Colloid cysts of the third ventricle: fatal outcomes associated with unusual presentation

It is always unfortunate when benign, surgically removable lesions cause unnecessary death. In three of five cases of third ventricular colloid cyst the patients presented with or developed severe headache which was like no other they had experienced before. The headache was of long enough duration to enable detection and removal of the cyst before its fatal outcome. In one case involving a fight it was considered that the third vetricular colloid cyst played an important part in the fatal outcome. In the fifth case the patient was found dead in bed without any preceding history of illness.

Empowerment: from philosophy to practice

Our paper reviews the philosophical and theoretical foundations of the empowerment approach to chronic disease care and education. The fundamental differences between the compliance and empowerment approaches are elucidated. The empowerment philosophy is based on the premise that human beings have the capacity to make choices and are responsible for the consequences of their choices. Empowerment is defined as an educational process designed to help patients develop the knowledge, skills, attitudes, and degree of self-awareness necessary to effectively assume responsibility for their health-related decisions. Using empowerment as an intellectual foundation, an holistic approach to health education is presented. Topics such as well-being, self-image, motivation, adaptability, stress management, problem-solving, social support, self-awareness, and hope, are discussed. Our paper asserts that health educators have a responsibility to address the physical, emotional, cognitive, and spiritual needs of persons challenged to live with a chronic disease.

Potential impact of low efficacy HIV-1 vaccines in populations with high rates of infection

A safe and effective HIV vaccine to prevent infection and/or to moderate disease is urgently needed. Research progress has been slower than anticipated for a variety of reasons including uncertainty over which immunogen to use (i.e. recombinant subunit envelope proteins or whole HIV-1 products), confusion on which immunological markers best correlate with protection, the relevance of the HIV-1 chimpanzee model to infection in humans and the significance of the rapid evolution of HIV-1, with different clades of the virus emerging in different parts of the world. However, what some would interpret as encouraging results, from Phase I and II trials of recombinant envelope glycoprotein vaccines, have raised the question of whether the time is right to start Phase III trials in humans with immunogens that may have low to moderate efficacy. By using mathematical models and data from epidemiological studies, we examine the potential impact of such vaccines within heterosexual communities with high rates of infection. Analyses suggest that it will be difficult to block HIV-1 transmission even with very high levels of mass vaccination. The cost of sustaining high levels of herd immunity with a vaccine of short protection duration is likely to be high. However, assessments of impact over the long duration of an HIV-1 epidemic indicate that many cases of HIV infection and associated mortality can be prevented by immunogens with efficacy of 50% or less and a five year protection duration.(ABSTRACT TRUNCATED AT 250 WORDS)

Strategies for limiting the spread of HIV in developing countries: conclusions based on studies of the transmission dynamics of the virus

Possible interventions to reduce the spread of human immunodeficiency virus (HIV) include actions that attempt to alter sexual behaviour, such as education aimed at reducing the rate at which individuals acquire new sexual partners, and methods that reduce the probability of transmission between partners, such as the promotion of condom use and the treatment of so-called "cofactor" sexually transmitted diseases. A mathematical model of HIV transmission that is able to mimic different approaches to the control of HIV transmission is employed to study the relative values of different approaches, either used in isolation, or in combination. The nonlinear nature of the term that describes the per capita rate of transmission dictates that for a given degree of intervention, the benefit accruing in terms of reduced HIV spread depends on the prevalence of infection before the introduction of control. Benefit is greatest when HIV prevalence is low. Combination approaches are predicted to be effective but the outcome is less than would be expected on the basis of simply summing the benefits resulting from each type of intervention used in isolation. The success of targeted interventions, aimed at those with high rates of sexual partner change, depends on the heterogeneity in levels of sexual activity within populations and what proportion of the population HIV is able to establish itself in. Targeted interventions are predicted to be very cost effective but their overall success in reducing HIV spread by a significant degree depends on the timing of their introduction (within the time frame of the development of the epidemic) and the pattern of mixing between different risk groups or sexual activity classes.

Patient empowerment. Results of a randomized controlled trial

OBJECTIVE

The purpose of this study was to determine if participation in a patient empowerment program would result in improved psychosocial self-efficacy and attitudes toward diabetes, as well as a reduction in blood glucose levels.

RESEARCH DESIGN AND METHODS

This study was conducted as a randomized, wait-listed control group trial. The intervention group received a six-session (one session per week) patient empowerment education program; the control group was assigned to a wait-list. At the end of 6 weeks, the control group completed the six-session empowerment program. Six weeks after the program, both groups provided follow-up data.

RESULTS

The intervention group showed gains over the control group on four of the eight self-efficacy subscales and two of the five diabetes attitude subscales. Also, the intervention group showed a significant reduction in glycated hemoglobin levels. Within groups, analysis of data from all program participants showed sustained improvements in all of the self-efficacy areas and two of the five diabetes attitude subscales and a modest improvement in blood glucose levels.

CONCLUSIONS

This study indicated that patient empowerment is an effective approach to developing educational interventions for addressing the psychosocial aspects of living with diabetes. Furthermore, patient empowerment is conducive to improving blood glucose control. In an ideal setting, patient education would address equally blood glucose management and the psychosocial challenges of living with diabetes.

Guidelines for facilitating a patient empowerment program

The traditional medical treatment model often ignores the emotional, spiritual, social, and cognitive aspects of living with a chronic disease such as diabetes. Empowerment programs address these psychosocial areas by helping individuals develop skills and self-awareness in goal setting, problem solving, stress management, coping, social support, and motivation. Although many diabetes educators have been taught to use an empowerment curriculum to facilitate self-management, there is minimal research concerning the actual process of providing such programs to patients. We evaluated an empowerment curriculum (Empowerment: A Personal Path to Self-Care) with a diverse group of individuals with diabetes to determine the key elements of planning and implementing a successful diabetes patient empowerment program.

Sudden death due to undiagnosed medullary-pontine astrocytoma

A 20-year-old woman died suddenly and unexpectedly from low-grade medullary pontine fibrillary astrocytoma. She had experienced neurological symptoms including coughing and choking thought to be asthma, poor motor coordination, nasopharyngeal incompetence, and arm pain since the age of 11 months. Despite the long history of symptoms, the tumor remained clinically undiagnosed. This case demonstrates the minor, nonlocalizing, and relapsing remitting nature of symptoms and signs related to this slow-growing tumor. To the best of our knowledge, this is the first case of sudden, unexpected death due to brainstem glioma in the English-language literature. Since autopsy disclosed a 5-7 week pregnancy, this case is also an example of a rare cause of maternal death.

Density-dependent processes in the transmission of human onchocerciasis: relationship between the numbers of microfilariae ingested and successful larval development in the simuliid vector

A previous paper reported that the intake of Onchocerca volvulus microfilariae (mff) by different species of Simulium is essentially proportional to the parasite load in the skin of infected carriers. This paper examines the fate of the ingested mff in susceptible vectors to assess the relationship between parasite intake and infective larval output in blackfly species with and without well-developed cibarial armatures. Analysis is based on data from 3 onchocerciasis endemic areas: Guatemala (S. ochraceum s.l.), West Africa (S. damnosum s.l./S. sirbanum) and the Amazonian focus between South Venezuela and Northern Brazil (S. guianense and S. oyapockense s.l.). The data, which include published and unedited information collected in the field, record experimental studies of parasite uptake by wild flies maintained in captivity until the completion of the extrinsic incubation period. The relationship between L3 output (measured as the mean number of successful larvae/fly or, as the proportion of flies with infective larvae) and average microfilarial intake, was strongly non-linear. This non-linearity was best represented by a sigmoid function in case of armed simuliids (S. ochraceum s.l., S. oyapockense s.l.), or by a hyperbolic expression in that of unarmed flies (S. damnosum s.l., S. guianense). These results are compatible, respectively, with the patterns of 'initial facilitation' and 'limitation' described in culicid vectors of lymphatic filariases. A maximum mean number of 1-3 L3/fly was observed in all 4 vectors. It is concluded that O. volvulus larval development to the infective stage is regulated by density-dependent mechanisms acting at the early phase of microfilarial migration out of the blackfly's bloodmeal. Damage by the bucco-pharyngeal armature may also be density dependent. A hypothesis, based on this density dependence is forwarded to explain initial facilitation, so far only recorded in vectors with well-developed cibarial teeth. Our results provide quantitative support for the conjecture that chemotherapy alone is likely to have a greater impact on reducing onchocerciasis transmission in endemic areas where the main vector has a toothed fore-gut than in foci where the vectors have unarmed cibaria.

Predicting the impact of measles vaccination in England and Wales: model validation and analysis of policy options

Measles incidence in England and Wales has fallen to an all-time low. Attention is now focused on preventing local outbreaks, and, in the long run, on the elimination of indigenous measles. A realistic age-structured (RAS) mathematical model of measles transmission is used to reconstruct the impact of measles vaccination in England and Wales from 1968 to the present and to evaluate the merits of future policy options. In general, the predictions of the model show good agreement with long-term age stratified case reports and seroprevalence surveys. The model underestimates the proportion of cases that are notified in 0-2-year-old children. However, recent work suggests a high degree of misdiagnosis in this age group. Projections on the basis of the existing vaccination strategy in the UK suggest that the present level of measles vaccine coverage will be insufficient to eliminate small seasonal outbreaks of measles. This result is, however, sensitive to the assumed level of vaccine efficacy. Explorations of a variety of changes to current vaccination strategy favour a 2-dose schedule with the second dose administered at age 4 years irrespective of vaccination history. A vaccination campaign in school-age children, to reduce deficits in herd immunity, would accelerate progress towards measles elimination.

Early onset of multiple sclerosis with autopsy confirmation

A female had her first generalized epileptic seizure at age 11 yrs. Apart from intermittent seizures she remained well until 15 yrs of age when she developed double vision, unsteadiness and bilateral plantar responses which resolved spontaneously. Brain MRI scan at this stage revealed changes typical of multiple sclerosis. She died at 17 yrs of age from asthma and epilepsy. Autopsy confirmed the presence of multiple sclerosis and showed the disease to be very active. We consider it likely that multiple sclerosis was present at the age of 11 yrs when she had her first epileptic seizure. This case of multiple sclerosis is presented because of the rarity of the early age of onset, unusual presentation with epilepsy, marked activity of disease and early death. Also it is uncommon to have autopsy confirmation of such disease.

Evolutionary pressures in the spread and persistence of infectious agents in vertebrate populations

Infectious agents have considerable potential to regulate or constrain the population growth of vertebrate hosts in natural habitats. A broad theoretical framework provides many insights into how the biology of the parasite and the demography of the host interact to determine this impact. It may manifest itself as a steady influence over time via stable endemic infection or in a recurrent epidemic fashion, sometimes with unpredictable intervals between epidemics depending on the generation time of the pathogen (time from infection to recovery or host death), its ability to induce lasting immunity and the population growth rate of the host species. Building on these notions, the paper focuses on recent work on the population dynamics of genetically variable pathogen populations and examines the factors that determine the evolution of virulence and the maintenance of genetic diversity in both host and pathogen. Recent research extends conventional theoretical templates to include population genetic elements and the within-host dynamics of the parasite and its interaction with the vertebrate immune system.

The Croonian Lecture, 1994. Populations, infectious disease and immunity: a very nonlinear world

The interaction between the variables that determine the typical course of infection in an individual patient and those that determine transmission in communities of people is often complex and very nonlinear in form. Mathematical models of infection and immunity are used to study the interaction in a wide variety of problems including the role of antigenic variation in pathogen persistence in the host, the design of vaccination policies for the control of childhood viral infections, the role of heterogeneity in sexual behaviour as a determinant of the epidemiology of sexually transmitted diseases and the demographic impact of infectious disease on human population growth. The themes of dynamical complexity in outcome deriving from simple biological assumptions, the evolution of the parasite under selection by the immune system, heterogeneities in the interacting systems, and the necessity of comparing prediction with observation reoccur in each problem. It is argued that much is to be gained from the use of mathematics in biology, concomitant with experiment and observation, in providing precision in interpretation and in facilitating the formulation and testing of hypotheses to explain observed pattern. Special emphasis is placed on the need for interdisciplinary research on the epidemiology of infectious diseases that combines molecular, immunological, field study and theoretical approaches.

Community diabetes care. A 10-year perspective

OBJECTIVE

To compare diabetes care and education at the community level in 1981 and 1991 in order to record progress achieved in the decade of the 1980s, determine if there is a gap that must be closed to reach diabetes-related objectives for 2000, and establish a baseline to which changes stimulated by the Diabetes Control and Complications Trial can be compared.

RESEARCH DESIGN AND METHODS

In eight Michigan communities, representative primary-care physicians (61 in 1981; 68 in 1991) and their diabetic patients (428 and 440) were identified. Communities, physicians, and patients were randomly selected. Participating patients were interviewed and examined in their community or home to assess the kind and extent of diabetes care they had been receiving; their metabolic, nutritional, educational, and psychosocial status; their diabetic history and current status; and other related factors. The diabetic status, care, and education of the 1981 community patients were compared with those of patients studied in 1991.

RESULTS

Positive changes in diabetes care and education at the community level from 1981 to 1991 were seen in the areas of patient glucose monitoring, insulin administration practices, hypertension control, exercise recommendations in diabetic management; and smoking rates. Negative changes occurred in the percentage of non-insulin-dependent diabetes mellitus (NIDDM) patients receiving diabetes education and frequency of office visits to the patient's primary-care physician. Changes of indeterminate value included a sharp decline in primary diabetes admissions to the hospital and a decrease in the proportion of NIDDM patients managed with insulin. Many other hoped-for changes from 1981 status, such as screening for retinopathy, foot-care practices, and overall metabolic control of diabetes, did not occur.

CONCLUSIONS

The decade of the 1980s produced modest, but not impressive, improvements in diabetes care and education at the community level. Progress must be accelerated if the diabetes-related objectives included in the national targets for health promotion and disease prevention for 2000 are to be met.

A device for cutting brain slices

A device for cutting brain slices is described as an alternative to cutting angle guides and the "brain macrotome." With this new device, slices of uniform thickness optimal for assessing morphological detail and photography can be produced. A similar but smaller device for cutting pieces of tissue for paraffin embedding is also presented. These devices should be useful in either the histopathology laboratory or mortuary.

The diabetes education experience of randomly selected patients under the care of community physicians

The purpose of this study was to describe the diabetes education and nutritional counseling received by patients under the active care of community physicians. The study population consisted of 440 patients with diabetes from the practices of 68 primary care physicians in eight Michigan communities. Fifty-eight percent of the sample reported having received diabetes education, and the mean number of years since the most recent education was 4.15 years. Sixty-six percent reported having seen a dietitian. Patients who had received diabetes education scored higher on a basic diabetes knowledge test (70% correct vs 60%) than patients who had not received diabetes education. From 1981 to 1991, a decline was observed in the percentage of patients who reported having received diabetes education (70% to 58%). Although patient education is an integral part of comprehensive diabetes care, too few patients are receiving it. Furthermore, diabetes education often results in less-than-optimal levels of knowledge. The situation has deteriorated over the past 10 years, and patients who are not on insulin typically are the least well served.

Influence of a highly focused case on the effect of small-group facilitators' content expertise on students' learning and satisfaction

BACKGROUND

There has been considerable debate over the need for content expertise to lead a successful small-group discussion for medical students. Some authors feel process expertise related to the conduct of a small group is of more value than content expertise related to the case. At least one study has presented data that suggest content expertise can lead to teacher domination of the learning environment. In an earlier study, the present authors found that students learned more and were more satisfied with small-group instruction when the instruction was facilitated by a faculty member who was an expert in the content of the case. That study also identified no tendency for content experts to dominate the sessions (e.g., through lecturing or otherwise controlling the learning environment). The purpose of the present study was to explore the efficacy of a carefully designed and highly focused case problem to remove the influence of group facilitators' content expertise on students' learning outcomes.

METHOD

The 211 students in the University of Michigan Medical School class of 1994 were randomly assigned to 28 groups in a microbiology and immunology course in the fall of 1991; each small group was led by a faculty facilitator. Complete data were available from 27 groups: 13 groups led by experts and 14 groups led by non-experts. Data collection included observers' codings of interactions between the students and the facilitators (interactional analysis), test scores, and students' ratings of the experience.

RESULTS

Unlike in the previous study, group leaders who were content experts devoted significantly more time to teacher-directed activities than did non-content-expert leaders. However, overall, 62% of the time was devoted to student-initiated activity. The results of the multiple-choice tests that were related specifically to the goals of the case indicated there was no significant difference between the students' performances in the groups led by experts and those led by non-experts. With respect to students' satisfaction, all students gave consistently high ratings to the experience and there was no difference between groups led by expert and non-expert facilitators.

CONCLUSION

The data from this study suggest that a facilitator's content expertise alone does not determine the amount of teacher-directed behavior in a group, the amount of students' learning, or students' satisfaction. The focus built into the case and the amount of facilitator's training directly related to the content of the case are also significant variables related to students' learning, teacher's behavior, and students' satisfaction.

Is HIV-1 likely to become a leading cause of adult mortality in sub-Saharan Africa?

Concerns are sometimes expressed at the extent to which HIV-1 is prioritized within international and national health budgets and as a research issue, on the grounds that much larger numbers of people in developing countries currently die from other diseases, such as malaria and tuberculosis. We use a previously described mathematical model to explore how the HIV-1 epidemic could develop within a sub-Saharan African context and investigate the trends and patterns of adult mortality which could follow. Two contrasting scenarios are studied, one which turns population growth rates negative and another which does not. In both cases, HIV-1-related disease accounts for over 75% of annual deaths among men and women aged 15-60 years by year 25 of the epidemic. Relatively little change in mortality is seen in the early years of the simulated epidemics. However, by year 15, expectation of life at age 15 has fallen from 50 to below 30 years. The fragmentary evidence now available from empirical studies supports the impression that HIV-1 is rapidly emerging as a leading cause of adult deaths in areas of sub-Saharan Africa. Observed patterns of age-dependent mortality reflect those projected in the model simulations.

Two signal activation as an explanation of high zone tolerance: a mathematical exploration of the nature of the second signal

Much work on the induction of non-responsiveness in lymphocytes suggests that it takes two signals to activate a cell correctly, and that receipt of the first signal alone not only causes suboptimal response, but also subsequent non-responsiveness or anergy. This paper discusses not anergy, but the original suboptimal response in the context of the well known but poorly understood phenomenon of high zone tolerance in experiments studying immunological responses to a range of antigen concentrations (low to high "zones"). We proceed to ask specific questions about the nature and timing of the signals involved. We construct three different models describing how the second signal might be received and use them to predict the shapes of dose-response curves. Comparison with data enables us to select, from a dynamical perspective, the most likely mechanism and to tentatively exclude a number of proposed mechanisms for high zone tolerance. We suggest that the stage at which a cell becomes susceptible to anergy is crucial and that it is over-contact, rather than lack of contact, which is important in the induction of tolerance.

Sexual behaviour survey in a rural area of northwest Tanzania

OBJECTIVE

Little is known about variations in patterns of sexual behaviour in different countries, cultures, and subpopulations that determine the spread of HIV-1. Quantitative studies are required to improve understanding.

METHODS

To assess reported patterns of sexual behaviour, we administered a standardized questionnaire to 416 men and 498 women aged 15-49 years from a rural population in northwest Tanzania.

RESULTS

Reported levels of sexual activity were highest in men and among younger age groups. The number of sexual partners and number of sex acts per unit of time were strongly correlated: men reported 10 times as many lifetime partners than women. Frequency of sexual partner exchange plateaued earlier in women (by age 25 years) than in men (by age 35 years). For the great majority, age of first intercourse was 15 years or younger; older subjects were older at first intercourse and had fewer lifetime partners than younger subjects.

CONCLUSIONS

This age-related pattern suggests that more recent birth cohorts have behaviour patterns that increase the risk of sexually transmitted infectious agents such as HIV. Preventive education programmes should be targeted at young adults, who adopt higher risk profiles of frequent partner exchange linked with first intercourse at an early age.

Adapting a diabetes patient education program for use as a university course

A study was conducted to determine if a patient education program, "Life With Diabetes," could be converted to an undergraduate course. The course consisted of seven 2-hour sessions with presentations by a physician, dietitian, psychologist, and clinical nurse specialists. Topics included definition, treatment, nutrition, monitoring, children, older adults, and patient empowerment. A total of 52 students (45 without diabetes, 7 with diabetes) have completed this one-credit course. A patient diabetes knowledge test and a 50-item Diabetes Attitude Survey were administered before and after the course. For the students without diabetes, mean knowledge posttest scores improved significantly, and significant changes were seen on the attitude subscales, with posttest scores moving closer to those of a national panel of diabetes experts. Students with diabetes scored closer to the national panel on the pretest and improved significantly only on the patient autonomy subscale. This course measurably improved knowledge and attitudes among undergraduates, suggesting that a patient education program can be adapted successfully to provide additional training opportunities for diabetes education programs.

Mathematical studies of parasitic infection and immunity

The techniques that underpin modern molecular biology have been rapidly adopted by those interested in the major parasitic infections of humans. The parasitological literature is full of reports of genes and their amino acid sequences, of molecules, of cell membrane receptors and channels, and of the fine details of the immunological responses mounted by the host to combat infection. Much less enthusiasm has been shown for the mathematical techniques that facilitate the analysis and interpretation of dynamical processes such as transmission, evolution, and the interplay between parasite population growth and immunological responses within the host. Molecular techniques provide enormous opportunities for description, but ultimately, understanding biological systems with the precision that physicists and engineers aspire to in their own fields will require quantitative description of the many rate processes that dictate both an observed pattern and the dynamics of its change.

Theoretical studies of the effects of heterogeneity in the parasite population on the transmission dynamics of malaria

Periodicity in malaria transmission has generally been ascribed to seasonal fluctuations in mosquito population density or spatial heterogeneity with periodic migration. In this paper we demonstrate that simple models of strain heterogeneity can generate periodic behaviour as a consequence of the interaction between parasite strains and host immunological defences. As the degree of cross-immunity between strains increases, the system moves from a régime of independent strain transmission and coexistence, through increasingly coupled behaviour, to the displacement of the strain of lower transmissibility by the strain with a higher basic reproductive rate (R0). Cross-immunity thus serves both to bring the strains into competition, and also to couple the dynamics. We find analytical and numerical results on strain coexistence to show how the range of possible outcomes may be read as an effect of the tension between these two effects of cross-protection.

Generalised nuclear and cytoplasmic inclusion disease: a rare case investigated by microscopy and immunohistochemistry

A Caucasian female who was noted to be mildly microcephalic at birth was diagnosed as having cerebral palsy at the age of 1 year. Her development was delayed and she never walked or talked. She appeared relatively stable neurologically until the age of 17 years when she had an illness with fever thought to be due to a virus. She was noted to deteriorate from this time on until her death at the age of 19 years. Autopsy revealed intranuclear and cytoplasmic inclusions wide-spread throughout the brain and visceral organs. There was no evidence of inflammation. Immunohistochemistry revealed strong immunoreactivity for tau protein and neurofilament protein. Electron microscopy revealed the inclusions to be composed of homogeneous finely granular material. Scattered within the granular material in the cytoplasmic bodies were crystalline structures with a honeycomb appearance. The possibility of these changes representing an old viral infection or a primary metabolic disorder are discussed.