[Clinical studies on cefoxitin in the prevention of postoperative infections and the treatment of postoperative pulmonary and urinary tract infections]

This clinical trial was designed to evaluate the efficacy, safety and patient tolerance of cefoxitin (CFS) in 46 patients who were admitted to the hospitals from June 1983 to April 1984. The daily doses of CFX for 34 patients (ages ranged from 6 to 75 years old) were 2 to 8 g to prevent the infections and for 12 patients (ages ranged from 55 to 81 years old) were 2 to 6 g to treat the infections by intravenous drip infusion 1 or 3 times a day in divided doses. The following results were obtained. All of 34 patients with intracranial operation who received CFX for prevention of postoperative infections showed good results. Of 12 patients with postoperative pneumonia, infections of urinary tract and late meningitis, 11 patients showed good results. One patient was discontinued on the 3 days because of the drug eruption which improved 3 days after. The side effect was noted in only 1 patient. This was eruption which improved 3 days after the stop of the administration. The influences to the laboratory data due to CFX were not recognized. The results of this study demonstrated that CFX was an excellent drug for the prevention and treatment of the postoperative infections in the neurosurgical field because of high efficacy rate and safety.

Plasma GH responses to GHRH and insulin-induced hypoglycemia in man

Changes in plasma GH levels in response to an intravenous bolus injection of 200 micrograms GHRH-44 or 0.1 U/kg body weight regular insulin were examined in normal men who were pre-treated with 200 micrograms GHRH-44 or 0.1 U/kg body weight regular insulin 120 min in advance. The prior bolus injection of GHRH-44 inhibited the plasma GH response to the subsequent administration of GHRH-44 whereas the plasma GH response to the subsequent injection of insulin was not influenced by the prior administration of GHRH-44. The prior administration of insulin attenuated the plasma GH response to the subsequently given GHRH-44. These results suggest that desensitization of GHRH receptors in somatotrophs and/or somatostatin hypersecretion induced by increase in plasma GH levels following the prior GHRH-44 administration may be involved in the mechanism by which the prior GHRH-44 administration or insulin-induced hypoglycemia suppressed plasma GH responses to the following GHRH-44 administration. Sudden suppression of somatostatin secretion, which causes rebound of GH secretion, may occur in insulin-induced hypoglycemia.

Defective endocytosis of low-density lipoprotein in monensin-resistant mutants of the mouse Balb/3T3 cell line

Two monensin-resistant clones show similar low-density lipoprotein binding activity but less internalization or degradation of low-density lipoprotein than the parental Balb/3T3 or other resistant clone. Sterol synthesis from radioactive acetate in the resistant mutant, MO-5, is inhibited by more than 70% of control in the presence of tenfold higher amounts of low-density lipoprotein than the dose that inhibits the parental Balb/3T3 to similar level. 3-Hydroxy-3-methylglutaryl coenzyme A reductase activity of Balb/3T3 and MO-5 is inhibited by 48% and 27% of control, respectively, in the presence of 10 micrograms/ml of low-density lipoprotein. Colloidal silica gradient centrifugation shows that transport of low-density lipoprotein from the surface membrane to the lysosome is much slower in MO-5 cells than in Balb/3T3 cells. Down regulation of low-density lipoprotein receptors on the cell surface in Balb/3T3 is observed by exposing the cells to 5-15 micrograms/ml low-density lipoprotein, whereas only slight if any down regulation is observed when MO-5 cells are treated with low-density lipoprotein. The altered endocytosis of low-density lipoprotein behaves as a dominant trait in hybrids of MO-5 and THO2-2, a derivative of Balb/3T3 resistant to both ouabain and 6-thioguanine.

The effect of glucose on growth hormone (GH)-releasing hormone-mediated GH secretion in man

The effect of glucose on GH-releasing hormone (GHRH)-mediated GH secretion was examined in six normal young men. In two paired experiments, the six men drank a 75-g glucose solution or an equal volume of water 30 min before receiving, iv, 100 micrograms of the 44-amino acid form of human pancreatic GHRH (hGHRH-44). One week later, the same men underwent an identical experimental protocol in a cross-over trial. Basal plasma GH concentrations before hGHRH-44 administration were not statistically different in the two experiments [glucose experiment, 2.1 +/- 0.1 (+/- SE) ng/ml; water experiment, 2.6 +/- 0.6 ng/ml]. The mean peak plasma GH level occurred 30 min after hGHRH-44 administration in both experiments. However, the mean GH response was significantly diminished when the men received glucose (8.12 +/- 1.12 ng/ml) compared to that when they received only water (23.70 +/- 8.46 ng/ml; P less than 0.01). Thus, hyperglycemia may exert an inhibitory effect on the plasma GH response to hGHRH-44.

The effect of free fatty acids on growth hormone (GH)-releasing hormone-mediated GH secretion in man

The effect of FFA on GH-releasing hormone (GHRH)-mediated secretion of GH was examined in six normal young men. Three of the men were infused with 250 ml of a lipid-heparin solution at 1.67 ml/min for 150 min, and the other three were given an equivalent volume of saline in the same manner. Thirty minutes after the start of infusion, 100 micrograms GHRH (the 44-amino acid form) were injected iv, and plasma GH and FFA were measured. One week later, the same men participated in an identical experiment, but the ones who had received lipid-heparin previously were given saline and vice versa. In both experiments, plasma FFA increased to 2.25 +/- 0.16 meq/liter (mean +/- SEM) 60 min after the start of lipid-heparin infusion, whereas FFA levels did not change significantly in the saline-treated group. Mean plasma GH levels reached peak concentrations in both groups 30 min after GHRH treatment. However, the peak GH response when lipid-heparin was given was significantly diminished (8.4 +/- 1.7 ng/ml), compared with the peak response when saline was given (28.9 +/- 7.1 ng/ml). These data suggest that plasma FFA elevations induced by lipid-heparin infusion inhibit GH secretion induced by GHRH.

Enhancement of N-bis(2-hydroxypropyl)nitrosamine-initiated lung tumor development in rats by bleomycin and N-methyl-N-nitrosourethane

Potential modification of N-bis(2-hydroxypropyl)nitrosamine (DHPN)-induced lung carcinogenesis by bleomycin and N-methyl-N-nitrosourethane (MNUT) was investigated in male F344 rats. Rats were given 0.2% DHPN for 1 week followed by a weekly i.p. injection of either bleomycin at 2.0 mg/kg body wt or of MNUT at a dose of 1.0 mg/kg body wt for 35 weeks. Animals given DHPN followed by solvent administration alone, either saline or 0.02% ethanol and animals given bleomycin or MNUT without DHPN pretreatment were served as controls. Bleomycin treatment increased the incidence of cancer, whereas hyperplasia, adenoma and cancer of the lung were all significantly elevated after MNUT administration. MNUT alone induced low incidences of lung tumors. Bleomycin also increased the incidence of papillary or nodular hyperplasia of the urinary bladder while it inhibited the development of thyroid tumors. MNUT, however, did not affect tumor development in other organs.

DNA cloning of Plasmodium falciparum circumsporozoite gene: amino acid sequence of repetitive epitope

A clone of complementary DNA encoding the circumsporozoite (CS) protein of the human malaria parasite Plasmodium falciparum has been isolated by screening an Escherichia coli complementary DNA library with a monoclonal antibody to the CS protein. The DNA sequence of the complementary DNA insert encodes a four-amino acid sequence: proline-asparagine-alanine-asparagine, tandemly repeated 23 times. The CS beta-lactamase fusion protein specifically binds monoclonal antibodies to the CS protein and inhibits the binding of these antibodies to native Plasmodium falciparum CS protein. These findings provide a basis for the development of a vaccine against Plasmodium falciparum malaria.

In vitro study on contribution of oxidative metabolism of isolated rabbit heart mitochondria to myocardial reperfusion injury

The present study was performed to clarify oxygen-induced damage following myocardial reperfusion, using three mitochondrial preparations from isolated rabbit hearts (nonischemic hearts and those subjected to 40 and 90 minutes of normothermic global ischemia). The viability of mitochondria was evaluated by adenosine triphosphate generation. The extent of mitochondrial injury produced by reactive oxygen metabolism was assessed by the intensity of hydroxyl radical signal detected with electron spin resonance spectroscopy and the reduction of coenzyme Q10 level. The greatest oxygen-induced injury was observed in 40-minute ischemic mitochondria exposed to pure oxygen. The use of superoxide dismutase and catalase satisfactorily prevented the oxygen-induced injury. Moreover, the net adenosine triphosphate generation of the 40-minute ischemic mitochondria was comparable to that of the nonischemic mitochondria without the enzymes. These results suggest that reperfusion of the ischemic myocardium with viable mitochondria is deleterious, because mitochondria are susceptible to injury resulting from oxidative metabolism, and that the use of superoxide dismutase, together with catalase, is beneficial for the restoration of cardiac function after ischemia.

Distribution of growth hormone-releasing hormone-like immunoreactivity in human tissue extracts

A specific RIA for human pancreatic tumor GH-releasing hormone [hpGRH(1-44)NH2] was developed using an antiserum which recognizes the region (Met27-Leu44)NH2 of hpGRH(1-44)NH2. This RIA was used to measure GH-releasing hormone-like immunoreactivity (GRH-LI) in various human tissue extracts. The highest concentration of GRH-LI was detected in extract of pituitary stalk with moderate amounts found in hypothalamus and optic chiasm but none in the cerebrum, cerebellum, medulla oblongata, spinal cord, and anterior pituitary. In peripheral organs appreciable quantities of GRH-LI were found in the pancreas, whereas extracts of thyroid, lung, stomach, duodenum, ileum, colon, adrenal, and kidney contained very low concentrations of GRH-LI. No GRH-LI was detected in liver and spleen extracts. Gel permeation chromatographic analysis of the tissue extract from the hypothalamus revealed only one peak which eluted at the same position as that of 125I-hpGRH(1-44)NH2. Similar analysis of an extract from the optic chiasm showed one peak at the same position as that of 125I-hpGRH(1-44)NH2 and another peak which eluted after hpGRH(1-44)NH2. In contrast, an extract from the pancreas contained only one peak which eluted before 125I-hpGRH(1-44)NH2, indicating a possible precursor form of hpGRH(1-44)NH2. Limited trypsin digestion of the GRH-LI material from the pancreas, followed by gel permeation chromatographic analysis, yielded a major peak eluting at the same position as that of 125I-hpGRH(1-44)NH2. These results suggest that the GRH-LI detected in the hypothalamus most likely corresponds to hpGRH(1-44)NH2 in structure and that the GRH biosynthesized in the hypothalamus is transported to the stalk median eminence and stored there for release into the portal vessels.

Chinese hamster cell mutants with defective endocytosis of low-density lipoprotein contain altered fatty acid composition in the membrane

Chinese hamster V79 cell mutants resistant to compactin (ML236B), a specific inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A reductase, are defective in endocytosis of low-density lipoprotein (1). Two resistant clones, MF-2 and MF-3, differ in lipid composition from the parental V79 strain. In both the total cells and membrane fraction, the ratio of palmitoleic acid (16:1)/palmitic acid (16:0) is 0.4-0.5 in MF-2 and 1.7-1.8 in MF-3 while that in V79 is 0.2-0.3. By contrast, a hybrid clone between V79 and MF-3 shows a ratio of palmitoleic acid to palmitic acid very similar to that of V79. The synthesis of palmitoleic acid from acetate in the resistant clone is higher than in V79.

[Three surgically treated cases of spontaneous rupture of the esophagus with reference to a new surgical approach--eversion stripping and esophagogastrostomy through the posterior mediastinum]

Three surgical cases of spontaneous rupture of the esophagus were reported. Case 1 was a 56-year-old man who was admitted 3 days after the onset was treated with open drainage. He had no complications whatsoever 8 years after the treatment. In case 2 (a 55-year-old man), eversion stripping of the esophagus and gastrostomy were performed 2 months after diagnosis, but esophageal reconstruction was not successful. He died of acute congestive heart failure 5 years after surgery. The Third case was a 60-year-old women whose rupture was confirmed 11 days after the onset. Cervical esophagostomy, gastrostomy and jejunostomy were performed 16 days after the rupture. Thereafter, esophageal eversion stripping and esophagogastrostomy through the posterior mediastinum were successfully carried out 2 months after the first surgery. She had no postoperative complications. Eversion stripping of the esophagus with esophagogastrostomy through the posterior mediastinum is an effective and safe method for some advanced cases of spontaneous esophageal rupture. We have not found any reports of surgical cases with spontaneous esophageal rupture treated by this approach in the literature.

Effects of butylated hydroxyanisole, butylated hydroxytoluene, and NaCl on gastric carcinogenesis initiated with N-methyl-N'-nitro-N-nitrosoguanidine in F344 rats

Promoting activities of butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), and NaCl and of combinations of these antioxidants with NaCl on gastric carcinogenesis initiated by N-methyl-N'-nitro-N-nitrosoguanidine [(MNNG) (CAS: 70-25-7; 1-methyl-3-nitro-1-nitrosoguanidine] were investigated in male inbred F344 rats. Animals, 6-week old, were given an intragastric administration of MNNG at 150 mg/kg body weight by gastric tube and 1 week later were placed on a diet containing BHA (0.5%), BHT (1.0%), NaCl (5.0%), BHA (0.5%) plus NaCl (5%), or BHT (1.0%) plus NaCl (5.0%) for 51 weeks. Control rats received no further treatment after MNNG administration. A single intragastric application of MNNG to rats induced multiple epithelial tumors of the forestomach and a few epithelial tumors of the glandular stomach after 52 weeks. Squamous cell carcinomas of the forestomach were seen in 2 of 18 effective rats (11.1%) in the control groups, and the incidences in the groups receiving the subsequent treatment were 45.0% with BHA, 15.8% with BHT, 30% with NaCl, 70% with BHA plus NaCl, and 52.9% with BHT plus NaCl. Differences in the incidences of squamous cell carcinoma between the controls and groups given BHA, BHA plus NaCl, and BHT plus NaCl were statistically significant. NaCl given alone after MNNG administration also significantly increased the incidence of papillomas in the forestomach. Incidences of glandular stomach tumors, adenomas and carcinomas were not affected by any of the subsequent treatments. No tumors of the stomach developed in the groups given BHA, BHT, and NaCl without MNNG pretreatment. Thus the present experiment revealed that BHA and NaCl but not BHT exert promoting activity on MNNG-induced forestomach carcinogenesis in rats and that, when BHA and BHT were given with NaCl, promotion was more marked, suggesting a synergistic effect on tumor promotion.

Phenylthiourea enhances Cu cytotoxicity in cell cultures: its mode of action

PTU markedly enhanced the cytotoxic effects of CuCl2 on chick embryonic PECs cultured in vitro. We investigated this newly discovered effect of PTU and its analogues in relation to the toxic effects of Cu ion. Most PECs maintained in medium containing 0.5 mM PTU were lysed within 4 h by the addition of 0.1 mM CuCl2, which addition killed no PECs in the absence of PTU. The effect of PTU was not specific to PECs. All the cell lines tested, KB, N-18, N-115 and B-16, reacted against exogenous Cu in the presence of PTU as did the PECs. Analogues of PTU had effects on PECs similar to those on PTU in the presence of Cu ion. ANTU had a greater effect than PTU. MTU and TU had less effect than PTU. PTU did not affect the cytolysis induced by the addition of the divalent cations Mn, Co and Zn. About 6-fold the 64Cu-uptake by PECs was scored in the presence of PTU. The relation between this cytotoxic-enhancing effect and other biological activities of PTU are discussed.

Beating activity of heterokaryons between myocardial and non-myocardial cells in culture

Cultured mouse myocardial cells grown as monolayers fused upon treatment with HVJ (Sendai virus). The myocardial cells also fused with quail myocardial cells, neuroblastoma cells and non-excitable cells, such as KB cells. The beating activity of these heterokaryons was studied in the present work. Heterokaryons composed of myocardial cells from different species maintained spontaneous beating activity for 2 days or more. Those of one myocardial and one neuroblastoma cell maintained the activity for 22-26 h, while those of one myocardial and one non-excitable cell, such as KB cell, lost the activity within 2-4 h after addition of HVJ. Heterokaryons that had stopped spontaneous beating did not contract on application of electrical-field stimulation. The ration of non-myocardial cells in the heterokaryons increased in inverse proportion to the decrease in beating activity of the heterokaryons. Study of the rapid disappearance of beating activity in heterokaryons composed of one myocardial and one KB cell showed that both excitability of the cell membrane and myofibril organization were rapidly lost.

Insulin-induced formation of ruffling membranes of KB cells and its correlation with enhancement of amino acid transport

Insulin induced the formation of ruffling membranes in cultured KB cells (a cell strain derived from human epidermoid carcinoma) within 1-2 min after its addition. The ruffled regions were stained strongly with antibody to actin but not that to tubulin. Pretreatment of KB cells with agents disrupting microfilaments (cytochalasins), but not with those disrupting microtubules (colcemid, nocodazole, and colchicine) completely inhibited the formation of ruffling membranes. Pretreatment of KB cells with dibutyryl cyclic AMP, but not with dibutyryl cyclic GMP, also inhibited the formation of ruffling membranes. Addition of insulin enhanced Na+-dependent uptake of a system A amino acid (alpha-amino isobutyric acid; AIB) by the cells within 5 min after the addition, and decreased the cyclic AMP content of the cells. Treatments that inhibited insulin-induced formation of ruffling membranes of KB cells also inhibited insulin-induced enhancement of their AIB uptake. From these observations, the mechanism of insulin-induced formation of ruffling membranes and its close correlation with AIB transport are discussed.

Promotion of 2-(ethylnitrosamino)ethanol-induced renal carcinogenesis in rats by nephrotoxic compounds: positive responses with folic acid, basic lead acetate, and N-(3,5-dichlorophenyl)succinimide but not with 2,3-dibromo-1-propanol phosphate

The promoting effects of nephrotoxic chemicals, folic acid (FA), N-(3,5-dichlorophenyl)succinimide (NDPS), 2,3-dibromo-1-propanol phosphate (Tris-BP), and basic lead acetate (LAB), on 2-(ethylnitrosamino)ethanol (EHEN)-induced renal carcinogenesis were examined in F344 rats. The rats were treated with 0.1% EHEN in their drinking water for 1 week and then given one of the nephrotoxic chemicals for 35 weeks. FA was injected sc once a week at a dose of 300 mg/kg for the first 8 weeks and thereafter at 100 mg/kg. NDPS, Tris-BP, and LAB were mixed in the diet at concentrations of 0.5, 0.01, and 0.1%, respectively. At week 3 the right kidney was removed to enhance renal neoplasia. Renal cell tumor incidence was significantly increased by both FA and LAB and was slightly increased by NDPS, whereas Tris-BP had no effect. The data show that FA, LAB, and NDPS are promoters of EHEN-induced renal carcinogenesis.

Cytological characteristics of cultured epithelial cells from thymomas in BUF/Mna rats

Epithelial cells (ECs) from spontaneously developed thymomas in BUF/Mna rats were cultured, characterized and compared with ECs from normal thymuses. The ECs from thymomas had many more keratin filaments and PAS-positive vesicles in the cytoplasm than ECs from normal thymuses. The size and shape of ECs and their nuclei were heterogeneous and about 20% of ECs from thymomas had more than one nucleus. However, the growth rates and saturation densities of ECs from thymomas in monolayer culture were not markedly different from those of normal thymuses. The ECs from thymomas cultured in soft agar did not form any colonies. The distribution of the numbers of chromosomes found in ECs from thymomas was slightly broader than that in normal ECs, but no specific abnormalities nor marker chromosomes were noted. These findings indicate that ECs from thymomas are abnormal, but suggest that they are not malignant in nature.

Plasma growth hormone response to growth hormone-releasing factor in acromegalic patients

Synthetic growth hormone-releasing factor (hpGRF-44) (100 micrograms) was administered intravenously to ten acromegalic patients. The time when the peak of plasma GH occurred as well as the magnitude of the response were highly variable among these ten patients. From the GH response patterns the ten acromegalic patients were tentatively classified into three groups: (1) those highly GRF-dependent whose GH level increased to four times basal, (2) those moderately GRF-dependent whose GH level rose to less than two times basal and (3) those GRF-resistant whose GH level did not change. These data suggest that there may be differences in the GRF-receptor system in pituitary adenomas causing acromegaly.

Age-related changes in plasma growth hormone response to growth hormone-releasing factor in man

The response of plasma growth hormone to synthetic growth hormone-releasing factor (hpGRF-44) administered intravenously was examined in normal men of various ages ranging from 20 to 75 years. Most of the subjects who were over forty years old had either no or much lower response of plasma growth hormone to hpGRF-44. In contrast plasma growth hormone increased markedly after hpGRF-44 injection in all men in their twenties and thirties. The mean peak level of plasma GH following hpGRF-44 administration was 29.6 +/- 20.4 (SD) ng/ml in men in their twenties, 30.2 +/- 26.5 ng/ml in their thirties, 9.7 +/- 5.2 ng/ml in their forties, 10.9 +/- 5.4 ng/ml in their fifties, 8.4 +/- 4.8 ng/ml in their sixties and 8.1 +/- 7.5 ng/ml in their seventies. These results suggest that somatotroph cells become less sensitive to growth hormone-releasing factor with aging.

Increased surface binding sites of insulin in ML236B (compactin)-resistant mutants of Chinese hamster cell line

Mutants resistant to ML236B (compactin) were isolated from the Chinese hamster lung V79 cell line (1). Three ML236B-resistant mutants, MF-1, MF-2 and MF-3, were enhanced in insulin-specific binding activity about 2 to 3 times over the parental V79 cell lines. Compared to V79, endocytosis of insulin was also increased 2 to 3-fold in ML236B-resistant mutants than V79. Scatchard analysis showed that 5,000 insulin binding sites per cell in V79 and 16,000 in a NL236B-resistant clone, MF-2. Insulin receptors in mutant and parental strains are down-regulated to a similar extent in the parental V79 treated with an excess insulin. This is the first somatic cell mutant with increased surface binding sites for insulin.

Secondary mutation resistant to 7-ketocholesterol rescues a sterol metabolic defect in amphotericin B-resistant Chinese hamster cell line

Amphotericin B-resistant mutants isolated from Chinese hamster V79 cells (1) are defective in cholesterol synthesis and more sensitive to an oxygenated sterol analog, 7-ketocholesterol, than their parental cell line. We isolated 7-ketocholesterol-resistant mutants from an amphotericin B-resistant mutant, AMBR-1. The 7-ketocholesterol-resistant mutants had regained increased level of free cholesterol, and they showed somewhat similar dose-response curves to amphotericin B as that of V79. Sterol synthesis from acetate, but not from mevalonate, in 7-ketocholesterol-resistant clones was threefold higher than that of AMBR-1. 7-Ketocholesterol-resistant clone, unlike AMBR-1, could form colonies in the presence of lipoprotein-depleted serum. The results are discussed in terms of probable change in the sterol biosynthetic pathway by the different lesions.

Ultrastructural changes during the enhancement of cellular 3-hydroxy-3-methyl-glutaryl-coenzyme A reductase in a Chinese hamster cell mutant resistant to compactin (ML 236B)

Chinese hamster V79 cell mutants resistant to compactin (ML236B) were isolated. A resistant clone, MF-2, grown in the presence of 2 micrograms/ml of ML236B for 1 week showed a 30-fold increase in 3-hydroxy-3-methyl-glutaryl-coenzyme A (HMG-Co A) reductase activity compared to MF-2 grown in the absence of ML236B, and cells grown for 4 weeks showed a 53-fold increase. Apparent ultrastructural changes in thin sections of the MF-2 cells were observed after growth in ML236B: dilated cisternae in the rough endoplasmic reticulum had or did not have flocculated contents; there was significant distension of perinuclear space; and vesicular inclusion bodies were present in nuclei.

Chinese hamster cell mutant resistant to ML236B (Compactin) is defective in endocytosis of low-density lipo-protein

A fungal metabolite, ML236B (Compactin), isolated from Penicillium citrinum, is a specific inhibitor of 3-hydroxy-3-methylglutaryl (HMG)-coenzyme A reductase (EC 1.1.1.34). Three ML236B-resistant (ML236Br) mutants, MF-1, MF-2, and MF-3, were isolated from V79 after N-methyl-N'-nitro-N-nitrosoguanidine mutagenesis. The fluctuation test showed 2.2 X 10(-6) mutants per cell per generation of a spontaneous mutation frequency of ML236Br clones. These ML236Br clones showed a four- to fivefold-higher resistance to the drug than did their parental V79. Radioactive acetate, but not mevalonate, incorporation into the sterol fraction increased about 10-fold in ML236Br clones in comparison with that in V79. The cellular level of HMG-coenzyme A reductase in three ML236Br mutants was found to be a few-fold higher than that of V79 when cultured in the presence of lipoproteins. The 125I-labeled low-density lipoprotein-binding assay showed binding activity in three ML236Br clones comparable to that of the parental V79 cells. By contrast, an internalization assay of 125I-labeled low-density lipoprotein into the cells showed significantly reduced activity in three ML236Br clones in comparison with V79.

Hypertonic solutions induce hemorrhage in the anterior pituitary in mice

Acute and intense hemorrhage in the anterior lobe of the pituitary was observed in mice treated with hypertonic solutions. The onset of hemorrhage and the spontaneous recovery phase were studied with light and electron microscopes. Ten minutes after ip injection of 9% NaCl, 8% NaHCO3, 3 M glucose or 3 M sucrose at a dose of 0.03 ml/g B. W. there was selective bleeding in the anterior lobe of the pituitary. The maximum extent of hemorrhage was reached 12 h after the injection of hypertonic solution and lasted for approximately 3 days. Ontogenetic study indicated that no pituitary hemorrhage occurred in mice younger than 2 weeks of age. Hypophyseal cleft was found to be not merely a residual lumen but an active site providing for accumulation and digestion of blood cells which flowed out of the bleeding anterior pituitary. By the end of a week, the necrotic tissue in the center of the anterior pituitary was replaced by granulation tissue consisting of fibroblasts, macrophages, capillaries and a stack of excess basal lamina.

Potentiation of antifungal effect of amphotericin B by squalene, an intermediate for sterol biosynthesis

The antifungal effect of a polyene antibiotic amphotericin B (AMB) was almost completely abrogated by exogenous addition of 0.1 microgram/ml ergosterol in the medium. The cytocidal effect of AMB on Saccharomyces cerevisiae was synergistically enhanced when cultured for more than 4 hours with squalene, an obligatory intermediate molecule for sterol formation. However, we could not find significant increase in cellular level of ergosterol content in the yeast cells fed with squalene.

Microenvironments controlling the transdifferentiation of vertebrate pigmented epithelial cells in in vitro culture

The transdifferentiation of pigmented epithelial cells in vitro is briefly introduced. Several environmental conditions regulating the process have been demonstrated experimentally. On the basis of these data we have suggested regulatory factors in relation to the mechanisms for the initiation of the transdifferentiation of pigmented epithelial cells, focussing particularly on cell surface functions. Finally, we have presented data which contributes to the establishment of a useful and powerful cell culture system which makes it possible for us to analyse the molecular basis of transdifferentiation.

Murine cytomegalovirus stimulates natural killer cell function but kills genetically resistant mice treated with radioactive strontium

Treatment of C3H/St mice with 100 microCi of 89Sr weakened their genetic resistance to murine cytomegalovirus (MCMV) infection. The criteria utilized to detect increased susceptibility were: (i) survival of mice; (ii) numbers of MCMV-infected cells in the spleens and liver; and (iii) serum glutamic pyruvic transaminase levels. The natural killer (NK) cell activity of spleen cells from mice treated with 89Sr is very low. However, the NK activities of spleen cells of both normal and 89Sr-treated mice were greatly augmented 3 days after infection with MCMV. These NK cells lysed a variety of tumor cells and shared several features with conventional NK cells, but were not lysed by anti-Nk-1.2 serum (specific for NK cells) plus complement. Splenic adherent cells did not lyse tumor cells themselves but were necessary for the stimulation of NK cells by MCMV. The paradox of high NK cell function and poor survival in 89Sr-treated mice infected with MCMV was a surprise. We conclude that these augmented NK cells, of themselves, cannot account for the genetic resistance of C3H/St mice to infection with MCMV.

Enhancement of the antitumor effect of 6-mercaptopurine by vitamin A

The inhibition of the growth of HeLa cells in culture by 6-mercaptopurine was greatly enhanced in combination with retinol, retinal or retinol acetate, but not in combination with retinoic acid or retinol palmitate. The antitumor effect of retinol palmitate combined with 6-mercaptopurine was examined in BDF1 mice with L1210 leukemia. The blood level of retinol, a strong potentiator of 6-mercaptopurine among vitamin A compounds, was increased in BDF1 mice after retinol palmitate injection. Retinol palmitate was found to enhance the antitumor effect of 6-mercaptopurine against murine L1210 leukemia to a significant extent (69% increase in life span).