Structure-activity studies on bradykinin and related peptides: agonists.

1. Bradykinin, kallidin, T-kinin, [Hyp3]-bradykinin and several analogues were prepared by solid-phase synthesis and purified by high performance liquid chromatography. 2. The various peptides were tested for their abilities to relax the dog carotid and renal arteries, or to contract the rabbit jugular vein and aorta, in order to measure their activities on BK2 (the first three preparations) or BK1 (the rabbit aorta) receptors. The dog renal artery without endothelium was also used as a BK1 receptor system. 3. T-kinin was found to be less active than bradykinin, while the replacement of Pro3 with Hyp favoured BK2 receptor occupation. [Hyp3,Tyr(Me)8]-BK was found to be a selective BK2 receptor agonist. 4. Amidation or methylation of the C-terminal carboxyl decreased activity, while extension of the N-terminal with Sar or D-Arg increased affinity and selectivity for BK1 (Sar) and affinity for BK2 (D-Arg) receptors. Acetylation of N-terminal amide brought affinity down to 10% or less. 5. Replacement of the peptide bonds Phe8-Arg9 to protect from kininase I and II, decreased affinities slightly, but was incompatible with additional changes at the N-terminal or in the peptide bond Gly4-Phe5. 6. Substitution of C-terminal Phe in desArg9-BK (the BK1 receptor stimulant) with D-Phe increased potency and selectivity for BK1 receptors while protecting from carboxypeptidases. Sar[D-Phe8]desArg9-BK was found to be a potent and selective BK1 receptor agonist.     

Importance of plasmapheresis in the treatment of paraneoplastic cerebellar degeneration

Paraneoplastic neurologic syndromes are disorders of the nervous system function caused by cancer but not due to metastatic disease, vascular or metabolic deficits, infections, nutritive deficiency, nor side effects of antineoplastic drugs or irradiation. Immunologic factors probably play the crucial role in the pathogenesis of paraneoplastic neurologic syndromes, but nonimmunologic mechanisms that include metabolic abnormalities and competition for substrate are also involved. Paraneoplastic cerebellar degeneration most commonly occurs in the setting of gynecologic cancers, but it accompanies the small-cell lung cancer too. Other tumors are infrequently associated with cerebellar degeneration. Several paraneoplastic antibodies have been identified in patients with paraneoplastic cerebellar degeneration. Their association with particular cancers may help identify an occult lesion. Anti-Yo antibodies are directed against Purkinje cell antigens and occur in patients with cerebellar degeneration who have breast cancer or gynecologic tumors. A target antigen of anti-Yo antibody is CDR2 protein that is normally expressed only in the brain and testis. Patients with paraneoplastic cerebellar degeneration present with dizziness, nausea and vomiting followed by gait instability, diplopia, gait and appendicular ataxia, dysarthria and dysphagia. Therapeutic options include tumor excision, chemotherapy and/or irradiation, and adjuvant therapy with glucocorticoids, immunoglobulins and plasmapheresis. The role of plasmapheresis in the treatment of paraneoplastic cerebellar degeneration is still uncertain. Reports of its efficacy are anecdotal. We present patient with paraneoplastic cerebellar degeneration with positive anti-Yo antibodies and tumor of the ovaries whose neurologic status significantly improved after four daily plasmaphereses, which was accompanied by a fourfold decrease in the anti-Yo antibodies titer. Further investigations are needed to define a protocol for plasmapheresis in the treatment of patients with paraneoplastic syndromes.     

Is There Association between Altered Adrenergic System Activity and Microvascular Endothelial Dysfunction Induced by a 7-Day High Salt Intake in Young Healthy Individuals

This study aimed to test the effect of a 7-day high-salt (HS) diet on autonomic nervous system (ANS) activity in young healthy individuals and modulation of ANS on microvascular endothelial function impairment. 47 young healthy individuals took 7-day low-salt (LS) diet (3.5 g salt/day) followed by 7-day high-salt (HS) diet (~14.7 g salt/day). ANS activity was assessed by 24-h urine catecholamine excretion and 5-min heart rate variability (HRV). Skin post-occlusive reactive hyperemia (PORH) and acetylcholine-induced dilation (AChID) were assessed by laser Doppler flowmetry (LDF). Separately, mental stress test (MST) at LS and HS condition was conducted, followed by immediate measurement of plasma metanephrines’ level, 5-min HRV and LDF microvascular reactivity. Noradrenaline, metanephrine and normetanephrine level, low-frequency (LF) HRV and PORH and AChID significantly decreased following HS compared to LS. MST at HS condition tended to increase HRV LF/HF ratio. Spectral analysis of PORH signal, and AChID measurement showed that MST did not significantly affect impaired endothelium-dependent vasodilation due to HS loading. In this case, 7-day HS diet suppressed sympathetic nervous system (SNS) activity, and attenuated microvascular reactivity in salt-resistant normotensive individuals. Suppression of SNS during HS loading represents a physiological response, rather than direct pathophysiological mechanism by which HS diet affects microvascular endothelial function in young healthy individuals.     

The Effect of Tobacco Smoking on Salivation

Aim

The purpose of this study was to examine the detrimental effect of smoking on the function of the salivary glands.

Material and Methods

The study was conducted on 60 patients who were divided into two groups: a test group which included smokers and control group represented by non-smokers. Each group included 30 patients. General information was collected from all the respondents via a questionnaire as well as the data on the duration of smoking and number of cigarettes smoked per day. Saliva was collected by spitting method in a graduated tube and the amount of unstimulated and stimulated saliva was measured and recorded in ml per minute. Stimulated saliva was collected immediately after rinsing the mouth with a 2% aqueous solution of citric acid which is carried salivary stimulation. The presence of pigmentation on the teeth and coated tongue were recorded during clinical examination. The degree of oral hygiene was determined by plaque index. All the obtained data were statistically analyzed with significance level p <0.05.

Results

The results showed no significant differences in the amount of saliva between smokers and non-smokers, however, the amount of saliva decreases significantly with the duration of smoking and increasing age of smokers. Also proven was the difference in the quality of saliva: smokers have thick saliva and nonsmokers predominantly serous. In addition, smokers have poorer oral hygiene status than non-smokers, and demonstrated a positive correlation between the level of oral hygiene and length of smoking tobacco.

Conclusion

This study has proven that smoking adversely affects salivation: long-term smoking reduces the secretion of saliva and changes its quality.Key words: Smoking, Tobacco Use Disorder, Saliva, Salivation, Xerostomia     

Selective silencing of DNA-specific B lymphocytes delays lupus activity in MRL/lpr mice

The pathological DNA-specific B lymphocytes in lupus are logical targets for a selected therapeutic intervention. We have hypothesized that it should be possible to suppress selectively the activity of these B cells in lupus mice by administering to them an artificial molecule that cross-links their surface immunoglobulins with the inhibitory FcgammaIIb surface receptors. A hybrid molecule was constructed by coupling the DNA-mimicking DWEYSVWLSN peptide to a monoclonal anti-mouse FcgammaRIIb antibody. This chimeric antibody was added to cultured spleen cells from sick MRL/lpr mice, immunized with diphtheria toxoid, resulting in reduction of the numbers of anti-DNA but not of anti-diphtheria IgG antibody-producing cells. Intravenous infusions with the DNA-peptide antibody chimera to 7-wk-old animals prevented the appearance of IgG anti-DNA antibodies and of albuminuria in the next 2 months. The administration of the DNA-peptide chimeric antibody to 18 wk-old mice with full-blown disease resulted in the maintenance of a flat level of IgG anti-DNA antibodies and in delay of the aggravation of the lupus glomerulonephritis. The use of chimeric antibodies targeting inhibitory B lymphocyte receptors represents a novel approach for the selective suppression of autoreactive disease-associated B cells in autoimmune diseases.     

Effects of fulminant hepatic encephalopathy on the adult rat brain antioxidant status and the activities of acetylcholinesterase, (Na+,K+)- and Mg2+-ATPase: comparison of the enzymes’ response to in vitro treatment with ammonia

Hepatic encephalopathy can be a life-threatening complication of fulminant hepatic failure. By understanding the pathophysiology involved in the induction of this neuropsychiatric disorder, future therapeutic and/or preventive attempts could be considered. In this study, an attempt has been made in order to shed more light on the mechanisms involved in the effects of thioacetamide (TAA)-induced fulminant hepatic encephalopathy on: (a) the adult rat brain total antioxidant status (TAS) and (b) the activities of acetylcholinesterase (AChE), (Na(+),K(+))-ATPase and Mg(2+)-ATPase. Moreover, in vitro experiments were conducted in order to evaluate the possible role of ammonia (incubated as NH(4)Cl, in a toxic concentration of 3mM) in the observed effects of TAA-induced fulminant hepatic encephalopathy on the examined adult rat brain enzyme activities. Fulminant hepatic encephalopathy caused a significant decrease in TAS (-22%, p < 0.001) and the activity of Na(+),K(+)-ATPase (-26%, p < 0.001), but had non-significant effects on the whole brain AChE and Mg(2+)-ATPase activities. The in vitro experiments (conducted through a 3h incubation with ammonia), showed no significant alterations in any of the examined parameters. Our in vitro and in vivo findings suggest that alterations in AChE and Mg(2+)-ATPase activities are not involved in the pathophysiology of the adult-onset fulminant hepatic encephalopathy, while the observed Na(+),K(+)-ATPase inhibition could be a result of the oxidative stress, neurotransmission deregulation, and/or of the presence of other toxic substances (that appear to act as direct or indirect inhibitors of the enzyme) and not due to the excess accumulation of ammonia in the brain.