Identification of pharmacokinetically stable 3, 10-dibromo-8-chlorobenzocycloheptapyridine farnesyl protein transferase inhibitors with potent enzyme and cellular activities

Farnesyl protein transferase (FPT) is a promising target for the development of cancer chemotherapeutics because it is responsible for the farnesylation of oncogenic p21 Ras proteins which are found in nearly 30% of all human cancers and necessary for cellular development and growth. The recent discovery and progression to phase II clinical trials of trihalobenzocycloheptapyridine Sch-66336 as a potent inhibitor of FPT with oral, in vivo efficacy in mice have spawned extensive structure-activity relationship studies (SAR) of this class of compounds. Of the many trihalobenzocycloheptapyridine analogues prepared, we have identified several which inhibit FPT and cellular proliferation at single-digit nanomolar concentrations and which have good pharmacokinetic properties in mice.

Liver mRNA expression of IGF-I and IGFBPs in adult undernourished diabetic rats

To investigate the role played by factors other than GH, such as nutrients and insulin, on IGF-I secretion, adult male rats of 200 g.b.w. were food-restricted for 7 days and then made diabetic by streptozotocin administration (UD). Different groups of UD rats were submitted to the following four day treatments: left untreated (UD), refed (UD+R), treated with insulin (UD+I), or a combination of both refeeding and insulin (UD+R+I). Serum concentration of IGF-I and liver mRNA expression of IGF-I, IGF-binding proteins and GH receptor were measured. Insulin treatment alone partially recovered liver IGF-I and IGFBPs mRNA expression, while refeeding alone had no effect. Only a combination of both insulin and refeeding recovered both parameters. Contrary to the results obtained with a longer period of recovery, these experiments show that serum and mRNA expression of IGF-I and IGFBPs in adult undernourished diabetic rats can be restored by insulin and nutrients administration with no prior restoration of serum and pituitary GH to control values and no compensatory changes in GH receptor gene expression.

Factors contributing to laparoscopic failure during the learning curve for laparoscopic Nissen fundoplication in a community hospital

This study was done to determine the factors contributing to laparoscopic failure (conversion to open surgery or early reoperation) during the learning curve for laparoscopic Nissen fundoplication in a 228-bed nonteaching community hospital. Data were gathered prospectively for the first 100 consecutive patients booked for elective laparoscopic Nissen fundoplication by the four general surgeons at the hospital. All complications were recorded contemporaneously, and particular note was taken of the factors surrounding conversion to open surgery and reoperation within 100 days of surgery. There were no deaths. The conversion rate was 20% and the early reoperation rate 6%. There were two late recurrences. The average operative time was 117 minutes and the average length of stay 1.8 days; 37 operations were performed on outpatients. The laparoscopic failure rate was 26% (18/68) during a surgeon's first 20 operations and 11% (3/28) thereafter (P < 0.09); the corresponding conversion rates were 22% and 4% (P < 0.05). During a surgeon's first 20 operations, the laparoscopic failure rate rose from 21% (12/57) to 55% (6/11) (P < 0.04) if a second surgeon did not assist. After 20 operations, this difference lost its significance. Intrathoracic herniation of the stomach was found preoperatively in 11 (44%) of 25 operations followed by laparoscopic failure and (8%) 6 of 75 without (P < 0.0002). Laparoscopic failure had no correlation with patient age, sex, ASA classification, duration of symptoms, or referring physician's specialty. The individual learning curve for laparoscopic Nissen fundoplication requires about 20 operations to surmount. Factors leading to laparoscopic failure during the learning curve are the surgeon's inexperience, absence of experienced help, and the presence of intrathoracic herniation.

Kinetics and mechanism of St I modification by peroxyl radicals

St I is a toxin present in the Caribbean Sea anemone Stichodactyla helianthus which is highly hemolytic in the nanomolar concentration range. Exposure of the toxin to free radicals produced in the pyrolysis of 2,2'-azobis(2-amidinopropane) hydrochloride leads to a progressive loss of hemolytic activity. This loss of hemolytic activity is accompanied by extensive modification of tryptophan residues. On the average, three tryptophan residues are modified by each inactivated toxin. The loss of hemolytic activity of St I takes place without significant changes in the protein structure, as evidenced by the similarity of the fluorescence and CD spectra of native and modified proteins. Also, the native and modified ensembles present a similar resistance to their denaturation by guanidinium chloride. The hemolytic behavior and the performance of the toxin at the single-channel level when incorporated to black lipid membranes suggest that the modified ensemble can be considered as composed of inactive toxins and active toxins whose behavior is similar to that of the native proteins. These results, together with the lack of induction time in the activity loss, suggest that the fall of hemolytic activity takes place by an all-or-nothing inactivation mechanism in which the molecules become inactive when a critical amino acid residue is modified.

Antiparasite activity of sea-anemone cytolysins on Giardia duodenalis and specific targeting with anti-Giardia antibodies

The killing activity of sea-anemone cytolysins on Giardia duodenalis was investigated. Three different toxins, sticholysin I and II from Stichodactyla helianthus (St I and St II) and equinatoxin II from Actinia equina (EqtII) were all found to be active in an acute test, with a C50 in the nanomolar range (St I, 0.5 nM; St II, 1.6 nM; and EqtII, 0.8 nM). A method to target the cytolysin activity more specifically towards the parasite cells by using anti-Giardia antibodies was then investigated. Parasite cells were sensitised with a primary murine monoclonal or polyclonal antibody followed by a biotinylated secondary anti-mouse-IgG monoclonal antibody. Subsequently, avidin and a biotinylated EqtII mutant were added, either in two separate steps or as a pre-formed conjugate. When the monoclonal antibody was used, the C50 of biotinylated EqtII was 1.3 nM with sensitised cells and 5 nM with non-sensitised cells, indicating a four-fold enhancement of activity with the cell treatment. Treatment with the polyclonal antibody was somehow more effective than with the monoclonal antibody in an acute test. This indicates that sea-anemone cytolysins can efficiently kill Giardia cells, and that it is possible to improve, to a certain extent, the anti-parasite specificity of these toxins with anti-Giardia antibodies. However, the feasibility of this approach "in vivo" remains to be demonstrated.

Role of transforming growth factor-beta in growth and injury response of the pancreatic duct epithelium in vitro

Chronic pancreatitis is characterized by increased levels of expression of transforming growth factor-beta (TGF-beta), particularly in and around the ducts. To examine the consequences of elevated exposure to TGF-beta on the pancreatic duct epithelium, we cultured segments of the main bovine pancreatic duct in the presence of increasing doses of TGF-beta. We also studied the effect of TGF-beta on epithelial injury, produced in this model by exposure to a bile acid. The extent of proliferation, migration, and epithelial damage was measured morphometrically on sections stained with hematoxylin and eosin. Proliferation and apoptosis were qualitatively determined by means of immunohistochemical analysis. In this model of duct cell culture, TGF-beta stimulated cell migration in areas of the explants where the native basement membrane of the duct epithelium was absent. In segments where the native basement membrane remained intact, proliferation was inhibited and apoptosis induced. When the explants were exposed to bile acid, extensive epithelial injury was observed. TGF-beta exposure at high doses (1 nmol/L protected epithelial integrity, but cellular morphology was altered and the process of apoptosis appeared to be increased. Our results suggest that increased periductal levels ot TGF-beta in the setting of pancreatic injury may be intended to promote repair of acute epithelial damage but may have detrimental long-term effects.

Precocious development of parvalbumin-like immunoreactive interneurons in the hippocampal formation and entorhinal cortex of the fetal cynomolgus monkey

The calcium-binding protein parvalbumin (PV), a reliable marker of the hippocampal basket and chandelier cells, is first expressed on embryonic day 83 (E83), corresponding to midgestation of the macaque monkey, in restricted hippocampal groups of immature neurons (Berger and Alvarez [1996] J. Comp. Neurol. 366:674-699). In the present study, PV-like immunoreactivity (LIR) was used to follow the further development of this subclass of interneurons. Asynchronous area-specific developmental sequences were observed, predominating initially in the caudal half of the hippocampal formation and the laterocaudal division of the entorhinal cortex and occurring relatively simultaneously in the interconnected hippocampal and entorhinal subfields. Dendritic elongation of PV-like immunoreactive interneurons and perisomatic distribution of PV-like immunoreactive terminal boutons on their cellular targets were first observed in the subiculum around E127; then from E127 to E142 in CA3/CA2 and layers III-V of the entorhinal cortex and, to a lesser extent in CA1, the dentate hilus and deep granule cell layer; and finally from E156 to postnatal day 12 in the rest of the dentate gyrus, the presubiculum and parasubiculum, and layers III-II-I of the entorhinal cortex. These data provide the first indication that a population of basket cells, a major gamma-aminobutyric acid (GABA)ergic component of the hippocampal intrinsic inhibitory circuitry, reaches its cellular targets several weeks before birth in primates in contrast to rodents. The role of the prenatal PV expression in the hippocampal formation of nonhuman primates and whether it coincides with the onset of postsynaptic inhibitory potentials or is accompanied or preceded by a period of gamma-aminobutyric acid-mediated excitatory effects as in rat pups, are crucial questions. They underline the need to pursue direct investigations on primates to be able to legitimately extrapolate the data obtained in rodents.

Brefeldin A (BFA) disrupts the organization of the microtubule and the actin cytoskeletons

Previous inquiries into the effects of Brefeldin A (BFA) have largely concentrated on dynamics of ER-Golgi membrane traffic, predominantly after relatively short treatments with the drug. We have now analyzed the effects of long BFA treatment on overall cell morphology, behavior of resident and cycling Golgi proteins, and microtubular and actin cytoskeletons organization. Prolonged (15 h or 40 h) treatment of normal rat kidney (NRK) cells with BFA caused dramatic swelling of the Endoplasmic Reticulum (ER) and shifted its localization to the periphery of the cells. The Golgi complex was disassembled and Golgi proteins redistributed and persisted in partially distinct compartments. Prolonged BFA treatment resulted in marked disruption of the MT and actin cytoskeleton. Peripheral MT were absent and tubulin staining was concentrated in short astral MT emanating from the microtubule organizing center (MTOC). Actin stress fibers were largely absent and actin staining was concentrated within a perinuclear area. Within this region, actin localization overlapped that of the membrane transport factor p115. BFA effects on Golgi structure and on MT and actin organization showed the same threshold -- all could be partially reversed after 30 min and 15 h BFA treatment but were irreversible after 40h incubation with the drug. The observed effects were not induced by signaling pathways involved in apoptotic phenomena or in ER stress response pathways. These results suggest that BFA inhibits the activity of key molecules that regulate MT and actin cytoskeleton dynamics. The findings can be used as the basis for elucidating the molecular mechanism of BFA action on the cytoskeleton.

Molecular cloning, characterization, and dynamics of rat formiminotransferase cyclodeaminase, a Golgi-associated 58-kDa protein

A peripherally associated 58-kDa Golgi protein (58K) of unknown function has been previously described (Bloom, G. S., and Brashear, T. A. (1989) J. Biol. Chem. 264, 16083-16092). To molecularly characterize 58K, we used a monoclonal anti-58K antibody (monoclonal antibody 58K-9) to screen a rat liver cDNA expression library. Positive clones were isolated, characterized, and partially sequenced. The obtained sequences show a high level of identity with sequences of porcine formiminotransferase cyclodeaminase (FTCD), suggesting that 58K is rat FTCD. Rat FTCD is structurally similar to porcine FTCD, a metabolic enzyme involved in conversion of histidine to glutamic acid, and exists in dimeric, tetrameric, and octameric complexes resistant to proteolysis. To define parameters of FTCD association with the Golgi, comparison of its behavior with various Golgi and ER-to-Golgi intermediate compartment marker proteins was examined under specific conditions. The results show that extraction parameters of FTCD are similar to those of GM130, a tightly associated Golgi matrix protein. FTCD appears to be a dynamic component of the Golgi, and a proportion of FTCD molecules cycle between the Golgi and earlier compartments of the secretory pathway. FTCD remains associated with Golgi fragments during microtubule disruption and is not released into cytosol during brefeldin A treatment. Instead, FTCD relocates from the Golgi, but the time course of its redistribution is distinct from that of mannosidase II relocation. FTCD is already dispersed into small punctate structures at a time when mannosidase II is still largely localized to Golgi structures. FTCD is not observed in tubules originating from the Golgi and containing mannosidase II. Instead, it appears to redistribute in small vesicles arranged in a linear "pearls on a string" pattern. These results suggest that FTCD relocation is temporally and spatially distinct from mannosidase II relocation and that FTCD provides a novel marker to study Golgi dynamics.

Mechanism of hypothyroidism action on insulin-like growth factor-I and -II from neonatal to adult rats: insulin mediates thyroid hormone effects in the neonatal period

The effects of thyroid hormone deficiency on serum levels and liver messenger RNA (mRNA) expression of insulin-like growth factors (IGFs) were studied in neonatal (until 20 days of life), weaned (22-37 days), and adult (72-87 days) rats, short periods (5, 10, and 15 days) after thyroidectomy (T). Serum levels and liver mRNA expression of IGF-I, plasma and pituitary GH, plasma insulin, and glycemia were measured in all populations; and serum levels and liver mRNA expression of IGF-II were measured only in the neonatal populations. Surprisingly, plasma insulin and GH and serum and liver mRNA expression of IGF-I were found elevated in T neonatal rats, and they decreased in weaned and adult rats and in neonatal rats rendered hypothyroid by mercapto-1-methylimidazole (MMI) treatment (MMI-hypothyroid). T and MMI-treatment of neonatal rats disturbed the normal pattern of progressive decrease of IGF-II with age. A positive correlation between insulin and IGF-I and a poor correlation between GH and IGF-I were found in both hypothyroid neonates (T and MMI-hypothyroid). On the contrary, a positive correlation between GH and IGF-I and a poor correlation between insulin and IGF-I were found for control and T adult rats. Because plasma insulin and GH changed in the same direction in all groups, insulin secretion in T neonatal was suppressed by streptozotocin, and insulin was given to T adult rats. The combined results of these experiments support the idea that the effects of thyroid hormones on IGF-I secretion are age-dependent, and they are mediated mainly by insulin during the neonatal period and by GH during adulthood.

The membrane transport factor TAP/p115 cycles between the Golgi and earlier secretory compartments and contains distinct domains required for its localization and function

The mammalian protein TAP/p115 and its yeast homologue Uso1p have an essential role in membrane traffic (Nakajima et al., 1991; Waters et al., 1992; Sztul et al., 1993; Rabouille et al.; 1995). To inquire into the site and mechanism of TAP/p115 action, we aimed to localize it and to identify domains required for its function. We show that in interphase cells, TAP/p115 localizes predominantly to the Golgi and to peripheral structures that represent vesicular tubular clusters (VTCs) involved in ER to Golgi transport. Using BFA/ nocodazole treatments we confirm that TAP/p115 is present on ER to Golgi transport intermediates. TAP/ p115 redistributes to peripheral structures containing ERGIC-53 during a 15 degreesC treatment, suggesting that it is a cycling protein. Within the Golgi, TAP/p115 is associated with pleiomorphic structures on the cis side of the cis-Golgi cisterna and the cis-most cisterna, but is not detected in more distal compartments of the Golgi. TAP/p115 binds the cis-Golgi protein GM130, and the COOH-terminal acidic domain of TAP/p115 is required for this interaction. TAP/p115 interaction with GM130 occurs only in the Golgi and is not required for TAP/p115 association with peripheral VTCs. To examine whether interaction with GM130 is required to recruit TAP/p115 to the Golgi, TAP/p115 mutants lacking the acidic domain were expressed and localized in transfected cells. Mutants lacking the GM130-binding domain showed normal Golgi localization, indicating that TAP/p115 is recruited to the Golgi independently of its ability to bind GM130. Such mutants were also able to associate with peripheral VTCs. Interestingly, TAP/p115 mutants containing the GM130-binding domain but lacking portions of the NH2-terminal region were restricted from the Golgi and localized to the ER. The COOH-terminal domain required for GM130 binding and the NH2-terminal region required for Golgi localization appear functionally relevant since expression of TAP/p115 mutants lacking either of these domains leads to loss of normal Golgi morphology.

Modification of sticholysin II hemolytic activity by free radicals

Sticholysin II is a highly hemolytic toxin present in the caribbean sea anemone Stichodactyla helianthus. Pre-incubation of St II with 2,2'-azobis(2-amidinopropane), a source of peroxyl radicals in air saturated solution, readily reduces its hemolytic activity. Analysis of the amino acids present in the protein after its modification shows that only tryptophan groups are significantly modified by the free radicals. According to this, the loss of hemolytic activity correlates with the loss of the protein intrinsic fluorescence. The results indicate that, at high toxin concentrations, nearly a tryptophan residue and 0.2 toxin molecules are inactivated by each radical introduced into the system. Association of St II to multilamellar liposomes (egg yolk phosphatidyl choline:sphingomyelin 1:1) increases the toxin intrinsic fluorescence, indicating a more hydrophobic average environment of the five tryptophan groups of the protein. In agreement with this, incorporation of St II to the liposomes reduces the rate of fluorescence loss during its modification by free radicals, particularly at long incubation times. These results are explained in terms of two populations of tryptophans that are quenched at different rates by acrylamide and whose rates of inactivation by free radicals are also different.

[Drug-induced agranulocytosis: clinical study of 19 cases]

Agranulocytosis is one of the most serious side effects to drugs. From January 1991 to June 1996 were diagnosed 19 cases of agranulocytosis associated with drugs at our hospital (incidence rate: 9.4 over million hab. per year). The average age was 62 and 11 cases were women. The drugs most commonly involved were metamizol and ticlopidine. In 15 of the patients fever blew up and 16 presented some infectious location. In 9 of the cases some positive microbiological culture was obtained, gram-negative bacilli being the commonest. G-CSF was used in 13 of the patients, observing a quicker haematological recovery (5.7 days vs 9.1, p = 0.07), though without any difference in mortality, which was of 0%. All this leads to the following conclusions: a high incidence of agranulocytosis in our environment and the important role of metamizol and ticlopidine in its origin.

Clinical resolution of Scedosporium prolificans pneumonia associated with treatment with liposomal amphotericin B in a patient with acute leukemia

Scedosporium prolificans is a filamentous fungus which has been recently identified as the aetiologic agent of severe infections in patients with haematological malignancies. Due to the resistance of S. prolificans to all known antifungals there are very few patients recovering from invasive infections. We describe the case of a patient with acute leukaemia who developed a S. prolificans pneumonia successfully treated with liposomal amphotericin B and who underwent autologous peripheral blood stem cells transplantation. The patient is in good health and has shown no evidence of reactivation of S. prolificans infection over one year after the transplant. Liposomal amphotericin B may be an effective treatment of pneumonia caused by S. prolificans in haematological patients.

Efficacy of octreotide in the regression of a metastatic carcinoid tumour despite negative imaging with In-111-pentetreotide (Octreoscan)

We present the case of a 52-year old patient diagnosed with carcinoid tumour of the rectum with liver metastases in which treatment with somatostatin analogues (octreotide) proved very effective in the disappearance of the symptomatology and dramatic efficacy in the regression of the tumour. Imaging by octreoscan was always negative. The role of octreotide in the treatment of carcinoid tumour and the usefulness of In-111-pentetreotide (octreoscan) in the localization and prediction of the response to treatment with octreotide is discussed. We conclude that the negative result of the scintigraphic image with octreoscan does not necessarily suppose the inefficacy of octreotide treatment. We believe that this may constitute an important issue since some patients may be denied octreotide treatment in the absence of a positive octreoscan result.

Pneumocephalus after shunting for hydrocephalus

A case of tension pneumocephalus that occurred after ventriculoperitoneal shunting is presented. We have reviewed 12 cases of pneumocephalus in association with ventriculoperitoneal shunt placement. This phenomenon occurs when air is forced through the shunt or enters through the cranial base because of: iatrogenic postsurgical connection, congenital fistula, trauma, or thinning of the cranial base. Ways of preventing and treating this problem are outlined.

[Cutaneous zygomycosis caused by Rhizopus arrhizus in a surgical wound.]

We report a case of cutaneous zygomycosis caused by Rhizopus arrhizus in a surgical wound following colostomy. The patient was a diabetic and in addition presented others risk factors. Zygomycosis was suspected when a necrotic wound surface appeared in the appropiate clinical setting. Diagnosis was confirmed on a combined histological and microbiological study. Extensive surgical resection, high doses of amphotericin B and treatment of the underlying conditions permitted the control of the infection.

Risk factors associated with human cystic echinococcosis in Florida, Uruguay: results of a mass screening study using ultrasound and serology

Sonographic evidence of asymptomatic Echinococcus granulosus lesions in the liver was found in 156 of 9,515 persons in the Department of Florida, Uruguay. The sensitivity of ELISA and latex agglutination serology compared with ultrasound was 47.6% and 28.1%, respectively, and specificity was > 85%. There was a significant positive association between positive sonography and a personal history of previous but treated Echinococcus infection while those that were seropositive but ultrasound-negative were significantly more likely to have a personal history of infection or a history of infection in their family. Prevalence of infection increased significantly with age. There was no correlation between echinococcosis and dog ownership or home slaughter of sheep but offal disposal was important, with an increased prevalence of infection of 3.2%, 2.8%, and 3.1%, respectively, in persons feeding offal to dogs or burying or burning it compared with a prevalence of 0.8-1.5% in those using other methods of disposal. Almost half the population, when questioned, seemed to have sound knowledge about E. granulosus and described correct treatment of E. granulosus in dogs but this did not affect prevalence. There was a significant positive association between infection and the presence of a fenced fruit/vegetable garden and use of rural waters, particularly the cachimba (a small dam) and the aljibe (a cistern or tank) that collect rainwater from the ground surface and roofs, respectively.

Effect of naloxone on behavioral changes induced by subchronic administration of ethanol in rats

Endogenous opioid peptides appear to be involved in acute behavioral effects induced by single doses of ethanol. However, its role in repeated ethanol exposure has not been studied. In the present study ethanol was given to rats at the doses of 2 and 4 g/kg by a stomach gauge for 15 days, and its effects on spontaneous motility, open-field activity, and active avoidance behavior recorded on the 3rd, the 6th and the 15th days. Then the effect of naloxone (0.5 and 2 mg/kg by intraperitoneal route) was tested against a challenge ethanol dose, administrated by oral route, on the 16th day. Control animals received tap water and saline instead of ethanol or naloxone, respectively. Both doses of ethanol induced a decrease in spontaneous motility that was antagonized by naloxone. Open-field ambulations were increased by the high dose of ethanol, low-dose lacking effect; naloxone did not modify these ethanol effects. The low dose of ethanol shortened latency time in shuttlebox, the high dose causing escape and freezing responses; none of these effects were modified by naloxone. Therefore, endogenous opioid peptides appear to play a limited role in the chronic effects of ethanol in rats; particularly its effects in tests inducing an increase in the level of anxiety were resistant to naloxone.

[Home oxygen therapy in children with chronic respiratory failure]

BACKGROUND

Home oxygen therapy improves survival and quality of life in adults with chronic obstructive airways disease. The few studies about home oxygen therapy in children show improvements in weight gain, school performance and decreases in hospitalization expenses.

AIM

To report our experience in home oxygen therapy in children followed for six months to four years.

PATIENTS AND METHODS

Fifty five children, less than 15 years old, discharged from a University hospital with the diagnosis of chronic respiratory failure, were followed up at their homes.

RESULTS

Discharge diagnoses were bronchopulmonary dysplasia in 36% of children, postinfectious pulmonary damage in 22%, neonatal distress in 13%, chronic aspiration in 9%, cystic fibrosis in 7% and miscellaneous in 13%. Forty six completed at least 6 months of follow up, five moved to other hospitals, three required ventilatory support and one died. Oxygen was discontinued in 33 patients, and this occurred before the ninth month of follow up in 88% of those children. Neonatal distress and bronchopulmonary dysplasia had the best prognoses, and oxygen was discontinued at 4 +/- 1 and 5.7 +/- 3 months respectively. Patients with postinfectious pulmonary disease had a higher incidence of bronchoneumoniae, and those with bronchopulmonary dysplasia a higher incidence of acute bronchiolitis, that motivated hospital admissions. Expenses due to home oxygen were lower than hospitalization costs. No adverse effects were detected.

CONCLUSIONS

Infants and newborns on home oxygen therapy have a good prognosis, specially those with reversible diseases. This type of therapy allows an earlier hospital discharge with considerable cost reductions.