Mitochondrial DNA mutations in an outbreak of optic neuropathy in Cuba

Since October 1991, nearly 51,000 Cubans have been afflicted in an outbreak of optic and peripheral neuropathies. To begin an investigation of the possible role of mitochondrial DNA (mtDNA) mutations in the outbreak, we studied mtDNA from 14 affected and two unaffected Cubans for the 12 mutations associated with Leber's hereditary optic neuropathy. Eleven probands (12 patients) had optic neuropathy and two had peripheral neuropathy only. We also studied two unaffected relatives of one proband. We identified two mtDNA mutations, at nucleotides 11778 and 3460, in two of the 11 probands with optic neuropathy. Although this data set is too small to reach statistically valid conclusions, it does suggest that mtDNA mutations might be contributing to the outbreak of optic neuropathy in Cuba.

A-bomb survivors: further evidence of late effects of early deaths

Reanalysis of A-bomb survivor data has shown the following: a) in the high-dose (> 1 Gy) subgroups of the life span study cohort of 5-y survivors, there is a significant deficit of individuals who were < 10 y or > 50 y at the time of the bomb; and b) in the cohort on in utero children, there is a significant deficit of individuals who were < 8 wk of fetal age when exposed. This paper discusses how this selection bias has affected the perception of three effects of A-bomb radiation: marrow damage, carcinogenesis, and second-generation effects.

Reanalysis of Hanford data: 1944-1986 deaths

Reanalysis of Hanford data by a method, which is new only in the sense that it makes new uses of standard epidemiological procedures, has produced evidence of a cancer risk at low dose levels. By a conservative estimate, about three per cent of the pre-1987 cancer deaths of Hanford workers had occupational exposures to external radiation as the critical (induction) event. These radiogenic cancers were evenly distributed between five diagnostic groups, but as a result of there being much greater sensitivity to "cancer induction by radiation" after, rather than before, 50 years of age, they were concentrated among the cancers which proved fatal after 70 years of age. The reanalysis provides no support for the idea that radiation is more likely to cause leukemia than solid tumors, or the idea that there is reduced cancer effectiveness of radiation at low dose levels (dose rate effectiveness factor or DREF hypothesis), but the estimated proportion of radiogenic cancers was much higher for the 175 nonfatal cancers (which had other certified causes of death) than for the 1,732 fatal cases. Finally, according to the latest publication of the US Committee on Biological Effects of Ionizing Radiation (BEIR V), dose rate is more important than exposure age, and even a single exposure to 10 rem would only increase the normal cancer risk by four percent. Nevertheless, for all recorded exposures of Hanford workers, the estimated doubling dose was close to 26 rem; for exposures after 58 years, it was close to 5 rem, and for exposures after 62 years, it was less than 1 rem.

Report on Euro Ergo: 4th European Congress of Occupational Therapy, 5–8 May 1992, Ostend

This report is a kaleidoscope of patterns and images perceived by some of the UK representatives and described here with the intention of inspiring others to participate in the next international congress, which will be the WFOT Congress to be held in London in April 1994.

An overview of the Hanford controversy

In 1964, the Atomic Energy Commission agreed to sponsor "a study of the lifetime health and mortality experiences of all employees of AEC contractors." The commission put in charge of this study a physician (Thomas Mancuso) who had recently shown how the U.S. Social Security system could be used to identify the dates and causes of death of all insured workers. As director of the AEC project, Mancuso was at liberty to include any or all the postwar offshoots of the Manhattan Project. His master plan included workers from Oak Ridge, Los Alamos, and Hanford, but it soon became apparent that his attempts to link radiation exposures to subsequent events were proving more successful at Hanford than elsewhere. The authors of this paper, who participated in the study, review the controversy surrounding its eventual publication.

A randomised study of outcomes in a defined group of acutely ill elderly patients managed in a geriatric assessment unit or a general medical unit

The aim of this study was to identify differences in the medical management and clinical outcome in a group of elderly patients admitted to a designated geriatric assessment unit (GAU) or to two general medical units (GMUs). A prospective randomised controlled trial was undertaken in 267 patients aged 70 years and over (mean age = 78.3 years). Following discharge from hospital, patients were followed up at three monthly intervals for a total of 12 months. At the time of discharge, no significant differences were found in inpatient management, length of stay, mortality rates, discharge rates to institutional care or utilisation of community services in patients admitted to the GAU and the GMUs. Similarly, no significant differences were found at three, six, nine, and 12 month follow up in case fatality, activities of daily living indices, mental health status, rates of institutional referral and the level of community service support in patients admitted to the GAU and the GMUs studied. These findings do not show any advantage for the unselected 70+ acutely ill elderly patient who is admitted to a designated geriatric assessment unit rather than to a general medical unit. Therefore, an admission policy to GAU, based solely on age 70+ is medically inappropriate and cost-inefficient. Evidence from other sources suggests that an age cohort of acutely admitted patients beyond 80 years may well have returned more optimistic findings for the GAU. In future, GAUs will require a more selective admission policy to maximise the benefits of their rehabilitative and interdisciplinary approach.

Changing interactions between astrocytes and neurons during CNS maturation

The environments of the developing brain and injured adult brain differ in their abilities to support axonal growth. To determine if astrocytes contribute to this difference, neurons were plated onto astrocytes cultured from the neonatal rat cortex and from the injured adult brain. Two patterns of neurite growth were observed in these two astrocyte culture systems. Neurons contacting the neonatal astrocytes had neurites that were twice as long as those contacting the injured adult astrocytes. Furthermore, in cultures with neonatal astrocytes, neurites faithfully followed the astrocytic processes, maximizing their contact, while in cultures of injured adult astrocytes, the neurites had a tendency to cross the processes orthogonally, minimizing their interaction with the astrocytes. When neurons were grown suspended over either neonatal or injured adult astrocytes, no difference in neurite length or the pattern of neurite growth was observed, indicating that neurite growth was not differentially affected by soluble factors released from the two populations of astrocytes. The addition of fetal calf serum, which is known to contain protease inhibitors, did not alter neurite growth when compared to serum-free medium, suggesting that a substantial difference in protease activity does not account for the variations in neurite length observed. Based on these results, it appears that the molecular components of the external surface of injured adult astrocytes do not support neurite growth to the same extent as those found on neonatal astrocytes. The differing abilities of these two populations of cultured astrocytes to support neurite growth in culture may reflect a change in the functional role of these cells that occurs during the development of the central nervous system.

Evaluation of delayed effects of ionizing radiation: an historical perspective

It is widely assumed that after the bombing of Hiroshima and Nagasaki there were no lasting effects of the acute injuries (which included extensive damage to blood forming tissues by the radiation) or the massively high death rate (which was caused by environmental effects of the blast as well as personal injuries). However, close inspection of the dose response curves for non-cancer deaths has shown that this could be a false impression caused by one effect of marrow aplasia being confused with leukemia (defective erythropoiesis) and a second effect being confused with early selection in favor of general fitness (defective immune responses). Possible consequences of such confusion (for cancer risk coefficients) are discussed in relation to what is known about late effects of prenatal x-rays and occupational exposures to radiation.

Immunizations against infectious diseases and childhood cancers

A study based upon an unusually large series of childhood cancers and matched controls found a significant deficit of case/control pairs in which the cancer case had fewer immunizations against infectious diseases than the matched control. All types of immunizations and cancers were affected but the case/control differences were more pronounced for older cases with late immunizations than for younger cases with early immunizations, and more pronounced for solid tumours than leukaemia. Therefore there may be immune system responses to immunizations (or simulated infections) which make it difficult for small clones of cancer cells to enlarge and are more successful in preventing localised tumours in adolescents than childhood leukaemias.

Non-cancer effects of exposure to A-bomb radiation

A slight rearrangement of the data included in a recent report from the Radiation Effects Research Foundation (RERF) has shown differences between cardiovascular and other non-malignant diseases of A-bomb survivors which probably result from two factors: selection effects of early infection deaths and residual effects of marrow damage. Both effects were dose related but neither was obvious becasue one reduced the risk of later infection deaths and the other increased the risk. Allowance for these factors is bound to alter present RERF estimates for cancer effects of radiation and the change will probably be in an upward direction, thus bringing these estimates closer to ones based on radiation workers.

Identification of occupational mortality risks for Hanford workers

Though most of the production work at Hanford is done by manual workers, 46% of the most dangerous jobs are performed by people who have professional or technical qualifications. For these privileged workers occupational mortality risks are positively correlated with radiation doses but for manual workers, who have relatively high death rates, there is an inverse relation with dose. The high ratio of professional to manual workers is clearly the reason for the industry having fewer observed than expected deaths and the inverse relation with dose for less privileged workers is probably a sign that there has been selective recruitment of the most highly paid manual workers--that is, skilled craftsmen into the more dangerous occupations. Evidence of this selective recruitment was obtained by equating danger levels with levels of monitoring for internal radiation. Therefore, there should be some control for these levels in any analysis of cancer effects of the measured dose of radiation.

Job related mortality risks of Hanford workers and their relation to cancer effects of measured doses of external radiation

This paper continues the series by Mancuso, Stewart, and Kneale (MSK) on studies of cancer risks for radiation workers at Hanford. It concentrates on the statistical problems posed by the need to estimate and control for job related mortality risks when there are several changes of occupation and no certainty about how different occupations are related to two socioeconomic factors which have strong health associations--namely, education and income. The final conclusion is that for tissues which are sensitive to cancer induced by radiation there is a risk of cancer for Hanford exposures whose dose response is curvilinear with long latency and increasing effect with increasing exposure age.

A 12-month comparative trial of auranofin and D-penicillamine in rheumatoid arthritis

The oral gold salt auranofin, 6 mg per day, was compared with oral d-penicillamine, 500 mg per day, in a single-blind trial in 40 patients suffering with definite or classic rheumatoid arthritis. The patients were randomly allocated into the two therapeutic regimens (19 patients auranofin; 21 patients d-penicillamine) and monitored at a minimum of four-week intervals during the first year of treatment. Significant diminution in rheumatoid disease activity, as assessed by numerous clinical and laboratory parameters, was observed in both the auranofin- and penicillamine-treated groups. No significant differences existed for these parameters between the two groups, either initially or at the end of the trial period. Ten patients were lost from the trial over the 52-week period. Three subjects were withdrawn from the auranofin-treated group (increasing severity of rheumatoid arthritis at four weeks; severe diarrhea at four weeks; probable drug-related erosive gastritis at 40 weeks). Seven subjects were permanently withdrawn from the penicillamine-treated group (four, skin rashes four to eight weeks; one, heavy proteinuria at 24 weeks; one, therapeutic failure at 32 weeks; one, compliance failure at eight weeks), and treatment was temporarily withheld in three further patients because of thrombocytopenia (two) and proteinuria (one). We conclude that both drugs are effective in rheumatoid arthritis and that the lesser toxicity with auranofin will make it a valuable addition to our therapeutic armamentarium.

The Effect of Lattice Discreteness on the Linewidth of the Electron Spin Resonance of Local Moments in Metals

Solutions of the Hasegawa-Bloch equations for the electron spin resonance of local moments in metals are obtained which take account of the discrete nature of the lattice. The most notable result derived is that the resonance linewidth is proportional to T - () for any degree of bottlenecking, where () is the paramagnetic Curie temperature calculated with lattice discreteness. An alternative derivation of the appropriate Hasegawa-Bloch equations is also given.

Delayed effects of A-bomb radiation: a review of recent mortality rates and risk estimates for five-year survivors

A review of published data relating to A-bomb survivors has led to the conclusion that since they were based on the mortality experiences of five year survivors estimates of radiation effects should have been controlled for two opposing forces-namely, selective survival of exceptionally fit individuals during the period of heavy acute mortality and residual disabilities. Both effects were dose-related and beyond question, and the disabilities probably included the effects of incomplete repair of bone marrow damage. Therefore, in addition to differences between high and low dose being largely obliterated, there was probably distortion of cancer effects. The two opposing forces are clearly the reason why the change from the high mortality rates of 1945-6 to the low rates of the 1950s was not accompanied by a change from a position to a negative association with dose, and imperviousness to the residual disabilities is probably the reason why sudden deaths of previously healthy individuals (exemplified by suicides) were an exception to this rule. Finally, impairment of bone marrow function probably accounts for the early epidemic of myeloid leukaemia; the apparent absence of other cancers at this time, and the relatively high dose-related death rates for blood diseases other than leukaemia.

The immune system and cancers of foetal origin

Evidence of early loss of immunological competence in cases of neoplasms occurring in juveniles was found in an analysis of OSCC data (Oxford Survey of Childhood Cancers). The effects observed included heightened sensitivity to infection from birth onwards for all types of childhood cancer, higher levels of sensitivity for leukaemia than for lymphomas, and higher levels for lymphomas than for other solid tumours. The findings as a whole are consistent with in utero loss of immunological competence, which is an essential promoter of cancers of foetal origin and thus allows the outcome of an in utero cancer induction to be influenced both by maternal levels of immunological competence and postnatal infection.

Hanford radiation study III: a cohort study of the cancer risks from radiation to workers at Hanford (1944-77 deaths) by the method of regression models in life-tables

This paper reports on results from the study initiated by Mancuso into the health risks from low-level radiation in workers engaged in plutonium manufacture at Hanford Works, Washington State, USA, and attempts to answer criticisms of previous reports by an in-depth study. Previous reports have aroused much controversy because the reported risk per unit radiation dose for cancers of radiosensitive tissues was much greater than the risk generally accepted on the basis of other studies and widely used in setting safety levels for exposure to low-level radiation. The method of regression models in life-tables isolates the effect of radiation after statistically controlling for a wide range of possible interfering factors. Like the risk of lung cancer for uranium miners the dose-response relation showed a significant downward curve at about 10 rem. There may, therefore, be better agreement with other studies, conduct at higher doses, than is widely assumed. The findings on cancer latency (of about 25 years) and the effect of exposure age (increasing age increases the risk) are in general agreement with other studies. An unexplained finding is a significantly higher dose for all workers who developed cancers in tissues that are supposed to have low sensitivity to cancer induction by radiation.

Pre-conception X-rays and childhood cancers

An analysis of data collected during the course of the Oxford Survey of Childhood Cancer has shown that it is possible to recognize different facets of memory bias without systematic checking of individuals' records, and to make use of the biased data. The position of foetal irradiation in the aetiology of childhood cancers has been re-affirmed, but there is no support for the idea that exposure of parental gonads to diagnostic X-rays is conducive to cancer in the next generation.

Simple Theory of the ?Negative Residual Linewidth? in Reflection Spectroscopy of Magnetically Concentrated Local Moment Systems

A mathematically improved analytical approximation is obtained to the solutions of the phenomenological equations of H. Hasegawa that describe the electron spin resonance of local moments in metals and the bottleneck effect that frequently occurs. The approximation shows that at all temperatures above the Curie point () the Iinewidth is proportional to T -- () for any degree of bottlenecking, and not to temperature T. The solution also reveals that the g shift remains explicitly independent of temperature down to the Curie point. The expressions obtained take into account explicitly the direct local moment spin lattice relaxation rate and show that it is effective in breaking the bottleneck.

Pre-cancers and liability to other diseases

Data of 10,556 case-control pairs from the Oxford Survey of Childhood Cancers and related sources have shown that when cancers originate in the reticuloendothelial system (RES neoplasms) they are liable to cause loss of immunological competence before they are clinically recognizable. Since these early effects may have lethal consequences, the true prevalence of RES neoplasms is difficult to identify, especially in infection-sensitive age groups and populations with high death rates from infection. An inevitable consequence of a nuclear holocaust is a high infection death rate. Therefore, a population of A-bomb survivors is a totally unsuitable one for studying the precise nature of the association between ionizing radiation and human cancers.

C-peptide and insulin in liver disease

The liver is the primary organ of insulin clearance; thus, hyperinsulinism in peripheral blood may result from diminished insulin degradation rather than hypersecution. Proinsulin is cleaved in the pancreatic β-cell to insulin and C-peptide, which are released into the circulation in equimolar quantities. Unlike insulin, C-peptide is not degraded by liver, and in liver disease the peripheral C-peptide concentration is a better index of insulin secretion than is peripheral insulin concentration.

Fasting plasma insulin concentration was raised in 21 cirrhotic patients (0.13 ± 0.02 vs. 0.06 ± 0.01 nmol per liter) despite normal fasting blood glucose concentrations. C-peptide concentrations and, therefore, insulin secretion did not differ from controls', and the C-peptide:insulin ratio was decreased in cirrhotic subjects (4.0 ± 0.5 vs 7.0 ± 1.1). After oral glucose, hyperinsulinemic cirrhotic subjects had similar C-peptide concentrations to those of cirrhotics with a normal insulin response in whom glucose values were similar. Hyperinsulinism (both fasting and after glucose) appears to result from diminished insulin degradation, therefore.

To distinguish the roles of liver damage and of portal-systemic shunting, similar studies were performed in patients with ostensibly normal liver function but long-standing portal venous block. Despite mild hyperglycemia, hyperinsulinism was not found in these subjects, either fasting or after oral glucose. The fasting C-peptide:insulin ratio was normal, and only after stimulation of insulin secretion by glucose was a mild impairment of insulin degradation seen.

The hyperinsulinism of hepatic cirrhosis is due to impaired insulin degradation; this is more likely to result from liver damage per se than from portal-systemic shunting.

Age variation in the cancer risks from foetal irradiation

A modified Mantel-Haenszel analysis of data from the Oxford Survey of Childhood Cancers has shown that cases associated with foetal irradiation (X-rayed cases) accounted for a higher proportion of deaths between 5 and 10 years than of earlier or later deaths. This finding is compatible with somewhat later origins for the cancers actually caused by the radiation exposures (radiogenic cases) than for other (idiopathic) cases which proved fatal before 10 years of age. Therefore the usual time for incurring congenital anomalies (or the first trimester of foetal life) could be the commonest time for initiating childhood cancers. The theoretical implications of this and other findings of the Oxford Survey are discussed within the framework of a theory which assumes that all mutant cells have cancer potentialities and that defects in the immune surveillance mechanism favour multiplication of these cells (or endogenous sources of self-replicating foreign proteins) as well as live pathogens (or exogenous sources of self-replicating foreign proteins).