Abtötungsfestigkeit und Entwicklungsfestigkeit

Zusammenfassung Es wird auf die Möglichkeit hingewiesen, daß es sich bei der sog. Resistenz der Bakterien gegen Gifte zum zwei verschiedene voneinander unabhängige Arten handelt, nämlich 1. um die Fähigkeit, auf Nährböden zu wachsen, welche das betreffende Gift enthalten und 2. um die Widerstandsfähigkeit gegen die abtötende Wirkung des Giftes. Die erstere Eigenschaft wird als Entwicklungsfestigkeit, die zweite als Abtötungsfestigkeit bezeichnet.Es gelingt leicht, Colistämme durch systematische Züchtung auf malachigrünhaltigem Nährboden dahin zu bringen, daß sie noch bei einem etwa 1000mal so hohen Gehalt des Nährbodens an Malachitgrün wachsen, als die Ausgangsstämme. Diese Stämme, die also sehr stark erhöhte Entwicklungsfestigkeit besitzen, verhalten sich der abtötenden Wirkung des Malachitgrüns gegenüber nahezu ebenso wie die Ausgangsstämme. Entwicklungsfestigkeit und Abtötungsfestigkeit sind also zwei voneinander unabhängige Eigenschaften.Die entwicklungsfesten Stämme werden, wenn durch niedrige Temperatur oder Mangel an Nährstoffen ihr Wachstum verhindert wird, schon durch Konzentrationen abgetötet, welche weit unter denjenigen liegen, auf denen sie in gutem Nährboden noch wachsen können. In gutem Nährboden, wenn sie von ihrer Entwicklungsfestigkeit Gebrauch machen können, sind sie natürlich bis zur Grenze der Entwicklungsfestigkeit auch gegen die abtötende Kraft geschützt.Es gelingt nicht, durch Auslese der resistenten Keime bei einem Desinfektionsversuch einen widerstandsfähigeren Stamm zu bekommen. Die Abtötungsfestigkeit ist bei den einzelnen Keimen einer Kultur sehr verschieden, aber keine erbliche Eigenschaft.Eine erhöhte Entwicklungsfestigkeit läßt sich nur dann erreichen, wenn sich die Keime unter dem Einfluß des Desinfektionsmittels vermehren, nicht dadurch, daß sie in ruhendem Zustande mit ihm in Berührung sind.     

Validity of predicting left ventricular end systolic pressure changes following an acute bout of exercise

ObjectivesLeft ventricular end systolic pressure (LV ESP) is important in assessing left ventricular performance and is usually derived from prediction equations. It is unknown whether these equations are accurate at rest or following exercise in a young, healthy population.DesignMeasured LV ESP vs. LV ESP values from the prediction equations were compared at rest, 15 min and 30 min following peak aerobic exercise in 60 participants.MethodsLV ESP was obtained by applanation tonometry at rest, 15 min post and 30 min post peak cycle exercise.ResultsMeasured LV ESP was significantly lower (p < 0.05) at all time points in comparison to the two calculated values. Measured LV ESP decreased significantly from rest at both the post15 and post30 time points (p < 0.05) and changed differently in comparison to the calculated values (significant interaction; p < 0.05). The two LV ESP equations were also significantly different from each other (p < 0.05) and changed differently over time (significant interaction; p < 0.05).ConclusionsThe two commonly used prediction equations did not accurately predict either resting or post exercise LV ESP in a young, healthy population. Thus, LV ESP needs to be individually determined in young, healthy participants. Non-invasive measurement through applanation tonometry appears to allow for a more accurate determination of LV ESP.     

Donor derived HSV hepatitis in a kidney transplant recipient leading to liver fibrosis and portal hypertension

The unexpected transmission of donor‐derived infection through organ transplantation is a rare event with current donor screening practices. In this case report we describe a probable donor‐derived transmission of Herpes Simplex Virus (HSV)‐2 via deceased donor kidney transplantation resulting in HSV hepatitis in the recipient. This manifested as acute liver failure which resolved with appropriate anti‐viral therapy. Following recovery from the acute liver insult, the patient developed fibrotic liver morphology and portal hypertension, an unusual departure from the typical course.     

Comparison of minimally invasive surgical skills of neurosurgeons versus general surgeons: is there a difference in the first exposure to a virtual reality simulator?

OBJECTIVE: The increasing use of minimally invasive surgery, which has a longer learning curve compared to open surgery lets the necessity to develop training programs to improve endoscopic skills of trainees become ever clearer. The aim of this study was to compare the endoscopic skills of neurosurgeons versus general surgeons at first exposure to a virtual reality simulator. METHODS: 72 general surgeons who visited the 122nd Conference of the German Surgeons Society (DGCH in Munich 2005) and 35 neuroendoscopic surgeons, who visited the Third World Conference of the International Study Group of Neuroendoscopy (ISGNE in Marburg 2005) participated in this study. Each participant performed the basic module "clip application" on the virtual reality simulator (LapSim). All participants were given the same pretest instructions. Time to complete the task, error score and economy of motion were recorded. RESULTS: The general surgeons performed the clip application faster, but with more errors than neuroendoscopic surgeons. However, the difference of both parameters was not significant. Both surgeon groups have a similar score for economy of motion. CONCLUSION: Although neuroendoscopic surgeons were exposed to a foreign procedure and unfamiliar equipment, they were able to perform virtual endoscopy with similar accuracy as general surgeons, who are adapted to these endoscopic instruments and procedures and do these daily.     

Surgical management of dural arteriovenous fistulas with transosseous arterial feeders involving the jugular bulb

Dural arteriovenous fistulas located in the vicinity of the jugular foramen are complex vascular malformations and belong to the most challenging skull base lesions to treat. The authors comprehensively analyze multiple features in a series of dural arteriovenous fistulas with transosseous arterial feeders involving the jugular bulb. Four patients who underwent surgery via the transcondylar approach to treat dural arteriovenous fistulas around the jugular foramen were retrospectively reviewed. Previously, endovascular treatment was attempted in all patients. The success of the surgical treatment was examined with postoperative angiography. Complete obliteration of the dural arteriovenous fistulas (DAVFs) was achieved in three patients, and significant flow reduction in one individual. All patients had a good postoperative outcome, and only one experienced mild hypoglossal nerve palsy. Despite extensive bone drilling, an occipitocervical fusion was necessary in only one patient with bilateral lesions. The use of an individually tailored transcondylar approach to treat dural arteriovenous fistulas at the region of the jugular foramen is most effective. This approach allows for complete obliteration of the connecting arterial feeders, and removal of bony structures containing pathological vessels.     

Heparininduzierte Thrombozytopenie (HIT) als schwerwiegende Komplikation der Thromboseprophylaxe mit Heparin

Thrombembolic prophylaxis with heparin has been established in surgery for years. There has been some controversy about it recently because of the serious complications it can have. In the literature, the incidence of heparin-induced thrombocytopenia (HIT) type II is given as about 5%. The pathophysiological mechanism is well known; the laboratory tests that allow detection of HIT II are well established; and an alternative medication is known. In a retrospective study we investigated the medical records of 14,975 patients with particular reference to this complication. We also validated a screening method for early detection of HIT II by means of frequent platelet counts. In our study group we found HIT II in 0.2% of the subjects. Thromboembolic complications of heparin that occurred were deep vein thrombosis in 35% and pulmonary embolism in 25%. Counting the platelets on days 0, 3, 5, and 7 and then weekly during thromboembolic prophylaxis allows early detection of HIT II and helps to avoid life-threatening complications.     

Changes in the classification of carcinogenic chemicals in the work area

Carcinogenic chemicals in the work area were previously classified into three categories in section III of the German List of MAK and BAT values (the list of values on maximum workplace concentrations and bio‐logical tolerance for occupational exposures). This classification was based on qualitative criteria and reflected essentially the weight of evidence available for judging the carcinogenic potential of the chemicals. In the new classification scheme the former sections IIIA1, IIIA2, and IIIB are retained as categories 1, 2, and 3, to correspond with European Union regulations. On the basis of our advancing knowledge of reaction mechanisms and the potency of carcinogens, these three categories are supplemented with two additional categories. The essential feature of substances classified in the new categories is that exposure to these chemicals does not contribute significantly to the risk of cancer to man, provided that an appropriate exposure limit (MAK value) is observed. Chemicals known to act typically by non-genotoxic mechanisms, and for which information is available that allows evaluation of the effects of low-dose exposures, are classified in category 4. Genotoxic chemicals for which low carcinogenic potency can be expected on the basis of dose/response relationships and toxicokinetics and for which risk at low doses can be assessed are classified in category 5. The basis for a better differentiation of carcinogens is discussed, the new categories are defined, and possible criteria for classification are described. Examples for category 4 (1,4-dioxane) and category 5 (styrene) are presented. Received: 11 August 1998 / Accepted: 24 August 1998     

Patient and Caregiver Attitudes and Practices of Exercise in Candidates Listed for Liver Transplantation

Background

Impaired physical capacity increases peri-liver transplant complications. Patient perceptions regarding exercise prior to transplantation are not known.

Aims

This study aimed to assess patient and caregiver activity levels, perceptions of willingness to exercise, and of provider advice.

Methods

Consecutive patients listed for liver transplant and caregivers presenting for routine outpatient visits were evaluated over a 3-month interval. Anonymous surveys adapted to patients and caregivers addressed the importance and safety of exercise, type and duration of exercise performed, barriers, willingness to wear a monitoring device, and perceived provider recommendations. Responses were logged on a Likert scale from 1 to 5.

Results

Three hundred and sixty-eight responses were received. Most participants perceived exercise as important. Patients exercised three times per week for 30 min. Eighty percent endorsed walking (median response: 2—agree; IQR 1–2). Most did not jog, swim, cycle, or strength train. Fatigue, reported by 70%, was the major barrier (2, IQR 1–3). Over 90% of caregivers endorsed exercise as important (1—strongly agree, IQR 1–2) and encouraged exercise (median response 2, IQR 1–2). Over 60% of patients (median response 2, IQR 1–3) and caregivers (median response 2, IQR 2–3) felt providers encouraged exercise.

Conclusions

Patients and caregivers are willing to exercise to optimize physical fitness prior to liver transplantation.