differing clinical service needs. Enhancing collaborative practice could improve health care access for women, which would be especially beneficial for those who are underserved and vulnerable.
PURPOSE: To report the ocular findings in HIV-1 seropositive individuals and HIV-negative controls in a population-based cohort in rural Uganda. METHODS: Participants were examined by an ophthalmologist, who was unaware of their HIV-status. RESULTS: 238 participants were examined, 43 were HIV-1 prevalent cases (infected prior to 1990); 62 were HIV-1 incident cases and 133 were HIV-negative controls. Eleven of the HIV-positive participants had AIDS, and a further 8 had a CD4 count of less than 200 cells/mm3. Bilateral low vision was recorded in 9 participants and cataracts were the main cause of bilateral low vision. The mean intra-ocular pressure (IOP) was 12.6 mm Hg, and no association was found between IOP and CD4 lymphocyte count. Although significantly more HIV positives had some sign of intraocular inflammation compared to the negatives (p = 0.02) there was no significant linear trend in the HIV positives with decreasing CD4 count. Overall, 11 (26%) prevalent, 6 (10%) incident cases and 8 (6%) HIV-negatives controls had some evidence of intraocular inflammation, however, only one person had reduced visual acuity attributable to these lesions. Punctate epithelial erosions and keratic precipitates in the anterior chamber were seen significantly more frequently in HIV-positives compared to the HIV-negative controls. Cotton wool spots were not seen. CONCLUSIONS: A substantial proportion of HIV-infected persons had ocular findings which may have been attributable to their infection, however in only one case did this result in reduced visual acuity. Although the ocular complications of AIDS seem to comprise a large extra element in the work load of tertiary care hospitals dealing with eye problems, on a population basis such cases are infrequent.
AIMS: To examine the extent to which problem alcohol users' self reports of drinking pattern and symptomatology derive primarily from a functional, learned social-cognitive schema (referred to as a 'script' in this paper), rather than from acts of recall or memory. METHODS: Using a between-groups design with one repeated (within-subjects) measure, problem drinkers and non-problem drinkers were asked to complete a questionnaire about drinking behaviour and symptoms. Each group filled in the questionnaire twice, under both of two conditions. In condition one, they used the questionnaire to describe their own drinking and in condition two they were asked to describe the drinking of the other group (i.e. the problem drinkers filled out the questionnaire to describe non-problem drinking and the non-problem drinkers described problem drinking). RESULTS: Using analyses of variance for the different sub-scales of the questionnaire, no overall differences were found between the two groups on four of the five subscales. However, clear and significant differences were found between the two conditions. That is, both groups were able to produce clearly differentiated scripts for both problem drinking and non-problem drinking. CONCLUSIONS: These data, together with related data from other sources, suggest that 'scripts' for problem drinking and for non-problem drinking can be elicited from both problem-drinking and non-problem-drinking groups. The data support conclusions from an earlier study, suggesting that subjects may use learned 'scripts' rather than recall when responding to certain types of questionnaire instruments.
Psychophysiologic reactions to behavioral challenges were examined in men aged 55 or less with no prior history of cardiovascular disorder. Three age-matched groups of twelve were recruited through factory screening: mild hypertensives (blood pressure in the range 175/105-145/90 persisting on retest), transient hypertensives (blood pressure above criterion on screening, falling on retest), and normotensives. Clinical examination, a laboratory rest session and period of blood pressure self-monitoring were followed by a laboratory stress session. The latter involved performance of two tasks demanding active behavioral coping (the Stroop interference task and video game) and one passive condition (a distressing movie). Mild hypertensives showed significantly greater pressor reactions (both in absolute and percentage terms) than normotensives to tasks requiring active behavioral coping, but not to the passive condition. The transient hypertension group produced heightened reactions in diastolic but not systolic pressure. Greater heart rate and pulse transit time reactions were also observed in the transient group, suggesting that exaggerated cardiac responsiveness to active challenges may be characteristic of the prehypertensive profile. No differences were recorded in electrodermal or respiratory variables, or in self-reported tension. Exaggerated pressor responses were also associated with high scores on the Hostility and Direction of Hostility questionnaire, and an absence of coronary-prone behavior. Implications for the etiology of essential hypertension are considered.
This paper describes a test which was developed for use in assessing the functional oral hygiene status of an elderly population. The instrument was tested among 80 community-dwelling elderly subjects 65 or more years old. The instrument, the Oral Hygiene Performance Test [OHPT], is a direct-observation measure which objectively quantifies the individual's ability to perform oral hygiene and thus reduces subjective evaluation. The test utilized several items from other already-validated instruments currently in use in geriatric medicine to assess functional abilities in a geriatric population. Additional items were developed by the research team and were included in this 17-item test. The OHPT was validated with common measures of physical function and direct-observation measures. Construct validity was assessed by comparison of the OHPT scores with other commonly used measures of other dimensions. The instrument proved to be reliable and demonstrated construct as well as concurrent validity. It appears that the OHPT can prove useful to clinicians in assessing the oral physical function of elderly patients with regard to their maintenance of oral hygiene. Because the OHPT is a direct-observation instrument, it can even elicit higher functions in elderly patients. While effective among the studied population, the instrument may still need to be validated among more diverse populations, such as various ethnic groups and demented or severely impaired populations.