[The omega connector--a module for jointed coupling of titanium total prostheses in the middle ear]. / Der Omega-Connector: ein Modul zur gelenkigen Ankopplung von Titantotalprothesen im Mittelohr.

BACKGROUND: Hearing improvement after reconstruction of a defect ossicular chain depends on material, design and - crucially - coupling of the prosthesis. Coupling a total ossicular replacement prosthesis to the stapes footplate can be problematic and lead to prosthesis instability. In order to solve this problem, the Omega Connector was developed, a module allowing the middle ear surgeon to couple a titanium total prosthesis to the stapes footplate in a flexible, angle-variable manner. MATERIAL AND METHOD: The Omega Connector is made of pure titanium and consists of three compenents: head, neck and base plate. The head allows a jointed coupling to the stem of a titanium total prosthesis. Positioned between the remnants of the stapes crura, the bas plate proves for a stable connection with the stapes footplate. RESULTS: The Omega Connector was implanted during 14 revisions surgeries. In 10 of these surgeries a total ossicular replacement prosthesis was removed which was implanted at an earlier date and which was fixed and no longer functioning. In all 14 cases it was possible intraoperatively to position the Omega Connector correctly and to couple it to a titanium total prosthesis. The postoperative hearing gain was between 10 to 25 dB, with an average of 18 dB. CONCLUSION: For the first time, the Omega Connector offers to the surgeon the option to couple a titanium total prosthesis via a micro ball joint. Hearing results achieved so far are satisfying. The results confirm the advantages of the Omega Connector during implantation of a titanium total prosthesis. For a final evaluation, long-term studies have yet to be made.

Precursor structures in the crystallization/ precipitation processes of CaCO3 and control of particle formation by polyelectrolytes.

The formation of CaCO3 is usually discussed within the classical picture of crystallization, i.e. assuming that the formation of CaCO3 crystals proceeds via nucleation and growth. This may be true for the case of low supersaturation. In this work it is shown that the formation process is far more complex at high supersaturation, i.e. during precipitation. New insight into the mechanisms of precipitation is obtained by analyzing structure formation with a time resolution down to the millisecond range from the initiation of the reaction. The techniques used are scanning electron microscopy, electron diffraction, X-ray microscopy and cryo-transmission electron microscopy combined with a special quenching technique. It is seen that upon mixing CaCl2 and Na2CO3 solutions (0.01 M) first an emulsion-like structure forms. This structure decomposes to CaCO3-nanoparticles. These nanoparticles aggregate to form vaterite spheres of some micrometers in diameter. The spheres transform via dissolution and recrystallization to calcite rhombohedra. Once a suitable amount of additive, in our case polycarboxylic acid, is present during the precipitation the nanoparticles are stabilized against compact aggregation; instead they form flocs. This stabilization is either of a temporary nature if the amount of polymer is insufficient to cover the surface of the nanoparticles formed or more long lived if there is enough polymeric material present. By means of Ca-activity measurements it can be shown that the polymers are partially incorporated into the forming crystals.

Supramolecular Structure of Precipitated Nanosize beta-Carotene Particles.

A combination of analytical methods and molecular modeling calculations has provided a detailed picture of the supramolecular and microscopic structure of precipitated lipophilic carotenoids. The nanoparticles have a core/shell structure (see schematic representation) in which the particle core (120 nm) consists of a variety of molecular aggregates of different sizes, and the shell (40 nm) consists of an adsorbed gelatin layer.

Typology of drug abuse deaths in Hamburg.

Based on a multidisciplinary approach (social-scientific questionnaire and forensic-pathological investigations), a typology of the drug-related fatalities in Hamburg during the period from July 1991 to June 1992 was achieved. A distinction between 3 types of addicts is proposed. Each group represents a different consumption pattern: (1) the opioid type, (2) polyvalent-drug users, and (3) primary alcoholics. With respect to these 3 types of abuse, some medical (concentration of alcohol and opioids in the blood) and social-scientific data (age at the beginning of the drug career, consumption of different drugs, distribution of age and sex, the quality and frequency of contact to facilities of the drug aid in Hamburg) are discussed.

HIV prevalence, attitudes and behaviour in clients of a confidential HIV testing and counselling centre in Uganda.

OBJECTIVE: To describe clients, operation and impact of an African public HIV testing and counselling centre. DESIGN AND SETTING: Analysis of samples from clients attending the AIDS Information Centre (AIC) in Kampala, Uganda in early 1991. SUBJECTS: HIV-1-positive and HIV-negative consecutive clients (250 of each), 86 consecutive couples, and 200 consecutive clients who were HIV-negative in 1990 and were attending for their repeat test. MAIN OUTCOME MEASURES: HIV seroprevalence rates, attitudes, behaviour and behaviour change. RESULTS: HIV-1 prevalence was 28% overall, 24% in men and 35% in women. Reasons for taking the HIV test were a planned marriage or a new relationship (27%; 84% in couples), to plan for the future (35%), distrust of sexual partner (14%) and illness or disease/death (not HIV-specific) of partner (20%). The majority of the reported intentions in response to a positive or a negative HIV test result were positive, demonstrating the ability to cope with this information. Of repeat clients, two (1%) had become HIV-1-positive. The majority of repeat clients reported one sexual partner only (67%) or sexual abstinence (25%). Compared with pre-test information from AIC clients attending for the first time, repeat clients reported casual sexual contacts less often (6 versus 25%) and, of those, the majority used condoms. CONCLUSIONS: Our study demonstrates the demand for and the feasibility of confidential HIV testing and counseling services in Uganda, and illustrates the value of these services in achieving behaviour changes. Such services should be considered an additional approach for the reduction of HIV transmission in Africa, especially in areas with high HIV seroprevalence rates.

HIV prevention among IVDUs in the Federal Republic of Germany: stability and change.

These comments on German drug and AIDS policy are based on the author's two decades of experience in the field of drug user treatment, on recent studies about the epidemiology and etiology of HIV among IVDUs, and on evaluative studies on demonstration projects. German drug use/user policy did not change much in the face of AIDS: no large maintenance or needle-exchange programs were initiated. This is because a well-prepared system of low-threshold methods targeted at IVDUs not ready to undergo treatment was in place before the epidemic. This system has been modified to integrate the aims of HIV prevention among IVDUs and is free of charge and available throughout the country.

[Use of methadone in obstetric and gynecologic management of drug-dependent females with and without HIV infection]. / Der Einsatz von Methadon bei der geburtschilflichen und gynäkologischen Versorgung von drogenabhängigen Frauen mit und ohne HIV-Infektion.

In the course of obstetrical and gynecological care, 113 women with acute intravenous drug use (IVD) participated in a methadon detoxification. In addition to medical treatment, socio-paedagogical intervention was part of the approach. A total of 212 cycles of methadon detoxification have been administered since patients' relapse during or after detoxication had a chance of readmission. In 45% of the attempts, detoxification could be fully achieved. An investigation of actual drug behaviour of the participating women in October 1990 showed, that 23.9% had abstained from drug consumption for at least 6 months ("drug free"). According to the HIV status and pregnancy 4 groups with comparable age (mean 27.7 years) and duration of drug dependency (mean 7.5 years) were classified. There were remarkable differences in drug behaviour between these groups. Of the HIV-infected women treated during pregnancy, 36% were drug free. Of the HIV-infected women without pregnancy and pregnant women without HIV-infection, comparable proportions (approx. 27% each) were living without drugs. All but one HIV-negative women of the group without pregnancy (3.8%) consumed drugs. In conclusion, pregnancy and subsequent motherhood seems to enhance and stabilize the motivation to quit drug consumption. The significant difference between the HIV-negative and HIV-positive women without pregnancy suggests, that besides pregnancy, the awareness of HIV-infection and of a limited life expectancy has also a positive influence on drug behaviour.