The Effect of Propranolol and Phentolamine on Serum Gastrin Concentration in Response to Respiratory Acidosis in Normal Man

Abstract. Serum gastrin concentration and basal acid secretion were studied in normal subjects under the influence of respiratory acidosis induced by CO2 rebreathing. During the intragastric instillation of 100 ml/h 0. 5 M bicarbonate a significant increase of gastrinaemia from 130 to 158 pg/ml (p < 0. 01) occurred in ten subjects during respiratory acidosis (pCO₂ 62 torr, pH 7. 25). Under, the intragastric instillation of 100 ml/h 0. 1 N HC1 the rise of gastrin concentration in response to CO2 rebreathing (pC02 68 torr, pH 7. 20) was not significant. The relationship between the decrease of pH and the increase of the gastrin concentration was shifted in the direction of a greater systemic acidosis compared to the results performed in the presence of a neutral intragastric pH. 50 μg/kg propranolol intravenously produced a decrease of gastrin concentrations from 145 to 127 pg/ml (p < 0. 01) and a total suppression of hyper-gastrinaemia in respons'e to CO₂ rebreathing, suggesting activation of beta-cell receptors in respiratory acidosis. The infusion of phentolamine in a dose of 0. 6 to 1. 8 mg/min. resulted in a rise of gastrin concentration from 140 to 165 pg/ml (p < 0. 01) which was not further elevated during respiratory acidosis. The basal acid secretion showed a significant rise in response to CO2 rebreathing, which was abolished by the administration of propranolol.     

Low-level resistance to rifampin in Streptococcus pneumoniae

Rifampin is recommended for combination therapy of meningitis due to beta-lactam-resistant Streptococcus pneumoniae. High-level rifampin resistance (MIC, > or =4 mg/liter) has been mapped to point mutations in clusters I and III of rpoB of the pneumococcus. The molecular basis of low-level resistance (MICs, > or =0.5 and <4 mg/liter) was analyzed. Spontaneous mutants of clinical pneumococcal isolates were selected on Columbia sheep blood agar plates containing rifampin at 0.5, 4, 10, or 50 mg/liter. Low-level resistance could be assigned to mutations in cluster II (I(545)N, I(545)L). Sensitive (MIC, <0.048 mg/liter) wild-type strains acquired low-level resistance at a rate approximately 10 times higher than that at which they acquired high-level resistance (average mutation frequencies, 2.4 x 10(-7) for low-level resistance versus 2.9 x 10(-8) for high-level resistance [P < 0.0001]). In second-step experiments, the frequencies of mutations from low- to high-level resistance were over 10 times higher than the frequencies of mutations from susceptibility to high-level resistance (average mutation frequencies, 7.2 x 10(-7) versus 5.0 x 10(-8) [P < 0.001]). Mutants with low-level resistance were stable upon passage. Sequencing of a clinical isolate with low-level resistance (MIC, 0.5 mg/liter) revealed a Q(150)R mutation upstream of cluster I. The frequencies of mutations to high-level resistance for this strain were even higher than the rates observed for the in vitro mutants. Therefore, a resistance-mediating mutation located outside clusters I, II, and III has been described for the first time in the pneumococcus. In vitro low-level rifampin resistance in S. pneumoniae could be mapped to cluster II of rpoB. Mutants of pneumococcus with low-level resistance may be selected in vivo during therapy in tissue compartments with low antibiotic concentrations and play a role in the development of resistance.     

Coccidioidomycosis outbreak among United States Navy SEALs training in a Coccidioides immitis-endemic area--Coalinga,California

An outbreak of coccidioidomycosis among 22 Navy SEALs occurred during training exercises in Coalinga, California. Ten (45%) of the 22 men had serologic evidence of acute coccidioidomycosis, the highest attack rate ever reported for a military unit. All case patients were symptomatic, and 50% had abnormal chest radiographs. There were no cases of dissemination and no deaths to date. Coccidioidomycosis continues to be a threat to military members and civilians who reside or train in areas where Coccidioides immitis, the causative agent, is endemic.     

Primary permanent arterialization of the portal vein in liver transplantation

Permanent total arterialization of the portal vein in liver transplantation has been described as a method of providing portal inflow after insufficient thrombectomy due to chronic occlusion of the portal-vein system. A specific problem is the restriction of the arterial inflow and its long-term adaptation after transplantation. We describe here the surgical techniques and clinical course of three patients who underwent portal-vein arterialization for liver transplantation. Two patients had an uneventful course. In one patient, a flow reduction by means of coil embolization of one arterial inflow branch was performed; thereafter, the patient recuperated well. Analysing the microcirculation of an arterialized graft in comparison with liver grafts with normal non-arterialized portal-vein inflow, we observed an increase in inter-sinusoidal distance and a decrease in sinusoidal red blood cell velocity. From a technical point of view, we recommend permanent portal-vein arterialization by an iliac artery graft interposition from the subdiaphragmatic aorta. The inflow to the portal vein can easily be reduced by the banding of the arterial graft interposition.     

External-beam radiation therapy in the treatment of diffuse tracheobronchial amyloidosis

Tracheobronchial amyloidosis is characterized by deposits of amyloid in airway walls. No effective treatment is known. We describe a 59-year-old woman who presented with increasing symptoms of airway obstruction due to diffuse deposition of amyloid throughout her tracheobronchial tree. She was treated with external-beam radiation therapy (20 Gy) with marked improvement in her symptoms, effort tolerance, bronchoscopic appearance, and forced expiratory volume in 1 second (1.39 L to 1.97 L [42%]). This improvement was maintained during 21 months of follow-up.