Histamine and tryptase modulate asthmatic airway smooth muscle GM-CSF and RANTES release.

Degranulating mast cells are increased in the airway smooth muscle (ASM) of asthmatics, where they may influence ASM function. The aim of the present study was to determine whether histamine and tryptase modulate ASM cell granulocyte-macrophage colony-stimulating factor (GM-CSF) and RANTES (regulated on activation, normal T-cell expressed and secreted) release and also to examine which receptors are involved in this release. Confluent, quiescent ASM cells from asthmatic and nonasthmatic donors were treated with histamine (1 microM-100 microM) with and without histamine receptor antagonist pre-treatment, or the protease-activated receptor (PAR)-2 agonists tryptase (0.5-5 nM) and SLIGKV (100 and 400 microM). The cells were then stimulated with interleukin (IL)-1beta and/or tumour necrosis factor (TNF)-alpha (10 ng.mL(-1)) or left unstimulated for 24 h. Release of GM-CSF and RANTES was determined by ELISA and prostaglandin (PG)E(2) measured by enzyme immunoassay. Neither histamine nor tryptase induced ASM GM-CSF or RANTES secretion. However, histamine increased IL-1beta-induced GM-CSF release and markedly reduced TNF-alpha-induced RANTES release by both asthmatic and nonasthmatic cells to a similar extent, but did not modulate PGE(2) release. All changes involved activation of the histamine H1 receptor as they were partially or fully blocked by chlorpheniramine, but not ranitidine. Tryptase, via its proteolytic activity, also potentiated GM-CSF, but not RANTES, release from asthmatic and nonasthmatic ASM cells induced by both cytokines. PAR-2 involvement in the tryptase potentiation was unlikely because SLIGKV had no effect. In conclusion, mast cells, through histamine and tryptase, may locally modulate airway smooth muscle-induced inflammation in asthma.     

Epicardial distribution of ST segment and T wave changes produced by stimulation of intrathoracic ganglia or cardiopulmonary nerves in dogs

Sixty-three ventricular epicardial electrograms were recorded simultaneously in 8 atropinized dogs during stimulation of acutely decentralized intrathoracic autonomic ganglia or cardiopulmonary nerves. Three variables were measured: (1) isochronal maps representing the epicardial activation sequence, (2) maps depicting changes in areas under the QRS complex and T wave (regional inhomogeneity of repolarization), and (3) local and total QT intervals. Neural stimulations did not alter the activation sequence but induced changes in the magnitude and polarity of the ST segments and T waves as well as in QRST areas. Stimulation of the same neural structure in different dogs induced electrical changes with different amplitudes and in different regions of the ventricles, except for the ventral lateral cardiopulmonary nerve which usually affected the dorsal wall of the left ventricle. Greatest changes occurred when the right recurrent, left intermediate medial, left caudal pole, left ventral lateral cardiopulmonary nerves and stellate ganglia were stimulated. Local QT durations either decreased or did not change, whereas total QT duration as measured using a root-mean-square signal did not change, indicating the regional nature of repolarization changes. Taken together, these data indicate that intrathoracic efferent sympathetic neurons can induce regional inhomogeneity of repolarization without prolonging the total QT interval.     

Continuous warm blood cardioplegia preserves cardiac autonomic function.

We studied in anesthetized dogs, the effects of cardiopulmonary bypass with normothermic whole blood, crossclamping of the aortic root, and continuous warm blood cardioplegia on the ability of the efferent sympathetic nervous system to augment the heart and that of the efferent parasympathetic nervous system to depress the heart. In control states, heart rate, atrial force of contraction, and right and left ventricular wall systolic pressures were augmented by stimulation of the intrathoracic efferent sympathetic nervous system and by administration of isoproterenol into the systemic circulation. After 1 hour of normothermic cardiopulmonary bypass that utilized aortic crossclamping and continuous perfusion of the coronary arteries with normothermic blood (20 mEq/L potassium), cardiac-augmenting effects induced by the efferent sympathetic nervous system and by isoproterenol were similar. Depressive responses elicited by the efferent parasympathetic nervous system were also unaffected by these procedures. Continuous warm blood cardioplegia does not result in impairment of the efferent sympathetic nervous system regulating the heart.     

Vigabatrin in adults with poorly-controlled epilepsy and learning disabilities.

Twenty-two adult patients with uncontrolled epilepsy and severe learning difficulties were included in an open study of vigabatrin. Patients were all in residential care and had experienced at least 12 seizures during the previous 12 months despite all attempts to optimize antiepileptic drug (AED) treatment. Following a 4 month baseline period, vigabatrin 500 mg twice daily was added to the current AED treatment and the dose increased according to response, up to a maximum of 4 g/day. Ten patients achieved a reduction in seizure frequency of more than 50% during this 4 month dose titration phase. Two patients had no seizures during the baseline period. For the 30 patients with seizures during the baseline period the median improvement in seizure frequency with the addition of vigabatrin was 49% (P = 0.014). The response rate was higher for patients with partial seizures than for those with generalized seizures. Ten patients continued with vigabatrin while the dose of one of their other AEDs was gradually reduced and successfully withdrawn in three patients. Adverse events were reported in 20 patients during the 64 week study period. The most frequently reported events were sedation (8 patients), aggression (4 patients), agitation (3 patients) and ataxia (3 patients). No patients were withdrawn from the study as a consequence of adverse events. Vigabatrin was therefore an effective add-on therapy in 45% of these difficult-to-treat patients and allowed reduction of other AED treatment in a small number.     

Neurokinin A with K channel blockade potentiates contraction to electrical stimulation in human bronchus

This study investigated the effects of neurokinin A (NKA) on cholinergic neural responses in human bronchus. NKA (0.1 nM) did not alter the contractile response to submaximal electrical field stimulation. However, K⁺ channel blockade with 4-aminopyridine (4-AP) (0.1 mM) potentiated the response to electrical field stimulation (to 182 ± 25% of control, n = 4, P < 0.05) and subsequent addition of NKA in the presence of 4-AP produced further potentiation (to 123 ± 6% of the response to 4-AP n = 4, P < 0.05). Neither 4-AP (0.01 or 0.1 mM) nor NKA in the presence of 4-AP potentiated the actions of exogenous acetylcholine but in these experiments 4-AP itself produced a marked direct contractile response. Thus NKA in the presence of K⁺ channel blockade potentiates cholinergic neural response in human bronchus and this occurs at a prejunctional site.     

Reduction of plasma insulin levels does not restore integrated concentration of growth hormone to normal in obese children.

Obesity in childhood is characterized by subnormal integrated concentrations of growth hormone (IC-GH) and elevated integrated concentrations of insulin (IC-I). We tested whether a reduction of IC-I induced by a low calorie diet would lead to a rise of IC-GH into the normal range for age. Six obese children (body mass index (BMI) 39.1 +/- 9.2 kg/m2) underwent integrated concentration (IC) studies by continuous withdrawal before and again 5-8 weeks after being on a low calorie diet. In response to the diet BMI was lower 34.7 +/- 9.4 kg/m2 (P less than 0.003), and IC-I was considerably reduced, 479 +/- 255 pM initially vs. 109 +/- 109 pM on the diet, P less than 0.0008. IC-GH increased modestly from 1.6 +/- 0.6 micrograms/l initially to 2.4 +/- 0.6 micrograms/l, P less than 0.01 on the diet. None of the patients had repeat IC-GH levels which were above the lower limit of normal for lean children of normal stature (3.2 micrograms/l). Single sample insulin-like growth factor 1 (IGF-1) levels were unchanged: 40.9 +/- 23.1 nM initially vs. 49.7 +/- 25.7 nM (314.6 +/- 197.7 vs. 382.5 +/- 217.0 ng/ml, n.s.). Thus reduction of high insulin concentrations during 5-8 weeks of a low calorie diet has only a small effect on IC-GH in obese children. Factors other than circulating insulin levels are likely to play the major role in mediating the reduced levels of GH observed in obesity.     

Tumor vascular signals in renal masses: detection with Doppler US

The vascularity of 49 renal masses (26 malignant and 23 benign lesions) was investigated with duplex Doppler ultrasound. Doppler signals obtained at the margins of renal masses were defined as "tumor signals" when the Doppler-shifted frequency of the lesion exceeded the frequency shift in the ipsilateral main renal artery. These exceeded 2.5 kHz with a 3-MHz insonating frequency. Among the 26 renal masses that subsequently proved to be malignant, tumor signals were obtained in 15 of 18 (83%) untreated renal cell carcinomas, in three of four Wilms tumors, and in two patients with metastases to the kidney, but not in the one patient with lymphoma. None of the 23 benign renal masses demonstrated tumor signals. Tumor vascularity in malignant lesions gives rise to abnormal, high-velocity, Doppler-shifted signals that can help in the differential diagnosis of renal masses.     

The herpes simplex virus type 1 Fc receptor discriminates between IgG1 allotypes

Herpes simplex virus type 1 (HSV-1) expresses a complex of two virally encoded glycoproteins, gE and gl, which is capable of binding nonimmune human IgG. The gE-gl complex has thus become known as an Fc receptor (FcR), which reportedly binds human IgG subclasses in the order IgG4 > IgG1 > or = IgG2 and does not bind IgG3 from many individuals. There is, however, allelic variation in the genes encoding the human IgG1 heavy chain constant region and this gives rise to allotypes of IgG1. Using recombinant monoclonal IgG molecules of known isotype and mutants thereof we have unexpectedly discovered that the HSV-1 FcR discriminates between IgG1 allotypes. This is evidence of functional differences between IgG1 allotypes that may account for their distribution in populations. Furthermore, these findings suggest HSV-1 FcR binding sites on the IgG molecule some distance from the proposed binding site in the CH2-CH3 domain interface.