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At least 19 recordsLinked to original sources
PubMed1988

Yaw direction neurons in the cat inferior olive.

1. Single units that responded to yaw rotation were recorded extracellularly in the caudal inferior olive (IO) of barbiturate-anesthetized cats. Of 276 neurons, 55 responded reliably to yaw, and extensive quantitative data were recorded from 25. 2. No yaw-sensitive IO neuron responded to somatosensory or auditory stimuli but two responded, though unreliably, to flash. 3. Yaw-sensitive IO cells fired at low (1-4 spikes/s), irregular rates during one direction of rotation. Though cells responded reliably during yaw, firing rates varied considerably from cycle to cycle. Rotation speed and acceleration were not represented in any cell's firing rate. 4. Eighty five percent (47/55) of yaw-sensitive cells fired during contralateral rotation, 9% (5/55) during ipsilateral rotation, and 6% (3/55) fired from late in the ipsilateral phase of a sinusoidal oscillation to the middle of the contralateral phase. 5. Responses were tested to 0.1-Hz sinusoidal yaw oscillations with a range of peak angular velocities (1-200 degrees/s). Thresholds were not sharp because of the cycle to cycle variability in response rates but were estimated using averaged responses. The peak rate of the most sensitive cell was driven to criterion (2 SD above spontaneous rate) by an oscillation with a peak velocity of 1 degrees/s. Other cells reached criterion between 5 and 50 degrees/s. 6. Sinusoidal oscillation at all frequencies tested (0.01-0.5 Hz) elicited approximately the same firing rates. Even at 0.01 Hz cells responded well. Responses lagged acceleration by approximately 25 degrees at 0.01 Hz and shifted to later parts of the cycle as frequency increased so that firing lagged acceleration by approximately 200 degrees at 0.5 Hz. 7. Histological reconstruction showed that yaw-sensitive neurons were recorded in olivary subnucleus beta (N beta), the dorsal cap of Kooy (DC), the posterior medial region of the medial accessory division of the inferior olive (MAO), and in the medial-lateral center of the caudal MAO. 8. Yaw-sensitive neurons in the inferior olive provide a signal to the cerebellum that indicates the direction of passive rotation over a wide range of velocity and acceleration. The signal from individual neurons does not reliably encode either rotation velocity or acceleration. Yaw-sensitive IO neurons are therefore unlike other central vestibular neurons but are similar to somatosensory IO cells which signal the presence, but not the intensity of a stimulus.

Action Potentials↗
PubMed1995

Evaluation of immunoglobulin G enzyme immunoassay for serodiagnosis of yaws.

A commercially available enzyme immunoassay (EIA), the Captia Syphilis-G immunoglobulin G (IgG) EIA, for the detection of IgG antibodies to Treponema pallidum was evaluated for use as a screening test for yaws (Treponema pallidum subsp. pertenue). The IgG EIA was compared with the fluorescent treponemal antibody absorption (FTA-ABS) test. All sera were also examined by the T. pallidum hemagglutination test and the Venereal Disease Research Laboratory test. Serum samples from 271 subjects (23 control serum samples from an area nonendemic for yaws, 58 control serum samples from an area endemic for yaws, and 190 serum samples from yaws patients and contacts) were investigated. The overall agreement between the IgG EIA and the FTA-ABS test was 90%, the sensitivity was 99%, and the specificity was 70.2%. The specificity fell as the endemicity of the disease increased: from 94.4% in the nonendemic area controls to 86.4% in the endemic area controls and to 52.3% in the yaws contacts. There was no difference in specificity between children and adults within each of the three groups. Fifteen children with clinical yaws were monitored for 9 months after treatment. The level of treponemal antibody fell consistently in 9 of the 15 children as measured by the antibody index (ratio of absorbance of the test serum to the mean absorbance of the low-titer-positive controls). Reinfection was seen in three children, with the antibody index rising with the Venereal Disease Research Laboratory test titer. The Captia Syphilis-G test is a sensitive assay for the detection of treponemal antibodies in yaws patients. However, the apparent low specificity of the test in the yaws endemic area limits its use as a screening test for yaws.

Adult↗
PubMed1976

After smallpox eradication: yaws?

The WHO-coordinated Smallpox Eradication Program (SEP) has reduced the number of smallpox-endemic countries from 30 to 1, and now expects to complete the eradication of smallpox after a 10-year campaign. Campaigns to eradicate yaws were begun in the early 1950's with WHO and UNICEF support, and have greatly reduced the prevalence of that disease. Yaws has not yet been eradicated from any large geographic area, however, and is already resurgent in some countries. Some of the differences between the two diseases and available control measures are discussed. The thesis of this paper is that yaws programs have been deficient in failing to aggressively seek and contain yaws cases and contacts after mass treatment campaigns reduced yaws prevalence to low levels. It is further suggested that by using a modified SEP-type strategy to focus investigation and control efforts on infections yaws cases and their contacts, and by taking advantage of new methods to obtain more accurate diagnosis of yaws cases in the field, it should be possible to control yaws more effectively and efficiently, and perhaps to eradicate it. Outstanding barriers to yaws eradication are also discussed.

Adolescent↗
PubMed2002

Cross-axis adaptation of torsional components in the yaw-axis vestibulo-ocular reflex.

The three pairs of semicircular canals within the labyrinth are not perfectly aligned with the pulling directions of the six extraocular muscles. Therefore, for a given head movement, the vestibulo-ocular reflex (VOR) depends upon central neural mechanisms that couple the canals to the muscles with the appropriate functional gains in order to generate a response that rotates the eye the correct amount and around the correct axis. A consequence of these neural connections is a cross-axis adaptive capability, which can be stimulated experimentally when head rotation is around one axis and visual motion about another. From this visual-vestibular conflict the brain infers that the slow-phase eye movement is rotating around the wrong axis. We explored the capability of human cross-axis adaptation, using a short-term training paradigm, to determine if torsional eye movements could be elicited by yaw (horizontal) head rotation (where torsion is normally inappropriate). We applied yaw sinusoidal head rotation (+/-10 degrees, 0.33 Hz) and measured eye movement responses in the dark, and before and after adaptation. The adaptation paradigm lasted 45-60 min, and consisted of the identical head motion, coupled with a moving visual scene that required one of several types of eye movements: (1) torsion alone (-Roll); (2) horizontal/torsional, head right/CW torsion (Yaw-Roll); (3) horizontal/torsional, head right/CCW torsion (Yaw+Roll); (4) horizontal, vertical, torsional combined (Yaw+Pitch-Roll); and (5) horizontal and vertical together (Yaw+Pitch). The largest and most significant changes in torsional amplitude occurred in the Yaw-Roll and Yaw+Roll conditions. We conclude that short-term, cross-axis adaptation of torsion is possible but constrained by the complexity of the adaptation task: smaller torsional components are produced if more than one cross-coupling component is required. In contrast, vertical cross-axis components can be easily trained to occur with yaw head movements.

Adaptation, Physiological↗
PubMedDate not supplied

Integration of yaws control and primary health care.

Where a primary health care (PHC) system (e.g., a community health worker and a health center as the first referral level) is fully operational, control activities for yaws should be part of PHC. Where the whole population is adequately covered, the PHC system is responsible for early detection of cases of active clinical yaws, treatment and follow-up of these cases, treatment and follow-up of contacts, and health education related to yaws control. In circumstances where PHC is not as yet fully implemented, the structure for a yaws control program must be different. In areas with adequately functioning static health services or with a nascent PHC system, yaws control could be started as a vertical program--initial treatment survey and resurvey by a yaws team working in close collaboration with a health worker selected by the community. Subsequently, active yaws surveillance is taken over by that worker who also assumes the other functions of primary health care. In areas with nonexisting or poorly functioning static health services, a program for yaws control should not be implemented because control and effectiveness are likely to be poor.

Adolescent↗
PubMedDate not supplied

Yaws in Colombia.

By the beginning of this century, yaws was a well-known endemic disease in Colombia. Colombian authorities estimated that by early 1930 there were 70,000 active cases of yaws, most of which were located in the Pacific coastal regions. With the advent of penicillin therapy, Colombia organized an anti-yaws campaign, which began in 1950. The campaign relied on the use of penicillin and house-to-house case finding. From 1950 to 1953 more than 111,000 persons with active cases of yaws and 125,000 of their contacts were treated with penicillin. The reported incidence of yaws declined dramatically, and by 1973 only 573 cases were reported in the endemic areas. By 1983 this number had fallen to 31. Because of the persistence of small foci of yaws activity, the anti-yaws campaign has been reorganized to provide a firm basis for the final eradication of the disease in Colombia.

Colombia↗
PubMed1977

Yaws in the Americas, 1950-1975.

Yaws was introduced into the Americas by African slaves beginning in the 16th century and may have already been present before the arrival of Columbus. In the 1950s, programs for the eradication of yaws were undertaken in almost all American countries in which yaws was endemic. By mass treatment of cases and contacts with penicillin, the programs against yaws have dramatically reduced the incidence of reported cases throughout the Western Hemisphere from greater than 44,000 cases per year during 1950-1954 to 437 cases in 1975. In Brazil, efforts against yaws reduced the number of patients treated by 99% between 1965 and 1974. By 1975, yaws apparently remained a significant public health problem in only a few communities in Brazil, Columbia, Dominica, Ecuador, Haiti, Peru, St. Lucia, and St. Vincent, and possibly in Guiana and Surinam. It may be possible to eliminate infectious yaws entirely from the Western Hemisphere within the next few years.

Humans↗
PubMedDate not supplied

Occurrence of congenital, cardiovascular, visceral, neurologic, and neuro-ophthalmologic complications in late yaws: a theme for future research.

Late lesions of yaws are thought to be limited to skin, bones and joints, without congenital, visceral, or central nervous system (CNS) involvement. However, the treponemes isolated from patients with yaws, endemic syphilis, and venereal syphilis are genetically identical subspecies of Treponema pallidum. The controversy surrounding distinctions between syphilis and yaws is presented in its historical context, and reports of congenital, visceral, and CNS complications of yaws are reviewed. Isolation of treponemes from aqueous humor, as well as CSF abnormalities in 24.9% of 902 patients with yaws, indicate the existence of CNS involvement. The high prevalence of tropical myeloneuropathies of unknown origin discovered in areas of previous treponemal endemicity, particularly in Jamaica and Colombia, may represent late complications of yaws. Careful analysis of the collected evidence indicates that potential sequelae of yaws include congenital, visceral, and tertiary CNS lesions identical to those of venereal syphilis. The current worldwide resurgence of endemic treponematoses provides an unparalleled opportunity to settle conclusively questions still unanswered regarding the natural history of these infections.

Cardiovascular Diseases↗
PubMed1985

Studies on a focus of yaws in Ubangi, Zaire.

Yaws (buba, Frambösie, pian), a non-venereal treponematosis of skin and bones is a tropical disease that affects primarily children. Eradication programs launched between 1950 und 1970 reduced the incidence substantially; resurgences, however, have been reported from several countries. We have studied a geographically isolated focus of yaws in the Ubangi area of northwestern Zaire. In survey I, in 1981, of the 4.407 participants from 11 villages, 348 (7.9%) had active lesions of yaws. All patients and their contacts were treated immediately with benzathine penicillin G. In survey II, in 1982, in 6 of the previously studied villages, of 5,390 participants, 136 (2.5%) had active lesions of yaws. In 1981, the predominance of primary lesions (86%) and high numbers of patients in all age groups, with the highest prevalence (23.4%) in children 10-14 years of age, suggest that yaws recently recurred at this focus. In 1982, only 25.7% of the lesions were primary and the highest prevalence (6.5%) had shifted to the younger age group of 5-10 years-old. In survey I more males (63%) were infected in the age group 0-24 years, and more females (89%) in those over 40 years. In survey II, more males (61.3%) were infected in the age group 0-14 years, and only females (100%) in the age groups 25 years and older. Seventy-one percent (1981) and 86% (1982) of the initial lesions were on the lower limbs. Participation of the population in survey I was 41.7% and was greatest (62%) in the locality where there was a newly established dispensary. In survey II, participation rose to 73.8%. Areas adjacent to the focus of yaws with longstanding dispensaries were free of yaws.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1992

Relationship between direction of rolling and yawing of golden hamster and sea urchin spermatozoa.

As a first step towards understanding the function and mechanism of spiral movement of spermatozoa swimming through a medium, the direction of rolling (rotational movement of the spermatozoa around their long axis) and that of yawing (circular motion of spermatozoa upon the surface of a glass microscope slide and coverslip) were examined for golden hamster and sea urchin spermatozoa. Most golden hamster spermatozoa yawed clockwise over the upper surface of a glass slide when viewed from above, whereas in most sea urchin spermatozoa yawing was counterclockwise. Under the lower surface of a coverslip, the direction of yaw of golden hamster or of sea urchin spermatozoa was reversed. Most golden hamster spermatozoa rolled counterclockwise as seen from the anterior end, whereas all examined sea urchin spermatozoa rolled clockwise relative to the observer. On the basis of quantitative analysis of the proportion of spermatozoa rolling (or yawing) clockwise to those rolling (or yawing) counterclockwise, a close relationship between the direction of rolling motion and that of yawing motion was shown for both golden hamster and sea urchin spermatozoa.

Animals↗
PubMed1991

Yaws in West Sumatra, Indonesia: clinical manifestations, serological findings and characterisation of new Treponema isolates by DNA probes.

The results of a yaws survey on the island of Sumatra in Indonesia are presented. The prevalence of yaws in the investigated region was found to be very high, a minimum of 300 cases per 100,000 individuals, which indicates that yaws is far from being eradicated and that campaigns for treatment are necessary. Patients suffering from early infectious yaws showed florid skin lesions. Of 101 serum samples from such patients, 100 had a positive reaction in one or more treponemal tests. The Treponema pallidum haemagglutination assay was found to be the most sensitive test (97% positive) in detecting antibodies against Treponema pallidum subsp. pertenue, followed by the fluorescent treponemal antibody absorption test (94%), the Venereal Disease Research Laboratory test and the TmpA enzyme immunoassay (91%), and analysis by Western blot using Treponema pallidum antigens (88%). Of 42 asymptomatic contacts of yaws patients 32 showed positive reactions in one or more tests, indicating that many people in the investigated region have been infected with treponemes. Eight new Treponema pallidum subsp. pertenue strains were isolated from yaws skin lesions. In vitro amplification of treponemal DNA and hybridisation with specific DNA probes showed that all eight strains were identical with Treponema pallidum subsp. pertenue CDC 2575, with regard to the subsp. pertenue specific tyfl gene.

Adolescent↗
PubMed2003

Efficacy of a targeted, oral penicillin-based yaws control program among children living in rural South America.

Yaws is endemic in rural Guyana. An observational study was conducted to determine the efficacy of oral penicillin V therapy in treating skin lesions of yaws in children. In 1999, inhabitants of 7 rural villages near Bartica, Guyana, were screened for skin lesions of yaws. Cases were confirmed by serological testing. A control program was implemented in 2000: children < or =14 years old were screened, and those with active lesions were treated with oral penicillin V for 7-10 days. In 2001, children were rescreened and active cases were treated. Prevalence of yaws skin lesions fell from 5.1% (52 of 1020 children screened in 2000) to 1.6% (8 of 516 in 2001), a 71% drop. Sixteen (94%) of 17 children treated in 2000 and reassessed in 2001 had complete resolution of lesions. A targeted, oral penicillin-based treatment regimen can successfully treat dermatologic yaws in individual children and can decrease the prevalence of skin yaws in a community in which it is endemic. This information may aid in the implementation of additional control efforts.

Administration, Oral↗
PubMedDate not supplied

Surveillance and control of resurgent yaws in the African region.

Yaws, once one of the most common infections in Africa, was expected to be eliminated in some countries and controlled in others after the mass treatment campaigns sponsored by the World Health Organization and the United Nations Children's Fund during the 1950s and 1960s and the implementation of improvements in education, sanitation, and other health-promoting activities. However, the curtailment of yaws control activity allowed the reservoir of untreated yaws to grow unchecked, and the number of reported cases of active yaws has increased in certain parts of Africa, especially in West Africa. In the Central African Republic, the prevalence of yaws is notably high among the Pygmies. Renewed programs for yaws control are under consideration. Mass campaigns are still necessary in some developing countries for the control of certain diseases but should be complementary to the development of general health services and should not be limited to the administrative borders of a given country.

Africa↗