Theophylline and dyphylline levels in serum by liquid chromatography

The widespread use of theophylline and dyphylline as bronchodilators in the treatment of acute and chronic obstructive airway disease, and recognition of the need to control the therapeutic drug level has created a demand for fast accurate measurement techniques. Measurement of theophylline levels by ultraviolet spectrophotometric techniques is hindered by interferences from barbiturates and caffeine, and thermal lability of the drug necessitates derivatization if gas chromatography is to be used. Because of these factors, a liquid chromatographic method has been developed which allows separation of the underviatized drug from interfering compounds, and quantitation of the theophylline in a single operation. In addition, the drug-containing fraction can be readily collected and subjected to mass spectral examination if there is any question as to its identify. The latter feature has particular significance in medico-legal cases.     

Conformations of satellite DNAs

X-ray fiber diffraction studies of satellite DNAs from Gecarcinus lateralis, Drosophila virilis and Mus musculus, all of which have highly repetitious base sequences but with different degrees of sequence complexity, reveal only classical polynucleotide duplex structures in contrast to some highly repetitious synthetic DNAs.     

Electrophysiologic effects of propranolol on sinus node function in patients with sinus node dysfunction

The electrophysiologic effects of intravenously administered propranolol (0.1 mg/kg) on three parameters of sinus node function were examined in ten symptomatic patients with sinus node dysfunction. The patients ranged in age from 26 to 79 years. Symptoms ranged from fatigue to frank syncope. Sinoatrial (SA) block and sinus pauses were observed in one patient; sinus pauses alone were observed in three patients. Five (5/10) patients had intraatrial block; three (3/10) patients had atrioventricular block; four (4/10) patients had an intraventricular conduction disturbance. At the time of electrophysiologic study, two patients had a control spontaneous sinus cycle length that exceeded 1000 msec. Following propranolol, the mean spontaneous cycle length increased by 17.4% (924 to 1085 msec, P less than 0.005) and spontaneous second degree SA block reappeared in the one patient. The maximum escape cycle ranged from 116% to 229% of the prepacing spontaneous cycle length and was considered to be prolonged in two of ten patients. Propranolol had no significant effect on the maximum escape cycle/prepacing cycle length X 100 (%). The estimated sinoatrial conduction time (SACT) was determined in seven patients and ranged in value from 120 to 238 mes. Propranolol increased the mean value of the estimated SACT from 179 to 213 msec, P less than 0.025. Propranolol may cause marked bradyarrhythmias in some patients with sinus node dysfunction, and should be used with caution in these patients.     

Treatment of antral and duodenal bleeding ulcers by Guevara's catheter

The catheter is based on the principle of compression and tamponage, assuring and guaranteeing hemostasis at the base of the ulcer. This method is suitable for permanently controlling an acute hemorrhage in the event medical treatment fails and surgery is contraindicated. Emergency surgery is changed to elective surgery with all its advantages.     

Release of renal prostaglandins during endotoxin-induced hypotension

The appearance of prostaglandins in dog's blood during endotoxin-induced hypotension was studied by use of the dialysis modification of the blood bathed organ technique. An increase in prostaglandins, mainly E2 and F2alpha was found in renal venous blood, whereas no such increase was seen in blood from the abdominal aorta, the inferior vena cava or the femoral vein. Three possible trigger mechanisms for this increase i.e. hypotension, reduced flow and reflexogenic sympathetic stimulation, have been investigated. It is suggested that, in addition to these three factors, circulating hormones such as noradrenaline, angiotensin or bradykinin, play a role in this release mechanism. Administration of indomethacin produced a restoration of the systemic blood pressure to its pre-endotoxin value; concomitantly a disappearance of the prostaglandins from the circulation was observed. It is concluded that prostaglandins contribute to the hypotension induced by endotoxin. Whether they are beneficial or detrimental remains to be resolved.     

Influence of the dentate fascia on the sensory responses of neurons in hippocampal field CA3

In experiments with unanaesthetized rabbits the influences of electric stimulation of the dentate fascia (DF) on the extracellularly recorded spontaneous and evoked activity of the CA3 neurones were investigated. Stimulation of a fixed locus in the DF during recording in the CA3 by a microelectrode, shifted along the longitudinal axis of the hippocampus, supported the notion of the topical, "segmental" organization of connections between the DF and CA3. A relatively narrow "active zone" (approximately 700 nm) appeared in the CA3 during the threshold DF stimulation: it was bordered by zones with predominantly inhibitory responses to stimulation. The CA3 neurones in the "active zone" rapidly lost their reactivity to sensory stimuli. In the "inhibitory" and "zero" zones the normal level of reactivity to sensory stimuli was preserved.     

Hemodynamics in sleep-induced apnea. Studies during wakefulness and sleep

Twelve patients with predominantly obstructive type sleep apnea underwent cardiac catheterization, hemodynamic monitoring, and arterial blood gas analysis during wakefulness and sleep. Abnormalities during wakefulness included systemic hypertension in four of 12, exercise-induced mild pulmonary hypertension in five of 12, and alveolar hypoventilation in one. During sleep nine patients had cyclic elevations of arterial pressure with each apneic episode, exceeding 200 mm Hg systolic in three of 12. Pulmonary artery pressures increased in 10 of 12, exceeding 60 mm Hg systolic in five. Marked degrees of hypoxemia (arterial P02, less than 50 mm Hg in eight of 12) and moderate hypercapnia with respiratory acidosis were associated with these hemodynamic changes. Cyclic upper airway obstruction during sleep may result in hypercapnia, acidosis, and pronounced hypoxemia, which can lead to hemodynamic abnormalities during sleep. Sustained pulmonary hypertension and possibly systemic hypertension may follow. Tracheostomy is an effective therapy and is recommended to symptomatic patients who have predominantly obstructive apnea but no relievable anatomic cause of upper airway obstruction.     

An outbreak of giardiasis in a group of campers

Thirty-four of 54 campers on a 2 week trip in mountains of Utah had diarrhea during and after their trip. Twenty-two (79%) of 28 symptomatic campers' stools examined contained Giardia lamblia cysts, whereas 4 (29%) of 14 asymptomatic campers' stools had cysts. The temporal distribution of cases and the absence of clustering among food preparation subgroups suggested a common source exposure. Although the epidemiologic data and fecal coliform counts implicated the remote mountain stream used as water source by the group as the vehicle of transmission, Giardia lamblia cysts were not recovered from stream water nor were they found in intestines or feces of sampled mammals living in the drainage area. Twenty-five other campers had stools examined before and after a subsequent hiking trip in another area of Utah; none had Giardia cysts before, but 6 (24%) had them after return. Questionnaires returned by 133 of the campers showed that 5% had an illness compatible with giardiasis within 2 weeks after their trip. These surveys show that campers exposed to mountain stream water are at risk of acquiring giardiasis.