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PubMedDate not supplied

Musculoskeletal lesions in yaws.

Yaws, a spirochetal infection that is endemic in certain tropical countries, including Malaysia, may present with various orthopedic problems. As the condition is relatively unknown, diagnosis is often missed, which leads to poor management. There are initial, early, and late phases of the disease process. By involving skin, bone, and joints, yaws can produce deep ulcerations, joint deformities, and bone destruction. Within a ten-year period in Malaysia, 14 cases of serologically proven yaws have been treated for chronic ulcers, gross joint deformities, and pathologic fractures.

Adult↗

PubMed1994

The initial yaw of some commonly encountered military rifle bullets.

The yaw angle in flight of high velocity bullets has been discussed for a number of years, due to its contribution to the tumbling of the bullet in the target. Since few unclassified reports of contemporary bullets are available, we investigated the yaw angles of the bullets used in the M16A2, G3, AK-47 and AK-74 rifles by the shadowgraph technique. Our results show that bullets from military rifles tend to stabilize at less than 3 degrees within 25 m, and this angle has been thought to be insignificant in the production of gunshot wounds. Bullets from some modern small calibre high velocity rifles such as the M16A2 and the AK-74 can have quite large yaw angles in their initial flight. The results, which confirm the opinion of contemporary writers, should settle the controversy in this area of wound ballistics.

China↗

PubMed1999

Vertical eye position-dependence of the human vestibuloocular reflex during passive and active yaw head rotations.

Vertical eye position-dependence of the human vestibuloocular reflex during passive and active yaw head rotations. The effect of vertical eye-in-head position on the compensatory eye rotation response to passive and active high acceleration yaw head rotations was examined in eight normal human subjects. The stimuli consisted of brief, low amplitude (15-25 degrees ), high acceleration (4,000-6,000 degrees /s2) yaw head rotations with respect to the trunk (peak velocity was 150-350 degrees /s). Eye and head rotations were recorded in three-dimensional space using the magnetic search coil technique. The input-output kinematics of the three-dimensional vestibuloocular reflex (VOR) were assessed by finding the difference between the inverted eye velocity vector and the head velocity vector (both referenced to a head-fixed coordinate system) as a time series. During passive head impulses, the head and eye velocity axes aligned well with each other for the first 47 ms after the onset of the stimulus, regardless of vertical eye-in-head position. After the initial 47-ms period, the degree of alignment of the eye and head velocity axes was modulated by vertical eye-in-head position. When fixation was on a target 20 degrees up, the eye and head velocity axes remained well aligned with each other. However, when fixation was on targets at 0 and 20 degrees down, the eye velocity axis tilted forward relative to the head velocity axis. During active head impulses, the axis tilt became apparent within 5 ms of the onset of the stimulus. When fixation was on a target at 0 degrees, the velocity axes remained well aligned with each other. When fixation was on a target 20 degrees up, the eye velocity axis tilted backward, when fixation was on a target 20 degrees down, the eye velocity axis tilted forward. The findings show that the VOR compensates very well for head motion in the early part of the response to unpredictable high acceleration stimuli-the eye position- dependence of the VOR does not become apparent until 47 ms after the onset of the stimulus. In contrast, the response to active high acceleration stimuli shows eye position-dependence from within 5 ms of the onset of the stimulus. A model using a VOR-Listing's law compromise strategy did not accurately predict the patterns observed in the data, raising questions about how the eye position-dependence of the VOR is generated. We suggest, in view of recent findings, that the phenomenon could arise due to the effects of fibromuscular pulleys on the functional pulling directions of the rectus muscles.

Acceleration↗

PubMed1999

Time constant of nystagmus slow-phase velocity to yaw-axis rotation as a function of the severity of unilateral caloric paresis.

OBJECTIVE: Complete unilateral loss of vestibular function results in a phase advance (reduced time constant) of the horizontal slow-phase nystagmus response to yaw-axis rotation. The objective of this study was to determine whether partial losses of lateral semicircular canal function would result in proportional reductions in the time constant. SETTING AND STUDY DESIGN: This was a retrospective study of consecutive patients' records at two tertiary referral centers for vestibular disorders. PATIENTS: Four hundred fifty-four patients who presented for evaluation of vertigo or imbalance or both and who were found to have partial or complete unilateral canal paresis on caloric testing. MAIN OUTCOME MEASURES: In 372 patients, the gain and time constant of the horizontal nystagmus response was measured using a 5-second velocity ramp of constant yaw-axis acceleration. Caloric responses to standard bithermal irrigations at 30 degrees and 44 degrees were obtained using an open-loop irrigation system. In a second group of 82 patients, the gain and time constant of the horizontal vestibulo-ocular reflex were measured using a sum-of-sines (pseudorandom) yaw-axis acceleration. The caloric response was measured using a closed-loop system. RESULTS: In both groups, the peak gain of the nystagmus response was independent of the level of the canal paresis. However, the time constant of the response both toward and away from the lesioned side decreased proportionally with increasing canal paresis. CONCLUSION: This result supports the hypothesis that bilateral symmetrical peripheral vestibular input is a necessary condition for the mechanisms or processes underlying normal horizontal slow-phase velocity storage.

Caloric Tests↗

PubMed1999

Yaw and pitch visual-vestibular interaction in weightlessness.

Both yaw and pitch visual-vestibular interactions at two separate frequencies of chair rotation (0.2 and 0.8 Hz) in combination with a single velocity of optokinetic stimulus (36 degrees/s) were used to investigate the effects of sustained weightlessness on neural strategies adopted by astronaut subjects to cope with the stimulus rearrangement of spaceflight. Pitch and yaw oscillation in darkness at 0.2 and 0.8 Hz without optokinetic stimulation, and constant velocity linear optokinetic stimulation at 18, 36, and 54 degrees/s presented relative to the head with the subject stationary, were used as controls for the visual-vestibular interactions. The results following 8 days of space flight showed no significant changes in: (1) either the horizontal and vertical vestibulo-ocular reflex (VOR) gain, phase, or bias; (2) the yaw visual-vestibular response (VVR); or (3) the horizontal or vertical optokinetic (OKN) slow phase velocity (SPV). However, significant changes were observed: (1) when during pitch VVR at 0.2 Hz late inflight, the contribution of the optokinetic input to the combined oculomotor response was smaller than during the stationary OKN SPV measurements, followed by an increased contribution during the immediate postflight testing; and (2) when during pitch VVR at 0.8 Hz, the component of the combined oculomotor response due to the underlying vertical VOR was more efficiently suppressed early inflight and less suppressed immediately postflight compared with preflight observations. The larger OKN response during pitch VVR at 0.2 Hz and the better suppression of VOR during pitch VVR at 0.8 Hz postflight are presumably due to the increased role of vision early inflight and immediately after spaceflight, as previously observed in various studies. These results suggest that the subjects adopted a neural strategy to structure their spatial orientation in weightlessness by reweighting visual, otolith, and perhaps tactile/somatic signals.

Electrooculography↗

PubMed1986

Subjective effects of combined-axis vibration: III. Comparison of Y-axis and Y-plus-yaw vibrations.

Two psychophysical matching experiments (Exps. III and IV in a series) were conducted to compare the perceived intensity of Y-axis and Y-plus-yaw vibrations. Seated subjects matched their perceptions of the intensity of single-axis vibrations in the Y-axis, or combined-axis vibrations made up of Y-axis and yaw motions, by adjusting the intensity of a sinusoidal, 5 Hz, Z-axis response vibration. Stimulus vibrations were sinusoidal at 3.15, 4, 5, 6.3, and 8 Hz. For each frequency, both types of stimulus vibrations were presented at three acceleration levels related to three axis-to-seat distances for the yaw motions. In Exp. III the subjects were seated forward of the rotation axis, and in Exp. IV they were seated aft of the axis. For both experiments the results showed that as frequency increased the acceleration of the matching response decreased for both types of stimuli. In addition, as stimulus acceleration (axis-to-seat distance) increased, response acceleration showed substantial increases at every frequency. However, the effects of vibration type were dependent on the location of the subject. In Exp. III the combined-axis stimuli produced higher response accelerations, but in Exp. IV matching responses were the same for both vibration types.

Acceleration↗

PubMed1975

An introduction to diagnostic criteria of syphilis, treponarid and yaws (treponematoses) in dry bones, and some implications.

Diagnostic criteria of syphilis and some other diseases are proposed from a study of 424 crania and calvariae and 250 long bones in 22 medical museums in Europe. Yaws bone lesions in Uganda and changes in Australian aboriginal bones also contributed to the establishment of these criteria. Any deductions about disease in the past or isolated populations must depend upon acceptable diagnostic criteria; post mortem damage must be recognised. In crania and calvariae the sequence of changes of Virchow's caries sicca, and in long bones nodes/expansions with superficial cavitation are sound indicators of syphilis, and of yaws and treponarid in relevant geographical areas. Attention is called to the cause of sequestra in European calvariae labelled syphilis, the absence of sequestra due to haematogenous pyogenic osteomyelitis in Australian and other aboriginal bones and possibly in Europe before the Middle Ages. The number of bones with diagnostic criteria needed to demonstrate the endemicity of a particular infection in a past community is discussed. There is also need for an extensive application of diagnostic criteria of syphilis to pre-Columbian or pre-European bones everywhere. The uncertain future of old dry diseased bones in medical museums, and the need for reference centres to provide sound advice and guidance in palaeopathology are stressed.

Bone and Bones↗

PubMed1993

Nonvenereal treponematoses: yaws, endemic syphilis, and pinta.

The nonvenereal treponematoses--yaws, endemic syphilis, and pinta--constitute a major health concern for many third world countries. These diseases are caused by an organism that is morphologically and antigenically identical to the causative agent of venereal syphilis, Treponema pallidum. Nonvenereal treponematoses differ significantly in their modes of transmission, epidemiology, and clinical presentation from venereal syphilis. Like venereal syphilis, they have a chronic relapsing course and have prominent cutaneous manifestations. Recently, several cases of imported yaws and endemic syphilis have been described in Europe. With the escalating U.S. military presence in many remote areas of the world and ever-increasing world-wide travel, the diagnosis of the nonvenereal treponematoses must be considered in appropriate clinical and historical situations.

Adolescent↗

PubMed1990

Immune response to Treponema pertenue and Treponema pallidum Nichols in patients with yaws.

Human sera from African patients with acute yaws were analysed by Western blot (WB) against antigens of Treponema pallidum Nichols and two Treponema pertenue isolates. The Western blot patterns were remarkably similar from one patient to another, and strains of both subspecies exhibited exactly the same banding pattern. Sera from yaws patients failed to detect at least one antigen in T. pertenue which was absent from T. pallidum.

Acute Disease↗

PubMed2001

[The role of yaws in the serologic screening of treponematoses in blood donors in Martinique].

Using TPHA instead of VDRL for syphilis blood-screening since 1995 showed an important increase of positive blood donors in Martinique. Yaws, another treponema disease, has been present on the island until 1975-1980. Usual tests are unable to identify which type--venereal or non venereal--of treponema is involved. Our study, carried out from January 1995 to May 1999, compares actual serological and epidemiological characteristics of TPHA reactive donors to former studies. In our results, the frequency of reactive TPHA is about 1.04% in blood donations. Donors are carrying serological tracks of a past treponema disease with very low rate of antibodies, sometimes linked to yaws. Among donors aged 18 to 30, prevalence is low and is going to become similar to the rate observed in Continental France. This means that this problem will disappear in new donor generations. We suggest the possibility for them to continue blood donation, if their personal preliminary enquiry fits the admission criteria for blood giving.

Adolescent↗

PubMed1992

Seroepidemiological characterization of a syphilis epidemic in the Republic of the Marshall Islands, formerly a yaws endemic area.

The annual numbers of reported cases of syphilis in the Republic of the Marshall Islands (RMI) increased from none in 1983 to more than 600 in 1989, suggesting a large outbreak of syphilis. Much of the increase resulted from expanded serological screening. The apparent outbreak of syphilis, therefore, may have been partly the result of increased surveillance or, since the RMI was formerly a yaws endemic area, possibly due to a resurgence of yaws. To address this problem and better characterize the epidemic, we analysed results from a 1989/90 Ministry of Health Services mass serological screening on Majuro Atoll, the main population centre. Serum specimens from 9160 people (86% of residents aged 15-44 years) on Majuro were screened with the rapid plasma reagin (RPR) card test; we repeated the RPR and performed a confirmatory microhaemagglutination assay for Treponema pallidum-specific antibodies (MHA-TP) on a sample of serum specimens. To estimate the seroprevalence of syphilis, we also tested a sample of RPR nonreactive specimens by MHA-TP. Among people less than 45 years of age, total (11.5%) and high-titre (5.2%) seropositivity rates were highest in the 20-24 year age group, as was MHA-TP seroprevalence (15.9%). These results suggested that a large outbreak of syphilis was responsible for the observed seroreactivity. Cumulative incidence modelling and comparisons with the results of a previous serosurvey conducted in 1985 suggested that the duration of the syphilis epidemic was approximately 10 years and that incidence had not increased appreciably since 1985.

Adolescent↗

PubMed1990

Disseminated early yaws: report of a child with a remarkable genital lesion mimicking venereal syphilis.

A 3 1/2-year-old boy, born and living in Indonesia, experienced disseminated skin lesions and an ulcerated, crusted, papillomatous lesion on the prepuce of his penis. This location suggested venereal syphilis, but on clinical, serologic, and epidemiologic grounds a diagnosis of early yaws was made. This treponemal disease should be considered in children who have traveled to or migrated from remote tropical regions, and who have unusual skin lesions in combination with a positive treponemal serology. Although yaws is considered a rare and exotic disease in the United States and Europe, it is still widespread in some parts of the world.

Child, Preschool↗

PubMed1988

Clinical aspects and usefulness of indirect absorbed immunofluorescence for diagnosis of yaws in Central Africa.

The incidence of yaws in 533 pygmies from the Central African Republic was surveyed. It appeared that there is still an impressive incidence of yaws in pygmy children who have poor hygiene. Laboratory investigations showed that the Treponema pallidum hemagglutination assay is often negative during the first stage of the disease, while the fluorescent treponemal antibody absorption test is positive and, thus, more sensitive.

Adolescent↗

PubMed1977

Comparison of RPR 'teardrop' card test, VDRL and FTA-ABS tests results on sera from persons with suspected yaws in Columbia.

A small study comparing results of the rapid plasma reagin (RPR) teardrop card test performed in the field, with results of Venereal Disease Research Laboratory (VDRL) and fluorescent treponemal antibody absorption (FTA-ABS) tests performed in the laboratory on venous blood specimens from the same suspected yaws patients was undertaken in Columbia in July 1975. The results suggest that the RPR teardrop card test may be used to screen for infectious, or potentially infectious, yaws patients under field conditions, but that it will not reliably detect patients with VDRL titres of 1:2 or less, or all patients in whom sera are reactive in the FTA-ABS test.

Colombia↗

PubMed1979

Attenuated yaws in Surinam.

Results of a pilot survey in the central, northern region of Surinam indicate that yaws is prevalent (hypoendemic) in this part of the country. No classical symptoms of yaws were seen. The observed lesions were scanty or solitary, dry papillomatous, or macular and scaly, which fits into the clinical picture of attenuated endemic treponematosis.

Adolescent↗

PubMed1989

Early yaws, imported in The Netherlands.

Early yaws in a 9 year old girl from Ghana, diagnosed as imported disease in The Netherlands is reported. She had lived in The Netherlands for six months. Tropical non-venereal treponematoses are rarely seen in Europe, and only a few case reports have been published. Migration and travelling may confront the medical profession with cases of tropical diseases such as yaws. Positive serological reactions in non-venereal tropical or venereal treponematoses cannot be distinguished at present.

Arm↗

PubMed1995

Yaws in Ecuador: impact of control measures on the disease in the Province of Esmeraldas.

OBJECTIVES: To determine the impact of a community-based programme of yaws control in Esmeraldas province in Ecuador. METHODS: Community health workers provided mass treatment and subsequent surveillance for the detection and treatment of new cases and their contacts over the period 1988 to 1993. Clinical and serological surveys were performed in the study area in 1988 and 1993. RESULTS: Over the 5 year observation period, the number of communities with active infections had decreased by 75%, from 20 communities in 1988 to 5 in 1993. In 1993, 4 communities were found free of clinical infections as well as latent infections. There was a corresponding decrease of 94.6% in the prevalence of dermal lesions (from 11.2% to 0.6%), and a reduction of 97.3% in latent infections (from 93.6% to 2.5%). CONCLUSIONS: The control of yaws using existing community-based health workers has proved very effective in Ecuador.

Adolescent↗

PubMed1956

Treponematosis eradication, with special reference to yaws eradication in Haiti.

This paper outlines the general administrative and therapeutic principles governing yaws eradication campaigns, with particular reference to the operational problems encountered in Haiti. The ways in which those problems were solved are described in the course of a relatively detailed account of the yaws eradication programme which began in that country in 1950 and which has now reached the end of the "mopping-up" phase. The author points out that lessons learnt in this mass treatment campaign can usefully be applied to eradication programmes against other diseases.

Biomedical Research↗