Search PubMed⌕ Search

Biomedical subjects

P Froom

Publications and source records attributed to P Froom.

At least 73 records · Page 4Linked to original sources
PubMed1995

Heart rate variability in health and disease.

Beat-to-beat fluctuations in heart rate (HR) or instantaneous HR is mainly determined by activity of the cardiac sympathetic and parasympathetic systems. Despite the need for standardization in methodology to facilitate the interpretation and comparison of results, the data presented in this review clearly show that there are individual differences in heart rate variability (HRV) and that these differences partly reflect differences in the degree of parasympathetic and sympathetic stimulation of the heart. HRV and its spectral components can be easily and noninvasively assessed and can provide valuable information to the occupational physician. Measurements of HRV and the quantification of its spectral components are powerful predictors of cardiovascular morbidity and mortality. Therefore, it may help assess the return to work of patients with ischemic heart disease. Studies in the workplace can also indicate the effects of various stresses of the work environment on such patients and even on asymptomatic workers.

Arrhythmias, Cardiac↗
PubMed1995

Common accidents among airport ground personnel.

Work-related accidents at the airport are common, but the incidence and type of such events occurring in aviation ground personnel have not been reported previously. Information regarding the most common ground accidents at the airport is essential in order to implement prevention programs. The purpose of this study was to examine the descriptive epidemiology of injury-producing accidents among ground personnel at a modern airline. In this study we recorded all reported accidents occurring over a 5-year period (1988-92) to workers of a major airline in Israel that resulted in 3 d or more of absence from work. During the study period 523 work-related accidents occurred in 2000 ground workers. The most common accidents were due to slips, trips and falls (n = 211, 40.3%), lifting and carrying accidents (n = 107, 20.4%), and machinery accidents (n = 98, 18.7%). Work transport accidents and accidents from physical and chemical exposures were less common (n = 67, 12.8%, and n = 40, 7.5%, respectively). The accident rate decreased from 71 accidents/1,000 worker-years in 1988 to between 40-56 accidents/1,000 worker-years in the subsequent 4-year period (p = 0.0002). We conclude that slips, trips and falls are the most common cause of accidents in airport ground personnel. Further studies in other airports are warranted to confirm our findings.

Accidents, Occupational↗
PubMed1994

Erythropoietin-independent colonies of red blood cells and leukocytosis in a worker exposed to low levels of benzene.

BACKGROUND: Exposure to high levels of benzene commonly results in the suppression of hemopoiesis, although cases of leukocytosis and leukocytosis with thrombocytosis have been reported. No hematologic abnormalities have generally been found with exposure to low levels of benzene. METHODS: A pipe fitter exposed to low levels of benzene (time-weighted average 0.9 ppm) developed leukocytosis. His blood counts and growth of erythroid burst forming units (BFU-E) was followed with and without the addition of erythropoietin. RESULTS: Erythropoietin-independent BFU-E colonies were increased to 40 per 4 x 10(4) cells (normal < 3 per 4 x 10(4) cells). Both the leukocyte count and the number of erythropoietin-independent BFU-E colonies decreased when exposure to benzene was terminated. On reexposure the white blood count again increased. After the work was terminated, the white blood count returned to normal, as did the number of erythropoietin-independent BFU-E colonies, over a period of 12 months. CONCLUSIONS: Our findings suggest that even low levels of benzene can result in perturbations of the hemopoietic system. Further studies are warranted to determine whether these findings are idiosyncratic, coincidental, or a more general phenomenon.

Adult↗
PubMed1994

Postural control in pilots and candidates for flight training.

Postural control may reflect the pilot's ability to deal successfully with the stresses of spatial orientation. In this study, we hypothesized that fighter pilots would have better performance on the "tetra-axiametric posture test" than would helicopter pilots (less rigorously selected) and candidates for flight training. We tested 28 fighter pilots, 23 helicopter pilots and 43 candidates by tetra-axiametric posturography. Fighter pilots were found on the level position to have significantly more compensatory anterior-posterior sway (moving anterior-posterior rather than laterally, p = 0.02) and required less movements to maintain balance (p = 0.02) than did candidates. Helicopter pilots had intermediate values. In stressed positions, fighter pilots demonstrated relatively more slow movements (p = 0.018) than did the candidates, which may be related to increased labyrinth control. In the stressed positions, helicopter pilots had postural profiles similar to the candidates. We conclude that there are significant differences in postural control as tested by tetraaxiametric posturography between fighter pilots, helicopter pilots, and candidates for flight training. This could be due to either innate ability, which could be used in the selection process, or to training. A prospective study is planned in order to determine if posturography can predict a candidate's ability to complete flight training.

Adolescent↗
PubMed1993

Deficiencies in structured medical abstracts.

This study was carried out to determine if the content of structured abstracts conforms with recommendations of the Ad Hoc Working Group for the critical appraisal of the medical literature as adopted by the Annals of Internal Medicine. The study design was a survey. All articles published in Annals of Internal Medicine in 1991, excluding editorials, case-reports, literature reviews, decision analysis, studies in medical education, descriptive studies of clinical and basic phenomena, and papers lacking a structured abstract, were studied. Of a total of 150 articles, 20 were excluded. The abstract and text of each article were assessed for the presence of the following items; patient selection criteria, statements concerning extrapolation of findings, need for further study, and whether or not the information should be used now. Number of refusers, drop outs and reason(s) for drop outs were assessed for intervention and prospective cohort studies only. Deficiencies of assessed items were noted in both abstracts and texts. For abstracts, patient selection criteria, numbers of refusers, number of drop outs and reason(s) for drop outs were reported in 44.6% (58/130), 3.1% (4/130), 16.9% (14/83) and 2.4% (2/83) respectively. These items were reported more frequently in the texts 87.7% (114/130), 9.2% (12/130), 60.2% (50/83) and 37.3% (31/83) respectively (p < 0.05). Statements concerning extrapolation of findings, need for further study and use of information now were also more frequent in texts than abstracts (p < 0.0001). A large number of structured abstracts published in the Annals of Internal Medicine in 1991, lack information recommended by the Ad Hoc Working Group. Our findings should not be extrapolated to other journals requiring structured abstracts.

Abstracting and Indexing↗
PubMed1993

Heat stress and helicopter pilot errors.

Helicopter pilots are subjected to degrees of heat stress that under laboratory conditions result in decreased performance. However, the effect of heat stress on the frequency of helicopter pilot errors is uncertain. The purpose of this study is to determine whether there is an association between ambient heat stress and pilot error. The records of 500 helicopter accidents and incidents due to pilot error during the months May through October were selected at random. On the day of the event, ambient dry bulb and wet bulb temperatures were recorded and compared to temperature and humidity readings on 1000 days chosen at random over the same time period, after eliminating days where events occurred. There was a significant difference between the dry temperature distributions of the days with pilot error compared with the control group (chi 2 = 47.54, P < .0001). A dose-response relationship was found, with a significantly lower risk when ambient dry bulb temperatures were 25 to 29 degrees C (odds ratio, 0.6; 95% confidence interval, 0.5 to 0.8, P < .0001), an increased risk of 1.6 (1.3 to 2.0, P < .0001) at 30 to 34 degrees C, and the highest risk at 35 degrees C or more (6.2, 95% confidence interval, 2.1 to 21.8, P < .0002). There is a dose-response relationship between ambient heat stress and pilot error in Israel military helicopter pilots. This is the first study outside the laboratory showing a connection between heat stress and accidents due to human error. Further studies are required to substantiate our findings and to determine whether extrapolation to other settings is warranted.

Accidents, Aviation↗
PubMed1993

Seasonal changes in red blood cell parameters.

Seasonal changes in blood count (haematocrit and haemoglobin values) have been described in studies of small samples. Since Israel is characterized by high summer temperatures, we attempted to determine whether there are circannual changes in blood count, and how they are influenced by mean monthly temperature. In a cross-sectional study, venous blood was drawn from 4317 male employees in industry aged 20-64 years. Blood count values were analysed by month. To estimate possible changes in serum osmolality, serum electrolytes were also examined. Values of haemoglobin and haematocrit in August were significantly lower than during the rest of the year. Circannual rhythms explained between 10% and 57% of the variances of all the variables as assessed by cosinor rhythmometry, although they had wide confidence intervals and most were not statistically significant. The lower mean haematocrit in August reflected reduction in mean corpuscular volume (MCV) rather than a decrease in red blood cell count (RBC). The change observed in haematocrit and haemoglobin in August is possibly related to heat acclimatization rather than to endogenous sinusoidal circannual rhythms. Both plasma and red cell volume expansion appear to occur. Possible seasonal changes should be taken into account in evaluation of blood counts.

Adult↗
PubMed1993

Soluble factors from peripheral blood T-cells of patients with polycythemia vera stimulate normal BFU-E.

T cells and monocytes from patients with polycythemia vera (PV) were isolated and grown in culture. The conditioned medium was tested for the presence of soluble factors that promote proliferation of erythroid colonies from the blood of healthy donors. We show that T cells from all 14 PV patients that were examined secrete factor/s that stimulate the proliferation of erythroid burst-forming units (BFU-E) in the absence of an external source of erythropoietin and BPA. Addition of cyclosporin A to the culture did not inhibit the production of this activity. The conditioned medium from monocytes of PV patients can also stimulate normal BFU-E but to a much lesser extent than T-cell conditioned medium. Such stimulation was not observed with control T cells or monocytes. We observed that the fraction of DR-positive T cells was significantly higher in PV patients comparing to normal. These results suggest that PV patients possess an abnormally high level of circulating activated T cells which may in turn be the source of the putative factor that facilitates uncontrolled erythroid differentiation.

Cells, Cultured↗
PubMed1992

Selection bias in using data from one population to another: common pitfalls in the interpretation of medical literature.

The prevalence, course and prognosis of diseases in patients referred to tertiary medical centers frequently differ from those treated in primary care settings. Extrapolation of findings from one population to another may therefore be unwarranted. Other factors that contribute to misinterpretation of medical literature include failure to distinguish statistical from clinical significance and advocacy of medical interventions prior to adequate clinical trials.

Epidemiology↗
PubMed1992

Extreme airborne asbestos concentrations in a public building.

Fibre concentrations of asbestos were measured in the air of a communal dining room in which the damaged ceiling had a sprayed on coating of insulation containing asbestos. The average concentration of crocidolite asbestos fibres was 4 f/cm3, 20 times the highest air concentration that appears to have been reported previously for a public building. It is concluded that although air concentrations of asbestos fibres in public buildings containing asbestos insulation materials are usually low, high concentrations can occur. This may have implications for the risk of exposed persons developing diseases associated with asbestos.

Air Pollution, Indoor↗
PubMed1992

The incidence of myopia in the Israel Air Force rated population: a 10-year prospective study.

It is important to define the risk in pilots of becoming myopic in order to determine the need for yearly screening, and to predict pilot eligibility in environments where the use of corrective lenses may present problems. We conducted a prospective study of 1400 air force personnel followed for 10 years, who could be divided into three major groups; those with 20/20 vision in both eyes, those with 20/25 in one eye only and whose vision was 20/20 using both eyes together, and those who were accepted despite the fact that they required corrective lenses. Over the 10-year period, 23.1% of those with 20/25 visual acuity in one eye needed corrective lenses, significantly more than the 7.4% observed in those with 20/20 vision in both eyes (relative risk 3.1, 95% confidence interval 2.2-4.3, p less than 0.0000). The prevalence of corrective lenses increased until age 26. We conclude that 7.4% of pilots will become myopic over a 10-year period if accepted with 20/20 vision in both eyes. The risk, however, is much higher in those with incipient growth myopia starting in one eye at entry. Therefore, the annual screening of visual acuity in air force personnel is essential.

Adolescent↗
PubMed1991

Increased spontaneous secretion of IL-6 from B cells of patients with B chronic lymphatic leukaemia (B-CLL) and autoimmunity.

We studied B cells from 18 patients with B-CLL, six of them with autoimmune haemolytic anaemia, for spontaneous secretion of IL-6. Our aim was to determine whether the increased incidence of autoimmune disease found in B-CLL patients is associated with enhanced spontaneous IL-6 secretion. IL-6 was measured by the effect of B cell supernatants on the proliferation of an IL-6 dependent plasmacytoma cell line T1165. The highest IL-6 values (7.4 +/- 1.8 U/ml) were measured in supernatants derived on day 3 of culture from lymphocytes of the six patients with B-CLL and concomitant autoimmune disease. The maximal IL-6 values for 10 patients with B-CLL only were 2.8 +/- 0.3 U/ml and for 10 age-matched controls, 0.8 +/- 0.3 U/ml (P less than 0.01, each group compared with the other). We conclude that there is an association between B-CLL, autoimmune disease and the spontaneous in vitro secretion of IL-6. Further studies are needed to determine whether the IL-6 secretion plays a role in the pathogenesis of autoimmune disease in patients with B-CLL.

Aged↗
PubMed1991

Heat stress on helicopter pilots during ground standby.

We attempted to use measurements of ambient thermal conditions to characterize and then predict thermal conditions in the cockpit before takeoff and during an hour standby period in Bell 206 and Bell 212 helicopters with a crew of two and with the cockpit doors opened. Dry bulb, wet bulb, and globe temperatures were measured on 28 separate summer days. The wet bulb globe temperature index (WBGT) was used to estimate heat stress. Ambient WBGT at time 0 ranged from 13 degrees C to 31 degrees C. There was a 2.9 +/- 3.7 degree difference in WBGT between ambient and cockpit conditions at time 0 which increased to 7.2 +/- 3.5 degrees after 1 h. Because of the cooling effect of opening the helicopter cockpit doors, the cockpit WBGT actually decreased over the standby period when cockpit WBGT values were 30 degrees C or more at time 0. Thus, there was an inverse correlation between cockpit WBGT at time 0 and the change in cockpit WBGT over the 1-h period (r = -0.767, p less than 0.001). The mean WBGT in the cockpit over the 1-h standby period was positively correlated with the ambient WBGT at time 0 (r = 0.783, p less than 0.001). We conclude that the greenhouse effect results in a cockpit WBGT which is significantly higher than ambient conditions. Subsequent changes in cockpit WBGT depend on the balance between heat transfer from the pilot's bodies to the cockpit and the loss of heat after the doors of the helicopters are opened. Ambient thermal conditions can be used to predict heat stress during the ground standby period.

Aerospace Medicine↗