Enhancement of benzodiazepine binding sites following chronic treatment with flumazenil

The aim of this study was to improve our knowledge of the mechanisms leading to adaptive changes in gamma-aminobutyric acid(A) (GABA(A)) receptors following chronic drug treatment. Exposure (48 h) of human embryonic kidney (HEK 293) cells stably expressing recombinant alpha1beta2gamma2S GABA(A) receptors to the antagonist of benzodiazepine binding sites, flumazenil (5 microM), enhanced the maximum number (B(max)) and the equilibrium dissociation constant (K(d)) of [3H]flunitrazepam binding sites. The flumazenil-induced enhancement in B(max) was potentiated by GABA (50 microM) and reduced by the GABA(A) receptor antagonist, bicuculline (100 microM). Flumazenil-induced enhancement in K(d) was affected by neither of these treatments. GABA (50 microM) enhanced the density of [3H]flunitrazepam binding sites, and this enhancement was greater in the presence of diazepam (1 microM). The results suggest that chronic flumazenil treatment up-regulates in a bicuculline-sensitive manner benzodiazepine binding sites at stably expressed GABA(A) receptors.     

The presence of surface CD30 on T cells in atopic dermatitis

Atopic dermatitis (AD) has cellular immunohistochemical features similar to those of allergic contact dermatitis (ACD) and there is plenty of evidence for T-cell activation in this disease. The involvement of CD30+ T cells in acute stages of atopic dermatitis might establish CD30 as a helpful marker in differentiating those two diseases. Tissue sections from the skin of 12 patients with active atopic dermatitis and 13 with allergic contact (nickel-induced) dermatitis were immunohistochemically analyzed for cell-surface antigens, including CD30, CD3, CD4, and CD45RO. The severity of the disease was graded by the SCORAD clinical scoring system. The analysis of CD30+, CD45RO+, CD3+, and CD4+ cells in the dermis and epidermis showed a much wider range of values and statistically higher median (p<0.01) in the inflammatory infiltrate of acute atopic dermatitis compared with that of allergic contact dermatitis. Our results showed an association of CD30 expression with atopic dermatitis, but not allergic contact dermatitis. CD30 expression in AD might be helpful in histologic differentiation of these disorders and further characterization of atopy patch testing. The results suggested a specific regulatory function of CD30+ T cells in acute AD. Abundant CD45R0+ cells were detected in both AD and ACD lesions.     

Growth hormone and epidermal growth factor together enhance amino acid transport systems B(0,+) and A in remnant small intestine after massive enterectomy

BACKGROUND: Sodium-dependent brush border nutrient transport is decreased 2 weeks after massive enterectomy. This downregulation is ameliorated by a 1-week infusion of parenteral growth hormone (GH) and epidermal growth factor (EGF) started 1 week after resection. We hypothesized that glutamine (GLN) transport would be enhanced by earlier and longer growth factor infusion, with differential effects on the Na(+)-dependent GLN transport systems A, B(0,+), and B0/ASCT2. MATERIALS AND METHODS: New Zealand White rabbits underwent 70% small bowel resection then immediately received parenteral EGF, GH, both, or neither for 2 weeks. Na(+)-dependent 3H-GLN uptake by jejunal and ileal brush-border membrane vesicles was measured and the contribution of systems A, B(0,+), and B0 then determined by competitive inhibition. Data were analyzed using one-way analysis of variance. RESULTS: In nonresected animals, the relative contribution of the systems was similar in jejunum (A, 9%, B(0,+), 20%; and B0, 71%) and ileum (A, 13%; B(0,+), 27%; and B0, 60%). Na(+)-dependent GLN uptake was reduced by half in resected, untreated controls, primarily because of decreased B(0) activity. EGF or GH alone did not affect Na(+)-dependent GLN transport, but as a combination, increased uptake in the residual ileum and jejunum by 144% and 150%, respectively, over resected controls (P<0.05). This was twice that achieved by delayed and shorter-duration combination treatment. This augmentation was due to a 6.1- to 8.2-fold increase in system A as well as a 3.8- to 3.9-fold enhancement of system B(0,+) activity in remnant ileum and jejunum (P<0.01). CONCLUSIONS: Parenteral EGF and GH, given in combination for 2 weeks immediately after massive enterectomy, synergistically enhance GLN uptake by systems A and B(0,+).     

The Impact of Systemic Vasoconstrictors on the Cerebral Circulation of Anesthetized Patients

Background: The effect of vasoconstrictors on intracerebral hemodynamics in anesthetized patients is controversial. The influence of phenylephrine and norepinephrine on the cerebral circulation was investigated in isoflurane- or propofol-anesthetized patients using transcranial Doppler ultrasonography.

Methods: Forty patients were randomly assigned to have vasoconstrictor tests with norepinephrine or phenylephrine during either isoflurane or propofol anesthesia. Blood flow velocities were simultaneously measured in the middle cerebral artery and ipsilateral extracranial internal carotid artery. Baseline recordings were done during stable anesthesia in a supine position (test 0). A second series of measurements were performed after norepinephrine or phenylephrine had increased mean arterial blood pressure by about 20% (test 1). With maintained norepinephrine or phenylephrine infusion, a final series of results were obtained after the increased mean arterial blood pressure was counteracted by a slightly head-up patient position (test 2).

Results: Both vasoconstrictors significantly increased mean flow velocities in the middle cerebral artery (norepinephrine: 43 +/- 11 cm/s to 49 +/- 11 cm/s; phenylephrine: 43 +/- 8 cm/s to 48 +/- 9 cm/s; +/- SD) and internal carotid artery (norepinephrine: 27 +/- 7 cm/s to 31 +/- 8 cm/s; phenylephrine: 27 +/- 9 cm/s to 31 +/- 10 cm/s) in the isoflurane-but not in the propofol-anesthetized patients. In the head-up position, only small and insignificant flow velocity changes were observed in both cerebral arteries independent of the vasoconstrictor or background anesthetic.     

Diazenecarboxamide UP-91, a potential anticancer agent,acts by reducing cellular glutathione content

Glutathione (GSH) is a ubiquitous non-protein thiol essential for cellular homeostasis and protection. Diazenecarboxamides (diazenes) are new compounds that could, according to their biochemical properties, lower the intracellular GSH content, thus inhibiting the growth of tumour cells. In the present study we examined four such compounds: JK-914, JK-918, JK-1013 and UP-91. Their cytotoxic effect on the growth of eight human tumour cell lines (glioblastoma, cervical and laryngeal carcinoma cells, mammary carcinoma cells and four drug-resistant sublines) was determined using a modified colorimetric MTT assay. The rate of reaction of thiophenol (as a model thiol) with diazenes leading to diphenyl disulfide was established by chromatography (TLC). Reactivity of diazenes with GSH under quasi-physiological conditions was determined by NMR spectroscopy. Intracellular GSH content was examined spectrophotometrically by the procedure developed by Tietze (1969). Diazene UP-91 reduced significantly the cell survival of all eight examined cell lines, including four drug-resistant cell lines. Other diazenes did not influence the survival of tumour cells. Reaction time for quantitative conversion of thiophenol to diphenyl disulfide was shortest for diazene UP-91, which is highly consistent with high reactivity of the same diazene with GSH, observed under quasi-physiological conditions. UP-91 reduced intracellular GSH level, while other diazenes had no effect on it. Thus, diazenecarboxamides UP-91 is a potential anticancer agent that may inhibit the growth of tumour cells due to reduction in glutathione level.     

Reflections on the development of health care and patients' rights in Croatia

Nowadays, in the world of markets and market economy, not only health care but medicine and medical practice in general, are looked upon more and more through the eyes of profit-making and financial interests. At the same time, there is an increasing number of initiatives intended to emphasise that human medicine should be at the service of society and that this fact should have priority over any market and financial interests of individuals even in "the market oriented world". The experience of the Croatian non-governmental organization to which the authors belong and which deals with patients' rights and helps in the development of partnership relations between patients and other subjects in the health care system, can be of a wider interest. This short review is the result of eight years' experience of the Croatian Association for Patients' Rights (CAPR), and its possible effects on the health care system in the future from the authors' points of view.     

The optimal pediatric induction dose of propofol in combination with reduced-dose rocuronium and alfentanil for day-case tonsillectomy in children

OBJECTIVE: Tonsillectomy in children may be performed on a day-case basis. To achieve quality anesthesia and successful, fast recovery with minimal morbidity without the use of volatile anesthetic, the choice of drug combination has to be centered on one rapid- and short-acting hypnotic, opioid and non-depolarizing muscle relaxant. The aim of our study was to determine the optimal pediatric induction dose of propofol that by means of alfentanil and reduced-dose rocuronium allows the highest percentage of excellent intubating conditions. METHODS: One hundred and eleven children were randomized in three equal groups and included in prospective, double blind study. Anesthesia was induced with 2.0 (Group A), 2.5 (Group B) or 3.0 mg kg(-1) (Group C) of propofol proceeded by alfentanil (0.02 mg kg(-1)). Muscle relaxation was achieved with reduced-dose rocuronium (1.5x ED(95)) (0.45 mg kg(-1)). The intubating conditions were assessed using the four-point scoring system based on the difficulty of laryngoscopy, presence of vocal cord movement and the intensity of coughing. Neuromuscular transmission was monitored by means of acceleromyography with supramaximal train-of-four stimulation of the ulnar nerve by the frequency of 1Hz. RESULTS: Adequate intubating conditions were achieved in high percentages in all study groups (A = 94%, B = 95%, C = 98%) (P = 0.352). Significant higher differences of excellent and good intubating conditions, attributed to quality of laryngoscopy, movement of the vocal cords and intensity of coughing were observed in Group C (excellent = 94%, good = 4%) (B = excellent 80%, good = 18% and A = excellent 47%, good = 47%) (P = 0.0001). MAP decrease of 12% from the baseline occurred immediately only after 3.0 mg kg(-1) induction dose of propofol (80+/-7 mm Hg; A = 92 +/- 6, B = 88 +/- 9) (P = 0.005). CONCLUSIONS: Induction dose of 2.5 mg kg(-1) of propofol preceded by 0.02 mg kg(-1) of alfentanil in addition to reduced-dose rocuronium (0.45 mg kg(-1)) is the optimal pediatric induction dose of propofol for improving the most excellent intubating conditions without significant hemodynamic changes.     

Tryptophan content in serum and brain of long-term insulin-treated diabetic rats

Summary The metabolism of tryptophan (TRP) was studied in diabetic and insulin-treated diabetic rats throughout a five-month period. In alloxan diabetic rats the serum and brain TRP levels were decreased (serum: 38 to 48 mmol/l, brain: 8.6 to 9.2 mmol/g) in comparison to the values of control rats (serum: 59 to 64 mmol/l, brain: 11.3 to 12.6 mmol/g). Daily long-term (for 45, 75, 90 or 135 days) treatment with intermediatly acting insulin (4 IU/rat, s.c.) was not able to restore brain concentration of TRP. On the contrary, the serum TRP concentrations were totally or partially restored. The concentrations of branched chain amino acids (BCAA) were increased in serum (valine=361.2 to 461.0 μmol/l or leucine + isoleucine=431.0 to 520.3 μmol/l) through-out the entire five-month examination period. Insulin treatment did not return serum concentration of BCAA to normal level in the observation period either.