Absorption of a novel prodrug of L-dopa, L-3-(3-hydroxy-4-pivaloyloxyphenyl)alanine (NB-355). In vitro and in situ studies

Absorption mechanism and absorption site of a prodrug of L-DOPA, L-3-(3-hydroxy-4-pivaloyloxyphenyl)alanine (NB-355, 1) was investigated using rats. Prodrug 1 (0.5 mM) was taken up by intestinal tissue segments time-dependently in vitro at pH 6.0. However, the rate of uptake was less than that of L-dopa. Inhibitors of the amino acid active transport system (L-Phe, dinitrophenol, ouabain) had no effect on the uptake of prodrug 1. In the intestinal tissue segments, prodrug 1 was extensively hydrolyzed by diisopropylfluorophosphate-sensitive esterase(s). To characterize the absorption site, gastrointestinal tracts were ligated to make acute loops in situ and prodrug 1 or L-dopa was injected into the loops. L-dopa disappeared rapidly from the lumen of the jejunum. In contrast, prodrug 1 disappeared rapidly from the ileum rather than the duodenum or jejunum. From these results, it was suggested that prodrug 1 was slowly absorbed primarily from the lower small intestine.     

A novel method for culturing sweat gland epithelia: comparison of normal and cystic fibrosis tissues.

A new method is described to produce epithelial sheets by direct explantation of human sweat glands onto matrigel-coated millipore filters. The method is applicable to whole glands, separated coils or ducts and to normal and CF tissues. Electrogenic transport studies show that epithelia develop sodium transporting capability, even when explants are derived from secretory coils.     

Effects of hypothermia on testicular ischemia

The ischemic effects of prolonged testicular torsion have been well documented; however, prevention or arrest of the damaging effects of prolonged ischemia has been incompletely studied. Two groups of Sprague-Dawley rats were subjected to varying lengths of bilateral testicular ischemia. Group I underwent normothermic ischemia for two, four, and six hours. Likewise, Group II underwent similar time periods of ischemia, however, after thirty minutes of normothermic ischemia the scrotum of each animal was placed into an ice bath maintained at 4C. Two weeks postoperatively, bilateral orchiectomy was performed. Histology of the testes of the two groups was compared. Neither group revealed significant destruction of the germinal epithelium after two hours of ischemia. Group I revealed only 25% preservation of the germinal epithelium at four hours and only 8% preservation at six hours of ischemia. In contrast, Group II which received ice showed 90% preservation of germinal epithelium at four hours and 85% preservation at six hours of ischemia. We conclude that external ice application significantly preserves seminiferous tubules at four and six hours of ischemic injury in the rat testicle.     

Neurogenic stress ulceration caused by laparotomy under anesthesia plus restraint. The device of a new rat model

We report herein, a new method devised of producing neurogenic stress ulceration in rats. An experimental subarachnoid hemorrhage (SAH) was produced in rats by injecting 0.2 ml of arterial blood from other rats into the cisterna magna. Three days later, the rats were laparotomized for 1 hour under ether anesthesia, followed by restraint for 3 hours in wakefulness. The SAH rats were found to develop stress ulcers (UL-I) in the glandular stomach, which were significantly (p less than 0.001) more marked than those in non-SAH rats. Measurements were performed on gastric acid secretion, an important aggressive factor. It was found that the SAH rats undergoing the laparotomy-restraint stress showed a more marked increase in gastric acid secretion and a more marked reduction in MBF, than the non-SAH rats. The effects of bilateral vagotomy, upper abdominal sympathectomy and bilateral adrenalectomy were examined, and it was revealed that the SAH rats were under the condition of hyperreactivity both in the sympathetic and parasympathetic systems and, on this basis, the laparotomy-restraint stress caused the stress gastric ulceration. In this rat model, the laparotomy stress was applied under anesthesia and any exposure to low temperatures which may have interfered with blood circulation was avoided.     

Altered serum immunoglobulin response to model intestinal antigens during dietary exposure to vomitoxin (deoxynivalenol)

The effect of dietary vomitoxin on the serum IgA and IgG responses to two model intestinal antigens, casein and cholera toxin (CT), were assessed in 4 experimental groups: (1) mice fed casein-based diet, (2) mice fed casein-based diet containing 25 ppm vomitoxin, (3) mice fed casein-based diet and immunized with CT, and (4) mice fed casein-based diet containing 25 ppm vomitoxin and immunized with CT. Unimmunized and CT-immunized mice that were fed vomitoxin exhibited increased levels of total serum IgA relative to matched control animals fed the standard diet. Relative concentrations of casein-specific IgA were greater in both unimmunized mice and CT-immunized mice fed standard diet with vomitoxin than in matched controls fed standard diet only. CT-specific serum IgA in CT-immunized mice was not affected by vomitoxin feeding, but relative levels of CT-specific IgA were higher in unimmunized mice fed vomitoxin than in unimmunized mice fed standard diet. Both casein- and CT-specific serum IgG were depressed in mice fed vomitoxin. Significant differences in total, casein-specific and CT-specific IgA within the intestinal contents were not observed between CT-immunized mice fed vomitoxin and those fed the control diet. The results suggest that vomitoxin altered regulation of the normal immunoglobulin response to intestinal antigens and that this was manifested in the systemic compartment.     

The effect of metronidazole on TPN-associated liver dysfunction in neonates

The effect of metronidazole (MNZ) on hepatic dysfunction associated with total parenteral nutrition (TPN) in neonates was investigated. Neonates receiving TPN for more than 2 weeks were divided into three groups. In group 1, TPN was given alone, in group 2, 25 mg/kg/d of MNZ was administered intravenously for the first 2 weeks of TPN, and in group 3, 50 mg/kg/d of MNZ was given for the first 3 weeks of TPN. Several parameters of liver function tests (LFTs) during the first 4 weeks of TPN were compared among these three groups. There was no significant difference of these parameters between group 1 and group 2. Although there was no significant difference of alkaline phosphatase, gamma-glutamyl transpeptidase, direct bilirubin, and total bile acid between groups 1 and 3, transaminase (glutamic oxaloacetic, glutamic pyruvic) of group 3 remained significantly lower than those of group 1. In conclusion, the administration of MNZ 50 mg/kg/d for 3 weeks, at least, prevented the elevation of transaminase during TPN in neonates, suggesting the possible involvement of intestinal anaerobic flora in the pathogenesis of TPN-associated liver dysfunction.     

Uptake of Adriamycin in tumour and surrounding brain tissue in patients with malignant gliomas

Summary Eight patients with malignant gliomas verified on CT scan, received an intravenous injection of 50 mg of Adriamycin R, 24 hours prior to surgical removal of the tumour. Peroperatively, both tumour and surrounding tissue specimens were obtained for determination of the tissue concentrations of Adriamycin and its reduced metabolite Adriamycinol. It was found that Adriamycin could be detected in tumour tissue from all patients. The concentration varied between 0,9 and 4,6 nmol/g tissue. In contrast, Adriamycin could only be detected in surrounding brain tissue from one patient.In anin vitro study a human malignant glioma cell line (U-251 MG) was exposed to various concentrations of Adriamycin for 24 hours. It was found that an intracellular drug concentration above 30 nmol/g cells caused a concentration dependent inhibition of cell growth. Thus, it is likely that the poor effect of Adriamycin on patients with malignant gliomas is due to an ineffective drug accumulation in the tumour tissue.     

Effect of venom from Cerastes cerastes (Egyptian sand viper) on luminol-dependent chemiluminescence of human blood phagocyte cells

Cerastes cerastes venom added in vitro to human whole blood caused a marked inhibitory effect on the luminol-dependent chemiluminescence induced by phorbol myristate acetate (PMA) or opsonized zymosan on phagocyte cells. The inhibitory effect produced by the venom was both dose- and time-dependent when PMA was used as the stimulant of the oxidative burst. Similarly, the venom produced a significant inhibitory effect when added to isolated polymorphonuclear leukocytes (PMNs). Incubation of the isolated PMNs with the highest concentration of the venom used (1000 micrograms/ml), however, did not result in any significant disruption of the membranes of these cells. The effect of the venom on the isolated PMNs was also reversible following washing of the venom-treated cells with phosphate-buffered saline. The scavenger of reactive oxygen species such as superoxide dismutase, catalase and dimethyl sulphoxide potentiated the effect of the venom on the luminol-dependent chemiluminescence of human phagocyte cells. Sodium azide, the myeloperoxidase inhibitor, and sodium benzoate produced a similar potentiating effect. The results suggest that some of the toxicity of the venom may be mediated by an action on the phagocytic immune system.