Using pharmacokinetics in drug therapy III: Estimating dosage regimens and blood levels using the fraction-lost method

The "fraction of drug lost during dosage interval" method, which yields rapid estimates for drug dosage regimens and blood levels, is described. Estimation of the fraction lost during a dosage interval allows further calculation of dosage regimens and steady-state blood levels. The estimates derived from this method are valid only when the pharmacokinetics of the drug are linear and elimination from the body occurs according to first-order kinetics. Other limitations of the method are discussed.     

Bogengeführte Zahnbewegung — Dynamik,Effektivität und Nebenwirkungen

Zusammenfassung Im Rahmen der vorliegenden Studie werden die Einflüsse der Parameter Drahtdimension (Rund- oder Kantdraht), krafterzeugendes Element (elastische Kette, Zugfeder, Zugfeder am Powerhook, Zugfeder mit Aufrichtefeder), Bracket (schmal, breit) und Lage des Wderstandszentrums auf die Bewegungseffektivität und Nivellierungsverluste (Kippung, Rotation, Extrusion) bei der bogengeführten Eckzahnretraktion untersucht. Neben Messungen am Stahldraht wurden vergleichsweise auch verseilte Drähte und Nickel-Titan-Drähte einbezogen. Die Simulation der Bewegung erfolgte mit Hilfe des orthodontischen Meßund Simulationssystems (OMSS). Die für das 0,018-Inch-Slotsystem ermittelten Ergebnisse bestätigen das allgemein übliche klinische Vorgehen der Eckzahndistalisation an einem 0,016×0,022-Inch-Vierkantstahlbogen, solange man mit der bogengeführten Technik arbeitet. Empfehlenswert ist der Einsatz einer Nickel-Titan-Zugfeder. Durch ihre relativ konstante Kraft über einen großen Aktivierungsbereich ermöglicht sie eine effektivere Distalisierung als eine elastische Kette. Bei Anwendung eines Powerhook bzw. einer Aufrichtefeder lassen sich Nivellierungsverluste weitgehend vermeiden und somit eine körperliche Bewegung am ehesten garantieren. Der Distalisierungseffekt wird dabei jedoch nur unwesentlich verstärkt. Die Gefahr eines zu groß gewählten Antitipmomentes ist streng zu beachten. Einen deutlichen Einfluß auf die Bewegungseffizienz zeigt die Lage des Widerstandszentrums. Je weiter apikal das Widerstandszentrum lokalisiert ist, wie beispielsweise bei einer längeren Zahnwurzel, desto geringer erweist sich die Distalisierungseffektivität. Gute Ergebnisse in bezug auf die Effizienz der Distalisierung wurden in Verbindung mit einem verseilten Bogen ermittelt. Seine Anwendung ist jedoch wegen zu starker Nivellierungsverluste in der Führungsphase abzulehnen.

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Summary Canine retraction on a continuous arch wire was simulated using the OMSS. The influence of wire dimension, force generating element (power chain, coil spring, powerhook, uprighting spring), bracket width and the position of the center of resistance on the effectiveness of the distalization of the canine and its side effects such as extrusion, rotation and tipping were examined. Stainless steel, nickel titanium and multistranded wires were tested. Employing the 0.018-slot system, the use of an 0.016×0.022-arch wire gave the best results. Comparing the NiTi coil spring with the elastic chain, the former should be preferred, because, due to its low load deflection it generates a nearly constant force over a wide range of activation. Using powerhooks or uprighting springs, a nearly bodily movement could be achieved. On the other hand, friction may increase if the uprighting is too strong. The rate of tooth movement decreases by increasing length of tooth root represented by the position of the center of resistance. Arch guided tooth movement along multi-stranded wires shows a high effectiveness, nevertheless, these wires should not be used for canine retraction because of the above mentioned side effects.

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Herrn Professor Dr. Dr.G. P. F. Schmuth zum 65. Geburtstag.

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Diese Arbeit wurde zum Teil gefördert durch die Deutsche Forschungsgemeinschaft (Dr 196/1).     

A new variety of "empty sella" with cystic intrasellar dilatation of the recessus infundibuli.

A new variety of the "empty sella" consisting of polycystic intrasellar dilatation of the infundibular recess is described. The underlying embryonal developmental anomaly of the pituitary gland and diaphragma sellae and the possible effect of increased intracranial pressure are discussed and the malformation is compared with embryonal stages of ventricular development.     

Volumetrie der Harnblase mittels implantierbaren Ultraschallsensoren

Experimental studies revealed that the contractile response of the urinary bladder to sacral anterior root stimulation depends on the actual bladder volume. Furthermore, no clinical relevant technique is available for continuous monitoring of the bladder wall distension respectively bladder volume in paraplegic patients. The presented study investigates the reliability of especially developed implantable ultrasound sensors as a sensoric system for continuous monitoring of the bladder volume. In six anaesthesized pigs two ultrasound sensors, one transmitter and one receiver, were implanted on the bladder wall at different locations (latero-lateral, dorsal-ventral, rostral-caudal). After closing the abdominal wall, the bladder was filled in 50 ml steps up to 250 ml. After each filling step the running time of the ultrasound signal was measured. In all experiments reproducible results and a high correlation of the measured running times with bladder volume were observed. The latero-lateral configuration of the sensors seemed to be most confidential. The presented study indicates that bladder volumetry with implantable ultrasound sensors is possible with minimal technical prerequisites. This promising technique for continuous bladder volumetry could play an important role in the development of an intelligent and autoadaptive neurostimulator of the urinary bladder in paraplegic patients.     

Urgent and emergency carotid TEA

Restoration of blood flow to reperfuse ischemic but not infarcted areas of the brain (ischemic penumbra) and the removal of an ongoing embolic source are the therapeutic aims of emergency and urgent carotid endarterectomy (CEA), both in patients with an acute or progressive ischemic stroke and in patients in the early period after a carotid-related stroke. Based on poor results in the 60ies and 70ies, many centers traditionally perform CEA four to six weeks after a carotid-related stroke at the earliest interval. Since natural history is associated with a high risk of an disabling and/or recurrent stroke in several subgroups of patients, some reports were able to show that urgent and emergency CEA could be worthwhile in well-selected patients.     

Does the architecture of hospital facilities influence nosocomial infection rates? A systematic review.

OBJECTIVE: To review the evidence regarding the effects of interventions to improve hospital design and construction on the occurrence of nosocomial infections. METHODS: Systematic review of experimental and non-experimental, architectural intervention studies in intensive care units (ICUs), surgical departments, isolation units, and hospitals in general. The studies dated from 1975, and were in English, French, German, Italian, and Spanish. Regardless of format, the studies were identified through seven medical databases, reference lists, and expert consultation. RESULTS: One hundred seventy-eight scientific articles were identified; however, none of these described a meta-analysis, systematic review, or randomized, controlled trial. Most of the articles were categorized at the lowest level of evidence (expert judgment or consensus statements). Only 17 described completed concurrent or historical cohort studies matching the inclusion criteria (ICUs, 9; surgical departments, 4; isolation units, 2; hospitals in general, 2). The interventions generally included a move to other premises or renovation. However, in many studies, the staff-to-patient ratio was also improved. Some studies showed lower infection rates after intervention, but this finding cannot be generalized because of confounding and frequently small study populations. CONCLUSIONS: The lack of stringent evidence linking hospital design and construction with the prevention of nosocomial infection is partly attributable to the multifactorial nature of these infections, and some improvement will be seen if basic conditions such as the availability of sufficient space, isolation capacity, and facilities for handwashing are met. However, to our knowledge, other factors, especially the improper hand hygiene of medical staff, have greater impact.     

Are the children of fatherless families more frequently emotionally disturbed in adult life?

It has been the subject of numerous debates recently whether children who grew up without fathers suffer more than others under the long-term consequences of their fatherless childhood. In 1994 we conducted a large-scale population-based investigation over a hundred subjects who had grown up without father to establish standardized norms for various psychometric questionnaires that were also relevant to this issue. This allows us to contribute to the discussion with some concrete data, which correspond without exception with the dominant trend of other research results. Whereas there was evidence to support the view that some children of fatherless families do indeed suffer from increased emotional disturbance in later life, there were also indications that others even profited emotionally from their fatherless childhood. In the area of bodily complaints the results were confounded to a high degree with gender differences, showing that women are more frequently negatively affected, and men more positively.     

The Antonovsky Sense of Coherence Scale. Test statistical evaluation of a representative population sample and construction of a brief scale

In this article we will describe the evaluation of Antonovsky's 29-items Sense of Coherence Scale (SOC-29) in a large community sample (n = 2.005) of the German population and the development of the Leipzig Short Scale (SOC-L9), which consists of only 9 items. The SOC-29 has a high internal consistency (alpha = 0.92), however, the SOC-subscales (comprehensibility, manageability, meaningfulness) were correlated with each other. A principal component factor analysis did not identify the 3-factor structure of the SOC-Scale. It appears that the best solution consists of one global factor. The newly developed SOC-L9, conceptualized as an unidimensional scale, is a reliable and valid instrument, which allows to assess the SOC economically. In our study the Sense of Coherence depended on age and gender. Women and older people reported a lower SOC. Furthermore we found significant associations between SOC and different subjective health measures. A high SOC was associated with both a lower extent of subjective body complaints and somatoform symptoms and with minor health-related problems in daily living.