Induction of complement resistance in cloned pathogenic Entamoeba histolytica

The lytic effect of complement activated through the alternative pathway (AP) was studied on pathogenic and nonpathogenic Entamoeba histolytica recently isolated from stool samples. Recent nonpathogenic isolates were nearly unaffected by exposure to AP whereas recent pathogenic stool isolates were highly susceptible to AP dependent complement-mediated lysis. Complement susceptible pathogenic stool isolates developed complement resistance in vivo during hamster liver passage and in vitro during cultivation in the presence of increasing concentrations of normal human serum (NHS). Since a clone of pathogenic HM-l.IMSS which initially was highly susceptible also acquired complement resistance during cultivation in the presence of NHS, it is concluded that complement resistance was caused by induction rather than by selection alone. Because cultivation in the presence of heat-inactivated NHS did not affect complement susceptibility of the cloned HM-l.IMSS, complement activation itself might induce complement resistance in pathogenic E. histolytica.     

Suicide attempts versus suicidal ideation in bulimic female adolescents

BACKGROUND: Suicide attempts by adolescents continue to be a major public health problem. The purpose of this study was to examine the difference in the family functioning and sociopsychopathological risk factor relationship between female bulimic adolescents with suicidal ideation only, and those who attempted suicide. METHODS: A group of 211 patients were observed for 12 months. Data from 63 subjects (SUG [suicide group], age 17.2 +/- 1.3 years) who had attempted suicide were then compared with 148 (control group, age 18.1 +/- 1.5 years) who had expressed suicidal ideation but did not follow through. RESULTS: Those in the suicide attempt group had been exposed more frequently to physical/sexual violence in childhood. As adults they either lived alone or were dissatisfied with their partnership. The frequency of borderline personality disorders and depressive disorders in this group was significant. Psychosomatic symptoms, disturbed coenesthesia, substance abuse, social impairment and interference with their perception of their own life circumstances, as well as their job performance, often preceded the suicide attempt. Nine genuine risk factors that occurred significantly more often in the SUG were calculated out of all the stress factors using stepwise logistic regression: 'as a child I was even hit with a stick or whip', 'I had no set orientation in life', 'I had a feeling of loneliness despite family and friends', 'I could not relax', 'incapable of dealing with the public', 'I do not like to be touched', 'parents have psychiatric disorders', 'misuse of stimulants', and 'as a child I felt lonely' (odds ratio, 10.56-1.90). CONCLUSION: Adverse family experiences and multiple sociopsychopathological factors may increase the risk of suicide in female bulimic adolescents.     

Cerebral processing of words and the development of chronic pain

The processing of pain-related, body-related, and neutral words was assessed in individuals with prechronic pain and matched healthy controls. Integrated surface electromyogram, heart rate, skin conductance level, and visual event-related potentials from 11 electrode sites were recorded during the presentation of three word types at perception threshold. Startle responses were recorded from words presented above perception threshold. The patient and control groups did not differ in recognition performance. Pain-related words evoked an enhanced early component (N100) of the visual event-related potential only in the prechronic pain group. In both groups the late slow wave and the startle response were enhanced for body- and pain-related words compared with those for neutral words. All word types elicited larger late positivities in the prechronic pain group and in the right compared with the left hemisphere. These data suggest differential cortical processing of pain-related material in persons at a prechronic pain stage.     

Suppression of vagus-mediated pancreatic polypeptide release by the μ-opiate receptor agonist loperamide in man

1Morphine suppresses the release of pancreatic polypeptide, a hormone under vagal cholinergic control. The intention of the study was to detect whether the μ-opiate receptor agonist loperamide is also able to inhibit pancreatic polypeptide release, and to define its site of action. 2In groups of healthy subjects (n=6 each) stimulation of pancreatic polypeptide was assessed in five different tests: (i) insulin-hypoglycaemia; (ii) modified sham feeding; (iii) intravenous infusion of the cholecystokinin analogue ceruletide; (iv) injection of corticotropin releasing hormone; (v) infusion of the muscarinic acetylcholine agonist bethanechol. All tests were performed after oral application of either a placebo or loperamide (16 mg), tests (ii) and (iii) were repeated with loperamide in smaller doses (2 and 6 mg), with loperamide plus naloxone, with naloxone alone, and with infusion of atropine. Plasma concentrations of pancreatic polypeptide were measured radioimmunologically. 3Release of pancreatic polypeptide in test (i) to (iv) was completely blocked by 16 mg loperamide, whereas bethanechol-stimulated release (test 5) was not influenced. Tests (ii) and (iii) showed that the inhibition was dose-dependent and could be attenuated by naloxone. The inhibitory effect of loperamide was comparable with that of atropine. 4We conclude that loperamide causes a dose-dependent inhibition of pancreatic polypeptide release mediated by vagal-cholinergic pathways, but does not have an atropine-like peripheral action.     

Changes in AV Node Conduction Curves Following Slow Pathway Modification

GELLER, J.C., et al. : Changes in AV Node Conduction Curves Following Slow Pathway Modification. Dual AV node physiology often persists after successful slow pathway (SP) ablation, and the mechanism of tachycardia elimination is unresolved. Therefore, AV node conduction curves were analyzed following successful ablation (  4 ± 1  energy applications) in 85 consecutive patients (58 women, age  50 ± 2  years) with typical AVNRT. Twenty-seven patients (32%) had complete elimination (group 1) whereas 58 (68%) patients had persistence (group 2) of dual AV node physiology. A significant increase in the AV node Wenckebach cycle length (WB-CL) was observed in both groups (  310 ± 9 to 351 ± 15 ms  in group 1, and  325 ± 8 to 369 ± 9 ms  in group  2, P < 0.05  ). A decrease in the fast pathway (FP) ERP (  339 ± 15 to 279 ± 12 ms  ) and an increase in the maximum FP AH interval (  141 ± 5 to 171 ± 7  ) were observed only in group 1 (P < 0.05). In group 2, no change in the SP ERP (  267 ± 7 to 280 ± 10 ms  ) was observed, and the change in the maximum SP-AH following ablation showed a significant inverse relation to the maximum SP-AH at baseline in group 2. In conclusion, (1) an increase in the WB-CL is observed independent of the persistence or elimination of dual physiology after successful ablation; (2) when dual physiology is eliminated, significant changes in the FP ERP and the maximum FP-AH occur; (3) when dual physiology persists, FP physiology and the SP ERP remain unchanged, and a significant inverse relation between the change in the maximum SP-AH following ablation and the maximum baseline SP-AH is observed.     

Mycobacterium kanasii infection limited to skin and lymph node in a patient with AIDS

The case of a 36-year-old HIV-1-positive patient is presented. After an episode of Pneumocystis carinii pneumonia and cytomegalovirus retinitis a pruritic lesion developed on the thigh with subsequent intracutaneous abscess formation and regional lymph-node enlargement. Mycobacterium kansasii was demonstrated in lymph-node and abscess material. With a tuberculostatic triple-drug regimen the lesions resolved completely. Cutaneous involvement in the course of non-tuberculous mycobacteriosis in the acquired immunodeficiency syndrome is discussed.     

Temperature-controlled Rate Responsive Pacing with the Aid of an Optimized Algorithm

On the basis of earlier studies of the behavior of the central venous blood temperature at rest and during exercise, we have developed an algorithm for the rate control of cardiac pacemakers. The central venous blood temperature serves as the control variable for the pacing rate. Control is effected via two different characteristic lines that relate pacing rate and temperature. A rest characteristic line relates absolute temperature values to heart rate and exercise lines relate relative changes in temperature to heart rate changes. The rest characteristic corresponds to conditions of slow temperature fluctations (e.g., fever and temperature changes due to circardian rhythm) and has a slope of 15 to 20 bpm per centigrade degree of temperature change. Starting at this rest characteristic, there are exercise characteristic lines that have a much greater slope and serve to regulate the pacing rate under exercise conditions. The two characteristics are distinguished via the temperature change per unit of time. In addition, a return characteristic connects the rest and exercise characteristics. This algorithm allows for optimized rate adaption of physiological cardiac pacemakers by central venous blood temperature. Clinical studies with the implanted device (Intermedics Nova MR) prove the correct function and beneficial effect of this algorithm in patients' everyday life.