The G protein β3 subunit splice variant Gβ3-s causes enhanced chemotaxis of human neutrophils in response to interleukin-8

A C825T polymorphism was recently described in GNB3, the gene encoding the Gβ3 subunit of heterotrimeric G proteins. The 825T allele is associated with the expression of a shorter splice variant (Gβ3-s) and enhanced signal transduction via pertussis toxin (PTX)-sensitive G proteins. Given the pivotal role of G protein βγ dimers in chemotaxis, we related the genotype at the GNB3 locus as a marker for Gβ3-s expression to chemotaxis of human neutrophils in response to stimulation with interleukin-8 (IL-8). IL-8, which activates a CXC receptor coupled to PTX-sensitive G proteins, induced at 10 nM an enhanced maximum chemotaxis of neutrophils from individuals with TC/TT genotype compared to CC genotype. Furthermore, migration of neutrophils from 825T allele carriers was 2.5-fold higher at 0.1 nM and 1 nM IL-8. At these concentrations of IL-8, no significant chemotaxis was observed in neutrophils from homozygous C825 allele carriers, indicating a genotype-dependent, different potency of IL-8 to chemoattract neutrophils. In contrast, IL-8-induced Ca²⁺ signals and O^2– generation were independent of genotype. The role of Gβ3-s in enhanced chemotaxis could be confirmed by determination of chemotaxis of COS-7 cells following transfection with either Gβ3-s or "wild-type" Gβ3. Upon stimulation of the transfected cells with the chemoattractant lysophosphatidic acid (LPA), we observed an enhanced chemotactic response of Gβ3-s-transfected compared to Gβ3-transfected COS-7 cells, confirming that Gβ3-s actually causes enhanced chemotaxis. Received: 25 March 1999 / Accepted: 21 April 1999 / Published online: 21 June 1999     

Proliferation of endocrine cells in the rat stomach caused by drug-induced achlorhydria

Time-related changes of serum gastrin levels, gastrin cell, and enterochromaffinlike cell densities, and proliferation kinetics of these cells have been examined in rats during treatment with the substituted benzimidazole BY 308 over a period of 73 days. Serum gastrin levels increased very rapidly from 74 +/- 6 pg/mL (controls) to 438 +/- 31 pg/mL (day 1) and 727 +/- 68 pg/mL (day 4). Thereafter, a steady increase was observed until day 70 (2097 +/- 208 pg/mL). Enterochromaffinlike cell density was unchanged until day 10, but then increased progressively without reaching a plateau (144% above control on day 73). The labeling index of these cells was enhanced shortly after drug application and remained on a constant elevated level from day 14 to day 73 (about 10-fold to 12-fold above controls from day 14 to day 70). The number of gastrin cells increased rapidly within the first week and reached a plateau after 17 days (96% increase above controls). In contrast to enterochromaffinlike cells, the labeling index did not change immediately but increased on day 7 by 37% and returned beneath control values after day 28. The results suggest that in drug-induced achlorhydria, the progressive increase of enterochromaffinlike cells is explained by an enhanced mitosis, whereas other factors in addition to proliferation are responsible for the augmentation of gastrin cells.     

Autologous blood donation for surgery in inflammatory bowel disease--a report of six cases

BACKGROUND: Surgery in inflammatory bowel disease (IBD) is frequently associated with need for perioperative blood transfusions carrying the potential risk of infection. Autologous blood donation is often limited by IBD-associated anemia which is reversible by intravenous iron and erythropoietin. We therefore tested the feasibility of autologous blood donation in IBD. METHODS: Six patients (five Crohn's disease, one ulcerative colitis) with indication for elective bowel resection were treated after informed consent was obtained. Two to four blood donations were scheduled during four weeks prior to surgery. Once a week 350-450 ml of blood were collected from patients with a hemoglobin level above 11.0 g/dl. After each donation 200 mg of iron saccharate diluted in 0.9% saline were given to all patients intravenously as substitute for donation-related iron loss. Patients with preexisting anemia or C-reactive protein above 2.0 mg/dl received concomitant erythropoietin. RESULTS: The scheduled number of packed red cells was donated successfully by four patients. Due to low hemoglobin levels two patients donated one unit less than intended. Four patients received autologous blood transfusions intra- or postoperatively. No patient needed homologous blood. No serious adverse events were observed during blood donations, perioperatively, and during the one year follow-up period. CONCLUSION: Preoperative autologous blood donation is save and feasible in IBD patients with elective bowel resection.     

Influence of glucose control and improvement of insulin resistance on microvascular blood flow and endothelial function in patients with diabetes mellitus type 2

OBJECTIVE: The study was performed to investigate the effect of improving metabolic control with pioglitazone in comparison to glimepiride on microvascular function in patients with diabetes mellitus type 2. METHODS: A total of 179 patients were recruited and randomly assigned to one treatment group. Metabolic control (HbA1c), insulin resistance (HOMA index), and microvascular function (laser Doppler fluxmetry) were observed at baseline and after 3 and 6 months. RESULTS: HbA1c improved in both treatment arms (pioglitazone: 7.52 +/- 0.85% to 6.71 +/- 0.89%, p < .0001; glimepiride: 7.44 +/- 0.89% to 6.83 +/- 0.85%, p < .0001). Insulin-resistance decreased significantly in the pioglitazone group (6.15 +/- 4.05 to 3.85 +/- 1.92, p < .0001) and remained unchanged in the glimepiride group. The microvascular response to heat significantly improved in both treatment groups (pioglitazone 48.5 [15.2; 91.8] to 88.8 [57.6; 124.1] arbitrary units [AU], p < .0001; glimepiride 53.7 [14.1; 91.9] to 87.9 [52.9, 131.0] AU, p < .0001, median [lower and upper quartile]). Endothelial function as measured with the acetylcholine response improved in the pioglitazone group (38.5 [22.2; 68.0] to 60.2 [36.9; 82.8], p = .0427) and remained unchanged in the glimepiride group. CONCLUSIONS: Improving metabolic control has beneficial effects in microvascular function in type 2 diabetic patients. Treatment of type 2 diabetic patients with pioglitazone exerts additional effects on endothelial function beyond metabolic control.     

The G1246A polymorphism in the hypocretin receptor 2 gene is not associated with treatment response in cluster headache

The risk of cluster headache (CH) is associated with the G-allele of the G1246A polymorphism in the hypocretin receptor 2 (HCRTR2) gene. First-line medication is effective in only about 70-80% of CH patients. We hypothesized that the HCRTR2 G1246A polymorphism is also of pharmacogenetic relevance in CH and may affect treatment response. We performed a prospective cohort study among 184 unrelated White CH patients. While the HCRTR2 1246G allele was significantly associated with CH in this group, treatment outcomes with triptans, oxygen, verapamil and corticosteroids remained unaffected. Our results do not support a role of the HCRTR2 G1246A polymorphism in drug responses in CH.     

Comparison of the TruView infant EVO2 PCD™ and C-MAC video laryngoscopes with direct Macintosh laryngoscopy for routine tracheal intubation in infants with normal airways

OBJECTIVE:

Videolaryngoscopy has mainly been developed to facilitate difficult airway intubation. However, there is a lack of studies demonstrating this method''s efficacy in pediatric patients. The aim of the present study was to compare the TruView infant EVO2 and the C-MAC videolaryngoscope with conventional direct Macintosh laryngoscopy in children with a bodyweight ≤10 kg in terms of intubation conditions and the time to intubation.

METHODS:

In total, 65 children with a bodyweight ≤10 kg (0-22 months) who had undergone elective surgery requiring endotracheal intubation were retrospectively analyzed. Our database was screened for intubations with the TruView infant EVO2, the C-MAC videolaryngoscope, and conventional direct Macintosh laryngoscopy. The intubation conditions, the time to intubation, and the oxygen saturation before and after intubation were monitored, and demographic data were recorded. Only children with a bodyweight ≤10 kg were included in the analysis.

RESULTS:

A total of 23 children were intubated using the C-MAC videolaryngoscope, and 22 children were intubated using the TruView EVO2. Additionally, 20 children were intubated using a standard Macintosh blade. The time required for tracheal intubation was significantly longer using the TruView EVO2 (52 sec vs. 28 sec for C-MAC vs. 26 sec for direct LG). However, no significant difference in oxygen saturation was found after intubation.

CONCLUSION:

All devices allowed excellent visualization of the vocal cords, but the time to intubation was prolonged when the TruView EVO2 was used. The absence of a decline in oxygen saturation may be due to apneic oxygenation via the TruView scope and may provide a margin of safety. In sum, the use of the TruView by a well-trained anesthetist may be an alternative for difficult airway management in pediatric patients.     

Human G protein β3 subunit variant does not alter hypercarbic or hypoxic ventilatory response

Hypercarbic respiratory drive is mainly determined by P_CO2 and pH with activity of the intracellular Na⁺/H⁺ exchanger (NHE) playing an important role in maintaining intracellular pH and respiratory drive. Because NHE activity varies with genetically different G‐protein β3 subunits (GNB3) (C/T polymorphism at nucleotide position 825) different genotypes might alter respiratory regulation. To test the hypothesis that short‐term ventilatory responses vary with different GNB3 healthy volunteers with different genotypes (CC, TC, TT) were exposed to either hyperoxic hypercarbia (n=33) or to isocapnic hypoxia (n=31), respectively. There was no difference between CC, TC, and TT genotypes in hypercarbic and hypoxic respiratory drive when assessed as the ratio of minute ventilation over endexpiratory P_CO2 changes (ΔV˙E /ΔPET _CO2), maximal tolerable PET _CO2, and ratio of changes in ventilation over arterial haemoglobin desaturation (ΔV˙_E/ΔS_O2), respectively. Thus, short‐term hypercarbic and hypoxic ventilatory drive do not differ between individuals with genotypes encoding different GNB3. Whilst respiratory control may still be influenced by G‐protein aberration, other mechanisms seem to have a more important role in controlling ventilation.