Posthyperventilation apnea associated with severe hypoxemia

We studied a 14-year-old girl who suffered fractures of her mandible and tegmen following a fall from a balance beam. Thirteen days after hospitalization, she developed severe, protracted, recurrent episodes of hyperventilation; subsequently, she suffered posthyperventilation apnea, which at times was prolonged and association with severe hypoxemia with an arterial oxygen pressure as low as 25 mm Hg. The patient was treated with added dead space and chlorpromazine hydrochloride (Thorazine). Postulated mechanisms for her disorder are discussed. The importance of close clinical and laboratory observation in similar cases is stressed.     

Diaphragm activation with intramuscular stimulation in dogs

We studied in 10 supine anesthetized dogs diaphragm contraction produced by electrical activation with intramuscular electrodes surgically implanted in the ventral surface of the diaphragm and compared this with activation of the ipsilateral phrenic nerve (C5, 6, and 7) before it entered the thorax. Repetitive 40-Hz pulse trains with supramaximal current stimulus were used after hyperventilation of the animals to apnea. A single intramuscular electrode within 1 to 2 cm of the site of phrenic nerve entry into the diaphragm produced a mean transdiaphragmatic pressure of 12.0 cm H2O +/- 0.97 SE and mean tidal volume of 0.27 L +/- 0.04 SE. Mean values observed with phrenic nerve stimulation were not statistically different, and both electrode systems produced equivalent outward abdominal motion and upper rib cage paradox, as monitored by inductive plethysmography. There was no difference in gas exchange during stimulation with a single hemidiaphragm electrode and mechanical ventilation compared at the same tidal volume and respiratory rate. Blockade of neuromuscular transmission with curare eliminated intramuscular and phrenic nerve stimulation proportionately, suggesting that activation of the diaphragm is dependent in both cases on the phrenic nerve. This technique does not entail manipulation of the phrenic nerve and may have clinical application as an alternative technique for diaphragm pacing.     

Biosynthesis of scarab beetle pheromones

Chemical communication in scarab beetles (Coleoptera: Scarabaeidae) is achieved with a wide variety of pheromones, but one typical structure is the gamma-lactone having a long unsaturated hydrocarbon chain. Several species utilize (R, Z)-5-(-)-(oct-1-enyl)-oxacyclopentan-2-one (buibuilactone), (R, Z)-5-(-)-(dec-1-enyl)-oxacyclopentan-2-one and (S, Z)-5-(+)-(dec-1-enyl)-oxacyclopentan-2-one [(R)-japonilure and (S)-japonilure]. Using deuterated precursors, we have demonstrated that these compounds are biosynthesized from fatty acids. (9, 10-d4)-Palmitic acid, (9,10-d4)-stearic acid, (9,10-d2)-palmitoleic acid, (9,10-d2)-oleic acid, (9,10-d2)-8-hydroxypalmitoleic acid and (9,10-d2)-8-hydroxyoleic acid were readily incorporated by female Anomala cuprea into the pheromone molecules, while (Z)-(5, 6-d2)-5-dodecenoic acid and (Z)-(5,6-d2)-5-tetradecenoic acid were not. Therefore, the reaction pathway starts from saturated fatty acids, involves their desaturation, followed by 8-hydroxylation, chain shortening and cyclization. The products obtained from racemic (9,10-d2)-8-hydroxypalmitoleic acid and (9,10-d2)-8-hydroxyoleic acid were also racemic, implying that the steps following hydroxylation were not stereospecific. Perdeuterated palmitic acid was applied to disclose the mechanism of the unique hydroxylation reaction. Retention of all deuterium atoms implied that this reaction was a direct process mediated by a specific fatty acid hydroxylase, and preceding desaturation or epoxidation was not involved.     

Physical and functional interactions between the herpes simplex virus UL15 and UL28 DNA cleavage and packaging proteins

Herpes simplex virus (HSV) DNA is cleaved from concatemers and packaged into capsids in infected cell nuclei. This process requires seven viral proteins, including UL15 and UL28. UL15 expressed alone displays a nuclear localization, while UL28 remains cytoplasmic. Coexpression with UL15 enables UL28 to enter nuclei, suggesting an interaction between the two proteins. Additionally, UL28 copurified with UL15 from HSV-infected cells after ion-exchange and DNA affinity chromatography, and the complex sedimented as a 1:1 heterodimer upon sucrose gradient centrifugation. These findings are evidence of a physical interaction of UL15 and UL28 and a functional role for UL15 in directing UL28 to the nucleus.     

A survey of seroprevalence of human papillomavirus types 16, 18 and 33 among children

The importance and natural history of HPV infections in childhood is incompletely understood. We performed a survey for presence of serum antibodies to HPV capsids among 1031 children aged 0 to 13 years, resident in Stockholm, Sweden. The HPV seroprevalence among these children was 3.0% for HPV16, 0.6% for HPV18 and 2.7% for HPV33. By comparison, among simultaneously analyzed positive control panels comprising women with CIN or healthy women with type-specific cervical HPV DNA, seroprevalence of HPV 16, 18 and 33 was 69%, 58% and 63% respectively. The results suggest that HPV infection in childhood is not common.     

Pharmacokinetics of nicotine carbomer enemas: a new treatment modality for ulcerative colitis

BACKGROUND: Ulcerative colitis is largely a disease of nonsmokers, and transdermal nicotine is of therapeutic value in the active disease. Because side effects are common, we developed a topical enema formulation of nicotine. OBJECTIVE: To study the pharmacokinetics of nicotine complexed with a polyacrylic carbomer and administered by enema to eight healthy volunteers and to eight patients with active ulcerative colitis, verified sigmoidoscopically. PATIENTS AND METHODS: All 16 subjects were nonsmokers. The mean age for normal subjects was 33 years; the mean for patients with ulcerative colitis was 60 years. Median stool frequency for patients with ulcerative colitis was four daily. Patients were taking 5-amino salicylic acid compounds and five were taking oral prednisolone (median dose, 12 mg daily). Nicotine, 6 mg, complexed with carbomer 974P, 400 mg, was administered in a 100 ml enema after an overnight fast, with serial blood measurements taken over 8 hours. Serum nicotine and cotinine were measured by gas liquid chromatography. Area under the concentration-time curves were calculated by the trapezoidal method, and the terminal elimination half-life was derived by extrapolation of the log-linear terminal phase. RESULTS: With the exception of nicotine time to reach peak concentration, which was longer in patients (median of 60 minutes compared with 45 minutes; p < 0.005), other comparisons between normal subjects and patients showed no statistically significant difference, although there was considerable inter-subject variation. Maximum concentration of nicotine, 8.1 +/- 3.5 ng/ml, in the 16 subjects occurred after a median of 60 minutes (range, 30 to 180 minutes); maximum cotinine concentrations of 60.4 +/- 11.5 ng/ml occurred after 4 hours. Side effects in five subjects were mild (four subjects) or moderate (one subject) and included lightheadedness, nausea, and headache; these five subjects were female lifelong nonsmokers of low body weight. CONCLUSION: Because most of the active ingredient of nicotine is converted to continine on the first pass through the liver, substantial concentrations can be achieved at the site of disease with only modest rises in serum nicotine, which are responsible for side effects; cotinine has low pharmacologic activity. Topical administration of nicotine may be useful treatment for distal ulcerative colitis.     

Age-dependent tetrahydrothiophenium ion formation in young children and adults receiving high-dose busulfan

Busulfan, a bifunctional alkylating agent, is a mainstay of myeloablative preparative regimens before hematopoietic stem cell transplantation. The apparent oral clearance of busulfan expressed relative to body surface area is 2-3-fold higher in children 1-4 years old than it is in adults. The first step in busulfan elimination is the formation of a tetrahydrothiophenium ion (THT+) in a glutathione S-transferase-catalyzed reaction. We present computer simulations that demonstrate that the ratio of the AUC of THT+ to that of busulfan over 6 h [(AUC(THT+)/AUC(BU))(0-->6)] is highly correlated (r2 = 0.805) with the determinants of THT+ formation and is virtually independent of the determinants of its elimination (r2 = 0.0201). We compared (AUC(THT+)/AUC(BU))(0-->6) determined in 14 children (0.5-4 years) to that of 11 adults (12-54 years) and found a 1.5-fold elevation in the area ratio (P = 0.0098) and a similarly significant increase in busulfan apparent oral clearance expressed relative to body surface area (P = 0.042). The only common explanation for the elevated busulfan apparent oral clearance and (AUC(THT+)/AUC(BU))(0-->6) is an enhanced ability of children to metabolize busulfan through glutathione conjugation.