Comments on occupational and environmental factors in the origin of non-Hodgkin's lymphoma

The review of the literature regarding non-Hodgkin's lymphoma and occupational and environmental factors presented at this workshop suggested associations with viruses, solvents, and hair dyes. A population-based case-control study among men from Iowa and Minnesota notes similar associations. Workers engaged in metal working, hair care, painting, and dry cleaning experienced nonsignificant excesses. Risks from specific exposures showed some variation by histological type. Both follicular and diffuse non-Hodgkin's lymphoma were associated with benzene. The diffuse type was linked to solvents other than benzene and formaldehyde, while the follicular was excessive among workers exposed to oils and greases.

Prenatal diagnosis of Klippel-Trenaunay-Weber syndrome: a case report

At 20 weeks of gestation, a typical combination of a massive enlargement of the right fetal leg and multiple cystic lesions was detected at ultrasound examination. Color-coded Doppler examination revealed no arteriovenous fistulae. These findings allowed an in utero diagnosis of the Klippel-Trenaunay-Weber syndrome, which was confirmed after subsequent termination of the pregnancy. The severe malformation involved the upper and lower right leg. No arteriovenous fistulae were found.

Normal fetal cardiac flow velocity waveforms between 11 and 16 weeks of gestation

OBJECTIVES

The purpose of our study was to determine the nature of fetal cardiac flow velocity waveforms in late-first- and early-second-trimester pregnancies.

STUDY DESIGN

Eighty-eight normal pregnancies were studied according to a cross-sectional study design between 11 and 16 weeks of gestation.

RESULTS

Fetal waveforms at the semilunar level showed a gestational age-related rise in peak systolic flow velocities, with significantly higher velocities in the ascending aorta. Similarly, a gestational age-related rise in peak-E wave (early diastolic filling) and peak-A wave (atrial contraction) velocity was observed at the atrioventricular level, with significantly higher velocities at the tricuspid valve level.

CONCLUSIONS

Compared with late gestation, these data suggest a reduced ventricular compliance or ventricular relaxation rate and a raised cardiac afterload in the normally developing late-first- and early-second-trimester fetus.

Doppler assessment of the normal early fetal circulation

Combined transvaginal and transabdominal Doppler ultrasound allows recording of fetal intra- and extracardiac flow velocity waveforms in late first- and early second- trimester pregnancies. At 10-12 weeks, end-diastolic flow velocities were always absent in the fetal descending aorta and umbilical artery, but were present in over half of the intracerebral artery waveforms. The pulsatility index in the three vessels decreased significantly with advancing gestational age, suggesting a reduction in fetal and umbilical placental vascular resistance. Peak velocities during atrial contraction (A-wave) were nearly twice as high as those during early diastolic filling (E-wave), reflecting low ventricular compliance. Continuous forward flow in the umbilical vein was associated with a pulsatile systolic and diastolic forward flow in the ductus venosus. Retrograde flow was only present in the inferior vena cava.

Modelling the use of health services by populations of small areas to inform the allocation of central resources to larger regions

Modelling the use of health services by local populations can inform the allocation of central resources to larger regions. At aggregate, e.g. regional, level, use is largely driven by supply and such analysis can be misleading. At small area level, however, populations effectively compete for services and their different relative use of services, after allowing for varying availability, reflects variations in their relative need. Empirical quantitative estimates can thus be made of the net relation of factors such as mortality or social deprivation to relative need for health services. These estimates can then be used in weighted capitation formulae for allocating resources to larger regions.

The risk of spina bifida aperta after first-trimester exposure to valproate in a prenatal cohort

Use of antiepileptic drugs (AEDs) during pregnancy is associated with an increased risk of congenital malformations. Spina bifida aperta has been linked specifically to valproic acid (VPA) (estimated risk, 1 to 2%). The actual risk, the exclusive association of VPA with spina bifida and not anencephaly, and the precise causative relation remain matters of discussion. A prospective cohort study of pregnant women with epilepsy receiving AEDs and referred for prenatal diagnosis before week 22 of gestation was conducted, with follow-up to 3 months after birth. Pregnancies (291 singleton and 6 twin) in 261 women were evaluated. The prevalence of anomalies after exposure to any AED was 6.9%. For fetuses exposed to VPA, the prevalence was 9.4%, including six cases of spina bifida, two of which were in monozygotic twins (giving a prevalence rate of 6.3%, or 5.4%, if twins counted as one). Spina bifida was associated with a significantly higher average daily dose of VPA as compared with pregnancies with normal outcome (1.640 +/- 136 mg/d vs 941 +/- 48 mg/d, p = 0.0001). No relation was observed between the occurrence of spina bifida and type of maternal seizure or epilepsy, family history of epilepsy or neural-tube defects, or medical history. From these results we suggest that when the use of VPA during pregnancy cannot be avoided, the teratogenic risk might be diminished by reduction of the daily dose.

Normal fetal Doppler inferior vena cava, transtricuspid, and umbilical artery flow velocity waveforms between 11 and 16 weeks' gestation

OBJECTIVES

Our objectives were to determine flow velocity waveform patterns in the fetal inferior vena cava and to relate these waveforms to transtricuspid and umbilical artery waveforms and fetal heart rate in early gestation.

STUDY DESIGN

Doppler waveforms were recorded in 40 normal fetuses at 11 to 16 weeks of gestation. Only transvaginal scanning was carried out at 11 to 12 weeks and only transabdominal scanning was used at 15 to 16 weeks.

RESULTS

The ratio of time velocity integrals of flow from the inferior vena cava during systole and early diastole, the percentage of reverse flow in this vessel, the pulsatility index from the umbilical artery, and the fetal heart rate were negatively correlated with gestational age. Peak E-wave and A-wave velocities and E/A ratios from the transtricuspid waveforms were positively correlated with gestational age.

CONCLUSION

Early normal pregnancies are associated with remarkable changes in fetal flow velocity waveforms at both the cardiac and the extracardiac level.

Intracerebral, aortic, and umbilical artery flow velocity waveforms in the late-first-trimester fetus

OBJECTIVES

Our objectives were to determine the success rate in obtaining flow velocity waveforms in the first-trimester fetal circulation and to establish possible preferential flow to the fetal cerebrum at this early stage of gestation.

STUDY DESIGN

Flow velocity waveform recordings were made in the umbilical artery, fetal descending aorta, and fetal intracerebral arteries in 30 normal pregnancies between 11 and 13 weeks of gestation.

RESULTS

Technically acceptable waveforms were obtained from the descending aorta in 15 fetuses, from the intracerebral circulation in 17 fetuses, and from the umbilical artery in all 30 fetuses. Absent end-diastolic velocities in the descending aorta and umbilical artery were associated with forward flow throughout the cardia cycle in intracerebral arteries.

CONCLUSION

A relatively low cerebral vascular resistance in the late-first-trimester normal fetus is suggested.

Horseradish peroxidase retention and washout in blood-brain barrier lesions

Horseradish peroxidase (HRP) is widely used to visualize blood-brain barrier (BBB) breakdown. In addition to its visual properties, HRP activity can be measured and can, therefore, be used to quantitate barrier leakage rapidly and simply. In addition, the same tissue can be used for electron microscopic studies in which the structural basis for the leakage can be resolved. Here we describe two methods for quantitation of barrier damage using HRP: one in small, multifocal barrier lesions caused by ethanol combined with barbiturates, and a second in large, single-focus, necrotic lesions. We determined the optimal circulation times and fixation methods for each. In the case of multifocal barrier damage, short-term HRP circulation for up to 1 min precisely marked individual leaking vascular segments, which could then be counted and their density calculated. Immersion fixation was necessary since perfusion fixation washed the extravasated HRP out of the tissue. In freeze-lesions, circulation times of at least 5 min were necessary to deliver acceptable amounts of HRP to the tissue. Tissue retention increased with longer circulation times to an optimum of 30 min, but then fell. Perfusion fixation for times as long as 1 h did not affect the tissue retention of HRP.

Delayed dehiscence of repaired bladder rupture

A case of dehiscence of a previously repaired bladder rupture occurring 3 years after the original repair is reported. There was no obvious predisposing cause to this event. As this occurrence is very rare, it brings into question the need for long-term review of patients with conservatively treated bladder rupture.

Do quantitative exposure assessments improve risk estimates in occupational studies of cancer?

Quantitative assessment of exposure intensity is a difficult process, particularly for jobs held long ago. Despite difficulties, the use of this approach is growing in occupational epidemiology because it is hoped that the estimates will more closely approximate delivered dose than more traditional measures such as duration of exposure. If this assumption is correct, development and use of quantitative exposure estimates should reduce nondifferential exposure misclassification, sharpen exposure-response gradients, and enhance interpretation of study results. In this report, we used two methods to assess the value of quantitative exposure assessments in cancer epidemiology. In one, we surveyed the literature for investigations on occupational cancer that included assessments of both duration and intensity of exposure. The results of this survey indicated that exposure measures based on some measure of intensity of exposure yielded monotonically increasing exposure-response gradients and larger relative risks more often than those based on duration of exposure. Duration of exposure, however, occasionally provided the larger relative risks. In another approach, we found that different measures of exposure to formaldehyde classified subjects quite differently. For example, duration of exposure was unrelated to average exposure and was only weakly associated with exposure intensity or peak exposure. Because different measures of exposure may classify subjects quite differently and because quantitative estimates usually, but not always, yield larger relative risks and sharper exposure-response gradients than other measures of exposure, we believe that the prudent approach in epidemiologic investigations would be to develop quantitative estimates of exposure and to conduct analyses using several different measures of exposure, or combinations such as duration by intensity. Multiple comparisons would, however, increase chance findings. The value of such an approach is twofold. When a true association exists, use of several different measures decreases the chances of an unfortunate selection of an exposure measure that is poorly related to delivered dose, which would tend to produce negative results, and increases the chances of uncovering sharper exposure-response gradients. Use of several exposure measures in investigations that fail to exhibit an association between exposure and disease would be of value because such an approach would provide greater confidence that negative findings were not simply due to exposure misclassification.

The Wardill test: does it predict future voiding flow?

A prospective study was undertaken to assess the predictive value of measuring the peak flow rate at completion of a transurethral prostatectomy with suprapubic pressure (the Wardill test). Twenty-six patients had their expressed flow rate measured on applying a standardised suprapubic pressure and compared to their peak flow rate measured at least 6 weeks postoperatively. No significant correlation was found to exist between the two variables.

Use of an Antibacterial Powder Spray to Prevent Post Prostatectomy Urinary Infection

To prevent ascending urinary infection in patients following transurethral prostatectomy, we have studied the use of a topical antibacterial agent applied to the groin and external genitalia. A prospective randomized controlled trial was conducted, with 50 patients being treated by daily application of a 2% polynoxylin powder, and 50 patients acting as untreated controls. Patient age and duration of catheterization were similar in the treated and untreated groups. No significant benefit was seen in the treated cohort (P greater than 0.05) in terms of reduction in postoperative urinary infection.

Fetal and umbilical flow velocity waveforms between 10-16 weeks' gestation: a preliminary study

Maximal flow velocity waveform recording was attempted in the umbilical artery, fetal descending aorta, and at the fetal intracerebral level using a cross-sectional study design in 77 normal singleton pregnancies between 10-16 weeks' gestation. At 10-12 weeks, end-diastolic flow velocities were always absent in the fetal descending aorta and umbilical artery, but were present in 58% of the intracerebral artery waveforms. The pulsatility index at all three levels decreased significantly with advancing gestational age, suggesting a reduction in fetal and umbilical placental vascular resistance during the late first and early second trimesters of normal pregnancy. Waveform changes were not related to fetal heart rate.

Reexamination of Stewart's quantitative analysis of acid-base status

To provide experimental verification to Stewart's quantitative approach to acid-base analysis, the effects of acute maximal treadmill exercise (VO2max test) on venous acid base status were studied in 17 male subjects aged 18-23 yr. Venous CO2 tension (PCO2) total plasma proteins ([PTOT]), [H+], and concentrations of strong ions [( Na+], [K+], [Cl-] and lactate ion concentration ([La-]) were measured before and within 1 min post-exercise. Mean post-exercise PCO2, [PTOT], [K+], and [La-] were significantly higher than the corresponding pre-exercise values (P less than 0.05), there was a strong tendency for a significant change in [Na+] (P less than 0.056), and no changes were found in [Cl-]. Changes in venous acid-base status were analyzed quantitatively by applying relevant physicochemical theory. Altered values measured in the independent variables ([PTOT], PCO2, and net strong ion difference, [SID]) were used to calculate the corresponding changes in the dependent quantities. Comparison of individual measured and calculated values for the only one of these that is normally measured, ([H+]), yielded the theoretically expected agreement. PCO2 and [SID] changes accounted for most [H+] changes. These results demonstrate the usefulness of the quantitative approach (i.e., [H+]-PCO2 diagram) in the analysis and in understanding of plasma acid base changes with exercise and in clinical situations.

Retrospective cohort mortality study of workers at an aircraft maintenance facility. I. Epidemiological results

A retrospective cohort study of 14,457 workers at an aircraft maintenance facility was undertaken to evaluate mortality associated with exposures in their workplace. The purpose was to determine whether working with solvents, particularly trichloroethylene, posed any excess risk of mortality. The study group consisted of all civilian employees who worked for at least one year at Hill Air Force Base, Utah, between 1 January 1952 and 31 December 1956. Work histories were obtained from records at the National Personnel Records Centre, St. Louis, Missouri, and the cohort was followed up for ascertainment of vital state until 31 December 1982. Observed deaths among white people were compared with the expected number of deaths, based on the Utah white population, and adjusted for age, sex, and calendar period. Significant deficits occurred for mortality from all causes (SMR 92, 95% confidence interval (95% CI) 90-95), all malignant neoplasms (SMR 90, 95% CI 83-97), ischaemic heart disease (SMR 93, 95% CI 88-98), non-malignant respiratory disease (SMR 87, 95% CI 76-98), and accidents (SMR 61, 95% CI 52-70). Mortality was raised for multiple myeloma (MM) in white women (SMR 236, 95% CI 87-514), non-Hodgkin's lymphoma (NHL) in white women (SMR 212, 95% CI 102-390), and cancer of the biliary passages and liver in white men dying after 1980 (SMR 358, 95% CI 116-836). Detailed analysis of the 6929 employees occupationally exposed to trichloroethylene, the most widely used solvent at the base during the 1950s and 1960s, did not show any significant or persuasive association between several measures of exposure to trichloroethylene and any excess of cancer. Women employed in departments in which fabric cleaning and parachute repair operations were performed had more deaths than expected from MM and NHL. The inconsistent mortality patterns by sex, multiple and overlapping exposures, and small numbers made it difficult to ascribe these excesses to any particular substance. Hypothesis generating results are presented by a variety of exposures for causes of death not showing excesses in the overall cohort.

Retrospective cohort mortality study of workers at an aircraft maintenance facility. II. Exposures and their assessment

Methods are presented that were used for assessing exposures in a cohort mortality study of 15,000 employees who held 150,000 jobs at an Air Force base from 1939 to 1982. Standardisation of the word order and spelling of the job titles identified 43,000 unique job title organisation combinations. Walkthrough surveys were conducted, long term employees were interviewed, and available industrial hygiene data were collected to evaluate historic exposures. Because of difficulties linking air monitoring data and use of specific chemicals to the departments identified in the work histories, position descriptions were used to identify the tasks in each job. From knowledge of the tasks and the chemicals used in those tasks the presence or absence of 23 chemicals or groups of chemicals were designated for each job organisation combination. Also, estimates of levels of exposure were made for trichloroethylene and for mixed solvents, a category comprising several solvents including trichloroethylene, Stoddard solvent, carbon tetrachloride, JP4 gasoline, freon, alcohols, 1,1,1-trichloroethane, acetone, toluene, methyl ethyl ketone, methylene chloride, o-dichlorobenzene, perchloroethylene, chloroform, styrene, and xylene.

Mortality among industrial workers exposed to phenol

We conducted a follow-up study to evaluate mortality among 14,861 workers employed in five facilities producing or using phenol and formaldehyde. More than 360,000 person-years of follow-up accrued. Mortality rates from all causes of death combined were similar to those in the general U.S. population. We observed excesses of cancer of the esophagus, cancer of the kidney, and Hodgkin's disease among workers exposed to phenol, but none of these excesses showed a dose-response relation with exposure to phenol. Excess lung cancer mortality (SMR = 1.2) showed no consistent pattern by any exposure index. Workers exposed to phenol had lower mortality ratios for cancer of the buccal cavity and pharynx, cancer of the stomach, cancer of the brain, arteriosclerotic heart disease, emphysema, disease of the digestive system, and cirrhosis of the liver. Of these, arteriosclerotic heart disease, emphysema, and cirrhosis of the liver were inversely related to duration of phenol exposure and to cumulative phenol exposure levels. Although these inverse associations may be due to chance or uncontrolled confounders, the ability of phenol to interfere with the generation of oxidants in experimental systems suggests that the pattern may have biologic plausibility.

Fetal cardiac flow velocities in the late 1st trimester of pregnancy: a transvaginal Doppler study

In 30 normal women with a singleton pregnancy, transvaginal Doppler ultrasound was used to record flow velocity at the fetal atrioventricular (AV) valve and outflow tract levels (ascending aorta and pulmonary artery) at 11 to 13 weeks of gestation. Technically acceptable flow velocity waveforms were recorded at the AV valve level in 19 fetuses and in the ascending aorta and pulmonary artery in 15 and 17 fetuses, respectively. Successful documentation of both transmitral and transtricuspid flow velocity waveforms was achieved in six fetuses only. Peak velocities during atrial contraction (A wave) were nearly twice as high as those during early diastolic filling (E wave), reflecting low ventricular compliance. Peak and time-averaged flow velocities in the outflow tract were lower than those observed in 2nd and 3rd trimester pregnancies with mean values of 32.1 +/- 5.4 (+/- SD) and 11.2 +/- 2.2 cm/s, respectively, in the ascending aorta and 29.6 +/- 5.1 and 10.8 +/- 2.1 cm/s in the pulmonary artery.

Human fetal foramen ovale flow velocity waveforms relative to fetal breathing movements in normal term pregnancies

The relationship between foramen ovale flow velocity waveforms and high-amplitude fetal breathing movements was studied in ten normal term pregnancies using Doppler ultrasonography. Peak systolic and averaged flow velocities demonstrated a statistically significant increase during fetal breathing activity, suggesting a raised pressure gradient between the right and left atria. This could be explained by a temporal reduction in pulmonary venous return to the left atrium during the inspiratory phase of the fetal breathing cycle. The breathing-related increase in foramen ovale flow velocity suggests that fetal breathing activity facilitates the distribution of well-oxygenated blood to the aorta and cerebral circulation.