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Biomedical subjects

R Frick

Publications and source records attributed to R Frick.

At least 19 recordsLinked to original sources
PubMed2000

Treatment with nimodipine or mannitol reduces programmed cell death and infarct size following focal cerebral ischemia.

The present study was conducted to evaluate the effects of nimodipine and mannitol on infarct size and on the amount of apoptosis after transient focal cerebral ischemia. Focal cerebral ischemia was induced in male Sprague-Dawley rats (weight 300-380 g) by transient occlusion of the right middle cerebral artery (MCAO) using an intraluminal thread model. All animals underwent ischemia for 2 h, followed by 24 h of reperfusion. Group I (n=16) was untreated. Group II (n=16) received 15% mannitol (1 g/kg as bolus) and group III (n=9) received 15 microg/kg/h nimodipine intravenously beginning 15 min prior to MCAO. Twenty-four hours after reperfusion, the brain was taken and sectioned in coronal slices. The slices were stained with H&E and with the transferase dUTP nick-end labeling (TUNEL) technique. Histopathological analysis revealed a significant (P<0.05) decrease in infarct size in the striatum with both drugs: mannitol (group II) 25.4+/-5.9% and nimodipine (group III) 21.5+/-11.0% versus control (group I) 34.9+/-7.0% and in the cortex 2.7+/-2.0% (group II) and 6.3+/-2.4% (group III) versus control 14.4+/-9.0% (group I). The number of apoptotic cells was statistically lower in the therapy groups (group III 9.6, group II 25.8) versus control (group I 57.9) (Mann-Whitney-Wilcoxon U-test Z>1.96, P<0.05). This study indicates that mannitol and nimodipine provide neuroprotection by preventing both the necrotic and apoptotic components of cell death after transient focal cerebral ischemia and may be effective as neuroprotective drugs for cerebrovascular surgery.

Animals↗
PubMed1999

Indirect methods for characterization of carbon dioxide levels in fermentation broth.

Various factors which influence dissolved carbon dioxide levels were indirectly evaluated in pilot scale and laboratory studies. For pilot scale studies, off-gas carbon dioxide (percentage in exit air) was measured using a mass spectrometer and then its potential impact on dissolved carbon dioxide concentrations qualitatively examined. Greater volumetric air flowrates reduced off-gas carbon dioxide levels more effectively at lower airflow ranges and thus lowered expected dissolved carbon dioxide levels through gas stripping. Lower broth pH values decreased off-gas carbon dioxide levels but increased expected dissolved carbon dioxide levels due to the pH-dependence of the gas/liquid carbon dioxide equilibrium. While back-pressure increases had an insignificant effect on off-gas carbon dioxide levels, they directly affected expected dissolved carbon dioxide levels according to Henry's law. Laboratory studies, conducted using both uninoculated and inoculated fermentation media, quantified the response of the media to pH changes with bicarbonate addition, specifically its buffering capacity. This effect then was related qualitatively to expected dissolved carbon dioxide levels. Higher dissolved carbon dioxide levels, as demonstrated by reduced pH changes with bicarbonate addition, thus would be expected for salt solutions of increased ionic strength and higher protein content media. In addition, pH changes with greater bicarbonate additions declined for fermentation samples taken over the course of a one week cultivation, most likely due to the higher protein content associated with biomass growth. The presence of weak acids/bases initially in the media or formed as metabolic by products, as well as the concentration of buffering ions such as phosphate, also were believed to be important contributing elements to the buffering capacity of the solution.

Journal Article↗
PubMed1995

Early suppression of viremia by ZDV does not alter the spread of feline immunodeficiency virus infection in cats.

Prophylactic zidovudine (ZDV) therapy in feline immunodeficiency virus (FIV) inoculated cats was evaluated for 12 months postinfection (pi) and 11 months post drug treatment. Plasma FIV antigenemia was prevented in six of six ZDV-treated and none of six untreated cats during the initial phase of infection. The present study is a continuation of that earlier work. CD4 lymphocyte numbers from ZDV-treated cats were higher than in the untreated cats. CD8 lymphocytes numbers were maintained within control limits in the ZDV-treated cats, while they declined in the untreated cats. Anti-FIV antibody titers were comparable between the ZDV-treated and the untreated cats. Histologically, lymphoid tissues for the untreated and ZDV-treated cats were unremarkable and similar to those of the uninfected control cats. Low-level FIV antigen was detected by enzyme-linked immunosorbent assay in thymus or lymph node homogenates from 3 of 11 cats tested. Polymerase chain reaction analysis showed FIV DNA in blood, lymph node, bone marrow, spleen, thymus, and brain from FIV-inoculated cats irrespective of ZDV treatment. Therefore, while prophylactic ZDV treatment prevented detectable plasma antigenemia and FIV-induced CD8 lymphocyte decline, it did not slow infection of tissues and blood cells of FIV-inoculated cats.

Animals↗
PubMed1991

Intracranial venous hypertension and the effects of venous outflow obstruction in a rat model of arteriovenous fistula.

A model of rat arteriovenous fistula (AVF) was created using a proximal common carotid artery to distal external jugular vein anastomosis. Anatomical dissections revealed that the external jugular vein is the primary vessel draining intracranial venous blood. Physiological measurements were made with the AVF open and closed, and during venous outflow occlusion of the contralateral external jugular vein. Opening the AVF increased torcular pressure from 6.5 +/- 0.6 to 13.5 +/- 1.1 mm Hg and decreased mean arterial pressure from 82.7 +/- 1.8 to 62.8 +/- 1.8 mm Hg (both P less than .05), decreasing cerebral perfusion pressure from 76.2 +/- 1.7 to 49.3 +/- 2.2 mm Hg (P less than .05). Middle cerebral artery blood flow velocity (MCA BFV) decreased from 6.8 +/- 1.1 to 4.2 +/- 0.7 cm/s (P less than 0.05). In rats with an AVF, occlusion of venous outflow increased torcular pressure to 34.8 +/- 3.1 mm Hg (P less than 0.05), MCA BFV decreased to 1.8 +/- 0.5 cm/s (P less than 0.05), and severe ischemic changes were seen on the electroencephalogram. Under this condition, torcular pressure and systemic arterial pressure had a positive linear relationship (P less than 0.05), whereas in control rats torcular pressure and arterial pressure had no relationship. Restoration of cerebral perfusion pressure by release of venous outflow occlusion and AVF closure transiently increased MCA BFV to 69% above baseline (P less than 0.05). Histological examination 1 week after permanent venous outflow occlusion revealed venous infarction, subarachnoid hemorrhage, and severe brain edema in rats with an AVF but not in control rats without an AVF. This model of cerebrovascular steal with venous hypertension reproduces both hemodynamic and hemorrhagic complications of human AVF and emphasizes the importance of venous outflow obstruction and venous hypertension in the pathophysiology of these lesions.

Animals↗
PubMed1977

[Placental metastases from a maternal angioblastic sarcoma of the vagina (author's transl)].

Metastasizing maternal tumors during pregnancy with spread to the placenta are spontaneous attempts of malignant tumor transplantation to the Fetus. Because of the resistance of the Syncytiotrophoblast to metastases, carcinomas do not appear to transgress the placental barrier wheras malignant melanomas and sarcomas may do so in some cases. In the described case of maternal angioblastic sarcoma the lack of resistance to tumor spread of the epithelial trophoblast was compensated by resistance of the fetal stroma of the chorionic villi against invasive spread of the tumor. The infant was delivered by Caesarean Section and showed no evidence of a malignant tumor acquired by transplacental spread at the age of 2 1/2 months.

Adult↗
PubMed1976

[Silicone embolism, fat embolism, and fibrin thrombosis in dogs after extracorporeal circulation using a bubble-oxygenator (author's transl)].

Following extracorporeal circulation with a bubble oxygenator (Rygg-Kyvsgaard) silicone emboli were found in the brain-and-kidney-capillaries of all dogs evaluated. There was no obvious correlation between intensity of silicone embolism and pump time. No cellular reaction was seen around the anti-foam agent. Occasionally single small areas of embolic brain damage were found. During extracorporeal circulation and within a recovery period up to one hour no silicone excretion through the kidneys could be demonstrated. Systemic fat embolism occurred less frequent than previously reported. Use of a filter in the cardiotomy suction line reduced its intensity further. In neither of the various organs examined, disseminated intravascular thrombosis could be found.

Animals↗
PubMed1976

[Primary combined chemotherapy following removal of an endodermal sinus tumor or yolk-sac tumor of the ovary (author's transl)].

The yolk-sac tumor or endodermal sinus tumor is a rare but highly malignant ovarian teratoma with its highest incidence in young women. The tumor is relatively resistant to radiotherapy but sensitive to combined chemotherapy and should therefore be differentiated in the diagnosis from embryonal carcinoma and radio-sensitive dysgerminomas of the ovary. It is possible that the determination of alpha-fetoprotein is of differential diagnostic value. Two patients are alive and well 8 months and 2 1/2 years following removal of a yolk-sac tumor and primary chemotherapy. One patient received chemotherapy for peritoneal recurrence after removal of the tumor and radiotherapy. She died 1 1/2 years following the primary operation. Long term chemotherapy of the yolk-sac tumor is indicated following operation, irrespective of the stage of the tumor.

Adult↗
PubMed1976

[Adequate treatment of micro-invasive carcinoma of the uterine cervix (author's transl)].

At the University Department in Heidelberg 58 micro-invasive carcinomas of the uterine cervix were found between 1965 and 1974. 8 cases were diagnosed in other institutions by directed biopsies. Three cases were detected during the microscopic examination of uteri removed for emergency indications and three cases were detected after hysterectomy for cytological findings indicative of carcinoma in situ of the uterine cervix. In 44 cases an optimal conization of the cervix was carried out. Microscopic examination of these cases showed early stromal invasion in 33 cases. In 6 cases a newtork infiltration was found und in 5 cases a plump infiltration was found. The incidence of radical Wertheim operations of 21 in this group is explained by cases in this group who had inadequate diagnosis prior to admission. In 8 cases the indication for the Wertheim radical hysterectomy was a carcinomatous lymphangiosis in the conization specimen. In none of these cases metastatic tumor was found in the lymph nodes although 13 to 44 lymph nodes were examined per case. In accordance with the newer literature it is recommended to limit treatment of micro-invasive changes of the uterine cervix to routine hysterectomy or to optimal conization of the cervix if certain prerequisites are met. The results of the follow-up examinations of the reported cases appear to justify this recommendation.

Adult↗
PubMed1976

[Morphological investigation of the neonatal lung with respiratory distress syndrome which was maximally distended with Somentor 33 and formalin (author's transl)].

The importance of morphological immaturity of the lung in the development of the respiratory distress syndrome was investigated. Atelectatic lungs of newborns were maximally expanded with a mineral oil of low kinematic viscosity (Somentor 33) or 10% Formalin. With this method, surface active forces of peripheral air spaces should not impede expansion of the lungs. 27 lungs of neonates who died of respiratory distress syndrome and 10 lungs of neonates without primary respiratory problems were examined. Following maximal expansion of the lungs with the respiratory distress syndrome show a hypercellular densely cellular tissue of the pulmonary segments, much like glanduloid hyperplasia with small peripheral air spaces and long distances for diffusion of the respiratory gases. The lungs of newborns without respiratory distress syndromes are well alveolar following expansion and show an optimal morphology for gas diffusion. A lack of a surfactant should have significant consequences in small air spaces.

Formaldehyde↗