Manipulating neuropeptidergic pathways in humans: a novel approach to neuropharmacology?

Given the tremendous number of neuropeptides, which are synthesized in the central nervous system, the brain can be viewed as one of the most prominent endocrine organs. Elucidation of the functions of these peptides is hampered by the facts that after intravenous administration access to brain receptors is prevented or impaired by the blood-brain barrier. Here, we provide evidence that intranasal administration can be a way to circumvent the blood-brain barrier. Selected experiments will be reported indicating that peptides after intranasal administration in humans can specifically alter a great variety of brain functions. For vasopressin, we demonstrated improving effects of long-term intranasal treatment on sleep in elderly people. Insulin showed improving effects of short-term memory functions. For adrenocorticotropin/melanocyte stimulating hormone, ACTH/MSH-(4-10), a twofold action was isolated: The melanocortin fragment diminished selective attention and, with subchronic administration, reduced body fat. These results could provide the basis for developing a new, specific, and "soft" neuropharmacology.

Microalbuminuria during cisplatin therapy: relation with pharmacokinetics and implications for nephroprotection

BACKGROUND

To assess the relation of cisplatin-induced nephrotoxicity to its pharmacology.

PATIENTS AND METHODS

In 22 chemonaive patients (median age, 32 years) receiving 100-150 mg/m2 cisplatin for a total of 54 courses of therapy pharmacokinetics of ultra-filtrable platin were analyzed. Nephrotoxicity was sensitively assessed by nephelometric analyses of urinary marker-proteins.

RESULTS

The parameters calculated for ultrafiltrable platin were (two-compartment-model): terminal half-life, 36 hours (coefficient of variation [CV], 22%); AUC, 12852 ng h/ml (33%); volume of distribution, 3531 (44%); total clearance, 285 ml/min (30%); renal clearance, 149 ml/min (23%); maximum concentration, 1720 ng/ml (66%); renal elimination, 57% of applied dose (26%). A pathological urinary excretion of albumin > 20 mg/l and alpha-1-microglobulin > 10 mg/l was detected in 39 out of 54 and 42 out of 54 cycles, respectively. The degree of albuminuria was related with urinary monoaquoplatin concentrations (p = 0.003).

CONCLUSION

Nephrotoxicity of cisplatin appears to depend on the urinary monoaquoplatin concentrations which may be modulated by application of saline.

Adaptation of cognitive function to hypoglycemia in healthy men

OBJECTIVE

Antecedent hypoglycemia reduces hypoglycemic counterregulation and symptoms, thereby provoking the hypoglycemia unawareness syndrome. The effects of antecedent hypoglycemia on hypoglycemia-induced cognitive dysfunction are less well established.

RESEARCH DESIGN AND METHODS

To determine whether antecedent hypoglycemia also reduces hypoglycemic cognitive dysfunction, we performed stepwise hypoglycemic clamp experiments (4.1, 3.6, 3.1, and 2.6 mmol/l) during a 6-h period in 30 young healthy men. A total of 15 subjects additionally received a 2.5-h antecedent hypoglycemic clamp (3.1 mmol/l) on the preceding day (prior-hypo group), whereas the other 15 subjects did not (control group). Cognitive function was assessed by auditory-evoked brain potentials (AEBPs) and reaction time during a vigilance task and short-term memory recall. Tests were performed during the stepwise hypoglycemic clamp at baseline and at each hypoglycemic plateau.

RESULTS

In both groups, performance on all measures of cognitive function deteriorated during stepwise hypoglycemia (all P < 0.01). However, after antecedent hypoglycemia, the hypoglycemia-induced decrease in the amplitude of the P3 of the AEBP was distinctly reduced compared with the control condition (P < 0.05). Also, short-term memory performance was less impaired in the prior-hypo group than in the control group (P < 0.005), and a minor hypoglycemic impairment of reaction time (P < 0.05) was evident in the prior-hypo group.

CONCLUSIONS

Data provide evidence that a single episode of mild antecedent hypoglycemia (3.1 mmol/l) attenuates several aspects of cognitive dysfunction during subsequent hypoglycemia 18-24 h later.

The pharmacodynamic basis for the increased antileukaemic efficacy of cytosine arabinoside-based treatment regimens in acute myeloid leukaemia with a high proliferative activity

The current study was initiated to explore the mechanisms underlying the previously demonstrated association between the proliferative activity of leukaemic blasts and the response to cytosine arabinoside (AraC)-based therapy in de novo acute myeloid leukaemia (AML). The activity of key enzymes of AraC metabolism-deoxycytidine kinase (DCK), cytidine deaminase (DCD) and polymerase alpha (PolyA) were determined in blast cells from 33 patients. In addition, formation and retention of intracellular levels of AraC triphosphate (AraCTP) and DNA incorporation of AraC were measured, as was the proliferative activity of leukaemic blasts by [3H]-TdR incorporation before and after stimulation with granulocyte-macrophage colony-stimulating factor (GM-CSF) or granulocyte CSF (G-CSF) for 48 h. AraC incorporation into the DNA (median 0.60 pmol/105 cells) was significantly related to the proliferative activity of AML blasts (r = 0.74, P < 0.001). Similarly, priming with GM-CSF or G-CSF increased both the proliferative activity of AML blasts by a median of 1.84- and 1.64-fold, respectively, and the incorporation of AraC into the DNA (1.29- and 1.40-fold respectively). In contrast, no relationship was found between the endogenous proliferative activity (EPA) and enzyme activities regulating AraC activation (DCK; median 4.70 pmol/min/mg protein), inactivation (DCD; median 2.92 pmol/min/mg protein) or inhibitory effects (PolyA; median 1.50 pmol/min/mg protein), nor the formation or retention of AraCTP (median 306.1 ng/107 cell and 1.6 h respectively). When samples were grouped according to EPA (more than or less than the median), slowly proliferating specimens had a higher response to cytokine priming for proliferative activity and incorporation of AraC into DNA. Clinical data of 15 patients were available. Although all eight patients with a high endogenous proliferative activity reached complete remission, only four out of seven patients with a low proliferative activity responded, whereas the other three patients were non-responders (P = 0.077).

Comparison of the inhibitory effect of insulin and hypoglycemia on insulin secretion in humans

Although both insulin and hypoglycemia are known to inhibit endogenous insulin secretion, their potency to suppress insulin secretion has not been directly compared thus far. The serum C-peptide concentration was measured during 28 euglycemic and 28 stepwise hypoglycemic (4.1,3.6, 3.1, and 2.6 mmol/L) clamp experiments using either a low-rate (1.5 mU x min(-1) x kg(-1)) or high-rate (15.0 mU x mU(-1) x kg(-1)) insulin infusion. The experiments lasted 6 hours and were performed in 28 lean healthy men. During both the euglycemic and hypoglycemic clamps, serum insulin was approximately 40-fold higher during the high-rates versus low-rate insulin infusion (euglycemia, 24,029 +/- 1,595 v 543 +/- 34 pmol/L; hypoglycemia, 23,624 +/- 1,587 v 622 +/- 32 pmol/L). Under euglycemic conditions, serum C-peptide decreased from 0.54 +/- 0.04 to 0.41 +/- 0.05 nmol/L during the low-rate insulin infusion (P < .05) and from 0.55 +/- 0.07 to 0.27 +/- 0.09 nmol/L during the high-rate insulin infusion (P < .001). Under hypoglycemic conditions, serum C-peptide decreased from 0.50 +/- 0.03 to 0.02 +/- 0.01 nmol/L during the low-rate insulin infusion (P< .001) and from 0.46 +/- 0.07 to 0.02 +/- 0.01 nmol/L during the high-rate insulin infusion (P< .001). In the euglycemic clamp condition, the high-rate insulin infusion reduced the C-peptide concentration more than the low-rate insulin infusion (P < .05). Independent of the rate of insulin infusion, the decrease in C-peptide was distinctly more pronounced during hypoglycemia versus euglycemia (P < .001). These data indicate that insulin inhibits insulin/C-peptide secretion in a dose-dependent manner. Hypoglycemia is a much stronger inhibitor of insulin secretion than insulin itself.

Preserved hypothermic response to hypoglycemia after antecedent hypoglycemia

Hypoglycemia is known to decrease the body temperature and to stimulate counterregulatory hormone secretion. Although it is well established that antecedent hypoglycemia reduces the hormonal response to subsequent hypoglycemia, the effects of antecedent hypoglycemia on the subsequent hypothermic response are obscure. In the present study, body temperature was measured orally during a total of 90 glucose clamp experiments in 45 healthy men. The clamps lasted 6 hours and were performed under 6 different experimental conditions: a euglycemic clamp with a low rate of insulin infusion, 1.5 mU/kg x min (low insulin-eu), a euglycemic clamp with a high rate of insulin infusion, 15.0 mU/kg x min (high insulin-eu), a hypoglycemic clamp with a low rate of insulin infusion, 1.5 mU/kg x min (low insulin-hypo), a hypoglycemic clamp with a high rate of insulin infusion, 15.0 mU/kg x min (high insulin-hypo), and 2 hypoglycemic clamps following an antecedent 2.5-hour hypoglycemia (56 mg/dL) induced by either a low (1.5 mU/kg x min, low insulin-ante-hypo) or a high (15.0 mU/kg x min, high insulin-ante-hypo) rate of insulin infusion. Plasma glucose was maintained normal during the euglycemic clamps and was decreased stepwise during the hypoglycemic clamps (76 --> 66 --> 56 --> 46 mg/dL). During the hypoglycemic clamps, body temperature decreased by 0.26 degrees +/- 0.09 degrees C in low insulin-hypo, 0.28 degrees +/- 0.09 degrees C in high insulin-hypo, 0.29 degrees +/- 0.09 degrees C in low insulin-ante-hypo, and 0.41 + 0.11 degrees C in high insulin-ante-hypo (all P < .01). There were no differences in the hypothermic response to hypoglycemia among the different hypoglycemic conditions (P > .1 for all comparisons). In contrast, body temperature remained unchanged during the euglycemic clamps, so the changes in body temperature differed significantly during the euglycemic clamps versus the hypoglycemic clamps (P < .05 for all comparisons). The data show that the body temperature decreases during hypoglycemia and this decrease is influenced neither by antecedent hypoglycemia nor by circulating insulin levels.

Successful modulation of high-dose cytosine arabinoside metabolism in acute myeloid leukaemia by haematopoietic growth factors: no effect of ribonucleotide reductase inhibitors fludarabine and gemcitabine

High-dose cytosine arabinoside (AraC)-containing regimens have shown the highest antileukaemic efficacy of all currently used regimens in the treatment of acute myeloid leukaemia (AML). This study aimed at increasing the antileukaemic potential of high-dose AraC by raising intracellular levels of AraC triphosphate (AraCTP), which is the mediator of cytotoxicity, via biochemical modulation by inhibitors of ribonucleotide reductase (RR) or haematopoietic growth factors (HGFs). Blasts from patients with de novo AML were analysed for their formation of AraCTP under high-dose AraC conditions (20 microM over 3 h) without prior modulation (n = 47) after a 2-h pre-exposure with fludarabine (50 microg/ml) (n = 40) or gemcitabine (30 ng/ml) (n = 40) and after a 48-h pre-exposure to granulocyte colony-stimulating-factor (G-CSF; 100 ng/ml) (n = 27) or granulocyte-macrophage colony-stimulating-factor (GM-CSF; 100 U/ml) (n = 28). Unmodulated formation of AraCTP (median 239.8 ng/107 cells) could not be increased via modulation by gemcitabine (232.4 ng/107 cells) or fludarabine (247.8 ng/107 cells). The lack of effect of RR inhibitors was also observed for all other known metabolites of AraC [Ara-cytosine monophosphate (CMP), Ara-cytosine diphosphate (CDP), AraCDP-choline, Ara-uridine monophosphate (UMP), Ara-uridine diphosphate (UDP) and Ara-uridine triphosphate (UTP)]. In contrast, pre-exposure to HGFs led to significant increases in AraCTP formation (G-CSF 556.0 ng/107 cells, 2.31-fold increase, P < 0.001; GM-CSF 447.9 ng/107 cells, 1.87-fold increase, P < 0.0001). To establish the mechanism responsible for these effects, the activity of the rate-limiting enzyme of AraC metabolism, deoxycytidine kinase (dCK), was investigated (n = 33). In vivo exposure to GM-CSF led to increases in dCK activity from unmodulated values at 0 h (29.8 pmol/min/mg protein) to 34.3 pmol/min/mg protein at 24 h (1.15-fold increase) and 54.5 pmol/min/mg protein at 48 h (1. 83-fold increase). The raise in dCK activity over 48 h was significant (P < 0.013).

Glucose metabolism rather than insulin is a main determinant of leptin secretion in humans

Circulating plasma insulin and glucose levels are thought to be major regulators of leptin secretion. There is evidence from in vitro and animal experiments that glucose metabolism rather than insulin alone is a main determinant of leptin expression. Here, we tested the hypothesis that in humans also leptin secretion is primarily regulated by glucose uptake and only secondarily by plasma insulin and glucose. In 30 lean and healthy men we induced 4 experimental conditions by using the blood glucose clamp technique. A total of 60 hypoglycemic and euglycemic clamps, lasting 6 h each, were performed. During these clamps insulin was infused at either high (15.0 mU/min x kg) or low (1.5 mU/min x kg) rates, resulting in low-insulin-hypo, high-insulin-hypo, low-insulin-eu, and high-insulin-eu conditions. Serum leptin increased from 0-360 min by 20.5 +/- 4.1% in the low-insulin-hypo, 33.6 +/- 7.6% in the high-insulin-hypo, 39.6 +/- 6.0% in the low-insulin-eu, and 60.4 +/- 7.6% in the high-insulin-eu condition. Multiple regression analysis revealed a significant effect of circulating insulin (low vs. high insulin; P = 0.001) and blood glucose (hypoglycemia vs. euglycemia; P = 0.001) on the rise of serum leptin. However, when the total amount of dextrose infused during the clamp (grams of dextrose per kg BW) was included into the regression model, this variable was significantly related to the changes in serum leptin (P = 0.001), whereas circulating insulin and glucose had no additional effect. These findings in humans support previous in vitro data that leptin secretion is mainly related to glucose metabolism.

Impact of the simultaneous administration of the (+)- and (-)-forms of formyl-tetrahydrofolic acid on plasma and intracellular pharmacokinetics of (-)-tetrahydrofolic acid

PURPOSE

To detect possible interactions between (-)-formyl-tetrahydrofolic acid (leucovorin, (-)-fTHF) and (+)-formyl-tetrahydrofolic acid ((+)-fTHF) on the plasma and intracellular pharmacokinetics following their simultaneous administration.

METHODS

Plasma levels of (-)-fTHF, (-)-methyl-THF, and (+)-fTHF were determined in samples from four volunteers following the administration of both (-)-fTHF and (+/-)-fTHF and in seven patients during a 5-fluorouracil (5-FU)/fTHF combination chemotherapy. In addition, the intracellular uptake of (14)C-(-)-mTHF in the presence of (+)-mTHF at increasing concentrations was measured in vitro. Analyses were performed using a highly specific high-performance liquid chromatography procedure.

RESULTS

The pharmacokinetic parameters obtained for (-)-fTHF following the administration of (-)-fTHF only were: terminal half-life, 1.2 h; area under the curve, 10 microg. h/ml; maximum concentration, 12 microg/ml; clearance, 305 ml/min; volume of distribution, 19 l. The parameters did not differ significantly as compared with those obtained following the administration of (+/-)-fTHF to both volunteers and patients. There were no differences in the pharmacokinetics of (-)-mTHF or in the protein binding of both substances with the different forms of administration. The intracellular uptake of (14)C-(-)-mTHF did not depend on the presence of (+)-mTHF at either concentration.

CONCLUSIONS

These data suggest that (-)-fTHF is not therapeutically superior to (+/-)-fTHF and that the latter is appropriate during combination chemotherapy with 5-FU/fTHF in patients with colorectal cancers.

Multivariate analysis of prognostic factors in patients with refractory and relapsed acute myeloid leukemia undergoing sequential high-dose cytosine arabinoside and mitoxantrone (S-HAM) salvage therapy: relevance of cytogenetic abnormalities

To improve the basis for the stratification of patients with refractory and relapsed acute myeloid leukemia (AML) univariate and multivariate analyses of prognostic factors were performed in 254 patients (median age 50 years, range 18-74) undergoing S-HAM salvage chemotherapy during two consecutive prospective trials of the German AML Cooperative Group. In a multivariate analysis, duration of the first complete remission (CR) was the only factor associated with time to treatment failure (P = 0.0223). Disease-free survival was influenced by a short duration of the first CR of less than 6 months (P = 0.0001), WBC (P = 0.0018), blast count (P = 0.0037), and neutrophil count (P = 0.0119). The achievement of CR was related to the hemoglobin level only (P = 0.0457), the early death rate was related to age only (P = 0.0109), and survival was related to the bilirubin level only (P = 0.0166). In the subgroup of 104 patients in whom additional karyotype analyses were performed prior to first-line therapy unfavorable chromosome abnormalities were associated with a lower CR rate (univariate analysis, P = 0.0342; CR 24% vs 53%) and were the only factor related to survival. These analyses warrant the further evaluation of the impact of cytogenetic abnormalities on the outcome of patients with advanced AML in order to improve the characterization according to duration of first CR and to WBC of distinct subgroups of patients with differing prognoses as a basis for stratification in future trials.

Management of acute myeloid leukemia in elderly patients

Acute myeloid leukemia (AML) at older age is associated with several biologic and clinical characteristics. Hence, it may arise from an early level of hematopoietic stem cells and has a high frequency of blast cells with multidrug resistance glycoprotein MDR1 expression and particularly a high incidence of poor prognostic karyotypes. These factors, rather than age per se, underlie the poorer outcome as compared with younger cases. Prospective randomized studies clearly demonstrate, however, that elderly patients benefit from more intensive induction therapy and particularly from full-dose application of anthracyclines and possibly also cytarabine. Hematopoietic growth factors accelerate the recovery from treatment-induced neutropenia and may improve the remission rate, remission duration, and even overall survival. New treatment strategies need to be developed, however, for poor-prognosis AML subtypes in order to further improve the therapeutic perspectives for elderly patients with AML.

Cytidine deaminase - the methodological relevance of AraC deamination for ex vivo experiments using cultured cell lines, fresh leukemic blasts, and normal bone marrow cells

The clinical effects of cytosine arabinoside (AraC) are highly dependent on schedule and dose. Many regimens administered to patients are derived from artificial model systems involving permanent leukemic cell lines. The differences in pharmacokinetics between the in vivo situation and such cell lines are largely neglected. However, cytidine deaminase activity in particular has a major impact on AraC pharmacokinetics by degrading AraC to its inactive metabolite AraU, and it has been shown to be of prognostic relevance in the treatment of acute myeloid leukemia. This study therefore investigated cytidine deaminase activities and AraC deamination in a variety of the most commonly used leukemic cell lines and fresh blasts and their impact on the results of an in vitro model system. It was found that cells from different cell lines (BLIN, CEM, HL60, K562, RAJI, REH, U937) vary greatly in cytidine deaminase activity (e.g., 1.89 nmol per min/mg in K562 versus 0.01 in BLIN cells) and degrade between 18.5 (BLIN) and 96.5% (REH) of AraC to AraU in the incubation medium. This degradation results in highly different AraC exposures for different cells (e.g., AUC of 960 ng per h/ml in REH versus 4048 ng per h/ml in BLIN cells) in spite of identical starting concentrations of the drug. Formation of AraCTP as the main cytotoxic metabolite of AraC is significantly influenced by the differences in cell type-dependent cytidine deaminase activity (e.g., 35.6 ng/10(7) cells in REH versus 180.2 ng/10(7) cells in BLIN cells). In contrast to permanent cell lines, fresh leukemic blasts and normal bone marrow mononuclear cells featured low AraC degradation in the model system.

Elevated serum leptin concentrations in type 2 diabetic patients with microalbuminuria and macroalbuminuria

Leptin levels are elevated in end-stage renal disease, suggesting an impairment of renal leptin degradation. The present study aimed to determine whether leptin levels are also elevated in patients with earlier stages of renal disease, ie, microalbuminuric and macroalbuminuric nephropathy. A total of 60 subjects were assigned to two study groups. Group A contained 10 type 2 diabetics with macroalbuminuria, 10 type 2 diabetics with normoalbuminuria, and 10 healthy control subjects. Group B contained 10 type 2 diabetics with microalbuminuria, 10 type 2 diabetics with normoalbuminuria, and 10 healthy controls. The subgroups of both study groups were matched for sex and body fatness. In group A, macroalbuminuric diabetic patients had higher serum leptin levels than the normoalbuminuric diabetics (11.90 +/- 2.98 v 4.13 +/- 0.92 ng/mL, P < .002) and control subjects (4.78 +/- 1.37 ng/mL, P < .006). In group B, microalbuminuric diabetics had higher serum leptin levels than the normoalbuminuric diabetics (21.16 +/- 5.80 v8.74 +/- 1.89 ng/mL, P < .04) and control subjects (10.06 + 3.00 ng/mL, P < .06). In both groups A and B, creatinine clearance was inversely correlated with the serum leptin level after adjusting for body fat. In conclusion, serum leptin levels are elevated in type 2 diabetic patients with microalbuminuria and macroalbuminuria, suggesting that renal leptin degradation is already impaired in the early stages of renal disease.

Supraphysiological hyperinsulinemia acutely increases hypothalamic-pituitary-adrenal secretory activity in humans

Hyperactivity of the hypothalamic-pituitary-adrenal (HPA) axis in association with hyperinsulinemia is frequently found in patients with type 1 and type 2 diabetes mellitus and in subjects with abdominal adiposity. We questioned whether insulin could cause HPA axis activation and, if so, whether this insulin action may arise at the adrenal level or at a central (i.e. hypothalamic-pituitary) level. Experiments lasting for 6 h each were done in 30 lean healthy men. In 15 men, insulin was infused at a rate of 1.5 mU min(-1) kg(-1). Plasma glucose concentration was held constant during an euglycemic clamp session and was decreased stepwise in a hypoglycemic clamp session. The sequence of the 2 clamp sessions was random, and a 4-weeks recovery period was allowed between the two sessions. The protocol was essentially the same in another 15 men, with the exception that insulin was infused at a rate of 15.0 mU min(-1) kg(-1). During the euglycemic clamp sessions, we found plasma ACTH levels to increase only in the high-, but not in the low-insulin group (group by time interaction, P < 0.01); serum cortisol levels were greater in the high than in the low-insulin group (P < 0.02). In the hypoglycemic clamp sessions, plasma ACTH levels increased in the same pattern in the 2 groups; serum cortisol was greater in the high than in the low-insulin group at the beginning of the clamp (plasma glucose approximately 4.1 mmol/L; P < 0.05). Our results demonstrate that insulin acutely stimulates the HPA secretory activity in humans. The pattern suggests an effect of insulin at both peripheral and central levels of the HPA axis.

Serum leptin is associated with serum uric acid concentrations in humans

This cross-sectional study aimed to evaluate the relationship between leptin and the cluster of abnormalities often referred to as the metabolic syndrome. The serum leptin concentration, body mass index (BMI), percent body fat, total fat mass (FM), waist and hip circumference, waist to hip ratio (WHR), prevalence of hypertension, and triglyceride (TG), lipoprotein, and uric acid concentration were determined in 86 type 2 diabetic (n = 59) and healthy (n = 27) subjects. Multiple regression analyses showed that the estimates of total body obesity (BMI, percent body fat, and total FM), sex, and serum uric acid concentration are independently associated with the serum leptin concentration. The finding of a positive correlation between serum leptin and uric acid levels suggests that leptin could be a pathogenic factor responsible for hyperuricemia in obesity.

[Glucocorticoid-induced diabetes mellitus in gastrointestinal diseases]

Glucocorticoid excess causes insulin resistance i.e. a reduced effectiveness of insulin to suppress hepatic glucose production and to increase glucose uptake in muscle and fat tissue. Persons who cannot compensate for the resulting additional insulin need develop overt diabetes during glucocorticoid therapy. In the field of gastroenterology, glucocorticoids are mainly employed for the therapy of chronic inflammatory bowel diseases, alcoholic and autoimmune hepatitis, and after liver transplantation. The risk of developing steroid diabetes depends among other things on the genetic predisposition, the body composition, the underlying gastrointestinal disease, the age, and the steroid dose. The treatment of glucocorticoid-induced diabetes resembles essentially the treatment of type 2-diabetes. In addition to dietary measures, oral antihypoglycemic drugs and/or insulin are applied. If oral antihypoglycemic drugs are used, specific problems that might result from the gastrointestinal diseases need to be observed. In the short and medium term, the prognosis of glucocorticoid-induced diabetes is good since it is well treatable. If glucocorticoid treatment is continued for a long time, the alterations of glucose metabolism and the resulting hyperinsulinemia may lead to increased cardiovascular risk.

Myelodysplastic syndrome with monosomy 7 after immunosuppressive therapy in Behçet's disease

Only few cases of Behçet's and hematological malignancies have been reported until now. We recently observed a 39-year-old female patient with Behçet's disease developing a myelodysplastic syndrome (MDS) FAB subtype refractory anemia with excess of blasts in transformation [RAEB-t] with a monosomy 7 after being treated with cyclosporin A and chlorambucil for several years. This case is reported and the occurrence of hematological malignancies and Behçet's disease is reviewed.

Protective effect of insulin against hypoglycemia-associated counterregulatory failure

Antecedent hypoglycemic episodes reduce the counterregulatory neuroendocrine response to hypoglycemia. The role of insulin in the mechanism responsible for the antecedent hypoglycemia causing subsequent counterregulatory failure has not been elucidated. We performed antecedent hypoglycemic clamps (56 mg/dL) lasting 2 h with differing degrees of hyperinsulinemia, which were followed by 6-h stepwise hypoglycemic clamps (76-66-56-46 mg/dL) on the next day. Experiments were carried out in 30 young, healthy men. Fifteen of these subjects were tested on 2 occasions. On 1 occasion the antecedent hypoglycemia was induced by insulin infusion at a rate of 1.5 mU/min x kg (low insulin-ante-hypo); on the other occasion the insulin infusion rate was 15.0 mU/min x kg (high insulin-ante-hypo). Both sessions were separated by at least 4 weeks, and their order was balanced across subjects. The remaining 15 subjects (control group) received the same stepwise hypoglycemic clamp as the other subjects, but without antecedent hypoglycemia. During the stepwise hypoglycemic clamp, the counterregulatory increases in ACTH, cortisol, and norepinephrine were significantly blunted after the low insulin-ante-hypo (P < 0.01, P < 0.05, and P < 0.05, respectively) but not after the high insulin-ante-hypo (P = 0.12, P = 0.92, and P = 0.19, respectively) compared to that in the control group. The cortisol, norepinephrine, and glucagon responses were greater after the high than after the low insulin-ante-hypo (all P < 0.05). In conclusion, the present study clearly demonstrates that even a single episode of mild hypoglycemia reduces neuroendocrine counterregulation 18-24 h later. Insulin has a moderate protective effect on subsequent counterregulation.

Leukaemic blasts differ from normal bone marrow mononuclear cells and CD34+ haemopoietic stem cells in their metabolism of cytosine arabinoside

Different metabolites of cytosine arabinoside (AraC) contribute to its cytotoxicity including incorporation of AraCTP into DNA, the incorporation of AraUMP into RNA, inhibition of polymerase alpha and beta (AraCMP/CTP), an impairment of repair mechanisms (AraCTP), alterations of phospholipid metabolism (AraCDP-choline), a direct membrane interaction (AraC), the alteration of signal transduction pathways (AraCDP-choline, AraCTP) and the induction of apoptosis. Since little is known about the potential differences in AraC metabolism between leukaemic blasts and normal haemopoietic progenitor cells, the formation of all known AraC metabolites was determined in bone marrow samples from patients with acute myeloid leukaemia (AML), healthy volunteers and specimens of cellsorted CD34+ haemopoietic stem cells. Highly significant differences were found for phosphorylated AraC metabolites (AraCMP, -CDP, -CTP, AraUMP) between AML and normal mononuclear bone marrow (ng/107 cells respectively 1.30 v 2.66; 2.65 v 7.50; 33.68 v 99.0; 1.18 v 5.70). The highest differences were found for formation of AraCDP-choline (3.75 v 12.86) which might be relevant for the high efficacy of high-dose AraC regimens. In contrast, no differences were found in the deamination product AraU (2.01 v 2.91). Only minute amounts of phosphorylated AraU derivatives were detected, providing an explanation for the lacking contribution of AraU to cytosine arabinoside cytotoxicity. Results in normal CD34+ haemopoietic stem cells did not differ significantly from normal bone marrow mononuclear cells and therefore justify their use as a surrogate in determining AraC-induced haematotoxicity. These data suggest a metabolic basis for the relative selectivity of AraC cytotoxicity for AML blasts and provide a means to determine the role of different metabolites and their related mechanism of action for overall AraC cytotoxicity.

Oxaliplatin pharmacokinetics during a four-hour infusion

A new platin compound, oxaliplatin, has significant activity in advanced colorectal carcinomas. However, its pharmacokinetics have not been characterized adequately yet. This study extensively analyzes the pharmacokinetics of both ultrafiltrable (free) and protein-bound platin in 13 patients receiving 130 mg/m2 oxaliplatin as a 4-h infusion in combination with 375 mg/m2 5-fluorouracil as a 24-h infusion for advanced colorectal carcinomas. The interpatient variability was very low for all parameters analyzed. The levels of free platin decreased triphasically, with a mean terminal half-life of 27.3+/-10.6 h. The area under the time-concentration curve was 20.17+/-6.97 microg.h/ml and the total and renal clearances amounted to 222+/-65 and 121+/-56 ml/min, respectively. The values for the volume of distribution and for the maximum concentration at the end of infusion were 349+/-132 liters and 1612+/-553 ng/ml, respectively. On the basis of the simulation of the plasma levels and the urinary excretion of platin following the long-term administration of oxaliplatin as a constant-rate and a chronomodulated infusion, additional analyses are warranted to fully characterize the pharmacokinetics of the drug in these settings.

Central nervous system effects of intranasally administered insulin during euglycemia in men

Insulin receptors have been detected in several structures of the brain, yet the biological significance of insulin acting on the brain remains rather unclear. In humans, direct central nervous effects of insulin are difficult to distinguish from alterations in neuronal functions because of insulin-induced decrease in blood glucose levels. Since several intranasally administered viruses, peptides, and hormones have been shown to penetrate directly from the nose to the brain, we tested whether insulin after intranasal administration likewise has access to the brain. After a 60-min baseline period, insulin (20 IU H-Insulin 100 Hoechst) or vehicle (2.7 mg/ml m-Cresol) was intranasally administered every 15 min to 18 healthy subjects according to a double-blind within-subject crossover design. Auditory-evoked potentials (AEP) indexing cortical sensory processing were recorded while the subjects performed a vigilance task (oddball paradigm) during the baseline phase and after 60 min of intranasal treatment with insulin or placebo. Blood glucose and serum insulin levels were not affected by intranasal insulin. Compared with placebo, intranasal administration of insulin reduced amplitudes of the N1 (P < 0.005) and P3 (P < 0.02) components of the AEP and increased P3 latency (P < 0.05). The reduction in P3 amplitude was most pronounced over the frontal recording site (2.42 +/- 1.00 vs. 4.92 +/- 0.79 microV, P < 0.0005). At this site, after insulin administration, a broad negative shift developed in the AEP between 280 and 500 ms poststimulus (area under the curve -166.0 +/- 183.8 vs. 270.8 +/- 138.7 microV x ms after placebo, P < 0.01). The results suggest that after intranasal administration, insulin directly enters the brain and exerts distinct influences on central nervous functions in humans.