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At least 55 records · Page 3Linked to original sources
PubMed2006

Pitch, roll, and yaw variations in patient positioning.

PURPOSE: To use pretreatment megavoltage-computed tomography (MVCT) scans to evaluate positioning variations in pitch, roll, and yaw for patients treated with helical tomotherapy. METHODS AND MATERIALS: Twenty prostate and 15 head-and-neck cancer patients were selected. Pretreatment MVCT scans were performed before every treatment fraction and automatically registered to planning kilovoltage CT (KVCT) scans by bony landmarks. Image registration data were used to adjust patient setups before treatment. Corrections for pitch, roll, and yaw were recorded after bone registration, and data from fractions 1-5 and 16-20 were used to analyze mean rotational corrections. RESULTS: For prostate patients, the means and standard deviations (in degrees) for pitch, roll, and yaw corrections were -0.60 +/- 1.42, 0.66 +/- 1.22, and -0.33 +/- 0.83. In head-and-neck patients, the means and standard deviations (in degrees) were -0.24 +/- 1.19, -0.12 +/- 1.53, and 0.25 +/- 1.42 for pitch, roll, and yaw, respectively. No significant difference in rotational variations was observed between Weeks 1 and 4 of treatment. Head-and-neck patients had significantly smaller pitch variation, but significantly larger yaw variation, than prostate patients. No difference was found in roll corrections between the two groups. Overall, 96.6% of the rotational corrections were less than 4 degrees. CONCLUSIONS: The initial rotational setup errors for prostate and head-and-neck patients were all small in magnitude, statistically significant, but did not vary considerably during the course of radiotherapy. The data are relevant to couch hardware design for correcting rotational setup variations. There should be no theoretical difference between these data and data collected using cone beam KVCT on conventional linacs.

Head and Neck Neoplasms↗
PubMed1988

Effect of active head movements about the pitch, roll, and yaw axes on human optokinetic afternystagmus.

Effects of active head movements about the pitch, roll, or yaw axes on horizontal optokinetic afternystagmas (OKAN) were examined in 16 subjects to test the hypothesis that otolith organ mediated activity induced by a change in head position can couple to the horizontal velocity storage in humans. Active head movements about the pitch axis, forwards or backwards, produced significant OKAN suppression. Pitch forward head movements exerted the strongest effect. Active head movements about the roll axis towards the right also produced OKAN suppression but only if the tilted position was sustained. No suppression was observed following sustained yaw. However, an unsustained yaw left movement after rightward drum rotation significantly enhanced OKAN. Sustained head movement trials did not significantly alter subsequent control trials. In contrast, unsustained movements about the pitch axis, which involve more complex interactions, exerted long-term effects on subsequent control trials. We conclude that otolith organ mediated activity arising from pitch or roll head movements couples to the horizontal velocity storage in humans, thereby suppressing ongoing OKAN. Activity arising from the horizontal canals during an unsustained yaw movement (observed mainly with yaw left), following drum rotation in a direction contralateral to the movement, may also couple to the velocity storage, resulting in increased activity instead of suppression.

Adolescent↗
PubMed1990

Ultrasound-induced yaw movements in the flying Australian field cricket (Teleogryllus oceanicus).

An ultrasonic stimulus induced negative phonotactic steering in the yaw axis of tethered, flying Australian field crickets. The forewings, hindwings and twisting of the thorax generated the forces which induced the yaw turn. However, abdominal ruddering did not contribute to yaw turns. Each aspect of the yaw steering response depended upon the stimulus intensity. At higher ultrasonic intensities, the magnitude and average angular velocity increased while the latency of the yaw turn decreased. Each of these factors varied in a graded manner, revealing that this behavior is more complex than a simple reflex.

Animals↗
PubMed2003

Community participation eliminates yaws in Ecuador.

Yaws is no longer a national and international health priority for intervention, but there is still a negative perception of the disease in the few affected communities. A survey in 1988 in the northern region of Ecuador documented a prevalence of 16.5% of clinical cases and 96.3% of serological cases. A continuous, long-term community-based surveillance programme was therefore put in place focusing on yaws as one of the sentinel diseases. The results of this intervention are reported here. In 1993, a second survey showed a reduction in the prevalence of clinical cases to 1.4% and of serological cases to 4.7%. Between 1993 and 1998, no other clinical cases were detected and the serological prevalence in 1998 was 3.5%, corresponding with clinical cases of primary or congenital syphilis, latent yaws under follow-up, and individuals with low serological titres indicating a 'serological scar'. These data indicate that yaws has been eliminated. Another important outcome of the intervention is the increased self-confidence in the communities that health problems can be tackled.

Attitude to Health↗
PubMedDate not supplied

Yaws in Southeast Asia: an overview.

A summary is presented of yaws control programs, from their initiation up to the present, in India, Indonesia, and Thailand. In all three countries, the prevalence was spectacularly reduced. From 1950 to 1961, in Java and Bali the rates fell from 11.34% to 0.72%, and comparable results were achieved in India and Thailand. In all programs, resurveys were carried out after the original mass treatment campaigns, and quite successful efforts were made to integrate the yaws control activities into more general health services. Although a small number of active cases of yaws in localized foci are still found, with the rapid expansion of primary health services and continuing surveillance for yaws and the appropriate use of selective or juvenile mass treatment approaches, it should be possible to achieve eradication in the foreseeable future.

Asia, Southeastern↗
PubMedDate not supplied

Yaws in Malaysia.

In 1954, with the assistance of the World Health Organization and the United Nations Children's Fund, a campaign against yaws was initiated in Malaysia with the formation of a yaws elimination unit in the Ministry of Health. Between 1954 and 1975, the reported annual incidence of yaws fell from 140.85 to 1.25 per 100,000 population. When rates dropped to less than two per 100,000, the program was merged with the general health services. Currently when cases are reported, contacts are traced, school and village surveys are carried out, and appropriate treatment is given. The major problems facing the control program today are a loss of interest in control activities; a smaller number of health workers experienced in the diagnosis, management, and control of the disease; and a growing reluctance to treat asymptomatic contacts with penicillin for fear of anaphylactoid reactions. Despite these problems, it is not an unreasonable expectation that, with continued stimulation from the individuals responsible for infectious disease control, yaws will eventually be eliminated.

Adolescent↗
PubMedDate not supplied

Yaws in Papua New Guinea: extent of the problem and status of control programs.

Yaws was a significant health problem in Papua New Guinea until the nationwide total mass treatment campaign, which took place from 1953 to 1958. The number of cases reported annually fell to less than 300 during the 1960s. In the early 1970s outbreaks occurred in East New Britain and Bougainville but were effectively controlled. A larger outbreak in 1977-1978 on Karkar Island was more difficult to bring under control despite the clinical appearance of the cases, which were less florid than those seen in the 1950s. The latter outbreak raised questions about decreased response to penicillin, lack of ability to develop effective immunity, and increased susceptibility to yaws. Smaller outbreaks were reported in 1983 and 1984 in remote areas, but the current extent of yaws in Papua New Guinea is not fully known. Action is being taken to rectify this situation and to ensure that reports of yaws are fully investigated and that cases are properly managed.

Female↗
PubMedDate not supplied

Yaws in the Americas.

Until the middle of this century, yaws was a major public health problem in the Americas Region of the World Health Organization. All countries located between the tropics of Cancer and Capricorn reported cases of yaws. From 1950 to 1957, major programs for the eradication of yaws were implemented throughout the region, and yaws rapidly ceased to be a threat. As of 1983, sporadic cases continued to occur in limited geographic areas of Colombia, French Guyana, Guyana, and Suriname.

Adolescent↗
PubMed1990

A new attempt to distinguish serologically the subspecies of Treponema pallidum causing syphilis and yaws.

In an effort to serologically differentiate syphilis from yaws, 69 monoclonal antibody species raised against Treponema pallidum subsp. pallidum were tested by immunoblotting for their reactivity with Treponema pallidum subsp. pertenue. All monoclonal antibodies reacted with antigens with the same molecular weight of both subspecies. Furthermore, no differences in reactivity between sera from yaws patients and from syphilis patients were found by Western blot (immunoblot) analysis of cell lysates of T. pallidum subsp. pallidum and T. pallidum subsp. pertenue. We tried to exploit the only known molecular difference between the subspecies. The subunits of the 190-kilodalton multimeric proteins TpF1 and TyF1 of T. pallidum subsp. pallidum and T. pallidum subsp. pertenue, respectively, have previously been shown to differ in one amino acid residue at position 40. In this study, no difference was found in immunoreactivity of TpF1 or TyF1 with either syphilis sera or yaws sera. Synthetic peptides based on the sequence of TpF1 and of TyF1 were used in an enzyme-linked immunosorbent assay with syphilis sera and yaws sera. Again, no difference in reactivity between the T. pallidum subsp. pallidum- and T. pallidum subsp. pertenue-derived peptides was observed.

Amino Acid Sequence↗
PubMed1990

Radiological and dermatological findings in two patients suffering from early yaws in Indonesia.

Two children suffering from early yaws in Indonesia are presented. Apart from skin lesions and a positive treponemal serology in both patients, involvement of tubular bones, particularly of the hands, was revealed by radiological examination. In one patient involvement of a distal phalanx was remarkable. Early diagnosis and treatment of yaws is important since a delay in treatment may result in severe and irreversible bone deformities of the late stage of the disease. This report illustrates that radiological changes, although rare, can still be detected in the early stage of yaws in areas where yaws is resurgent nowadays.

Adolescent↗
PubMed1993

The localisation of treponemes and characterisation of the inflammatory infiltrate in skin biopsies from patients with primary or secondary syphilis, or early infectious yaws.

OBJECTIVE: To study the localisation of treponemes and to analyse the inflammatory infiltrate in biopsy specimens from patients with primary or secondary syphilis, or early infectious yaws. MATERIALS AND METHODS: Skin biopsies originating from human lesions of primary (29x) or secondary (15x) syphilis (Rotterdam), or early yaws (18x) (West Sumatra) were studied. Different histochemical and immunohistochemical detection methods were used in this study. RESULTS AND CONCLUSION: The histochemical silver staining method according to Steiner revealed the presence of T. pallidum in all cases of primary syphilis studied. In 10 out of 14 cases of secondary syphilis, treponemes were demonstrated. With an immunofluorescence staining technique (IF) using anti-T. pallidum antiserum raised in rabbits (a-Tp), T. pallidum was demonstrated in 28 out of 29 cases of primary syphilis, and in 14 out of 14 studied cases of secondary syphilis. The silver staining method and IF showed identical localisations of T. pallidum (mainly in the dermal-epidermal junction zone or throughout the dermis). Using a-Tp antiserum in the indirect immunofluorescence technique, T. pertenue could be demonstrated in the dermis more often than with Steiner silver staining. However, epidermotropism of T. pertenue in yaws specimens was remarkable, compared with more mesodermotropism of T. pallidum; numbers of T. pertenue in the dermis were limited in all specimens. The dermal inflammatory infiltrate in primary and secondary syphilis was composed mainly of lymphocytes and plasma cells. In most cases more T (CD3 positive) cells than B (CD22 positive) cells were present. Regarding T cell subpopulations, in primary syphilis, T helper/inducer (CD4 positive) cells predominated in 86% of cases. In secondary syphilitic lesions, numbers of T helper/inducer cells were less frequent than or equal to T-suppressor/cytotoxic (CD8 positive) cells in 60% of cases. Remarkably, in yaws specimens the inflammatory infiltrate consisted mainly of IgG, but also IgA and IgM producing plasma cells. T or B lymphocytes were scarce, which is in sharp contrast with findings in syphilitic lesions.

Adolescent↗
PubMed1998

Failure of penicillin treatment of yaws on Karkar Island, Papua New Guinea.

The endemic treponematosis yaws remains a significant cause of morbidity in many tropical countries, despite mass treatment campaigns to eradicate it. An outbreak of yaws in Marup village on Karkar Island, Papua New Guinea in 1988 provided an opportunity to monitor the outcome of treatment with penicillin over an extended period. Thirty-nine children with clinical yaws (6% of 632 examined) were monitored clinically and serologically, for nearly two years after mass treatment of all villagers with the World Health Organization recommended dosages of benzathine penicillin. Lesions resolved within one month of treatment in all but four (10%) children, three of whom were initially successfully retreated. Before treatment, the Venereal Disease Research Laboratory (VDRL) test result was reactive in 67% of the children and treponema-specific IgM antibody test results were reactive in 41%. Within six months of treatment, of those reactive, the VDRL titer decreased significantly in 25 (96%) of 26 and IgM antibody test results became negative in 13 (81%) of 16 children. However, by the end of follow-up, 11 (28%) of the 39 children had developed clinical and/or serologic evidence of relapse. In these children, response to further treatment was slow and, in three, evidence of active infection persisted or recurred, despite repeated courses. Exogenous reinfection was unlikely in this isolated community, in which the occurrence of yaws was closely monitored after universal treatment. Treatment failure was most likely to have been due to reduced susceptibility to penicillin of Treponema pallidum subsp. pertenue.

Adolescent↗
PubMedDate not supplied

Yaws in the periurban settlements of Port Moresby, Papua New Guinea.

Yaws is a re-emerging disease in Papua New Guinea. A resurgence of yaws is documented in the periurban settlements around Port Moresby. A total of 494 cases were identified from April 2000 to September 2001. The age distribution ranged from 2 years to adult (median 9 years). Presenting symptoms were adequately recorded in 286 cases (58%). Of these, 42% presented with raised painless sores, 47% with bone/joint symptoms only and 11% with both sores and bone/joint symptoms. Children in communities with a suspected high prevalence were surveyed and examined for presence of primary yaws sores. 33 out of 227 children examined (15%) had evidence of primary yaws sores. Initial control measures have been case-finding and treatment of contacts, but in areas of known high prevalence mass treatment is planned.

Adolescent↗
PubMed1955

Serological studies of yaws in Thailand.

The serological aspects of anti-yaws campaigns are discussed. Serological reactions in untreated yaws are considered according to each type of lesion and by age-groups; the serological pattern in types I and II show much similarity in that the majority of cases fall in the high titre levels while with types IV and V there appears to be a more even distribution of cases at all titre levels. A uniform serological response is seen in the early lesions for all age-groups and this is also true of hyperkeratosis cases. There are more type IV cases among the younger age-groups showing high titres, while in the older groups there is an upward trend towards the negative side. Type V also shows a regressive serology.The serological response to treatment with penicillin in three different schedules (4 ml x 2, 2 ml x 2, and a single injection of 4 ml) is then compared. There was no marked difference between the response at the end of one year with all three schedules; with a larger amount of material, however, it is likely that the 2 ml x 2 dosage would be seen to be less effective than the other two schedules. Serological response to treatment with any schedule would be governed by the number of cases having a high initial titre among the group under consideration. The decrease in titre, after being comparatively rapid in the first six months after treatment, is slow, and reversal to seronegativity at the end of a year occurs only in a small number of cases.The role of mass serological examinations in large-scale campaigns is considered. While the serological approach is shown to be the only scientific one, the impracticability of mass serological investigation is brought out. It is stressed, however, that in a mass campaign a serological service is essential for pilot studies, orientation of incidence of latent yaws, check on diagnosis, and assessment of dosage and of the necessity for re-treatment.The possible reasons for prozone phenomena in slide flocculation tests are discussed. The presence of reagin-like substances of extraneous origin to treponemal infection, as well as of reagin, in yaws patients may be responsible for some of these phenomena.

Humans↗
PubMed1956

Some important aspects of yaws eradication.

The purposes of a yaws mass campaign are to eradicate yaws and to improve the environmental sanitation and standard of living of the people so that its re-introduction will be impossible. In a mass treatment campaign the importance of latent cases and contacts in maintaining the disease must be taken into account. The treatment of this group of the population, in addition to all active cases, hastens the success of the campaign.Resurveys at regular intervals must be carried out until the prevalence of active yaws is low and there are adequate facilities to continue the consolidation phase of the campaign. All the population should be seen at each survey. Serological screening is used to guide public health activities.All campaigns and post-campaign activities should be planned and budgeted for before the activities start. Campaigns should expand as compact areas and should be co-ordinated with similar campaigns in adjacent countries. Adequate supervision of field staff, the intelligent co-operation of the people and their leaders and continuous project evaluation are essential for the eradication of yaws.

Biomedical Research↗
PubMed2005

Yaws and its eradication in India--a brief review.

Until 1996-97, when Yaws Eradication Programme (YEP) in India was launched, there were three initiatives to assess/control the yaws disease in the country. YEP was initially started as pilot study in Koraput district, Orissa and later on extended to ten states covering 49 districts. The first goal has been to get the disease eliminated from the country with ultimate goal being its eradication. Strategies for YEP are active case detection and treatment including contacts and targeted IEC. The number of reported cases reduced from 735 in 1997 to "Zero Case" in 2004 from entire country. The recent Third Independent Appraisal of YEP could not confirm any new yaws case. However, before declaring the elimination (meaning no new early infectious case), there is need to make a thorough search in the affected areas. Future activities under the programme includes sero- surveillance among under-five children to demonstrate cessation of yaws transmission.

Adolescent↗
PubMed1990

Yaws in the Solomon Islands.

Yaws is a chronic, relapsing, non-venereally transmitted disease caused by Treponema pertenue. As a result of the WHO mass treatment campaign of the late 1950s, the prevalence in the Solomon Islands fell dramatically. Here the disease was thought to have been eradicated until an outbreak occurred in 1981. In 1984 a mass treatment survey following modified WHO guidelines was carried out. Subsequent to this campaign, yaws recurred and in 1987 a further treatment survey was required. Two observations were made as a result of our recent experience in controlling yaws in the Solomon Islands. (1) The disease appears to be attenuated. (2) WHO control policy may now be an inappropriate method for dealing with yaws in the Solomon Islands and should be replaced by a method which is integrated into the existing primary health care (PHC) structure.

Adolescent↗
PubMed1998

Off-center yaw rotation: effect of naso-occipital linear acceleration on the nystagmus response of normal human subjects and patients after unilateral vestibular loss.

Dual search coils were used to record horizontal, vertical and torsional eye movement components of one eye during nystagmus caused by off-center yaw rotation (yaw centrifugation). Both normal healthy human subjects (n=7) and patients with only one functioning labyrinth (n=12) were studied in order to clarify how the concomitant linear acceleration affected the nystagmus response. Each subject was seated with head erect on the arm of a fixed-chair human centrifuge, 1 m away from the center of the rotation, and positioned to be facing along a radius; either towards (facing-in) or away from (facing-out) the center of rotation. Both yaw right and yaw left angular accelerations of 10 degrees s(-2) from 0 to 200 degrees/s were studied. During rotation a centripetal linear acceleration (increasing from 0 to 1.24xg units) was directed along the subject's naso-occipital axis resulting in a shift of the resultant angle of the gravitoinertial acceleration (GIA) of 51 degrees in the subject's pitch plane and an increase in the total GIA magnitude from 1.0 to 1.59xg. In normal subjects during the angular acceleration off-center there were, in addition to the horizontal eye velocity components, torsional and vertical eye velocities present. The magnitude of these additional components, although small, was larger than observed during similar experiments with on-center angular acceleration (Haslwanter et al. 1996), and the change in these components is attributed to the additional effect of the linear acceleration stimulation. In the pitch plane the average size of the shift of the axis of eye velocity (AEV) during the acceleration was about 8 degrees for a 51 degrees shift of the GIA (around 16% of the GIA shift) so that the AEV-GIA alignment was inadequate. There was a very marked difference in the size of the AEV shift depending on whether the person was facing-in [AEV shift forward (i.e. non-compensatory) of about 4 degrees] or facing-out [AEV shift forward (i.e. compensatory) of around 12 degrees]. The linear acceleration decreased the time constant of decay of the horizontal component of the post-rotatory nystagmus: from an average of 24.8 degrees/s facing-in to an average of 11.3 degrees/s facing-out. The linear acceleration dumps torsional eye velocity in an manner analogous to, but independent of, the dumping of horizontal eye velocity. Patients with UVD had dramatically reduced torsional eye velocities for both facing-in and facing-out headings, and there was little if any shift of the AEV in UVD patients. The relatively small effects of linear acceleration on human canal-induced nystagmus found here confirms other recent studies in humans (Fetter et al. 1996) in contrast to evidence from monkeys and emphasizes the large and important differences between humans and monkeys in otolith-canal interaction. Our results confirm the vestibular control of the axis of eye velocity of humans is essentially head-referenced whereas in monkeys that control is essentially space-referenced.

Acceleration↗