A new input device: comparison to three commercially available mouses

This study was conducted to simultaneously compare the postural demands and performance of a new human-centred computer input device to three devices currently on the market. It was hypothesized that the new device would perform as well as the commercial devices while requiring less postural strain. A total of 24 experienced computer users performed a series of modified Steering and Fitts' Law Tests while their postural behaviour was captured using an opto-electric system. Analysis of the postural data revealed strong similarities between the new device and the commercially available devices, including some similarities that are not suggested in the literature. Analysis of the performance data reveals no significant difference between the new device and most commercial devices and suggests further examination of the difference between familiarity and mastery. This study has shown that it is possible to use the new device in a relaxed posture and yet achieve the same accuracy as commercial devices at no more postural risk than when the traditional mouse is used at a customized, ergonomic workstation.

Large atrial thrombus formation associated with tunneled cuffed hemodialysis catheters

AIMS

In the existing literature, there is a paucity of data regarding large atrial thrombus (AT) formation occurring as a complication of tunneled cuffed hemodialysis catheter (TCC) use. This study was performed to determine the risk factors, mortality and the appropriate management of TCC-AT.

METHODS

We report 6 new cases of TCC-AT and have amalgamated these data with data from 16 previously published cases of TCC-AT found by performing a PubMed literature search (total of 22 cases). Demographic data were collected prospectively over 2 years in 85 consecutive patients initiating hemodialysis who were using a TCC as their primary vascular access, so that comparisons could be made between the 6 patients with TCC-AT versus all patients with a TCC at our center.

RESULTS

In patients with TCC-AT, the mean time from TCC insertion was 4.5 months, and infection was present at the time of diagnosis in 68% of cases. The mean thrombus size was 3.7 cm, range 1.5-8 cm. All but 1 case were visualized by echocardiography; the remaining case required magnetic resonance imaging. Management included TCC removal and thrombectomy (n = 9), TCC removal and anticoagulation (AC) (n = 6), TCC removal alone (n = 5), and no intervention (n = 2). The overall mortality was 27%, and 5 of the 6 deaths (83%) occurred in patients with bacteremia. The mortality associated with each management strategy was as follows: TCC removal and thrombectomy (0%), TCC removal and AC (33%), TCC removal alone (40%), and no intervention (100%).

CONCLUSIONS

AT is a serious complication of TCC use in hemodialysis patients and may be associated with a high mortality rate. TCC-AT may occur more commonly than previously reported and therefore warrants a high index of suspicion.

Safety and antibody persistence following Haemophilus influenzae type b conjugate or pneumococcal polysaccharide vaccines given before pregnancy in women of childbearing age and their infants

BACKGROUND

Immunization of healthy women before pregnancy is a potential approach to providing increased levels of maternal antibody to newborns to protect them from infections occurring during the perinatal period and first months of life.

METHODS

Healthy nonpregnant Pima Indian women of childbearing age were randomized to receive one of two Haemophilus influenzae type b (Hib) conjugate vaccines [HbOC or Hib-meningococcal outer membrane protein complex (OMP)] or a 23-valent pneumococcal polysaccharide vaccine (PnPs). Infants received Hib-OMP vaccine at 2, 4 and 12 months of age. Vaccine safety and immunogenicity was evaluated in the women and their infants.

RESULTS

Anti-polyribose ribitol phosphate antibody titers were significantly higher in women in both Hib conjugate vaccine groups than in the pneumococcal vaccine group throughout the 37-month observation period. Antibody responses to HbOC vaccine were significantly higher than those to Hib-OMP. A subsequent booster dose of each Hib conjugate vaccine induced reactions and antibody responses similar to those of the first dose. Infants born to mothers immunized with Hib vaccines compared with PnPs had significantly higher polyribose ribitol phosphate-specific IgG antibody titers at birth and 2 months of age but lower antibody responses to Hib-OMP at 6 months and similar titers before and after boosting with Hib-OMP at 1 year of age. By contrast women immunized with PnPs did not have significantly elevated concentrations of pneumococcal-specific antibody at delivery, and their infants had pneumococcal antibody titers similar to those of infants born to mothers who did not receive pneumococcal vaccine before pregnancy.

CONCLUSION

Hib conjugate vaccine given to women before pregnancy significantly increased the proportion of infants who had protective Hib antibody levels at birth and 2 months of age.

Estimation of the indirect effect of Haemophilus influenzae type b conjugate vaccine in an American Indian population

BACKGROUND

Oropharyngeal carriage studies of Haemophilus influenzae type b (Hib) and the rapid drop in Hib invasive disease in countries with widespread Hib conjugate vaccine immunization programmes for infants have indicated there may be significant indirect effects (herd immunity) associated with these vaccines. Our goal was to quantify the magnitude of these effects in an American Indian population during its early years of Hib immunization.

METHODS

In a synthetic case-cohort study, we combined data from an efficacy trial, an immunization uptake records survey, and ongoing surveillance for Hib disease on the Navajo Nation from 1988 to 1992. Decline in the incidence of invasive Hib disease among children <2 years old was estimated via proportional hazards survival models as a function of individual immunization status and the proportion of immunized children in a community.

RESULTS

The predominant vaccine during the study period was Hib-OMPC (92% of immunizations). The effectiveness of receipt of at least one dose was 97.2%. Compared to communities with 0-20% coverage with at least one dose, residence in communities with 20-40% and 40-60% coverage was associated with risk reductions of 56.5% and 73.2%, respectively.

CONCLUSIONS

The results indicate substantial indirect effects of Hib-OMPC immunization may occur even at relatively low levels of immunization coverage. Countries that implement Hib immunization programmes may receive greater benefits at the community level than those due to the direct protection conferred to the individual through vaccination.

Efficacy and safety of high-dose rhesus-human reassortant rotavirus vaccine in Native American populations

OBJECTIVES

We compared the efficacy, safety, and immunogenicity of a rhesus rotavirus tetravalent vaccine (RRV-TV), a rhesus rotavirus monovalent (serotype 1) vaccine (RRV-S1), and placebo in healthy American Indian infants for two rotavirus seasons.

STUDY DESIGN

Infants aged 6 to 24 weeks were enrolled in a randomized, double-blind efficacy study. Infants were orally administered RRV-TV (4 x 10(5) plaque-forming units per dose), RRV-S1 (4 x 10(5) plaque-forming units per dose), or placebo at 2, 4, and 6 months of age. Stools collected during episodes of gastroenteritis were tested for detection of rotavirus antigen. A total of 1185 infants received at least one dose of a study vaccine or placebo, and 1051 received all three doses according to the protocol.

RESULTS

During the first year of surveillance, the estimates of vaccine efficacy (with 95% confidence interval) for preventing rotaviral gastroenteritis were 50% (26, 67) for RRV-TV and 29% (-1, 50) for RRV-S1. In this population only 6% of rotaviral gastroenteritis episodes among placebo recipients were associated with type G1 disease. For severe disease the estimates of vaccine efficacy were higher: 69% (29, 88) for RRV-TV and 48% (-4, 75) for RRV-S1.

CONCLUSIONS

These data indicate that RRV-TV is moderately efficacious in preventing all episodes of gastroenteritis caused by rotavirus and is most efficacious against the severe disease characteristic of rotaviral illness.

Diarrhoeal diseases in the White Mountain Apaches: clinical studies

Acute diarrhoeal diseases continue to be a major health problem in certain underprivileged populations in the United States, including native Americans living in reservations. To describe the features of patients with diarrhoeal diseases requiring medical care, those attending the medical facilities of the Fort Apache Indian Reservation, Whiteriver, Arizona, were studied during 1981-1985. Clinical and aetiological information was obtained on 535 patients which constitute a 20% sample of those attending the outpatient clinic and all 386 patients who required 550 hospitalizations. Rotavirus, enterotoxigenic Escherichia coli, and Shigella were the most common aetiologic agents, a pattern similar to that seen in the developing countries. The clinical features of diarrhoeal illness and the frequent associated occurrence of acute respiratory symptoms, however, were remarkably similar, regardless of aetiology.

Diarrhoeal diseases in the White Mountain Apaches: epidemiologic studies

Acute diarrhoeal disease in children is known to be a major public health problem among native Americans living in reservations in the southwestern part of the United States. This study was undertaken to describe the epidemiology and causative agents of diarrhoea more completely, with the expectation that this information may help in the ultimate control of the disease in this population. Three interrelated epidemiologic studies were carried out in the White Mountain Apache Tribe, Whiteriver, Arizona, during 1981-1985: a three-year longitudinal study on a cohort of 112 newborns, a longitudinal two-year study in a cohort of 200 families, and a case-control study on 1,072 children with diarrhoea attending a medical facility. Both epidemiologic and microbiological patterns of diarrhoeal disease were found to be very similar to those seen in developing countries, indicating the need for basic improvements in sanitation and hygiene in this population.

Postlicensure effectiveness of the Haemophilus influenzae type b polysaccharide-Neisseria meningitidis outer-membrane protein complex conjugate vaccine among Navajo children

The incidence of invasive Haemophilus influenzae type b (Hib) infection was decreased significantly among Navajo children since the licensure of Hib conjugate vaccines, even though two lots of Hib (polyribosylribitol phosphate)-meningococcal B outer-membrane protein conjugate vaccine (PRP-OMP) widely used among the Navajo were later found to be of low immunogenicity. We measured the effectiveness of all Hib conjugate vaccines combined, PRP-OMP alone, and the PRP-OMP lots with lower-than-expected immunogenicity among Navajo infants and children. This was a matched case-control study using active, laboratory-based surveillance for the ascertainment of Navajo children 2 1/2 to 59 months of age with invasive Hib infection; 45 patients with infection and 180 control subjects were enrolled. The effectiveness of one, two, and three doses, respectively, of all Hib conjugate vaccines combined was 96% (95% confidence interval (CI) 65%, 99%), 99% (95% CI, 69%, 100%), and 99% (95% CI - 57%, 100%). The effectiveness of one or more doses of PRP-OMP was 95% (95% CI, 66%, 99%). The effectiveness of a single dose of the lots of lower-than-expected immunogenicity was 89% (95% CI, -8%, 99%). The Hib conjugate vaccine coverage increased from 49% during 1991 to 94% during 1992; no control subjects younger than 18 months of age were enrolled during 1993. The occurrence of invasive Hib infections in this population after licensure of Hib conjugate vaccines was the result of gradual vaccine uptake, not poor vaccine effectiveness. The use of PRP-OMP has been highly effective despite concerns about the immunogenicity of several lots.

Hydrolyzed lactalbumin-based oral rehydration solution for acute diarrhoea in infants

The addition of different organic substrates to standard glucose oral rehydration solution (G-ORS) has been shown to improve the intestinal absorption of sodium and water, and thereby decrease stool losses. Therefore, we evaluated, in infants with acute diarrhoea, the safety and efficacy of three oral rehydration solutions (ORS) which had the same concentrations of electrolytes (with sodium 60 mmol/l) but different substrates of proteins and carbohydrates. One solution (LAD-ORS) contained hydrolyzed lactalbumin (LAD) with maltodextrin and sucrose, a second (MS-ORS) was identical but without LAD and a third (G-ORS) was standard glucose ORS. The three solutions were compared in a double-blind, randomized trial in 74 hospitalized well-nourished children in Panama and the United States. All three oral rehydration solutions were equally efficacious and safe in these children, 54% of whom were infected with rotavirus. There was no suggestion that hydrolyzed lactalbumin or maltodextrin provided any advantage over glucose-ORS in terms of stool output or in duration of diarrhoea. We conclude that all three solutions are efficacious in the therapy of acute diarrhoea in infants.

Immunogenicity, safety and tolerability of varying doses and regimens of inactivated hepatitis A virus vaccine in Navajo children

The Navajo are known to be at high risk for hepatitis A virus (HAV) infection. This study investigated the safety and immunogenicity of an investigational, alum-adjuvanted, formalin-inactivated HAV vaccine (VAQTA) developed by Merck Research Laboratories in Navajo children. One hundred two of 212 children, ages 4 to 12 years, were HAV-seronegative (< 10 mIU/ml by an enhanced sensitivity modification of the HAVAB; Abbott). Ninety of these children received the HAV vaccine. Study participants were given vaccines containing various viral protein concentrations: Group A (n = 18), 6 units; Group B (n = 36), 13 units; and Group C (n = 36), 25 units HAV protein (1 unit approximately 1 ng viral protein antigen). Three-dose (0, 8, 24 weeks) and two-dose (0, 24 weeks) regimens were compared in subgroups within B and C. The vaccine was well-tolerated and there were no serious adverse reactions; no vaccinee developed hepatitis A. After 1 dose 82 to 100% of children seroconverted (> or = 10 mIU/ml, modified HAVAB; Abbott) and 100% seroconverted after 2 doses. After 1 dose the geometric mean titer for antibody was: Group A, 22 mIU/ml; Group B, 18 mIU/ml; and Group C, 38 mIU/ml. After 3 doses geometric mean titers increased to 10,106 mIU/ml in Group A, 7258 mIU/ml in Group B and 11,856 mIU/ml in Group C. Further field studies are indicated to evaluate its use in high risk populations, such as the Navajo.

Antibody response of Navajo children primed with PRP-OMP vaccine to booster doses of PRP-OMP vs. HbOC vaccine

We compared in 12- to 15-month-old American Indian infants the safety and immunogenicity of two licensed Haemophilus influenzae type b (Hib) conjugate vaccines, PRP-OMP (PedvaxHib) and HbOC (HibTITER), administered as booster vaccinations. All infants previously received PRP-OMP for their primary Hib vaccinations at 2 and 4 months of age. The geometric mean Hib antibody concentrations (microgram/ml) measured by radioactive antigen-binding assay for those receiving PRP-OMP (n = 17) or HbOC (n = 18) were 0.593 and 0.449, respectively, before boosting (P not significant) and 7.46 and 29.5 micrograms/ml, respectively, after boosting (P < 0.05). PRP-OMP recipients also had lower geometric mean IgG anti-Hib antibody concentrations than HbOC recipients (7.21 vs 28 micrograms/ml, P = 0.003) and lower bactericidal titers (3.18 vs. 15.4, not significant). We conclude that HbOC vaccine produced a significantly greater booster response than PRP-OMP vaccine when given at 12 to 15 months of age to children primed with two doses of PRP-OMP vaccine at 2 and 4 months of age.

Screening for breast cancer by mammography: an Australian experience

Four years' experience of screening well women for breast cancer by mammography is described. Twenty-six cancers were detected in 11,927 women (2-2 per 1,000), of which 20 were unsuspected by the patient and 12 were impalpable. Of the 26 cancers detected, 18 had no histological evidence of tumour in axillary lymph nodes, and 10 were impalpable and had unaffected axillary nodes. Four patients whose mammograms did not suggest malignant disease were subsequently found to have cancer, within 12 months.