Dynamic imaging of functional nerve terminals and Schwann cells in presynaptic 'nerve plates' isolated from the skate electric organ

The cholinergic innervation and its glial support were isolated in a functional state from the electric organ of the skate (Raja species) using a combined enzymatic and mechanical dissociation technique. Examination using light and electron microscopy showed that this 'nerve plate' is a disc-shaped structure several hundred micrometres in diameter consisting of a dense plexus of nerve terminals attached to branching nerve fibrils with numerous associated myelinating and perisynaptic Schwann cells. In unfixed nerve plates, depolarisation and Ca2+-dependent staining of the nerve terminals was seen with RH-414, a fluorescent marker for functional motor terminals. The components of the nerve plate could be loaded with the Ca2+-sensitive dyes Fluo-3 and Fura-2. Depolarisation of nerve plates loaded with either dye leads to an immediate increase of intracellular Ca2+ levels ([Ca2+]i) in the nerve terminals. This response was blocked by certain Ca2+ channel antagonists from the -conotoxin family. Glial cell responses to depolarisation were in general minimal. However, increases of [Ca2+]i were seen in these cells, but not in nerve terminals, during applications of ATP and acetylcholine. These results show that both nerve terminal and glial elements in this 'nerve plate' preparation are functional. The ease of this preparation and its functional reliability give it considerable potential as a useful model for elucidating presynaptic mechanisms.

A medical school's plan for anti-tobacco-use education in community schools and hospitals

BACKGROUND

Tobacco use in the United States remains a significant health concern. In 1992, students at Dartmouth Medical School began a community service program that targeted the prevention of local tobacco use.

METHODS

The program combined primary prevention, through education of school-aged children, with secondary prevention, through smoking cessation clinics.

RESULTS

The program has received widespread community as well as national support for its actions. The program is in its initial stages of gathering data to determine whether there has been a significant impact on the tobacco use of the community.

CONCLUSIONS

This paper is an introduction to the program's efforts, and a potential template for other medical schools to follow.

Skin cancer in a subtropical Australian population: incidence and lack of association with occupation. The Nambour Study Group

Because it is not possible to monitor skin cancer accurately using routine methods, special surveys have been undertaken in Nambour, a typical subtropical community in Queensland, Australia. Estimates of incidence reported here are based on skin cancers medically treated between 1985 and 1992 and new cases diagnosed by dermatologists in two examination clinics in 1986 and 1992. Among men and women aged 18-69 years in 1986, age-adjusted incidence rates of basal cell carcinoma were 2,074 and 1,579 per 100,000 per year, respectively-the highest incidence rates of a specific cancer ever reported. Squamous cell carcinoma occurred at half the rate of basal cell carcinoma among men and at about one third the rate among women. Although as expected, fair skin, a history of repeated sunburns, and nonmalignant solar skin damage diagnosed by dermatologists were strongly associated with both types of skin cancer, outdoor occupation was not. Significant self-selection was observed among outdoor workers, whereby people with fair or medium complexions and a tendency to sunburn were systematically underrepresented among those in long-term outdoor occupations although they accounted for more than 80 percent of the community study sample. The mitigating effect of this selection bias may partly explain the paradox of the lack of quantitative evidence of a causal link between sun exposure and skin cancer in humans.

The Danish Conscription Registry: a resource for epidemiological research

According to the Danish constitution all Danish male citizens must appear before a Conscript Board for assessment prior to military or civil service. Conscript Board examinations have followed the same standardized procedures over many decades, and the Danish Conscript Registry represents a valuable resource for epidemiological research in Denmark. During the last two decades investigations based on information in the registry have produced significant contributions to many areas of medical science. Within the last decade new procedures and electronic data processing and storage have resulted in restricted possibilities concerning current and future utilization of the Danish Conscript Registry for epidemiological purposes. To improve this it is recommended to maintain all codes describing present illnesses and conditions together with the civic registration numbers in the computerized archive of all subjects assessed by the Conscript Board.

Occurrence of melanomas on the upper and lower limbs in eastern Australia

In view of the changing trends in the incidence of melanoma at different body sites and in particular on the limbs, the detailed distributions of over 10,000 invasive melanomas diagnosed on the upper and lower limbs in residents of mainland eastern Australia between 1987 and 1993 were examined. Cancer notifications and histopathology reports from the cancer registries of Queensland, New South Wales and Victoria were searched manually, and subsites when specified were recorded as shoulder, upper arm, forearm, elbow, wrist or hand, and thigh, leg, knee, ankle or foot. On the upper limbs relative tumour densities were highest on the shoulder, approximately equal on the upper arm and forearm and least on the hand in both men and women; on the lower limbs melanomas occurred more than twice as often on the leg than on the thigh or the foot, taking account of surface area. There was a clear inverse gradient of incidence of melanoma with latitude in the three eastern Australian states studied, but little difference between the states or between sexes in distribution of histological type: the majority specified being specified as superficial spreading melanomas. In contrast to predictions based on apparent frequency of sun exposure at subsites on the upper limbs, the relative concentration of melanomas on the shoulder suggests that wearing sleeveless garments outdoors in the sun should be avoided whenever possible. Also, the similar densities of leg and forearm melanomas seems inconsistent with the relative degree of exposure of each and further suggests that women's adoption of ankle-length skirts or trousers, in preference to knee-length skirts would be a worthwhile modern control measure.

Prevention of IDDM: the genetic epidemiologic perspective

Rational prevention of insulin-dependent diabetes mellitus (IDDM) requires knowledge about the aetiology and pathogenesis of the disease. The causation of IDDM is complex, involving genetic susceptibility as well as non-genetic determinants. The evidence of a genetic component to IDDM is based on the high concordance rate in monozygotic twins as compared with dizygotic twins, the higher recurrence risk among relatives of patients with IDDM as compared with the general population risk, and the well-established associations with genetic markers, including specific alleles from the HLA-locus. The evidence of a non-genetic component to IDDM is primarily based on the fact that the concordance rate in monozygotic twins is far from unity; the huge geographical variation in the incidence of IDDM, even between genetically similar populations, and the increasing incidence in many populations provide further support; associations between the risk of developing IDDM and exposure to several non-genetic determinants, including nutrients and viral infections, have been established and serve as additional evidence. In general, the relative risks conferred by the non-genetic determinants are rather small, and it is unknown how these factors initiate the autoimmune-mediated process that destroys the beta-cells of the pancreas. Recent findings suggest that non-genetic factors interact with genetic susceptibility genes in the causation of IDDM. Firstly, it appears that the increase in the incidence of IDDM has predominantly been observed in populations with high frequency of susceptibility genes. Secondly, it seems that the risk of IDDM among relatives of patients with IDDM is positively correlated with the general population risk level. All these lines of evidence considered together suggest that IDDM may develop from several different combinations of susceptibility genes acting together with non-genetic exposures. If so, prevention of IDDM will require assessment of disease risk at individual rather than at population level. Since genetic screening is neither feasible nor ethically acceptable in the population at large, possible prevention of IDDM will be restricted to individuals who, by means of a positive family history, may be classified as being at high disease risk.

Learning a partial-weight-bearing skill: effectiveness of two forms of feedback

BACKGROUND AND PURPOSE

Partial weight bearing (PWB) is a skill commonly taught by physical therapists. This study compared the effects of practice with either augmented feedback provided during the task (concurrent feedback) or augmented feedback provided after the task (postresponse feedback) for the learning of PWB with crutches.

SUBJECTS

Sixty young adults without known impairment of the neuromusculoskeletal system volunteered for the study.

METHODS

Subjects practiced supporting 30% of body weight while stepping onto a floor scale. Augmented feedback was provided during each trial for the concurrent feedback group and either following each trial or after every five trials for the postresponse feedback groups. Subjects returned 2 days later for a no-feedback retention test.

RESULTS

During practice, the concurrent feedback group was more accurate and consistent than either of the postresponse feedback groups. During retention, however, the postresponse feedback groups were the most accurate; all groups were equally consistent during retention.

CONCLUSION AND DISCUSSION

These results suggest that practice with concurrent feedback is beneficial for the immediate performance but not for the learning of this sensorimotor skill.

Tolerance of nicotinamide and carbogen with radiation therapy for glioblastoma

Nineteen patients with glioblastoma were treated with nicotinamide and carbogen and radiotherapy. Eight patients did not complete the protocol because of hepatic toxicity from phenytoin/nicotinamide drug interactions, persistent nausea or vomiting with nicotinamide, intolerance of the carbogen breathing apparatus, or other reason. In addition, early radiation neurotoxicity appeared increased.

An animal model for human melanoma

Experimental animal models that are directly relevant to human melanoma are lacking. We propose the Angora goat as a potentially useful field model with experimental potential and to this end have examined the prevalence and site distribution of all skin cancers in 28 Angora goat herds in Queensland, Australia. The prevalence of benign melanocytic lesions (lentigines) and their experimental induction by sunlight were also investigated. Among 1731 goats over 2 years of age, 139 malignant skin tumors were excised from 95 affected animals. The prevalence of squamous cell carcinoma (SCC) was 3.8% and of melanoma, 2.2%. Main site of occurrence of melanoma (83%) was the dorsal surface of the ear; in contrast SCC occurred mostly (84%) on the perineum. Lentigines were darker and more prevalent on the exposed compared with the unexposed surface of the ear in Angoras, analogous to the higher prevalence of nevi on the exposed compared with the less exposed inner surface of the arm in humans. Lentigines, which were also found on the perineum though lighter in color than on the dorsal ear, were absent in young animals under 3 months but were numerous in 1-3 year olds. Furthermore in an experimental substudy eight goats, having one flank repeatedly shorn and the contralateral flank left unshorn, revealed consistently more solar lentigines on the shorn flank (P < 0.05) when both sides were examined after 9 months. Histopathological examination of paired skin biopsies from five of these goats also showed more abundant pigmentation in skin from the exposed, as compared with the unexposed flank. These findings indicate that sunlight induces tumors and lentigines in goats in a highly site-specific manner. The Angora goat model may suggest paradigms for explaining the site differences observed for human melanoma and may also be useful in the future clarification of molecular changes following carcinogenic levels of sun exposure.

Unrelated donor bone marrow transplantation for children with relapsed acute lymphoblastic leukaemia in second complete remission

Allogeneic sibling bone marrow transplantation (BMT) is the recommended treatment for relapsed childhood acute lymphoblastic leukaemia (ALL), but appropriate donors are only available in 30% of cases. Unfortunately, BMT from unrelated donors (UD) has been associated with high rates of severe graft-versus-host disease (GvHD) and transplant-related mortality (TRM). In an attempt to improve outcome in UD-BMT we have assessed the impact of T-cell depletion using CAMPATH-1 (anti-CD52) monoclonal antibodies in 50 consecutively referred patients with relapsed ALL in second remission. All were previously treated according to MRC protocols UKALL X and XI, and then given chemotherapy on MRC R1 from relapse until UD-BMT, 19 patients had relapsed on and 31 off therapy. Patients and donors were fully matched at HLA-A, -B, -DR and -DQ loci in 29 cases and mismatched in 21 (four mismatched for more than one antigen). Pre-transplant conditioning comprised CAMPATH-1G, cyclophosphamide and total body irradiation. Bone marrow was T-cell depleted in vitro using CAMPATH-1 antibodies. Additional GvHD prophylaxis consisted of cyclosporin A (42 cases), cyclosporin plus methotrexate (four) or none (four). 47 patients engrafted. The incidence of acute GvHD was very low: two patients with grade II disease in the matched group, four with grade II-IV in the mismatched group. Only four patients have chronic GvHD. The actuarial event-free survival (EFS) at 2 years is 53%, with no significant difference between the matched and mismatched group. Further leukaemic relapse was the most important cause of failure. These results are similar to the most favourable published reports for HLA-matched sibling BMT in relapsed ALL.

Trends in the epidemiology of IDDM during 1970-2020 in Fyn County, Denmark

OBJECTIVE

To present an epidemiological model applicable to diabetes based on which prevalence rates are estimated from assumed rates of incidence and mortality of diabetes. Furthermore, this study illustrates the model by analyzing epidemiological data on IDDM in a Danish population during 1970-1990, with predictions of prevalence rates for 1990-2020.

RESEARCH DESIGN AND METHODS

The epidemiological model assumes known prevalence rates as well as incidence rates and mortality at a given time. Under assumed rates of incidence and mortality of IDDM and its complications, the prevalence rate is the dependent variable, estimated as a function of calendar time. We use epidemiological data on IDDM (operationally defined as insulin-treated diabetes with onset before age 30 years), blindness, and nephropathy, as well as mortality, as reported for 1973 and 1987 in Fyn County, Denmark.

RESULTS

During 1970-1990, the prevalence of IDDM increased steadily because of increasing incidence and decreasing risk of complications and mortality. The relative prevalence of patients with nephropathy increased, whereas that of blind patients decreased considerably. Under specified assumptions regarding the future levels of incidence of disease, complications, and mortality, it is estimated that the prevalence rate of IDDM in the year 2020 will be 45-60% higher than the level in the year 1990. The relative prevalence of patients with nephropathy will increase further, whereas the relative prevalence of blind patients will remain constant at a low level.

CONCLUSIONS

IDDM will represent an increasing public health problem in Denmark during the next decades, with increasing overall prevalence rates and a rising proportion of patients with nephropathy. The major determinant of this trend is increasing incidence combined with declining mortality and declining risk of complications. It is strongly recommended that epidemiological models like the one presented here be further developed and implemented at regional levels to provide data for the dimensioning of the current and future diabetes care systems.

Accuracy of case-reported family history of melanoma in Queensland, Australia

A positive family history is used in clinical practice as an indication of increased melanoma risk, yet there are no data on the accuracy of reported family histories of melanoma. The validity of case-reported family history of melanoma was assessed in the course of a family and twin study of melanoma in Queensland, Australia, conducted among the families of 2,118 melanoma cases diagnosed in Queensland between 1982 and 1990. A total of 913 melanoma cases made 1,267 reports of melanoma among their first-degree relatives. A total of 1,040 of these reports were checked, first through relatives themselves and then, if the relative also said they had had melanoma, through the relative's medical records. Medical confirmation of melanoma as the diagnosis was obtained for 623 reports (59.9%; 95% confidence interval 56.9-62.9): a false-positive reporting rate by cases of 40.1%. The level of false-positive reporting was lower for cases under 70 years of age, for women, for cases whose own diagnosis of melanoma was more than 5 years earlier, and for cases with three or more relatives with melanoma. Media campaigns in Queensland aimed at increasing skin cancer awareness, and confusion between melanoma and other more common actinic neoplasma (basal and squamous cell carcinomas), may partly explain the high false-positive reporting rate observed here. For this reason, It is difficult to generalize these findings to northern hemisphere populations where skin cancer is not such an important public health issue.

Desensitization of beta-adrenergic receptors in adipocytes causes increased insulin sensitivity of glucose transport

To determine the effect of desensitization of adipocyte beta-adrenergic receptors on insulin sensitivity, rats were continuously infused with isoproterenol (50 or 100 micrograms.kg-1.h-1) for 3 days by osmotic minipumps. Epididymal adipocytes were isolated. The cells from treated animals were desensitized to isoproterenol, as determined by response of lipolysis (glycerol release). Binding of [125I]iodocyanopindolol was decreased by approximately 80% in adipocyte plasma membranes isolated from treated rats, indicating that beta-adrenergic receptors were downregulated. Cellular concentrations of Gn alpha and Gi alpha were not altered. Insulin sensitivity was determined by measuring the effect of insulin on glucose transport (2-deoxy-[3H]glucose uptake). Cells from the isoproterenol-infused rats were markedly more sensitive to insulin than those from control rats. This was evidenced by an approximately 50% increase in maximal glucose transport rate in cells from the high-dose isoproterenol-treated rats and by an approximately 40% decrease in the half-maximal effective concentration of insulin in both groups. 125I-labeled insulin binding to adipocytes was not altered by the isoproterenol infusions, indicating that desensitization of beta-adrenergic receptors results in tighter coupling between insulin receptors and stimulation of glucose transport.

[The most recent part of the Danish Twin Registry. Establilshment and analysis of zygote specific twinning rates]

In order to be able to study the aetiology and pathogenesis of diseases with manifestation in childhood and youth a Danish register of young twins has been established. The compilation of the register is based on the Danish Civil Registration System, with the Danish Vital Statistics as source of validation. All twins were sent a one side questionnaire asking about diabetes, willingness to participate in other projects and pairwise similarity in the twins. Comprising 20,888 twin pairs the register covers 74.4% of all twin pairs born 1953-67 (incl.) and 97.4% of those born 1968-82 (incl.). The response rate of the questionnaire study was 92.3%. The responders represented 19 180 twin pairs. Ninety-six percent of the respondent twins declared their willingness to participate in additional studies. An analysis of trends in the twinning rates for the years 1968-82 showed that the rate in monozygotic twinning is increasing and the twinning rate of opposite-sexed twin pairs is decreasing, thus confirming earlier estimated trends in twinning rates. This register provides a valuable resource for future twin studies.

Opening the debate on DALYs (disability-adjusted life years)

The 1993 World Development Report is proving to be an influential document for the development of the health sector policies in developing countries. One important aspect of the Report concerns its proposals for Disability Adjusted Life Years as a measure of health change and hence effectiveness of interventions. This article comments on the use of such measures in the health policy arena.

An exploratory study of patients' memory recall of their stay in an adult intensive therapy unit

This study carried forward an exploration to determine if there is a need to visit patients in a ward following discharge from an adult intensive therapy unit (ITU), by ascertaining what patients remember of their stay and their ability to cope with this experience. Data were collected during interviews 48 hours following subjects' discharge from the ITU, and collated using an adaptation of thematic content analysis as described by Burnard (1991). Twenty-six subjects were studied over a 6-month period. The findings suggest that patients have vivid recollections of their stay in an ITU, and are consistent with previous research in respect of patients continuing to experience dreams, pain, sleep deprivation and worries about transfer out of an ITU to a ward. New themes suggest that ITU patients do not recall their "named nurse", but do recall detailed explanations given to them by nurses in the ITU. Patients also believe they would benefit from a follow-up visit to discuss and clarify aspects of their stay which were unclear or are causing them concern.