Prevalence and spread of enterohepatic Helicobacter species in mice reared in a specific-pathogen-free animal facility.

Infections with enterohepatic Helicobacter species (EHS) can change the results of animal experiments. However, there is little information about the prevalence of EHS in noncommercial animal facilities. The aim of this study was to investigate the prevalence and the spread of EHS in specific-pathogen-free (SPF) mice. Fecal samples of 40 mouse lines were analyzed for members of the family Helicobacteraceae using a group-specific PCR targeting the 16S rRNA gene. Additional experiments were carried out to evaluate the spread of EHS among mice harbored in different caging systems. Helicobacter species were detected in 87.5% of the mouse lines tested. Five different Helicobacter species were identified: H. ganmani, H. hepaticus, H. typhlonicus, and the putative Helicobacter species represented by the isolates hamster B and MIT 98-5357. Helicobacter infection did not spread between animals in neighboring cages when individually ventilated cages were used; in contrast, when the mice were reared in open-air cages, EHS were found to spread from cage to cage. However, the spread was prevented by adding polycarbonate filter tops to the cages. When Helicobacter-negative and infected mice shared the same cage, transmission of the infection occurred in 100% within 2 weeks. Furthermore, we found that mice from commercial breeding facilities may carry undetected Helicobacter infections. Taken together, we show that infection with EHS may frequently occur and spread easily in mice reared under SPF conditions despite extensive safety precautions. Moreover, there is a high prevalence of rather uncommon Helicobacter species that may be a consequence of the current routine procedures used for health screening of SPF mice.

[Five cytostatic substances in animal studies for prevention and treatment of experimentally induced peritoneal carcinomatosis]. / Fünf Chemotherapeutika in tierexperimentellen Untersuchungen zur Prävention und Therapie der Peritonealkarzinose.

High local recurrence rates within the previous tumor bed or at the peritoneum remain an unsolved problem after surgical resection of malignant gastrointestinal tumors such as gastric, colorectal or pancreatic carcinoma. Currently, there are no standardized treatment protocols available for the prevention or treatment of peritoneal carcinomatosis. In a basic experimental trial, mitomycin, cisplatin, 5-FU, oxaliplatin and CPT-11 were used to prevent or treat peritoneal carcinomatosis induced in rats. Experiments were performed in three groups (n = 8 each) of animals plus two control groups. In the first group, Mitomycin, Cisplatin, 5-FU, Oxaliplatin and CPT-11 (n = 24 each) were applied directly following tumor cell implantation into the peritoneal cavity. In the second group, early postoperative intraperitoneal (i. p.) chemotherapy (day [d] 5, 10, 15 following surgical intervention for tumor cell transfer) was administered, whereas in the third group, late i. p. chemotherapy (d 15, 20, 25 following surgery) was given via a port-a-cath aiming for significant reduction of a visible, already established peritoneal carcinomatosis. Mitomycin and cisplatin were highly effective to prevent peritoneal carcinomatosis (direct application immediately after tumor cell transfer - 1 (st) treatment group). Using early postoperative i. p. chemotherapy (2 (nd) group), 5-FU and CPT-11 were shown to be significantly effective to reduce the intraperitoneal tumor spread. None of the cytostatic agents was able to decrease significantly an already generated peritoneal carcinomatosis (3 (rd) treatment group). The results suggest that novel chemotherapeutic drugs should be proven for their potential to alter peritoneal metastases of GI tumors i) in comparison with established drugs and ii) depending on the application time and mode.

The response of focal ischemic cerebral edema to dexamethasone.

Twenty-four h after permanent occlusion of the middle cerebral artery (MCA) in the cat, the hemispheric swelling due to edema is markedly reduced under treatment with large doses of dexamethasone than is the case with the untreated group. The increase of regional water and sodium content in the MCA territory is less in the dexamethasone treated group, whereas the potassium changes in the ischemic tissue showed only small differences between the two groups. The potassium content of the non-ischemic tissue is slightly increased in the dexamethasone treated animals when comparing with the untreated group. RISA activity in the tissue is increased in the grey and the white matter of both groups. The less marked RISA-131 activity in the cortical grey matter of the treated animals indicates blood-brain barrier damage of a smaller degree due to dexamethasone. These findings indicate a beneficial effect of dexamethasone on local ischemic edema. Regarding our results and the pharmacokinetics of this steroid the dexamethasone loading of a patient has to be in the range of about 100 mg per day for the adult, and has to be started immediately after the onset of a stroke.

The effect of arterial hypertension of focal ischemic edema. An experimental study.

The middle cerebral artery (MCA) of cats was occluded permanently for 24h to study the influence of arterial hypertension during the early phase of focal ischemia upon the development of endema and changes of the blood-brain barrier (BBB). In normotensive animals MCA occlusion results in a hemispheric weight increase of about 8% and marked water and electrolyte alterations in both the grey and white matter of the MCA territory. The RISA space increases mainly in the grey matter. Hypertension aggravates these changes significantly, whereby water and electrolyte changes in the grey matter are predominantly concerned, while there is a preferential increase of the RISA space in the white matter. It is suggested that arterial hypertension aggravates the ischemic edema and enhances a vasogenic type of edema in the white matter.

Clearance of edema fluid into cerebrospinal fluid. A mechanism for resolution of vasogenic brain edema.

The authors present the results of an investigation studying the resolution of vasogenic brain edema using cold injury in cats. The appearance of RISA-I131 and sucrose-C14 lebeled edema fluid in the ventricular cerebrospinal fluid (CSF) was assessed by means of ventriculocisternal perfusion. The effect of low- or high-pressure perfusion on edema spread was determined by measuring the water, sodium, RISA-I131, and sucrose-C14 content of serial tissue blocks taken from the injured cortex through the white matter to the ventricular ependyma. The findings indicate that increasing the hydrostatic pressure gradient between edematous brain and CSF enhances the clearance of edema fluid into the ventricular CSF. This was conclusively demonstrated with low-pressure ventricular perfusion which markedly diminished the amount of edema close to the ventricles compared to the controls. The concentration of albumin, sodium, and potassium to the fluid removed from the tissue during low-pressure perfusion indicates that bulk flow was the primary method of edema movement through the extracellular space. With high-pressure perfusion the concentration profiles suggested alternative mechanisms of edema resolution, such as diffusion and reabsorption into capillaries.

Intracranial pressure and pressure volume relation in patients with subarachnoid haemorrhage (SAH).

The development of the intracranial pressure after a subarachnoid haemorrhage was evaluated in 21 patients. A statistically significant relation between the intracranial pressure and the neurological findings was found, whereas vasospasms did not influence the intracranial pressure. In patients in a clinically critical condition, rhythmic pressure waves of a frequency of 1/minute were repeatedly observed.