PubMed Health⌕ Search

Biomedical subjects

H Knolle

Publications and source records attributed to H Knolle.

At least 19 recordsLinked to original sources
PubMed1999

The heroin/cocaine epidemic in Switzerland 1979-1997: a mathematical analysis of law enforcement data.

The Swiss registry of charges concerning illegal trade and consumption of narcotics makes a distinction between first and subsequent charges as well as between several types of illegal drugs. It has been previously shown by using a mathematical model that changes in incidence of illegal drug use can be inferred from the time series of two indicators which are calculated from the numbers of first and subsequent charges. This method of data analysis is now refined in order to monitor the incidence of heroin/cocaine use. The conclusion is that 2,500 persons per year may have entered the population of habitual heroin/cocaine users in the early 1980s, and about 10,000 each year in 1991-93. After 1993, however, the incidence of heroin/cocaine use declined rapidly.

Cocaine-Related Disorders↗
PubMed1997

[Increasing use of heroine and cocaine in Switzerland since 1990: use of a generalized Poisson distribution in the collected data].

Estimates of the prevalence of deviant behaviour, which are based on the usual survey methods are by far too low. Therefore, the use of capture-recapture methods or of the truncated Poisson distribution is to be preferred, provided appropriate data are available. Here an extended Poisson approach was applied in order to estimate the number of users of hard illegal drugs (heroin, cocaine) in Switzerland for each year from 1990 to 1993. These estimates indicate an increase by about 50% during the period 1990-1993.

Adolescent↗
PubMed1997

Incidence and prevalence of illegal drug use in Switzerland in the 1980s and early 1990s: an analytical study.

The Swiss registry of charges concerning illegal trade and consumption of narcotics offers the possibility of monitoring the incidence and prevalence of illegal drug use in Switzerland. Of course, the relation between the number of charges against users of illegal drugs and the number of users is unknown and may vary in time and space. This makes it difficult to estimate the prevalence of consumption from law enforcement data, but it does not hinder the estimation of incidence if the numbers of first and subsequent charges are known. This is demonstrated by employing a dynamic model with two compartments which represent the not yet charged and the charged users. In contrast to methods which rely on treatment admission data, the new method can detect changes of incidence without time lag. Prevalence estimates can be obtained if the charge frequency distribution is known, as it is for Switzerland from 1990 to 1994. A theoretical distribution is fitted to the data which are available for all illegal drugs as well as for heroin and/or cocaine. This leads to estimates of the populations of users of illegal drugs in general and of heroin and/or cocaine.

Cocaine↗
PubMed1996

[Dynamics of the drug scene in Switzerland 1977-1990].

The registry of charges against users of illegal drugs in Switzerland is showing a steady increase from 1977 to 1990. Of course, the relation between the number of charges and the number of users is unknown and may vary in time and space. But it is shown here that the dependency of the data from the practice of the police can be circumvented with the help of a mathematical model and the distinction between first and subsequent charge. The least squares fit of the model to the data leads to an estimated time series of the number of illegal drug users that implies, with respect to 1977, the twofold in 1982 and the threefold in 1990.

Data Collection↗
PubMed1995

[Transmission of poliomyelitis by drinking water and the problem of prevention].

The role of drinking water as a source of infection with wild poliovirus in modern cities was denied nearly 50 years ago on the basis of arguments taken from bacteriology. Recent findings concerning the persistence of viruses in water and their resistance to antibacterial agents applied to fresh water and waste water require a revision of those older concepts. There is now convincing evidence that in New York City, where poliomyelitis struck with extreme severity, drinking water was a main source of infection. The phenomenon of water-borne poliomyelitis may become important in the near future as well. Since population growth and scarcity of water in many parts of the world makes recycling of waste water necessary, the eradication campaign of the WHO must consider the possibility that strains of vaccine virus excreted by vaccinees will be reproduced forever.

Developing Countries↗
PubMed1994

[Historical geographical epidemiology of poliomyelitis].

Poliomyelitis was considered a rare disease before it terrified Europe and North America with large-scale epidemics during the first half of the 20th century. In Africa and Asia the number of reported cases increased remarkably only after World War II. A theory which is widely accepted today assumes that infection with poliovirus 1, 2 and 3 has always been globally endemic, but that the proportion of cases with residual paralysis has increased only since 1900 as a consequence of the rise of the mean age at infection. Sabin, however, initially was convinced that virus strains with enhanced neurotropism had caused the dramatic increase in paralytic poliomyelitis. Epidemic outbreaks in anglo-american troops in Malta and in the Far East during the war played a crucial role in the discussion. Later, also Sabin sustained the theory mentioned first, which gradually assumed the position of a dogma. The present paper deals with the question of how this dogma became dominant, in spite of the weakness of its epidemiological and virological foundation.

Disease Outbreaks↗
PubMed1993

[The effect of perennial partnerships on the prospective development in the AIDS epidemic].

Long-term predictions of the AIDS epidemic in the general population are possible only on the basis of an epidemiologic model which contains explicit assumptions about partner choice and duration of partnerships. Several models proposed heretofore predict too many AIDS cases in the next century, because they neglect the correlation between ages of partners. In heterosexuals it is frequent that many years pass between acquisition and transmission of HIV. Therefore, the correlation implies that most infection chains are disrupted because the age in the year of infection increases as new links are added to a chain. These considerations can be put into quantitative terms by adapting the classical concept of the basic reproductive rate to the special situation of HIV infection. In this way the impact of age preference and partnership duration on the spread of HIV is analyzed.

Acquired Immunodeficiency Syndrome↗
PubMed1990

[Bilateral pleural mesothelioma--case report].

It is reported on the rare case of a 46-year-old female patient with a bilateral mesothelioma of the pleura without contact to asbest. Although the female was suspected in a malignant tumor and many diagnostic investigations were performed, diagnosis could be ensured morphologically only a short time before her death. Causes and development of mesothelioma, histological types, clinical symptoms and diagnostic procedures are described.

Diagnosis, Differential↗
PubMed1990

[Bilateral primary giant cell tumor (osteoclastoma) of the ribs].

The primary giant-cell tumour is a semimalignant bone tumour which occurs primarily on the epiphysis of the long tubular bones and the methaphysis. The present case report describes the bilateral occurrence of this tumour in the region of the osseous thorax. The paper also deals with diagnostic, therapeutical and prognostic problems.

Adult↗
PubMed1989

Host density and the evolution of parasite virulence.

Social and cultural habits of human populations affect the biological evolution of the agents of infectious diseases. Measles and similar diseases have evolved in the Old World and cannot have existed in their present form before the rise of the great river valley civilizations. It is suggested that increased virulence of measles in white and indigenous communities in America 1500-1800 may be due to a rare strain of the virus, which was selected during transfer from Europe. The release of viruses for biological pest control has provided new material for the study of the co-evolution of host-parasite systems, which has upset the dogma "evolution tends to avirulence". It is pointed out that this issue is closely related to the group selection debate among ethologists, i.e. to the problem: how can group selection overcome individual selection? A model is proposed in which differential growth of two strains of a parasite within the host and their transmission to new hosts is considered. It is supposed that transmission stages excreted by infectious hosts enter a common pool where they are mixed before infecting new hosts. Under these conditions, selection of the slower strain is possible only if the mean size of parasite inoculum is very small, i.e. if the density of transmission stages in the environment is low. The impact of this result on host pathology depends on the relation between virulence and transmission efficiency of the parasite.

Animals↗
PubMed1988

[Aluminum dust lungs].

In general aluminium dust induced fibrosis of the lungs occurs very rarely. Based on an own observation of a clinical case the problem of clinical and pathological diagnosis is discussed. Aluminium was detected in the lung by histological, chemical and atomic absorption spectroscopy procedures. Anamnesis, epicrisis, clinical symptomatology and the result of autopsy permit to diagnose aluminium dust induced fibrosis of the lung, taking into consideration the detection of aluminium dust by chemical and atomic absorption spectroscopy methods.

Aged↗
PubMed1986

Values of growth fraction and cell loss factor of sixty-five tumours re-examined.

It has been shown that the mathematical evaluation of data from many cell kinetic experiments, published up to 1977, was rather inaccurate. The discrepancies between published values of growth fraction (GF) and the cell loss factor phi, and the results of new calculations based on the same values of LI, Td, TC, TG1, TS and TG2, are sometimes surprising. Using a suitable approximation of ex-1, the known formulae for GF and phi are replaced by simpler ones of sufficient accuracy. This may help to avoid computational errors in future cell kinetic studies of tumours.

Animals↗